Hi guys,

What would be the symptoms of a failing Ignition control module?
Car is a 1990 190E 2.5-16 Auto...

Any Info would be great.

Thanks

Zak

Engine would be hard to start, stalling, or not start at all. Have you priced a new or used ICM lately?
Check the Crankshaft Position Sensor first. If it is open, dirty, or defective, it will give an indication of a faulty ICM.
You could also have a bad coil.

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1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

Hi SLK, thanks for the reply. No problems at all in starting the car and no stalling.
I have priced one up and to be honest the price is a disgrace to say the least.
The story is...
On WOT(wide open throttle) the car begins to hesitate/kangaroo back and forth, this is especially noticeable and worse when you use kick down.
Now, after going to many a specialist and after changing things like:

- Fuel distributor
- EHA valve
- All Injectors
- Fuel pressure regulator
- K-Jetronic ECU
- Fuel pumps
- Fuel pump relay
- Coolant temperature sensor
- Fuel accumulator
- Fuel filter
- Ignition leads
- Rotor arm
- Ignition coil
- Cold start valve
- Idle air valve
- Crankshaft position sensor

I finally gave the car into the main dealer. They have had it for six weeks and cannot work out the problem! Now they say they suspect it may be the ignition control module causing this hesitation. I understand that the ICM stores various ignition and load maps in its memory...

Any ideas or clues, because im stumped and so it seems is everyone else!

Hi Zak, you should keep your thread going on the other forum too, I added something then saw that you deleted it. There are some sharp W201 guys over there.

Wow, you've replaced quite a few expensive parts Zak. I hope the dealer can find the problem, if so, please post the resolution.

It would sure be a shame to have replaced all of those parts and find out that you have a bad ground connection!

I see that the EHA was replaced but I didn't see a Throttle Position Sensor on the parts list. Was is tested?

Dave

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1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

I should have bought a Lexus! LOL

Well they say they tested everything, but lord only knows if its true or not...

The TPS has not been changed, but hey what the hell i'll change that too! Just kidding

But seriously...Its the weirdest problem i have ever come across.

In a way changing all those parts is a bit sickening...BUT, its preventative maintenance! LOL

Well they are going to put a new ICM in there. Lets see what happens after that!

Let's hope that will fix it. ICM=$$$$$$$$$

Good luck,

Dave

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1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

Right, Mercedes finally put in a new Ignition control module and it solved ALL hesitation problems. Amazing really. I actually went out with them on the road test and drove the car myself. I could not replicate the problem at all. Only 30 mins before on my way to them i could replicate the problem on demand!

UPDATE:
Right guys, since MB removed my old Ignition Control Module, fitted a new one to test, removed it...Then fitted my old one back my car has been difficult to start. Before it started at the flick of a key. Now it will crank for several seconds at least before it starts...
What gives!??

had the same trouble with my 86 2.3-16. When i had the car towed to my Mbenz mechanic's shop, his diagnosis was the car had no spark. This was after I replaced all the level 2 ignition components ie car rotor plugs and coil. I swapped out the ezl module, a 30 second swap, and the car fired right up. The unit i used was from a regular 190e I believe. Car runs fine now

Is there any way to check the ICM? It is also called the EZL correct?

Its one of the only parts left that may be causing my idle misfire....I have a huge list like the OP of replaced parts.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

As I understand the back of the EZL module is coated with a white thermal paste and uses the car's fender to act as a heatsink to disperse the heat it produces.

I read that many older EZLs fail if the thermal paste coating drys out and prevents the EZL from cooling?

Is this true?

Aren't EZLs available off eBay for like $30? I see them all the time!

__________________
2006 BMW M5 "Heidi" @ 109,000 miles
2005 MBZ C55 AMG "Lorelai" @ 165,000 miles
1991 MBZ 300E "Benzachino II" @ 165,000 miles
1990 MBZ 500SL "Shoshanna" @ 118,000 miles

(On the hunt for a good used M103 engine as of 6/10/23, PM me if you have one to sell!)

Ya I was pissed I missed one last week for $10 Used...but what the heck right?

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

The used $10 EZL's come from Russia by way of Washington State and carry a $75 or $85 shipping charge. The vendor says most of them have 40-50KM or so but I don't believe that claim. You can generally buy US sourced EZL's for $100 or so on ebay.

I recently had intermittent ignition problems with my 91 300TE (245K miles). The car first started missing intermittently when warm and then after 50 total miles of operation since the intermittent missing began refused to start warm (it had the audacity to leave me stranded for the first time in the 130K miles I have owned it. After the car cooled down it started and ran fine a couple of times until it finally wouldn't start cold. When attempting to start the car at this point the engine locked up (I wondered if the timing chain had slipped a tooth or two) and backfired through the intake manifold (indicating improper ignition timing) before it finally wouldn't "fire" anymore. Although I could hear the fuel pumps operating, I sprayed starting fluid into the air cleaner and cranked the car to make sure it was getting fuel. It didn't fire once. Next, I cranked the car with the coil wire disconnected from the distributor and observed a healthy spark firing at what seemed to be the appropriate intervals. I checked the distributor rotor and since the resistance of the rotor appeared too high I replaced it with a new rotor I had available. Still no start. I suspected the CPS or the EZL was the culprit. Since it was easy to check the status of the CPS, I measured the resistance (800 Ohms) and the cranking voltage (.4V AC) and found all to be within specs. Although I am not in the habit of throwing parts at a problem, since I needed to make sure the car was operable within a very short time period, I ordered a coil and CPS from an online source and purchased a used EZL from ebay. I installed the ignition coil first (the easiest to do) and the car wouldn't start. Next, I installed the used EZL (next easiest to install) and the car wouldn't start. Finally, I installed the CPS and the car started without problem. When I removed the old CPS I noticed that the seal around the wires at the sensor itself had failed and moisture/oil had penetrated the area. It is a mystery to me why the voltage and resistance measurements of the old CPS were within spec and the system appeared to have good spark but I guess that happens sometimes. Because of the backfires I did try to use my timing light to get an idea of the timing situation but because the light was not bright enough at cranking speed, I could not confirm that the timing was off (although I know it was due to the backfiring). I pose this question to the experts like stevebfl, etc.---How could a defective CPS presumably retard ignition timing to where the engine won't run yet still seemingly operate the EZL/ignition coil properly?
Mark