Stumble idle after start-then smooth
02-21-2002, 10:55 PM
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1988 300E
Stumble idle after start-then smooth
88' 300E - 154,600 mi, clean, perfect - except that hot or cold, warm or cold weather, intermittently, car starts immediately upon cranking, then stumbles - sounds as if it will stop, runs at slow RPM for 3-6 seconds, then resumes normal slightly quick idle - otherwise, perfect operation and mileage - comments as to possible causes and how to repair will be appreciated
02-23-2002, 10:21 AM
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95 E 320 Cab
Idle fix
I have had an idle problem not as severe as yours. Had people telling me to replace engine mounts, etc. Too the path of least resistance and started with the plugs. Upon removal, noticed that although the plugs didn't look fouled, three of six had brown rings aroung the bottom of the ceramic part of the plug. Replaced all with Bosch standard plugs and no more bumpy idle. Give it a try. $20 and an hour of your labor may do it. Just make sure you have a 5/8" socket and about a six inch extension before you get the shroud off.
Dave
Dave
02-23-2002, 12:30 PM
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1988 300E
stumble idle after start - then smooth
Dave, thanks for response - another question to try to more accurately define my problem: was your idle problem continuous - or did it occur as mine does, upon start-up, with engine turning over so slowly that you can feel and hear and count maybe 5 - 8 individual revolutions and then it quickly resuming a normal 700 rpm smooth idle - also, were any other aspects of your engine operation troublesome, such as high speed missing, poor or delayed response, poor mileage - or other symptoms normally asociated with bad plugs?
02-23-2002, 06:35 PM
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95 E 320 Cab
BST-
My idle was different. Cold starts were no problem. Idled normally at about 700 rpm. The issue was with the car warmed up. Sitting a a traffic light for instance, I would feel a lurch, almost like someone had nudged me in the *** end. Also I noticed if I accelerated aggressively but not hard enough for the transmission to kick down, I would feel some sluggishness or missing in the 3500 to 4500 rpm range as speed rose. I tried fuel additives like Berryman's injector cleaners, checked the air filter, and talked to several repair shops. The mechanics suggestions ranged from possible bad ignition wires to the wiring harness, from motor mounts to whatever.
Anyway, was pleased when the plugs fixed the problem. Would have been no harm done had it not solved the problem. If you know your plugs are new and good, then skip it. If you are like me and had just bought the car a few months ago, were unsure about the service done, maybe you could give it a try. Good luck and ket us know how it turns out.
D
My idle was different. Cold starts were no problem. Idled normally at about 700 rpm. The issue was with the car warmed up. Sitting a a traffic light for instance, I would feel a lurch, almost like someone had nudged me in the *** end. Also I noticed if I accelerated aggressively but not hard enough for the transmission to kick down, I would feel some sluggishness or missing in the 3500 to 4500 rpm range as speed rose. I tried fuel additives like Berryman's injector cleaners, checked the air filter, and talked to several repair shops. The mechanics suggestions ranged from possible bad ignition wires to the wiring harness, from motor mounts to whatever.
Anyway, was pleased when the plugs fixed the problem. Would have been no harm done had it not solved the problem. If you know your plugs are new and good, then skip it. If you are like me and had just bought the car a few months ago, were unsure about the service done, maybe you could give it a try. Good luck and ket us know how it turns out.
D
