1995 Chevy Lumina LS

[drhere222]

1995 Chevy Lumina LS 3.4 v-6 mileage: 110000. When starting engine, car cold (overnight for example irregardless of outside temp 20-60 degrees) the engine wants to rev up to 3000+ rpm and idle back down to 2-300 rpm or just quit altogether. Unless you sit there and hold the rpm steady at about 2200 rpm, it will not idle at the correct rpm of 7-800 rpm. Car has done this since we have had it at 85000 miles. Took to Chevy dealer last winter (cold temps mean you can’t start car and go in where it is warm and wait for it to warm up!) and they could not find anything wrong. Replaced a hose and that is all. Nothing electronic found to be bad. Hope you can help with this problem. It would be greatly appreciated! Thought that you may have seen this problem on this engine (3.4L) and have a fix for it. Thanks

[jeffcoslacker]

1. It amazes me that your 3.4 has lasted that long. You must be doing something right.

2. You problem sounds typical of a vacuum leak, the engine surges while the control system tries to compensate. Try spraying water, ether, or wd-40, whatever, around the throttle body, egr, iac, and intake seams. If it hits the leak, the motor will stabilize momentarily as the fluid blocks the air leak. Then you have to pinpoint where it was drawn in from.

[jeffcoslacker]

Some GM motors would get a case of the "rolling" idle when the timing chain got stretched out after high miles, but your 3.4 has a belt.

Change that thing if you haven't. That motor tends to eat itself if it breaks.

[blitz9198]

I had the same problem, i have the same 95 with the 3.4L, im suprised that someone else actually has the same car, ive seen plenty of 95's but none with the 3.4....anyway your problem is in the Idle Air Control Valve, if not that, check your vacuum hoses, and make sure you have no water leaks coming from the block, also you might want to check your 02 sensor and the thermostat, but Im almost positive you need a new IAC, it was 19 bucks at Pep Boys