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Idle Issue!?!?!?!?!?!?

2K views 14 replies 11 participants last post by  w124uk 
#1 ·
1989 - 260E ~ 240K miles = Just recently, the car runs great, but when the car is in idle, either in "PARK" or engaged in "DRIVE", the car "hiccups" randomly. Pulling up to a stop/light, when the rpm's finally stabilize at it's resting state, that is when the car has this issue.

On occassion, off the line it stutters a little, but catches itself quickly and accelerates fine. Normal driving has no signs of the hiccups, but only when the car is still on idle. I checked the spark plugs and all were fine. Air filter is clean and good fuel with fuel injection cleaner did not help either.

Any ideas? Thanks again for everybody's help!!!!
 
#3 ·
My car currently has the same problem i just took it to a mechanic today and they looked at the fuel filter and said it was fine. So they decided to clean the fuel injectors with cheveron techron fuel additive(which i have already done in the past that is why i took it to a mechanic because it did not work, i thought they had a special way of cleaning the injectors apparently i was wrong). To say the least this has done nothing to help the problem. I paid $200 and the car still runs bad and on top of that they drove my car 30 miles. When i got in it this afternoon they said it was much better i drove it 1 mile down the road and at the first stop tried to accelerate hard and it sputtered. Tomorrow they are getting a call and i am going to give them an ear full. I will keep you posted.
 
#4 ·
check your sparkplugs. if they are dirty you may have an oil leak. also check the forums, because this problem has been documented.

if the car is running fine while warmed up then it is most likely a problem with the oil as it will burn off. when it is cold the oil is thick and harder to burn off. this may explain why the mechanics are able to drive the car fine and then you take it away from them the next day when the oil is cold and on the spark plugs and it stutters.
 
#5 ·
The reason you arent getting a lot of help here on this issue is that from your description it really could be anything. It could be OVP, ICV, Fuel mixture, Spark plug leads, Coil, EHA or O2 sensor.

I'm betting on the O2 sensor first so use a multimeter to check it to see if its current is fluctuating normally.
 
#8 ·
My car had the same problems I replaced the idle air control valve and the fuel distributor, it still ran rough; checked the spark plugs which were only 4 months old and they were HORRENDOUS!!! Covered with a ton of black gooey slop. After new plugs, it runs really smooth again now, I think the fuel distributor may have caused them to get all fouled up. Also it might be an oil issue? Only problem left is the idle is too low, at a red light I have to give it gas pedal to keep the RPM around 1000, otherwise it wants to idle too low, aroind 500RPM. I'm about to address the OVP if I could find it I'd check that out. So far though it is much improved, smooth ass ilk lots of power again.
 
#9 · (Edited)
tonylinc said:
My car had the same problems I replaced the idle air control valve and the fuel distributor, it still ran rough; checked the spark plugs which were only 4 months old and they were HORRENDOUS!!! Covered with a ton of black gooey slop. After new plugs, it runs really smooth again now, I think the fuel distributor may have caused them to get all fouled up. Also it might be an oil issue? Only problem left is the idle is too low, at a red light I have to give it gas pedal to keep the RPM around 1000, otherwise it wants to idle too low, aroind 500RPM. I'm about to address the OVP if I could find it I'd check that out. So far though it is much improved, smooth ass ilk lots of power again.
RPMs at idle, at normal operating temperature, shouldn't be 1000 -- thatis too high.

My 300TE (M103) with 196k on the clock idles at 500 - 650 RPMs. The idle is smooth and silky. If you need to keep the RPMs so high at idle there may be other problems with your engine. The high RPMs will eventually damage your engine.

The OVP is by the firewall, passenger side, behind a plastic panel cover. The OVP itself is a small, plastic box. I don;t thinkt hat your idle condition is related to the OVP.

As for the problem posted by the original poster could be a numb er of things -- the suggestions posted here are all good starting points.

Good luck.
 
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