Like many of you, I certainly appreciate all the information on this board, the breadth and depth of knowledge for a model with a relatively low production volume is simply amazing. Because I've been through 100+ posts as I went through my issue, I thought it would be helpful to document what my issues were and how they were resolved. Some help came here and some from Pierre here in Florida.
I've documented my purchase and work on my 1992 500e in my owner's post. Here I purchased the car in 2022 and have put a ton of work into to make reliable and drivable.
Problem #1- In the late fall I started to hear a knocking at idle from under the car. As many folks have pointed out, the LH module can can cause a pulsing the fuel lines. It sound like a transmission going bad or something expensive, but this turned out to be a relatively inexpensive and straightforward process. I purchased a cheap LH module on eBay, non 500e to keep it movable, and sent off my LH to @Alphasud40 who soldiered all the weak points and sent it back to me good as new! Clunking resolved.
Problem #2 - Once the LH was sorted, I still had a lumpy idle in P or D, but the car ran well down the road. I had done all the electrical parts previously about 1 year earlier, plugs, caps, rotors, insulators and coils so my assumption was these were not the issue, but it sure acted like an electrical issue, fine cold, poor when warm. My plug wire age was unknown and they were Bosch, so I decided to replace them to Beru factory wires which are more conventional vs the red plastic tops. Project done, but no improvement to the issue.
I tried many other things based on all the various rough idle threads, check all the vacuum lines, check / disconnect the MAF, check / disconnect the EGR. I replaced the Fuel pressure valve as it looked old and the crank position sensor. These weren't terribly expensive and now I know they are in good shape on this 100K+ mile car. I also ran fuel injector cleaner through the system to make sure the LH problem didn't cause some sort of of particle to come loose and impact a fuel injector. Problem still remained.
At this point, I decided to go back to Pierre and get a real expert on the problem. Basically what he found was one rotor had a pin hole in it, but that didn't cure all the lumpiness, so he replaced the plugs and bingo, bango, idle is smooth. Turns out when you order plugs from MB, they send you Beru. My plugs had the MB symbol etc, but these plugs basically failed in 1 year and about 7K miles. We put new MB's back in because the Bosch were a much longer order wait time, so I'll order up the Bosch to swap out and hopefully this will keep the car running much longer than this go around.
So for those with a similar problem, check those plugs even if they are relatively new.
On a side note, I have access to dry ice cleaning so before I did the wire sway, I did a dry ice deep clean. I attached a couple pics, top you can see down in the crevices and on the injectors it was filthy, but after everything is nice and clean. So much nicer, but for a 116K mile car, this car is very clean top to bottom.
I've documented my purchase and work on my 1992 500e in my owner's post. Here I purchased the car in 2022 and have put a ton of work into to make reliable and drivable.
Problem #1- In the late fall I started to hear a knocking at idle from under the car. As many folks have pointed out, the LH module can can cause a pulsing the fuel lines. It sound like a transmission going bad or something expensive, but this turned out to be a relatively inexpensive and straightforward process. I purchased a cheap LH module on eBay, non 500e to keep it movable, and sent off my LH to @Alphasud40 who soldiered all the weak points and sent it back to me good as new! Clunking resolved.
Problem #2 - Once the LH was sorted, I still had a lumpy idle in P or D, but the car ran well down the road. I had done all the electrical parts previously about 1 year earlier, plugs, caps, rotors, insulators and coils so my assumption was these were not the issue, but it sure acted like an electrical issue, fine cold, poor when warm. My plug wire age was unknown and they were Bosch, so I decided to replace them to Beru factory wires which are more conventional vs the red plastic tops. Project done, but no improvement to the issue.
I tried many other things based on all the various rough idle threads, check all the vacuum lines, check / disconnect the MAF, check / disconnect the EGR. I replaced the Fuel pressure valve as it looked old and the crank position sensor. These weren't terribly expensive and now I know they are in good shape on this 100K+ mile car. I also ran fuel injector cleaner through the system to make sure the LH problem didn't cause some sort of of particle to come loose and impact a fuel injector. Problem still remained.
At this point, I decided to go back to Pierre and get a real expert on the problem. Basically what he found was one rotor had a pin hole in it, but that didn't cure all the lumpiness, so he replaced the plugs and bingo, bango, idle is smooth. Turns out when you order plugs from MB, they send you Beru. My plugs had the MB symbol etc, but these plugs basically failed in 1 year and about 7K miles. We put new MB's back in because the Bosch were a much longer order wait time, so I'll order up the Bosch to swap out and hopefully this will keep the car running much longer than this go around.
So for those with a similar problem, check those plugs even if they are relatively new.
On a side note, I have access to dry ice cleaning so before I did the wire sway, I did a dry ice deep clean. I attached a couple pics, top you can see down in the crevices and on the injectors it was filthy, but after everything is nice and clean. So much nicer, but for a 116K mile car, this car is very clean top to bottom.
