Ive been chasing a problem for a while on my 1995 SL500. Cylinder 1,4,6 and 7 are not firing as they should. I thought it was spark related as I have an ignition system fault code and all those cylinders get spark from the same coil/ cap and rotor system. I have new cap/rotor/plugs/wires/fuel filter/regulator/ installed. Car has perfect fuel pressure and every cylinder is getting spark the upper harness is new as well. Using a big flathead screwdriver as a stethoscope today I can hear that the faulty cylinders fuel injectors are not firing as strong as the strong cylinders. I can still hear clicking of the injectors though so they are firing but clearly not as strong as the others. The car lacks full power. It can be driven as a car but doesnt have its full potential obviously. Feels like a 4 cylinder. My question is what would cause this. I have no lights on the dash and the only code that will not go away again is pin 19: 7 blinks “Ignition system faulty” coming from the DM (Diagnostic Module). Main question, what would make the fuel injectors not fire as powerful as the other?
-
Hi Guest !
Welcome to the 500Eboard forum.
Since its founding in late 2008, 500Eboard has become the leading resource on the Internet for all things related to the Mercedes-Benz 500E and E500. In recent years, we have also expanded to include the 400E and E420 models, which are directly related to the 500E/E500.
We invite you to browse and take advantage of the information and resources here on the site. If you find helpful information, please register for full membership, and you'll find even more resources available. Feel free to ask questions, and make liberal use of the "Search" function to find answers.
We hope you will become an active contributor to the community!
Sincerely,
500Eboard Management
SL500 Fuel injector problem, (“Ignition system faulty” code)
- Thread starter Krowley
- Start date
Like the post said I do have “ignition system fault” code stuck on unclearable. At one point recently I had “Ignition coil 1 output from ignition control module faulty or primary winding of ignition coil has open circuit”(pin17: 15 blinks). That code went away and as for now is not on, whos to say it wont be back. The injectors not firing as strong from the same coil system is what Im trying to figure out. I do not believe any of the injectors are bad.
When you clear pin 19 code 7, does this code return quickly? Most fault on the DM should trigger the CEL on the cluster. If you don't have a CEL, that is odd.
Also, you get a single blink indicating no faults storedon both LH (pin 4) and EZL (pin 17)? Were the coils replaced, and do you have a spare EZL and/or LH module to swap in for testing? Also wouldn't hurt to confirm your car has the correct 5.0L LH module and EZL.
Has the upper engine harness been replaced?
Simple test - disconnect those 4 cylinders and see if it runs the same or worse. If the same, it's pretty likely ignition. If it's worse, then it could be fuel.
This may be very difficult to diagnose without live data from both LH and EZL via SDS / HHT-Win.
Also, you get a single blink indicating no faults storedon both LH (pin 4) and EZL (pin 17)? Were the coils replaced, and do you have a spare EZL and/or LH module to swap in for testing? Also wouldn't hurt to confirm your car has the correct 5.0L LH module and EZL.
Has the upper engine harness been replaced?
Simple test - disconnect those 4 cylinders and see if it runs the same or worse. If the same, it's pretty likely ignition. If it's worse, then it could be fuel.
This may be very difficult to diagnose without live data from both LH and EZL via SDS / HHT-Win.
So to try an answer everything you suggested, yes the upper harnesses has been replaced. When I go to clear pin 19 code 7 it never clears no matter what (ignition system faulty code). Occasionally I do have a CEL but it can be cleared and goes away but the ignition fault will still be there.When you clear pin 19 code 7, does this code return quickly? Most fault on the DM should trigger the CEL on the cluster. If you don't have a CEL, that is odd.
Also, you get a single blink indicating no faults storedon both LH (pin 4) and EZL (pin 17)? Were the coils replaced, and do you have a spare EZL and/or LH module to swap in for testing? Also wouldn't hurt to confirm your car has the correct 5.0L LH module and EZL.
Has the upper engine harness been replaced?
Simple test - disconnect those 4 cylinders and see if it runs the same or worse. If the same, it's pretty likely ignition. If it's worse, then it could be fuel.
This may be very difficult to diagnose without live data from both LH and EZL via SDS / HHT-Win.
I could pull all the spark wires from 1,4,6,and7 (problem cylinders) but couldn’t I also just pull the plug wire going from the one coil going to all of them?
Coils have not been replaced
I can clear pin 4 and pin 17, they do go away. Pin 17 occasionally has that coil 1 problem code. It isnt on now. No spare EZL, what do you mean left hand module? Is that just meaning the LH drive EZL?
Everything but the coils have been replaced and it would seem to be the coil 1 which correct me if Im wrong but the one next to the ABS module. I almost thought about switching the 2 coils (just to see if the problem inverts) but Idk if they have any difference. One coil hast 3 wires going to it (abs one) (the extra wire is just stacked on the post) the other fender one has 2 wires going to it.
Past the coils (believing only one is bad) there is no other ignition system component not replaced. Thanks in advance
Pin 19 / DM codes typically require a restart before they fully clear. The 2 ignition coils are electrically identical, but physically different... if the wires will still connect, you can swap them for testing. The "extra" wire is likely a ground that goes to the other coil. And yes, you can pull the coil wire to disable the ignition to those 4 cylinders. You can disconnect the four fuel injectors to disable the fuel. Codes will be stored when you do this of course.
LH = the fuel injection computer, your car has LH-SFI engine management. EZL = ignition computer. They communicate & share data via CAN bus. LH module is located in the CAN box on the passenger side along with the ABS/ASR module, BM/GM power supply, E-GAS module, etc.
BTW, don't fall into the trap that all new ignition components must be "good". Several forum members, myself included, have had brand new ignition components (caps/rotors) defective out of the box which led to lots of frustration. What brand caps/rotors/wires were installed, btw?
LH = the fuel injection computer, your car has LH-SFI engine management. EZL = ignition computer. They communicate & share data via CAN bus. LH module is located in the CAN box on the passenger side along with the ABS/ASR module, BM/GM power supply, E-GAS module, etc.
BTW, don't fall into the trap that all new ignition components must be "good". Several forum members, myself included, have had brand new ignition components (caps/rotors) defective out of the box which led to lots of frustration. What brand caps/rotors/wires were installed, btw?
There are really only going to be two culprits if a whole entire bank of cylinders is not correctly firing -- a bad coil, or a bad EZL. And perhaps a coil wire going to the distributor cap.
Coils are much more often the culprit, and can result in some very wonky behavior. EZLs fail generally in one of two modes -- either the whole thing (all cylinders) fails, or one bank fails (this happened to me back in 2009).
If you swap the connections to the coils, and the behavior happens on the OTHER cylinder bank, then you know it is a coil. You can do the same temporarily with the coil wires to troubleshoot that.
With an EZL failure, the car either won't start at all (doesn't seem to be your problem), or it will start and run very roughly because only four cylinders are running. You will also typically smell gas coming out of the exhaust (because it is not being burnt). The engine will run very roughly at low RPMs, and take a lot of effort on the gas pedal to get going. Then, when you are moving faster, it smooths out.
It doesn't sound like this is your problem (EZL), so I would concentrate on the coils and associated wires. If you temporarily swap them you should be able to isolate the issue.
Coils are readily available; EZLs are a good item to have a spare of, for long-term owners, though they are not unduly unreliable.
Coils are much more often the culprit, and can result in some very wonky behavior. EZLs fail generally in one of two modes -- either the whole thing (all cylinders) fails, or one bank fails (this happened to me back in 2009).
If you swap the connections to the coils, and the behavior happens on the OTHER cylinder bank, then you know it is a coil. You can do the same temporarily with the coil wires to troubleshoot that.
With an EZL failure, the car either won't start at all (doesn't seem to be your problem), or it will start and run very roughly because only four cylinders are running. You will also typically smell gas coming out of the exhaust (because it is not being burnt). The engine will run very roughly at low RPMs, and take a lot of effort on the gas pedal to get going. Then, when you are moving faster, it smooths out.
It doesn't sound like this is your problem (EZL), so I would concentrate on the coils and associated wires. If you temporarily swap them you should be able to isolate the issue.
Coils are readily available; EZLs are a good item to have a spare of, for long-term owners, though they are not unduly unreliable.
So I pulled the coil wire going from the coil to the “bad” cylinders cap and rotor and the car didnt change at all. I then flipped the coil wires so the distributors had a different coils. I then pulled the switched wire from the same coil and the car shut down immediately. So the car is running on half the cylinders. Switching the coils inverted the problem but also proved both coils work. Im trying to read ohms on the wires but my multimeter is junk or I dont know how to use it correctly. Ill be going to an autoparts store to talk to someone and or try and read the resistance on the spark plug wires.
Sitting in the drivers seat, the right bank cap and rotor are supposed to route to the abs coil correct? And the left bank cap and rotor are supposed to route to the fender coil?
The remaining issue would then be your EZL, if you have proven that both coils work. You would need to source a good EZL.
I believe that there is information here regarding testing the wires for resistance. The search function should bring up some relevant information.
I believe that there is information here regarding testing the wires for resistance. The search function should bring up some relevant information.
+1 on defective EZL, if you have proven both coils & wires are good, AND if the cap/rotor is not defective on the "bad" side.
Coil wire resistance should be zero ohms from coil to cap. Plug wires will read 2000 ohms between cap and plug boot, ±20%.
Sorry, don't know which coil is which on an R129. This forum is W124-specific.
Coil wire resistance should be zero ohms from coil to cap. Plug wires will read 2000 ohms between cap and plug boot, ±20%.
Sorry, don't know which coil is which on an R129. This forum is W124-specific.
I havent proven the wires are good, Im trying to get a reading for ohms on any wire but cant seem to. Im not an electric pro. Switching the end wires from one coil to the other switches the problem (tried to explain in my last post but I guess it sounded like I changed the whole wire both ends which is confusing to explain I know). Im not even sure the coils are meant to even switch which cap and rotor they run. This though makes me believe the coils are good and the EZL is good. Im going to do more investigation though as I just went to Oreillys and none of the 5 employees there could read a multimeter for ohms either and just recommend me just buy all new wires which Im not going to do just yet. Id like to find a part out just to grab one wire.+1 on defective EZL, if you have proven both coils & wires are good, AND if the cap/rotor is not defective on the "bad" side.
Coil wire resistance should be zero ohms from coil to cap. Plug wires will read 2000 ohms between cap and plug boot, ±20%.
Sorry, don't know which coil is which on an R129. This forum is W124-specific.
Definitely do additional testing on the wires, caps, and rotors - a defective new cap/rotor is not out of the picture yet. You can swap caps/rotors (separately) to see if the problem switches to the other 4 cylinder, if so, it's a cap/rotor issue and the EZL is ok. No need to buy new wires, figure out the ohm meter first - has to be some YouTube tutorials out there. Touch the leads together and the meter should read zero ohms, or close to it (ideally 1 ohm or less).
The EZL has separate outputs to each ignition coil, and one of the EZL failure modes is not firing one of the coils. So if both coils are good but one still isn't firing properly, and the caps/rotors/wires all check out ok, the EZL is the next suspect.
BTW - once the car is running properly, I strongly suggest buying a full set of good used computer modules to have on the shelf as spares. Test each as you buy them and then keep them on the shelf for times like this. Would take all of 10 mins to swap in a spare EZL to see if there is any change. Deals on used modules can be found on eBay, but make sure they are returnable if defective!
The EZL has separate outputs to each ignition coil, and one of the EZL failure modes is not firing one of the coils. So if both coils are good but one still isn't firing properly, and the caps/rotors/wires all check out ok, the EZL is the next suspect.
BTW - once the car is running properly, I strongly suggest buying a full set of good used computer modules to have on the shelf as spares. Test each as you buy them and then keep them on the shelf for times like this. Would take all of 10 mins to swap in a spare EZL to see if there is any change. Deals on used modules can be found on eBay, but make sure they are returnable if defective!
This can’t be stressed enough. I was in the same situation a few years ago.. replacing coils, swapping EZL, etc.. and I overlooked the caps and rotors just because they were new. I spent far too long looking at everything else, before I decided to swap them to see if it gave me any insight. The problem shifted to the other bank of cylinders, and I knew immediately that I had a defective rotor. There was no external damage or visible signs of failure on the rotor.
If I bought new caps and rotors and the car runs the same youd think that both were effective or good. It would be extremely rare my cap and rotor are bad and I buy a new bad cap and rotor. If so I should play the lottery. Im hunting down coil to cap wires. There would be no reason that switching the coil wire ends spontaneously makes the EZL wake up on the other bank just to go to sleep again when I change back.Definitely do additional testing on the wires, caps, and rotors - a defective new cap/rotor is not out of the picture yet. You can swap caps/rotors (separately) to see if the problem switches to the other 4 cylinder, if so, it's a cap/rotor issue and the EZL is ok. No need to buy new wires, figure out the ohm meter first - has to be some YouTube tutorials out there. Touch the leads together and the meter should read zero ohms, or close to it (ideally 1 ohm or less).
The EZL has separate outputs to each ignition coil, and one of the EZL failure modes is not firing one of the coils. So if both coils are good but one still isn't firing properly, and the caps/rotors/wires all check out ok, the EZL is the next suspect.
BTW - once the car is running properly, I strongly suggest buying a full set of good used computer modules to have on the shelf as spares. Test each as you buy them and then keep them on the shelf for times like this. Would take all of 10 mins to swap in a spare EZL to see if there is any change. Deals on used modules can be found on eBay, but make sure they are returnable if defective!
So in my last post the new caps and rotors didnt fix the problem. I got new Beru spark plug wires and that as well didnt fix the problem. I guess it could be the EZL still but it has yellow writing on the side like its been replaced (so I dont even know if its the correct EZL to reference in getting a new to me one). I might buy a new EZL but Id rather just push the car off a cliff at this point. In replacing the wires the engine seemed to get hotter but not on the temp gauge but just in ambient heat. Probably from cylinder wash down.
Im just replying to myself at this point but got a new coil to switch out the 1 potential bad coil. It did nothing better (was a china coil) (parts stores dont even have bosch at the distributors anymore). I looked up my EZL because it looked to have been replaced being it had yellow part writing on it and sure enough it came out of a S420. No wonder it ran like junk. Looking for an EZL now. Will post again if and when the new EZL fixes the car. Thanks for all the recommendations though.
Attachments
015-545-60-32 is for a 4.2L engine.
015-545-61-32 is for a 5.0L engine.
Any time a previous mechanic has been monkeying with things, I like to confirm the part numbers in the car are correct (mentioned back in post #5). Years ago I bought a car that was not running properly. Turns out the previous mechanic had swapped in a wrong throttle control module in place of a defective module and there was no change, and he didn't know what to do. The owner had given up and I got a good deal on the car. I swapped in a good, correct module and the problem was solved. Gotta check their work!
The photo of the EZL you posted would be correct for a 5.0L engine, not sure if that is of your car?
015-545-61-32 is for a 5.0L engine.
Any time a previous mechanic has been monkeying with things, I like to confirm the part numbers in the car are correct (mentioned back in post #5). Years ago I bought a car that was not running properly. Turns out the previous mechanic had swapped in a wrong throttle control module in place of a defective module and there was no change, and he didn't know what to do. The owner had given up and I got a good deal on the car. I swapped in a good, correct module and the problem was solved. Gotta check their work!
The photo of the EZL you posted would be correct for a 5.0L engine, not sure if that is of your car?
My car is a 1995 SL500. Its been a long day. In talking to someone at Mercedes, yes the EZL matches up to the car. It might have worked but supposedly unplugging any ignition device while the car is on ruins it (I unplugged things so it may not have worked when I got the car but 100% doesnt work correctly now), live and learn. I bought an EZL off Ebay, the seller has a good ratings and accepts returns. A lot of sellers dont accept returns or have bizarre return policies. It was $220 without tax. Here is another picture of my EZL, as you can tell it more then likely has been replaced before. Who knows if it was known working though. Ill post again when I get the new to me EZL. Thanks again015-545-60-32 is for a 4.2L engine.
015-545-61-32 is for a 5.0L engine.
Any time a previous mechanic has been monkeying with things, I like to confirm the part numbers in the car are correct (mentioned back in post #5). Years ago I bought a car that was not running properly. Turns out the previous mechanic had swapped in a wrong throttle control module in place of a defective module and there was no change, and he didn't know what to do. The owner had given up and I got a good deal on the car. I swapped in a good, correct module and the problem was solved. Gotta check their work!
The photo of the EZL you posted would be correct for a 5.0L engine, not sure if that is of your car?
Attachments
Did your EZL have thermal grease between it and the fender? I can't vouch for R129s as I never took the EZL off of mine, but on W140s and W124s the EZLs had thermal grease to increase heat transfer from the EZL to the fender for cooling. Without this the EZL could overheat and fail.
Dan
Dan
It had some sort of white greasy stuff I whiped off when I just took it off. I havent ran it since then. I wanted to clean mine to see what kind of markings it had on it. As you can see by the pictures above, it did have markings from someone before. I’ll probably buy some thermal grease when I install the new to me one coming in the mail. Thanks
Get a couple tubes of CPU thermal grease from Amazon or some other supplier. Don't buy the cheap stuff, get a name brand like Arctic. It's money well spent considering the cost of an EZL and their increasing scarcity.
Dan
HOW-TO: Replacing Thermal Paste Behind EZL unit | "HOW-TO" Tutorial Articles
As many know, the EZL (ignition computer) is attached to the driver's side inner wheel well area in the engine compartment on the 500E/E500 (as well as the 400E/E420, 560SEL/SEC, and many other 1980s and 1990s MBs). There is a thin layer of white thermal paste that the factory used between the...
Hope everyone is having a good weeked. I hate when people dont finish a forum when they solve the problem. I have solved the problem:
I wired a new wire to coil 1. Coil 2 is just a jumper off one. I used a really sharp razor and cut into the harness from the coil to the fuse box. That one wire looked toasty, dont ask me why maybe it was jumped off.
The car works so good now it is incredible. With the new parts put on it like wires and plugs its smooth and powerful, everything I dreamed. I hope if anyone else has a problem like this they can solve it. If anyone else has a major ignition problem Id suggest doing the same and opening the harness and taking a look.
I will be releasing a video on my YouTube channel “maybe1someday” on the whole deal. ✌
I wired a new wire to coil 1. Coil 2 is just a jumper off one. I used a really sharp razor and cut into the harness from the coil to the fuse box. That one wire looked toasty, dont ask me why maybe it was jumped off.
The car works so good now it is incredible. With the new parts put on it like wires and plugs its smooth and powerful, everything I dreamed. I hope if anyone else has a problem like this they can solve it. If anyone else has a major ignition problem Id suggest doing the same and opening the harness and taking a look.
I will be releasing a video on my YouTube channel “maybe1someday” on the whole deal. ✌
Great work, and thanks for following up. Looking forward to the video!
I've never heard of a failed / toasty +12v feed wire to the coils. The FSM/ETM schematics show the feed wire goes to fuse #6, then appears to have a jumper between both coils. Where exactly was the failed wire? Did you get any photos?
Thanks for the update!!
I got you one better then a photoIve never heard of a failed / toasty +12v feed wire to the coils. The FSM/ETM schematics show the feed wire goes to fuse #6, then appears to have a jumper between both coils. Where exactly was the failed wire? Did you get any photos?
Thanks for the update!!
