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95 Chev Monte Carlo 3.4L idling issues


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GRod
New User

May 25, 2010, 11:09 PM

Post #1 of 1 (1918 views)
95 Chev Monte Carlo 3.4L idling issues Sign In

Hey all I've had this problem with Monte for awhile now and after replacing pretty much everything I can think of on the thing I'm at a loss...

Year: 1995
Make: Chevrolet
Model: Monte Carlo Z34
Engine size: V6 3.4L
Just over 250k KMs

Problem: Intermittent idling issue. A typical scenario of it happening is after a night of it sitting I come out to start it and it instantly shoot up to 4000 RPMs for a brief second and then die. I'll start it again and have a similar problem, if I pump the gas once or twice it might sit at .5-1k RPMs and just kind of "hop" on the verge of dying before dying. Start it again and it'll do the same thing though usually by now I'm pumping it to keep it alive, if I try to drive it as soon as I let off the gas it will either idle below 1 and then die or just die outright, however if I let it warm up enough it will eventually idle ok, though it still sounds like it might be missing. After the 2nd start you can also smell gas as if the car is flooding itself. It drives fine on the highway and after it's warmed up is fine driving around town. The problem seems to be completely random as some days when I start in the morning it will work as if it had been warmed up already. It will work fine sometimes first thing in the morning on days where it's minus 20 C and not work on days where it's plus 20 and vice versa.

A side symptom that may or may not be related is my radio clock dims randomly, it doesnt affect radio playback or my head and tail lights but it dims. The lights that light up my gears in the console (P/R/N/D etc) will also randomly turn on or off and doesnt seem to be in synch with the clock dimming or me hitting anything. I noticed while driving on the highway at night. I doubt it has anything to do with the idling issue (maybe a ground out affecting a sensor or something?) but figured I should include it.

What I've tried in no particular order: Spark plugs, all six, didnt seem to change anything. Idle air control valve. Oxygen sensor (the old one was pretty filthy but this still solved nothing). Temperature sensor. EKG valve(?). Air intake manifold/sensor. All 6 fuel injectors. The timing belt is new from when I replaced the alternator a little more then a year ago, the issue did not start until about 8 months after this. The cars computer. We have checked all hoses for vacuum leaks and havent been able to find any.

I didnt invest in all these parts new because I had a parts car that ran fine but had a totalled rear end...Plus it wouldnt be worth it on a 95 monte :p

I had 2 different journeymen mechanics attach a scan tool to it and the first said it failed at the O2 sensor and the other said 1 fuel injector was failing..Both of these were replaced with no change in it.

I'm at the point where I'm wondering if it's a timing issue or a fuel pump/filter issue. Though the weird thing is how intermittent the problem is and that it basically goes away once it's been driven/warmed up awhile.

I'd really appreciate any help anyone can offer on this site. I'm kind of lost on what this could be after replacing pretty much every sensor on the vehicle :p

Thanks in advance!


(This post was edited by GRod on May 25, 2010, 11:11 PM)






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