Author Topic: 190e buyer's guide / Mr. Tea the teal '93 190e 2.6  (Read 3878 times)

Offline Justin Danger

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190e buyer's guide / Mr. Tea the teal '93 190e 2.6
« on: January 29, 2016, 10:52:40 PM »
So you bought a W201, what now?

This article/forum thread will serve as not only a personal record for all the maintenance and modifications done to the third 190e to enter my life, but also as a guide for first time Mercedes or first time 190 owners to overcome some of the fear and dependance on shops that sometimes have about as little knowledge of these cars as you do.  Yes, even "Mercedes specialist" shops can be totally clueless when it comes to things like the engine management system, suspension and brake upgrades, or the little tweaks that us seasoned 190 owners know by heart.


If you want to skip the longwinded intro for the longwinded technical stuff, scroll to the second post.


My first 190 came as frustrated solution to not being able to find a decent '89-'91 325is five speed coupe.  My requirements were too specific for a time (2007) when most good e30s meeting those requirements were already snapped up.  Enter Charles, the $900 black on grey 1990 190e 2.6 automatic with not one, but two hundred and forty-eight thousand miles already logged.  A history check revealed most of those miles were recent since it had a paltry 90,000 miles in 2001.

The first drive sold me immediately; mileage or not I was driving this car home.  It had a solid, smooth, seriousness I had never, and still have not experienced in another car.  It hopped at 70MPH, it snapped out of first gear, it squeaked going around a sharp corner and rolling up the window blew fuses, but I loved it anyway.  Within the first few weeks I had it all sorted in the comfort of my driveway and proceeded to drive the snot out of it for five more years.

Having dove into the world of the W201 deep enough to solve all of my problems (thanks to 190rev.net and the Mercedes service manual), I learned about the 190s I should be lusting after.  The Sportline, the 16v (annoyingly referred to as a “Cosworth”), and the coveted, exceedingly rare six cylinder manual transmission.  So naturally I bought a white '93 Sportline as soon as I found one. 

It has been through a lot of budget fixes due to school, but is now the recipient of a factory worthy five speed swap thanks to a euro 260e donor car with 91,000km that I purchased for $700.  I have flogged this car every day, sort of keep up on cruises with much newer and much more powerful BMWs, revved it to 8k several times, and generally just floor it 70% of the time I drive it.  Despite this and my lack of ability to fund a complete restoration, it has held up admirably.  The only issues I’ve had are a direct result of the idiot previous owners doing a father and son backyard hack job on the poor car.

And that brings us to car number three.  I stupidly sold Charles to someone who destroyed it and sold it to a junkyard, but this car more than makes up for it.  Even better: this car isn't mine.  It’s my wife's.  As she patiently waited for me to get a real job again, her project 944 languished in the garage and her 2010 Hyundai Accent slowly sapped her will to live every day.  Solution?  Buy a near-mint '93 190e 2.6 in  a gorgeous teal with 150,000 miles for $700 and ditch the Hyundai.

Listed for $1800 in Tampa by a displaced Portlander who was moving back, a few texts revealed it no longer ran, was available for around $800, and had a big dent in the rear quarter.  The history showed a mileage of 78,000 in 2007, no gaps in registration, passing washington state emissions in 2013 and 2015, and no reported accidents.  We made the 4.5 hour trip to Tampa with our dog and a trunk full of spare parts a few days later.

It was supposed to have bilstein sports and lowering springs, but didn't.  Although the Bilstein tourings looked fairly recent, it had the stock monster truck ride height and the rear quarter dent was accompanied by adjacent door waviness as well as other cosmetic issue.    The disappointment ended there, however, when a close inspection revealed the cleanest and most complete, well cared for 190 I've ever seen.  Evidence of oil leaks that had been fixed (!) new timing tensioner and a sealed timing cover, not so much as a crumple from a misplaced jack, and the cleanest, armorall-free engine bay I've ever seen on an old car won me over.  We agreed on $700 due to brown goo in the coolant tank, the lack of sporty suspension bits, some crumbling cheap tierods I spotted and the extra dents. 

We grabbed some lunch and came back to see if I could get it running before calling AAA.  I quick inspection revealed an extremely worn Beru cap and rotor that looked fairly recent (which fits with what I know of Beru ignition parts).  I replaced it with a spare rotor and the cap from my car and we proceeded to drive it two hours to a friend’s house without a hitch.  We then drove it two and half hours home to Jacksonville trouble free as well.  The only issue on the trip being out-of-balance tires over 60mph.

Washing the car revealed a gorgeous metallic teal paint that I cannot wait to detail.  Chani (my previously mentioned wife and new owner of this 190) learned how to properly wash a car and we inspected it in detail while we awaited new parts.  Both of us were extremely happy with the car at this point and I’m much happier that it is in the driveway in place of the awful silver Hyundai death trap she used to drive.

Now that the backstory is established, on to the details of what we have done and will be doing to the car.  I will add extra detail to help with figuring out what to check, and what usually needs attention, and what to do to make your 190 reliable and enjoyable.
« Last Edit: June 25, 2016, 02:58:56 PM by Justin Danger »
1993 Mercedes 190e 2.6 sportline
1987 BMW 535is with getrag 265/6 swap
2010 Tamiya 190e Evo2 R/C car <-Best car I own
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Offline Justin Danger

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Re: 190 buyer's guide/Mr. T the teal '93 190e 2.6
« Reply #1 on: January 29, 2016, 11:00:18 PM »
The first order of business was replacing the ignition parts. Skimping here is ALWAYS a bad idea and you should only use genuine Bosch/Mercedes parts because they are very critical on these cars and most older Mercedes.  If you look around on Autohaus, FCP Euro, and Pelican Parts you can find the cap for around $55, rotor for $25, and the backing plate for around $60-$70.  The backing plate appeared good on this car, but its impossible to tell what it would do while the sparks are literally flying.  The wires were new and made by Bremi in Germany and, since I have had good experience with these wires and all of them were spot on with resistance (1k ohm), we kept them.  Spark plugs were all clean and light brown (except cylinder four which was slightly darker) but were the incorrect resistor plugs made by NGK.

The W201 ignition system has resistance built in to everything EXCEPT the spark plugs, so ideally you would use the original resistor-less Bosch Supers (part number H9DC0 or the cooler H8DC0 if you feel you need it).  These plugs are readily available at Brumos Mercedes and they are willing to ship them if you call.  Luckily for us, we live in the same city as Brumos and can just drop by.

We were in a hurry to get it back running so we could take it to the DMV (out of state title) so I checked amazon prime for the ignition parts and found them all with Prime shipping along with some genuine mercedes coolant for later. 



Amazon links here:







With the ignition bits back on with a used suppressor cover (missing from the old cap, good way to get wires chopped by the fan blade), a good coating of silicon in the appropriate areas (boots, backing plate oring) and the proper spark plugs installed to a sane tightness (20nm as per Mercedes), the car once again ran and was ready for further investigation.

A quick spray of throttlebody cleaner on the intake and injectors revealed a slight air leak on the fourth injector which explains the difference in color from the other plugs.  A check of the retaining hex bolts showed four through six to be loose. Tightening them fixed that problem for now.  No other vacuum leaks were apparent but the AFM boot clamp for the throttlebody was completely loose and most of the fuel lines on the new looking fuel distributor needed additional tightening.

 One of the one way valves for the emissions solenoids was broken and taped together so I replaced it with a spare and checked the EGR valve to see if the diaphragm was holding vacuum.  It was not; a project for another time.  I checked the transmission modulator line and it held vacuum so that annoying job can be avoided (confirmed by smooth shifts that would not be happening if the modulator was bad).

The throttlebody and AFM plate were so close to being clean it was hardly worth spraying them down, but for the sake of the valves I ran a can of TB cleaner through the intake to start cleaning off accumulated gunk.  A check of the throttle cable showed what I suspected from driving it: with the pedal fully depressed it was only achieving just over half throttle.  I tightened the cable until just before it caused movement in the linkage and then lubricated everything to do with the throttle and transmission linkage.  When doing this, make sure the throttle idle microswitch is in working order with a multimeter (its open or closed) and is making proper contact when the throttle is at idle.

The accelerator pedal was broken due to being plastic (although unlike BMWs you can still use it) and had an annoying clicking/stuck spot at the beginning of travel due to this.  Our parts shelf just happened to have a spare and was quickly installed by rotating the old one out and the new one in.  Easy!

A check of the duty cycle revealed no fluctation and a voltage of 5v (my other meter that does duty cycle is currently loaned out…  Paul) a check of the O2 showed 0.6 barely changing. Unplugging the air temp sensor in the intake to check its resistance made the check engine light come on, so that was nice to know.  Not sure why the CIS was in open-loop (meaning a problem is detected and the computer is ignoring external sensor information and using factory default) but I will figure that out later.  This is the first time I have ever seen a working CEL on a Mercedes.

 For more information on the duty cycle, what it means for you and your dog, and what to do about it, see the following link:  http://landiss.com/mixture.htm

A decent multimeter with a duty cycle reading can be had for around $50 and makes this task a little more precise.  Basically you want it to be about half alternator voltage if using a regular multimeter.

Anyway, impatience got the better of us and we went for a test drive.  Much better so far!  Chani agreed that it was amazingly better and it was mostly due to having full control of the throttle again.  Deciding to leave the remaining engine issues along due to the increasingly terrifying cracked shock mounts, we set about test fitting an extended, reinforced R129 shock mount from an SL500. 

The point of these mounts over the stock ones is to allow increased shock travel with a lowered car, which this was soon to be.  This would keep the Bilstein tourings in a more happy range that they were tuned for which would hold her over until she could buy some Bilstein sports.  The Bilstein sport shocks are designed with a shorter shaft and stroke to accommodate decreased suspension travel from lowered cars.  Anyway, thats theory.  Reality is, this doesn't work if you have a 16v or a late model 2.6 or 2.3.  The hood has additional bracing that hits the taller mounts.  Despite two hours of grinding, testing, shaping, grinding, and more test fitting, I determined there was no way to fit these to her car.  So the project is on hold as we await some regular shock mounts.

Other areas that need attention are the brown muck in the coolant from either mixing coolant or a failed headgasket that had since been fixed without flushing the cooling system.  The trunk contained a Mann power steering and transmission filter although the fluid was new and had spare bottle of AMSOIL synthetic ATF marked as spare fluid.  Not sure if the filter was changed but I’m not worried about it since it will get a manual swap eventually.  Power steering fluid was disgusting and will be changed shortly.  Differential fluid was overfilled and very thin, changed out with Valvoline 140w blended with a little 90w.  A faulty fan temperature switch is currently making the electric fans come on at random, so that will be addressed shortly as well as a check of the computer/ignition temp sender.

While we wait, we will turn our attention to cleaning the interior and I will add some pictures for the areas covered so far.

Next chapter is replacing the entire frontend with OE quality parts from Lemforder and installing Vogtland lowering springs.
« Last Edit: June 25, 2016, 03:06:46 PM by Justin Danger »
1993 Mercedes 190e 2.6 sportline
1987 BMW 535is with getrag 265/6 swap
2010 Tamiya 190e Evo2 R/C car <-Best car I own
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Re: 190 buyer's guide/Mr. T the teal '93 190e 2.6
« Reply #2 on: February 23, 2016, 02:38:40 PM »
So what has happened since the last update?  All of our parts arrived, although not on schedule thanks to Pelican parts selling things they don't actually have, and Vogtland USA being out of stock on the springs, but we got a lot done!

From FCP Euro:


From Pelican Parts:



We removed the entire front end consisting of springs, control arms, shocks, shock mounts, tie rods, drag link/steering stabilizer, idler arm, and anti-roll bar and cleaned everything underneath.  Since the control arms had a lot of rock chips and a little surface rust we decided to strip them, kill the rust and paint them.  First order of business was to remove the control arm bushings and ball joints and install the new, stiffer Sportline bushings and fresh ball joints.  Ball joints are crucial on this car because there is only one per side and the entire weight/forces on the car rest on this one point.  Let’s pause for two PSAs:


One:  Do not use a regular spring compressor that goes on the outside of the springs, do not use some combination of jacks and removing the control arm without compressing the spring.  Buy or borrow a proper Mercedes spring compressor that uses plates that go inside the spring.  I bought mine from SG Motorsports for about $180. 

Two:  Failed ball joints result in the spindle and wheel suddenly popping out of the control arm which results in disaster for the car and could potentially be fatal if you are on the highway.

I cannot stress enough that this is absolutely NOT optional once you buy your car.  Do not buy $3,000 wheels and ignore $18 balljoints.  You don’t even have to remove the control arm if you don’t want to, it can be done on the car with a rental tool.  Don’t be lazy or cheap, do this now and save your car and possibly yourself.   I’ve seen the results of balljoint failures on 190s at low speed and at 80mph, it’s not worth it.


With that said, they don’t just randomly fail (unless you have cheap replacements like Meyle or Uro) and you shouldn’t drive around deathly afraid of your ball joints.  Just replace them with Lemforder, TRW, or Mercedes and live your life.

Now back to it.  The balljoints on this car were in great shape with not even a hint of boot failure, in fact they were impossible to tear.  This is the only time I have seen this though and is just an example of how well preserved this particular car is.  Once the new bushings and balljoints were installed, we painted the arms with polyurethane wheel paint and clearcoated the balljoints to keep the rust away for another 23 years. 



Be sure you follow the instructions in the service manual on proper orientation for the bushings and balljoints.  A sand hammer, flat screwdriver, a couple mercedes lug bolts for the sleeves (cone seat from newer amg wheels is best), some rubber protectant (Gummi Pflege or Wurth), a hydraulic press and some random parts for the press are all that you need for this job. 

Service manual section for control arms/balljoints:  http://floridaeuro.net/resources/W201/10005-2.pdf
For steering (with power steering rebuild removed):  http://floridaeuro.net/resources/W201/10011-nops.pdf

After the arms were complete, we removed the steering components.  All this requires is a few hand tools and one of the terrifying separator tools to pop the tie rod ends out of their homes.  After removing the tie rods and drag link/steering stabilizer, it was time to replace the idler arm bushing.  This can be done without removing the exhaust and is fairly easy.  First remove the heat shield, then remove the nut from the idler arm bolt.  Hit the top bushing with a screw driver and it should pop out.  Then remove the bottom with pliers or by tapping it out like the top.  Once the bottom bushing is removed you can squeak the bolt, idler arm, and upper bushing out past the exhaust. 

To reinstall, coat the bushings with some rubber protectant and assemble the bolt, idler arm, and upper bushing, put them into the tube on the frame, and use both hands to pull the bushing straight down into its home.  Without the rubber protectant you risk damaging the rubber and its very hard to install.  If you aren’t strong enough to do this by hand, use a plain, non-locking nut and several washers to pull the top bushing into place.  After this is done, push the bottom bushing in using the same technique and install the lock nut.  Do not use grease on any of the rubber components, it will damage the rubber over time.  Only use something made for rubber as mentioned previously. Torque to 70nm.



Steering install is straight forward, the tapered ends can only go in one way, just make sure you clean each hole before installing and do not use grease on the tie rod ends!  Torque steering damper to 50nm and tie rods/draglink to 35nm and tighten pinch clamp (10nm)/locking sleeves (30nm) on the tie rods (don’t worry about alignment for now).



We opted to install a set of Vogtland lowering springs as they are just about the only springs left still available new for a 2.6.  There are also three or four different thicknesses of spring pads available and we went with the thinnest (8mm).  You can tell which ones you have by looking for nubs on the edge of the pad; one is the thinnest, two is thicker and found on most 190s, three is thicker, etc.  Figuring out where to put the spring compressor plates is tricky the first time you do it, but it gets easier.   Covering the plates with masking tape keeps the nice shiny finish on the springs intact.





Installing the new shock mounts is as basic as it comes, don’t over tighten the mount or the shock nut, torque the two short bolts that hold the shock to the spindle to 110nm and the pinch bolt to 60nm and then reinstall the control arms.  I use some light synthetic grease on the metal faces of the control arm bushings as well as the cam bolts.  I also put some grease on the ball joint to keep it from getting stuck in the spindle/rusting.  Tighten the balljoint pinch bolt to 125nm, but only snug the control arm bolts as you will need to tighten these with the full weight of the car on them to prevent binding the rubber bushings.  I put them all in the middle so it will at least be even until an alignment can be done.
 
Reinstall the anti-roll bar with new bushings (with some rubber protectant inside and out) and double check everything. 

Now is a good time to check your wheel bearings and we decided to just adjust them and pack some new grease on the outside for now.  Adjusting mercedes front wheel bearings comes with experience and takes some trial and error.  They need to be tight but not too tight, I have a feel for it and can’t explain it very well, just err on the side of being too loose.  Check once the wheel is back on for any play (grasping the top and bottom of the tire and trying to move it back and forth).

Once the car is back on the ground/lift/ramps, torque the control arm cam bolts to 125nm.  Now on to the rear of the car!
« Last Edit: June 25, 2016, 11:21:11 PM by Justin Danger »
1993 Mercedes 190e 2.6 sportline
1987 BMW 535is with getrag 265/6 swap
2010 Tamiya 190e Evo2 R/C car <-Best car I own
Decent micromachines collection

Offline Justin Danger

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Re: 190 buyer's guide/Mr. T the teal '93 190e 2.6
« Reply #3 on: February 23, 2016, 03:14:36 PM »
Everything at the rear of the car is in great shape; CV axle boots are in tact, all bushings/suspension links/control arms are perfect, really nothing that needs to be done besides installing the lowering springs and adjustable camber arms.  Usually the right, inboard CV axle boot will be split on 190s due to its location above the exhaust, but this one was still good.

Even from the factory, my sportline (which has lower, stiffer suspension than a normal 190) had the same length, non-adjustable camber arms for the rear, which results in too much negative camber.  On some suspension designs, negative camber improves handling during cornering (at the expense of tire wear in a straight line), but not on the 190.    Because of the multilink suspension, orientation of the wheel/tire remains almost unchanged through the suspension travel, meaning the negative camber will be maintained and that thin contact patch will persist instead of coming on to the full contact patch in a corner.  If you aren't following, look up some animations of the rear suspension.

So to remedy this, I made custom adjustable arms to replace the fixed camber arm using parts from Speedway (thanks to 190rev for part numbers!).    This will allow way more adjustment than you actually need and allow proper rear camber after lowering the car.  The assembly is pretty easy requiring only a sand hammer, a hydraulic press, a few sockets/cups and a piece of wood.

Grease the threads on the rod ends and thread a right hand thread and left hand thread jam nut on them and install one of each rod end in one of the aluminum rods (LH/RH).  This allows proper adjustment when turning the aluminum rod once it's installed on the car.  Grease the bushings (nylon or delrin, not sure) and press them into the ends by hand.  Use a hammer to install the metal center bushing in one end.  With the other metal bushing, you want to press the roll pin from the outboard end of the original camber arm into it before installing in the new camber arm.  Use a press to remove it from the old bushing and to press it into the new one until it is flush on one end.  Then use a hammer and tap it into the remaining bushing in the new camber arm.    We were in a hurry to get the car done before cars and coffee the next day so I don't have any pictures of this.  I will be adding the part numbers needed later but you can find them pretty easily by searching.

My experience has shown you need a few thick stainless washers on the outboard side to space the arm towards the front of the car to prevent an excessive angle.  The inboard side requires two very thin stainless washers on each side.  Use the original bolts to install and tighten to a little more than the factory arms.

If you don't grease the bushings they will start squeaking later!



Installing the rear springs was a bit more challenging than the front because I was not able to compress the spring all the way without bottoming out my tool on the floor of the car.  I compressed the old spring as much as possible, then supported the control arm at its inboard attachment and removed the bolt.  Since all of the tension was already released, this was safe and easy.  I simply pushed the control arm down out of the way and removed the spring.  Install was the reverse and easier since the spring was shorter.



Since there is no way to know what has been done to a car you've just acquired and I was changing the ride height of the car, I loosened every bolt for the suspension links (except for outboard control arm and outboard toe link) to ensure they would not be binding and have excess stress on them.  Once the car was back together, I put it on ramps and torqued/tightened all the suspension links with them in their proper place.

Afterward we were very happy with the new ride height and it handled so much better!  It was a completely different driving experience and was actually stiffer and better handling than my sportline, even without upgrading the anti-roll bars or shocks (my shocks are basically done on my sportline).








Very happy with the vogtlands although the front is a bit low with the 8mm spring pad.  Chani likes how it looks though so we will just get some camber plates in the future to bring it back out a little.  The least amount of negative camber we could get with the wheels/tires that are on it was -2.7.

This brings us to alignment.  Do yourself a favor and either learn how to do it yourself in the garage with strings and measuring tapes or make SURE you find someone who knows how to align these cars properly.  I had a decent experience the first time I took my sportline for an alignment even though the guy had never aligned a W201 or W124 before.  He let me give him tips and took his time to learn what was what and get it perfect.  It took him a little over an hour, but he did it and did it well.

The experience we had with this car was completely different.  I went to a recommended guy to do it and we were there for four hours.  When I told him I had all the tools we needed in the trunk and I could help, he dismissed me saying he had aligned mercedes before.  He then proceeded to use adjustable wrenches and pliers on all of our new components, managed to pop a pinch clamp off the tie rod and spend 30 minutes trying to get it back on, and had absolutely no clue what he was doing.  He didn't understand even the basic principles of alignment or suspension and didn't understand he couldn't just do one side, then do the other.  After four hours of Chani and I starving to death and freaking out about what he was destroying on the car, he finally finished (still not in the specs I wanted) and we were able to leave.  Absolute nightmare.  I will never take a car to a shop again.

So, the moral to this story is, do it yourself or find someone who actually knows what they are doing and has worked on these cars before.    Ask the person specific questions.  Have you aligned a w201 before?  Do you have a triple square bit for the toe adjustment?  Do you know the car has to be aligned on the rack, not lifted up?  Which control arm bolt adjusts the camber (the rear one)?  Do you know the control arm bolts have to be torqued to 125 nm with the weight of the car on them?  Do you understand that you have to monitor both front wheels and go back and forth adjusting them in order to get everything perfect?   Etc...

Aligning these cars is not hard, everything is adjustable, you just have to find someone who cares and isn't a moron. 

Anyway, can you tell that's still a sore spot?  I still have to go under the car and check everything and touch up the paint on all the new parts....
« Last Edit: March 02, 2016, 10:03:52 PM by Justin Danger »
1993 Mercedes 190e 2.6 sportline
1987 BMW 535is with getrag 265/6 swap
2010 Tamiya 190e Evo2 R/C car <-Best car I own
Decent micromachines collection

Offline Justin Danger

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Re: 190 buyer's guide/Mr. T the teal '93 190e 2.6
« Reply #4 on: February 23, 2016, 04:00:40 PM »
With the suspension and steering sorted out, we still have the following areas to address:

CIS not working properly
Power steering fluid/filter
Coolant flush
Temp sensors
Paint detailing
Dents and dings
Sound system wiring (I cut and removed all wiring from the radio that was installed since it was all sketchy and barely working)
Wheels and tires

I tackled the CIS first since it annoyed me that I had checked basically everything and it still wasn't right.  Cold start was difficult and the car would not rev itself up, after warming up the car worked perfectly and I could adjust the duty cycle/mixture just fine but then I would test drive it and it would immediately idle too high and go into open-loop mode.   I replace the fan temp sensor since it was bad (two pins, blue, towards the front of the head), and the ignition/CIS temp sensor (four pins, black, at the rear of the head) and there was no change other than the fans working properly again.  I couldn't think of anything other than possibly the speed sensor on the cluster was unplugged or not working so I checked for error codes.  This car has the LED and push button built in so I didn't have to use my homemade tool (google it or ask me about it) to check.  I got 14 blinks.  Guess what error 14 is?  Vehicle speed sensor.

Here are the codes for everything else while we are on the subject:

1990-1993: W201 with 2.3L M102 engine
Flashes------- Fault
1 No System Malfunction
2 Throttle Valve Swttch
3 Coolant Temperature Sensor
4 Airflow Sensor Position Indicator
5 Oxygen Sensor
6 Not Used
7 Td Signal
8 Altitude Correction Capsule
9 Electro-Hydraulic Actuator (EHA)
10 Throttle Valve Switch and/or Idle Speed Contact
11 Not Used
12 EGR Temperature Sensor

1991-1993: W201 with 2.6L M103 engines
Flashes------- Fault
1 No faults in system
2 Throttle Valve Switch (Full Throttle Contact)
3 Coolant Temperature Sensor
4 Airflow Sensor Potentiometer
5 Oxygen Sensor
6 Not Used
7 TNA (Engine RPM) Signal
8 Altitude Pressure Signal From EZL Ignition Control Unit
9 Current To Electro-hydraulic Actuator
10 Throttle Valve switch (Idle Contact)
11 Air Injection System
12 AbsoIute Pressure Valves From EZL Ignition Control Unit
13 Intake Air Temperature Signal
14 Road Speed Signal At CIS-E Control Unit
15 Not Used
16 Exhaust Gas Recirculation (EGR)
17 Oxygen Sensor Signal
18 Current To Idle Speed Air Valve
19 Not Used
20 Not Used
21 Not used
22 Oxygen Sensor Heating Current
23 Short Circuit To Positive In Regeneration Switch over Valve Circuit
24 Not Used
25 Short Circuit To Positive in Start Valve Circuit
26 Short Circuit To Positive In Shift Point Retard Circuit
27 Data Exchange Fault Between CIS-E Control Unit and EZL ignition Control Unit
28 Loose Contact In Coolant Temperature Sensor Circuit
29 Difference In Coolant Temperatures Between CIS-E Control Unit and EZL Ignition Control Unit
30 Not Used
21 Loose Contact In Intake Air Temperature Sensor Circuit
32 Not Used
33 Not Used
34 Faulty Coolant Temperature Sensor Signal from EZL Ignition Control Unit

More detailed fault code manual can be downloaded here:  http://floridaeuro.net/resources/W201/FaultCodeManual.pdf

So I thought, hey, maybe someone removed the cluster to do the radio installation and forgot to plug the wires back in.  There are two different connectors for the speed sensor as well as a distribution box under the knee bolster that the speed sensor signal gets plugged in to so I was pretty hopeful.  I removed the knee bolster and found one of the connectors unplugged from the distribution box so that was encouraging. 



I couldn't find the second one but further investigation revealed there is only one on the later model cars.  I did not get a picture of this area but I will add it later.

After removing the driver's side air vent, I unscrewed the speedo cable and pushed the cluster out.  One speed sensor wire had caught on the clip for the cluster and ripped in half, the other was nowhere to be found. 



After unplugging everything and sorting out the jumbled mess someone had created, I found the second speed sensor wire buried in the dash. 



I repaired the wire, connected everything and put all the warning light bulbs in their proper place and reinstalled the cluster and speedo.  If you have your cluster removed, its also a good time to loosen and wiggle the grounds located behind the air vent and clean them/put some anti-corrosion stuff on them. 

After putting everything back together I took it for a test drive and was happy to find the CIS did not go into open loop mode anymore.  The cold start issue is still present and the idle in gear is still around 500-600 RPM so I still have more to track down.  The cold start was fixed with a used cold start valve which actually surprised me since I've never had one fail.  Idle is still too low on initial cranking and in gear but at least it can be cranked when cold now.


To reiterate some quick easy things to do before you start fiddling with stuff and replacing parts:

Clean the intake/AFM plate/throttlebody with throttlebody cleaner FIRST.  Just having years of gunk built up here can drastically change everything about how the car runs.

Check for any and all vacuum leaks and fix these first.  You may need a new AFM boot or idle air hoses, this is annoying but must be done if they are split, hard, or leaking.  Check vacuum hoses and elbows, check the climate control system to see if it is leaking, check all fuel injectors and intake gasket areas, and check oil dipstick oring.

After that, check the throttle cable adjustment.  Loosen it and then tighten until the linkage just starts to move, then back up a notch.  This will ensure full idle position as well as the ability to engage the kickdown switch on the floor under the throttle and achieve WOT.  Check the idle microswitch as detailed earlier, if this is bad the idle will be very high in my experience.

Check or replace the overvoltage protection relay (OVP) or at least unplug it, check the fuse in the top, clean the connections and reinstall.  Unplug the MAS relay and make sure its clean/seated properly, do the same for the CIS computer connector.  Sometimes just a dirty connection will cripple a car. 

Carefully remove the idle air control valve and use electronics cleaner to clean gunk off the inside of the valve.  NEVER use the set screw on the valve to adjust the idle.  If you feel like you need to use this screw, stop.  You don't.  Something else is wrong and you shouldn't try to compensate by adjust the IACV or throttlebody stops.  On the later cars it is important to note that the valve does not get 12v on pin 2 straight from the OVP, rather both wires supply it come directly from the CIS computer and you should be checking for a duty cycle of about 30% rather than a voltage. 





Computers rarely fail on these cars, I've never had a bad OVP but it's a common issue if you start having odd problems, I've never had a bad IACV either.  I have had a MAS relay fail and leave me with no power to my fuel pumps...  Fuel pumps are rarely the culprit on these cars since there are two of them and the original bosch pumps have metal impellers; they can go well into the 200k range without issue.

One often overlooked issue present on every Mercedes with CIS-E is the AFM potentiometer.  It serves as a position sensor for the AFM plate and lets the computer know how much air is entering the engine much the same way as the BMW and Porsche equivalent.   Once the carbon tracks on the potentiometer wear through, the voltage becomes inconsistent and can affect idle and throttle response.  A voltage of 0.70v +-0.10v is what you should be getting from the middle of the three pins while the car is idling at the normal idle of ~750RPM.  A quick test of this is to turn the key on, engine off and put your volt meter on the middle pin (with plug still connected).  It should be around 0.1v completely closed increasing as you push the AFM plate down slowly.  Pay attention to the beginning range of the AFM plate since this is where the problem is 99% of the time.  The voltage should increase smoothly without dropping back down, if it goes from say, 0.55v to 0.3v then back to 0.7v that is the area with a worn spot.

Replacement and pictures can be found at SG Motorsports website:  AFM replacement and adjustment

The voltage inconsistency I just described is exactly what I found on this car so I will be removing it and replacing it with a very slightly worn spare.  Sadly they are no longer made by Bosch and are hard to find.  Reports of the generic replacements only lasting 6 months as well as not knowing how accurate they are means searching ebay and junk yards...

I will return to add more info later.

So flash forward.  I replaced the AFM pot with a used one I had that had barely any wear on it and things are working normally now.  Pictures of the old one and new one to follow.    I checked all wires from all the sensors to the computer harness and ignition module plugs and everything is perfect, no resistance.  I neglected to check for shorts to ground, but I feel that all the CIS electrics are fully functional now (see the following).

I also cured the rest of cold start issue that the replacement cold start valve did not fix by adjusting the EHA valve. It was almost two full turns too lean.  After correcting the EHA valve adjustment (I will link to some in-depth guides when I come back to edit this), I was able to dial in the mixture adjustment and the car starts right up.   It still is a little stumbly for a few seconds but smooths out on its own and does not shut off.  I replaced the fuel filter as well and that seemed to help (pictures of the old one cut open to follow).

Car is running almost normally now, quite an improvement from when we bought the car and it would barely move out of its own way.  Not quite as much oomph and throttle response as my Sportline, but part of that is the automatic trans.  It's getting close!
« Last Edit: April 13, 2016, 10:20:40 PM by Justin Danger »
1993 Mercedes 190e 2.6 sportline
1987 BMW 535is with getrag 265/6 swap
2010 Tamiya 190e Evo2 R/C car <-Best car I own
Decent micromachines collection

Offline Justin Danger

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Re: 190 buyer's guide/Mr. T the teal '93 190e 2.6
« Reply #5 on: February 29, 2016, 12:22:24 AM »
Pausing on the CIS troubleshooting, it was time to detail the car in order to color match the paint as accurately as possible when we repair the dent in a few weeks.   I began by using bug and tar remover for all tar, sap, road paint, etc and then a claybar on the entire car and glass to remove surface contaminates.  It looked much better afterward although it had a lot of swirls and scratches from being washed by either an automatic carwash or dirty rags.









Richard came up and did some high speed polishing while I worked on his 944 and improved the paint a great deal.  Still some scratches and swirls, but it looks way better and much brighter than before.





Worth mentioning in this post is that I finally got around to researching cotton terry towels vs microfiber and there was a resounding no on using terry towels for paint.  The catch is, not all microfiber is created equal and most cheap microfiber clothes will probably do more damage than a terry towel.  I found some affordable, good quality towels from The Rag Company and purchased this 9 pack from Amazon Prime for $20. 



I used to hate microfiber and not even want to touch them, but these are a whole different world.    Super soft, absorbent, and have no tags and a soft edging around the whole towel.  I'm going to order this basic detailing kit next and never using terry towels again for detailing:



For more information on microfiber, check this site out:  Incredibly Detailed - Microfiber Manifesto

Even after a dusting of pollen the car still looks great!


« Last Edit: February 29, 2016, 01:36:52 AM by Justin Danger »
1993 Mercedes 190e 2.6 sportline
1987 BMW 535is with getrag 265/6 swap
2010 Tamiya 190e Evo2 R/C car <-Best car I own
Decent micromachines collection

Offline Justin Danger

  • Jacksonville, Florida
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Re: 190e buyer's guide / Mr. Tea the teal '93 190e 2.6
« Reply #6 on: April 13, 2016, 10:21:18 PM »
Tomorrow begins the dent removal process, more to follow!  Still on the hunt for 16x8 Pentas to replace the crappy 8 holes and skinny tires, but one thing at a time.
1993 Mercedes 190e 2.6 sportline
1987 BMW 535is with getrag 265/6 swap
2010 Tamiya 190e Evo2 R/C car <-Best car I own
Decent micromachines collection