93 500e stalling issue

[DL2]

I need some help on my ‘93 500e. When the car sits for a few days, when I start it, it runs great until it reaches normal operating temperature. Then it will start to misfire. Occasionally at first, but then eventually getting worse and worse until the car dies. It will not restart. It kind of backfires when it is cranked over, but will not fire until the engine cools. When cool it runs great again.

Interestingly, if I start it everyday, the symptom gets better and in fact goes away and only stalls out every month or so.

It sounded like crank positioning sensor to me so I have tried a couple of them... but the problem remains.

Could it be the e-gas module? The wires and throttle body have all been replaced.

Any help would be greatly appreciated!

 

[r44raven]

I think you'll find you have a case of the (all too frequent on E500Es) damp under your distributor caps.
Your symptoms are classic. I believe it does not help if you live in an area of high humidity. There are lots (and lots!) of threads on this site detailing the problem - but unfortunately no long-term definitive cure!
Best advise is to use your car as frequently as possible.

 

[gsxr]

r44raven is 100% correct. Classic symptoms of liquid on the back of the insulators (not the caps, not the rotors). MANY threads discussing this in detail. When fixed, you can park the car for a year or more and have zero issues after starting & warmup.

 

[DL2]

r44raven is 100% correct. Classic symptoms of liquid on the back of the insulators (not the caps, not the rotors). MANY threads discussing this in detail. When fixed, you can park the car for a year or more and have zero issues after starting & warmup.

Well thank you both! I have been scratching my head for long time. I’ll check the threads on this issue. Mystery solved! Thank you!!

 

[nocfn]

Just had this very deal. Let her run in park when it started for 10 minutes, while revs at temp up and down to 2500 every few mins. Put her in gear and the moisture burned off, no trouble.

 

[gerryvz]

I second Ravenski's remote diagnosis. This is very well documented on the forums, probably in 5-10 threads.

 

[DL2]

It’s great to finally know what is going on! Thanks for everyone’s help! I see there are a few suggested fixes.

 

[DL2]

Just had this very deal. Let her run in park when it started for 10 minutes, while revs at temp up and down to 2500 every few mins. Put her in gear and the moisture burned off, no trouble.

Thanks I’ll give it a try.

 

[nocfn]

YMMV, the issues presenting as mentioned are well documented. The problem will re-occur, especially when the car sits and is not driven long enough at temp, consistently.

 

[DL2]

YMMV, the issues presenting as mentioned are well documented. The problem will re-occur, especially when the car sits and is not driven long enough at temp, consistently.

Thank you. The car sat for a number of years but my intention is to put it back into regular service which, from the sounds of it, will go a long ways toward eliminating this issue.

I’m glad the symptoms are so definitive! Thank you again.

 

[DL2]

As per our earlier discussion, I’ve been driving the car regularly but apparently not for long enough journeys. I drove it recently on a very damp day, and it once again stalled. After waiting 10 hours and it started right up and ran correctly. However, as I pulled into the garage it started to run roughly, was not backfiring or dying, just rough and reluctant to rev. like it was only running on four cylinders. Then the check engine light came on. Strong gassy exhaust smell. I suspect one bank’a distributer is simply damped out. If you agree with my suspicion, before I tear the distributers apart, what parts should I be sure to have on hand? Bosh caps, rotors, seals, dust cover, insulation seal? All of the above?

Thanks in advance for any suggestions.

 

[gerryvz]

Your ignition is fine.

Sounds to me from your latest description that you have either lost your EZL (which fails with either one bank or both banks of cylinders not firing), or you have lost a coil. The gas smell indicates that there is a lot of unburned gas. Do not drive the car, as it will poison the catalytic converters if you drive it much in this condition.

You are going to have to test whether it is one of the coils, or the EZL (which controls the coils).

If the problem does turn out to be the EZL -- you will want to replace both coils at the same time you replace the EZL.

Definitely do give your caps and rotors and insulators a visual check, but I think you will find that the problem is either a coil or EZL.

 

[gsxr]

Question... if you wait a few hours, does the engine run normally? Or at least fire on all 8 cylinders some of the time? If so, the EZL is OK.

Also, did you ever replace any ignition components as discussed last summer? Or are all the parts still the same?

Definitely check fault codes. If you don't have a scanner or blink code reader, you can at least use the built-in button/LED to find the code causing the CEL.

 

[DL2]

Your ignition is fine.

Sounds to me from your latest description that you have either lost your EZL (which fails with either one bank or both banks of cylinders not firing), or you have lost a coil. The gas smell indicates that there is a lot of unburned gas. Do not drive the car, as it will poison the catalytic converters if you drive it much in this condition.

You are going to have to test whether it is one of the coils, or the EZL (which controls the coils).

If the problem does turn out to be the EZL -- you will want to replace both coils at the same time you replace the EZL.

Definitely do give your caps and rotors and insulators a visual check, but I think you will find that the problem is either a coil or EZL.

Thanks, no I never replaced components due to the car running correctly after I dried it out. At this point it no longer runs correctly when cold started like it used to even with the damp. No backfiring ... just limp, weak running. I think coils and EZL sound like the probable culprit then.

Thank you both for your expert input.

How do I use the built-in reader? Sorry to be so ignorant... but I guess I am. Thanks again.

 

[gerryvz]

Thanks, no I never replaced components due to the car running correctly after I dried it out. At this point it no longer runs correctly when cold started like it used to even with the damp. No backfiring ... just limp, weak running. I think coils and EZL sound like the probable culprit then.

Thank you both for your expert input.

How do I use the built-in reader? Sorry to be so ignorant... but I guess I am. Thanks again.

Check the purple sticky threads at the top of this forum. You can use the built in blink code setup for the CHECK ENGINE light code diagnosis only. Let us know what it comes up with. For all other codes, either a hand-held code reader is needed, or a MB STAR type system. But for pulling your Diagnostic Module (CHECK ENGINE light) codes ONLY, you can use the built-in push-button and LED setup underhood.

De-Coding

Information pertaining to diagnostic codes, how to obtain and dechiper them, and how to remedy them.

www.500eboard.co

 

[gsxr]

EZL is unlikely if it will run normally after a few hours/days. But if you don't have a spare, buying a known-good one isn't a bad idea - same with the other modules. Handy for test purposes, and over time these items will get tougher to obtain.

To use the built-in reader, read the sticky threads at the De-Coding forum, linked below. Basically turn on key, hold button for 3 seconds, count the blinks, repeat until you get the same codes each time (may be more than 1 stored).

(Ooops, Gerry and I posted at the same time.)

De-Coding

Information pertaining to diagnostic codes, how to obtain and dechiper them, and how to remedy them.

www.500eboard.co

 

[DL2]

EZL is unlikely if it will run normally after a few hours/days. But if you don't have a spare, buying a known-good one isn't a bad idea - same with the other modules. Handy for test purposes, and over time these items will get tougher to obtain.

To use the built-in reader, read the sticky threads at the De-Coding forum, linked below. Basically turn on key, hold button for 3 seconds, count the blinks, repeat until you get the same codes each time (may be more than 1 stored).

(Ooops, Gerry and I posted at the same time.)

De-Coding

Information pertaining to diagnostic codes, how to obtain and dechiper them, and how to remedy them.

www.500eboard.co

Thanks I’ll give the on-board a try. And no, it no longer runs normally, ever.

 

[gsxr]

Thanks I’ll give the on-board a try. And no, it no longer runs normally, ever.

If it refuses to ever run on more than 4 cylinders, you MAY have a dead EZL or coil. But you should open up the distributors for inspection. If one side is really bad, it isn't going to fire even with good EZL/coils.

 

[gerryvz]

Repeating my earlier response:

1) Remove and visually inspect caps, rotors and insulators for any anomalies, breakage or defects
2) Pull code(s) for CHECK ENGINE light through underhood push-button. Record codes and clear them.
3) Diagnose and post codes here for interpretation (if needed)

There is an 80% probability, if the car is running on four cylinders, that you have a possible EZL failure (one of two possible failure modes, and one that I personally experienced back in 2009), or you have a coil failure. Based on earlier dialogue, you very well may need to replace ignition components. However, you need to diagnose the bigger issue -- the four cylinders' runnning -- first.

It is entirely possible that poor ignition components can put an unnecessary strain on the coils and/or EZL. This is why I recommended (and knowledgeable shops recommend) replacing BOTH coils if you put a new EZL on the car -- because a bad or faulty coil can take out an otherwise good EZL (they are directly connected). Other poorly performing ignition components also can hasten the demise of the coils and/or EZL.

 

[DL2]

If it refuses to ever run on more than 4 cylinders, you MAY have a dead EZL or coil. But you should open up the distributors for inspection. If one side is really bad, it isn't going to fire even with good EZL/coils.

Ok, thanks. The car had sat for a month or so, and I was expecting a damp issue, but this was a new wrinkle. I’ll try to get you the code when I get back to the car.

 

[gsxr]

I'm expecting the CEL to be a generic "Ignition system defective" fault code. Check it anyway though.

You really need to pull the distributor caps and look inside. This is a 5-minute job, 3 bolts each with a 5mm hex/Allen head, just pull the caps off and snap a photo of the insides. No need to unplug any wires.

 

[smilecenterlab]

I've had the same issue with my 93 500e.i tried every benz mechanic in the san Francisco area to no avail.(Robert fenton,octane,sfmercedes,san jose Mercedes dealer,pete's Mercedes...…....)still misfires and acts up if I don"t drive it after a few days.i could have bought a new car with the money spent on repairs

 

[DL2]

I'm expecting the CEL to be a generic "Ignition system defective" fault code. Check it anyway though.

You really need to pull the distributor caps and look inside. This is a 5-minute job, 3 bolts each with a 5mm hex/Allen head, just pull the caps off and snap a photo of the insides. No need to unplug any wires.

the impulse code reader consistently flashed 3 and only 3. Also, does the .036 use a different EZL from other W124s? On eBay there are a lot of similar EZLs but none with my exact part number that I can find so far. Mine is 014 545 43 32.

 

[gerryvz]

The 500E can use ANY EZL that works with an LH-injection 5-liter M119 engine -- so EZLs from the R129 and the W140 will also work, as long as they are 5-liter engines with LH injection.

A list of appropriate EZLs and related part nucan be found at the link below -- generally pretty much any information you would need will be available on this site.

https://www.500eboard.co/forums/wiki/?title=500E-and-E500-CAN-Computer-Part-Number-Reference

The 43 32 EZL units are made by Siemens, which are generally more reliable than the Bosch manufactured units. I've not heard of too many of the Siemens units failing. That tends to lead me to believe you may have a bad coil, rather than an EZL.

The "3" code means that your Lambda system is inoperative -- not a code that helps you. It's rather a "duh" type of code, given what you are experiencing.

It's too bad that you don't have a blink code reader, because you would be able to directly test the EZL/DI computer codes, which would give you MUCH more specific codes (and information) about what is happening.

A further clue (besides the unburned fuel smell) that you have a bad coil, is the fact that the car will fire up and run correctly after waiting some hours for things to cool down. Coils often have intermittent operation like that. For an EZL -- when it fails, it fails completely (either both engine banks, or a single bank).

My deduction is that there is a 90% chance you have a bad coil. That would be a very good place to start with purchasing and replacing.

 

[Jlaa]

I've had the same issue with my 93 500e.i tried every benz mechanic in the san Francisco area to no avail.(Robert fenton,octane,sfmercedes,san jose Mercedes dealer,pete's Mercedes...…....)still misfires and acts up if I don"t drive it after a few days.i could have bought a new car with the money spent on repairs

Wow, that is a lot of indy mechanic shops ... from north bay (R Fenton) to SF (Octane) to South Bay (SJ Mercedes).

Did you also similarly rule out the ignition system / insulators in the ignition system? It doesn’t really get damp in the SF area and this is intriguing.

 

[DL2]

The 500E can use ANY EZL that works with an LH-injection 5-liter M119 engine -- so EZLs from the R129 and the W140 will also work, as long as they are 5-liter engines with LH injection.

A list of appropriate EZLs and related part nucan be found at the link below -- generally pretty much any information you would need will be available on this site.

https://www.500eboard.co/forums/wiki/?title=500E-and-E500-CAN-Computer-Part-Number-Reference

The 43 32 EZL units are made by Siemens, which are generally more reliable than the Bosch manufactured units. I've not heard of too many of the Siemens units failing. That tends to lead me to believe you may have a bad coil, rather than an EZL.

The "3" code means that your Lambda system is inoperative -- not a code that helps you. It's rather a "duh" type of code, given what you are experiencing.

It's too bad that you don't have a blink code reader, because you would be able to directly test the EZL/DI computer codes, which would give you MUCH more specific codes (and information) about what is happening.

A further clue (besides the unburned fuel smell) that you have a bad coil, is the fact that the car will fire up and run correctly after waiting some hours for things to cool down. Coils often have intermittent operation like that. For an EZL -- when it fails, it fails completely (either both engine banks, or a single bank).

My deduction is that there is a 90% chance you have a bad coil. That would be a very good place to start with purchasing and replacing.

Well the car no longer runs correctly when cold. That is the new development. But my caps are a mess... also will this reader do if I can figure out which port is which?

 

[smilecenterlab]

Wow, that is a lot of indy mechanic shops ... from north bay (R Fenton) to SF (Octane) to South Bay (SJ Mercedes).

Did you also similarly rule out the ignition system / insulators in the ignition system? It doesn’t really get damp in the SF area and this is intriguing.

caps and rotors have been replaced a few times in the last 5 years,insulators I don't think so.

 

[gerryvz]

That reader will work fine to get codes from the EZL-DI computer, yes.

I've seen caps and rotors that are FAR worse than yours, and the car runs fine. Did you see the latest photos of my caps in my Top-End Refresh HOW-TO article, from last month? They were not that different than yours, and my car ran perfectly.

Trust me, those caps and rotors are NOT causing the running problems you are experiencing with rough/one-bank running. When I said inspect the caps and rotors in my post above -- I meant you should look for broken rotors, broken contacts inside the caps, that sort of thing.

What you have there with your caps is going to cause an occasional stumble or murmur, perhaps a slight hesitation, but the engine will run and fire fine.

All of the diagnostic information and instructions you'll need to check blink codes with a blink code reader is in the "sticky" threads I mentioned above. @gsxr details how to check the codes with the reader, and he also has a document that helps translate the codes into diagnostic information.

 

[gerryvz]

caps and rotors have been replaced a few times in the last 5 years,insulators I don't think so.

Can almost guarantee that insulators are your problem. There are probably at least a dozen threads on this forum of people who had similar running issues, with caps and rotors and tons of parts thrown at the problem -- but the mechanics were ignorant that the insulators were the real problem. And once this as figured out and the insulators changed, it transformed the car into a new car.

This is NOT the same problem that @DL2 is experiencing with one half of his engine's cylinders not even firing.

 

[smilecenterlab]

thanks Gerry I will do that.

 

[gsxr]

... also will this reader do if I can figure out which port is which?

That type of blink code reader works, but check out the threads Gerry linked to for more information. If you don't have a breakout box / mushroom adapter, you need a blinker box with 1mm pins and it's a PITA to figure out which socket is which.

WITH a breakout box (highly recommended, but extra cost) you need a reader with 4mm pins.

 

[smilecenterlab]

btw my vin# WDBEA36E4PB939091 in case you like to add it to your data base.thanks again for your hard work.

 

[DL2]

That reader will work fine to get codes from the EZL-DI computer, yes.

I've seen caps and rotors that are FAR worse than yours, and the car runs fine. Did you see the latest photos of my caps in my Top-End Refresh HOW-TO article, from last month? They were not that different than yours, and my car ran perfectly.

Trust me, those caps and rotors are NOT causing the running problems you are experiencing with rough/one-bank running. When I said inspect the caps and rotors in my post above -- I meant you should look for broken rotors, broken contacts inside the caps, that sort of thing.

What you have there with your caps is going to cause an occasional stumble or murmur, perhaps a slight hesitation, but the engine will run and fire fine.

All of the diagnostic information and instructions you'll need to check blink codes with a blink code reader is in the "sticky" threads I mentioned above. @gsxr details how to check the codes with the reader, and he also has a document that helps translate the codes into diagnostic information.

Alright thank you. I’ll see if I can figure out how to hook that reader up and go from there. I’ll just clean up the caps and rotors and go from there. I hate to complicate matters by replacing parts until I have the first problem fixed. Thanks again, Im sure you haven’t heard the lady from me!

 

[DL2]

Alright thank you. I’ll see if I can figure out how to hook that reader up and go from there. I’ll just clean up the caps and rotors and go from there. I hate to complicate matters by replacing parts until I have the first problem fixed. Thanks again, Im sure you haven’t heard the lady from me!

 

[DL2]

Haha! Heard The LAST from me**

 

[DL2]

Haha! Heard The LAST from me**

So I’ve ordered a box, but it looks like it may take a while getting here. I put the caps back on and the car wouldn’t start. Not a pop. After letting it sit for a day it started right up but ran like 1/2 an engine. Meanwhile while waiting for the box, just for giggles I bought and replaced both coils. Started the car and it ran exactly the same. Like it’s half an engine. Slow revs and feels like a four cylinder tractor at idle. A strong gas smell to the exhaust. Next I replaced the EZL with a used tested and cleared EZL with the exact numbers as the original unit. Started and ran just like before. Weak and gassy. The only difference is that now with the car’s onboard impulse reader, it blinks consistently 3 and 9 times alternately. It used to only blink 3. So I’m planning to put on rotors and caps next?

 

[gsxr]

DM (CEL) code 9 is for a disconnected intake air temp sensor, behind the driver's headlight. You may have forgotten to re-attach it, or you turned the key on at some point when it was unplugged. Not a big deal.

If you have changed EZL and coils and it still runs on 4 cylinders, it's pretty likely to be either wires or caps/rotors. A more definite test would be unplugging one coil lead at a time, if it runs the same with one disconnected and refuses to start with the other disconnected, you've at least narrowed the issue to one distributor or the other.

Live data from a digital scanner would be very helpful in this scenario.

Your caps look bad enough that yes, replacing caps/rotors/insulators would be the next logical step; assuming the wires test OK.

 

[DL2]

DM (CEL) code 9 is for a disconnected intake air temp sensor, behind the driver's headlight. You may have forgotten to re-attach it, or you turned the key on at some point when it was unplugged. Not a big deal.

If you have changed EZL and coils and it still runs on 4 cylinders, it's pretty likely to be either wires or caps/rotors. A more definite test would be unplugging one coil lead at a time, if it runs the same with one disconnected and refuses to start with the other disconnected, you've at least narrowed the issue to one distributor or the other.

Live data from a digital scanner would be very helpful in this scenario.

Your caps look bad enough that yes, replacing caps/rotors/insulators would be the next logical step; assuming the wires test OK.

 

[DL2]

Thanks. Yes I did turn the key on before connecting the intake. In fact I did just as you suggested... I started the car with each coil wire disconnected and determined it was the passenger bank that’s giving trouble. On the bright side I now have spare coils and an EZL! Although I’d be very happy not to do coils for a while! Caps and rotors it will be!

As I reflect I recall that when the car was having a damp fit, sometimes it would start to run in this wan manner while it was drying out for a few moments before hitting again on 8.

Thank you again for your prompt assistance and expertise!

 

[agsiress]

r44raven is 100% correct. Classic symptoms of liquid on the back of the insulators (not the caps, not the rotors). MANY threads discussing this in detail. When fixed, you can park the car for a year or more and have zero issues after starting & warmup.

where can I find the fix....

 

[gsxr]

where can I find the fix....

All you need to know is in the thread linked below.

For a permanent fix you may need to replace (at minimum, inspect) the exhaust cam sprocket seals behind the insulator, and you may also need to replace the cam solenoids if they are leaking oil (click here)... along with adding the ventilation slots to the caps. Depending on the condition of your caps/rotors, those may also need replacement unless they are relatively low-mile Bosch/Beru units. With zero oil leaks and good components, the issue SHOULD be resolved.

FYI - Essential M119 Ignition "Tune Up" mods [Distributor cap vent / slot] | M119 Engine

Hi all, I have been meaning to address this on my little used 500E for years.... it is a problem I myself recognised about 5 years ago when I first looked at an m119 distributer cap..... Compare to any other distributor cap of the era such as an m104 and you will see there are NO ventilation...

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