Post start engine issues - intermittent backfire/stalling

[frenchplane]

My 92 500e runs perfect! It has 80,000 miles and I have done very little to it aside from maintenance, AC system, ventilation fans, and rear suspension mods for camber adjustment.

Three times now I have taken the car out after a month or two of two of not running. Starts right up ! Drive it to my house, runs perfect, park it! No problem…. Half an hour later I start it up and either does not start or burbles and a few meek back fires and stalls! The cat gets loaded up with back fires and I can smell it. I do this for ten minutes and play with air intake and pumping a little extra gas and finally it idles barely! Trying not to push it I wait and restart and finally get a steady idle! Wait five minutes and it runs like new!

I know it’s a sensor issue or maybe TPS! But I’m am not a merc expert rather bmw! Suggestions from you geniuses out there? I want to test a system but need a little bit of guidance… thank you!

 

[gsxr]

This is a textbook case of secondary ignition problems. There are probably a couple dozen threads and literally hundreds of posts discussing the exact symptoms you describe. Search the forum for information about the caps & rotors, liquid on the back of the insulators, adding venting slots on the caps, and inspecting for oil leakage at the exhaust cam seal behind the insulator.

There will be no fault codes, no easy test, and if the car is driven frequently (daily, or almost daily) the issue will vanish. Park the car for a few weeks, and about 15-20 mins after a cold start it can be undrivable (or, impossible to restart). Fun stuff.

If the caps/rotors/insulators are of unknown age or old, might be time to replace it all, but read the threads on what brands to avoid...

 

[frenchplane]

This is a textbook case of secondary ignition problems. There are probably a couple dozen threads and literally hundreds of posts discussing the exact symptoms you describe. Search the forum for information about the caps & rotors, liquid on the back of the insulators, adding venting slots on the caps, and inspecting for oil leakage at the exhaust cam seal behind the insulator.

There will be no fault codes, no easy test, and if the car is driven frequently (daily, or almost daily) the issue will vanish. Park the car for a few weeks, and about 15-20 mins after a cold start it can be undrivable (or, impossible to restart). Fun stuff.

If the caps/rotors/insulators are of unknown age or old, might be time to replace it all, but read the threads on what brands to avoid...

Thank you for that I will look up the previous threads under secondary ignition

 

[smilecenterlab]

join the club! i changed caps,rotors,insulators and still misfires if i park it for more than a few days.I just learn to live with it.No fix .

 

[nocfn]

WHAAAAT? Did you replace wires, coils, are spark plugs resistor types? Cam seals original, cam advance magnets. Cam seals did it for me and if you can get some fiberglass insulation, just a small piece the size of you hand, cover up the PS distributor cap and replace the cover. See about driving it at temp for at least 30 minutes, then letting it sit for 30 and drive it again. YMMV but there is light at the end of the tunnel. On my 500e and Dad's E420, the cam seals did the job. Both cars had blow-by and the seals fixed it.

 

[smilecenterlab]

thanks nocfn ,car is in the shop ,one of the coils was bad so hopefuly there is light at the end of the tunnel unless it"s a train coming my way!

 

[gsxr]