My GL10 has become possessed. The car runs fine in driving mode but when I come up to a red light, the car will start idling at 2500 rpm. If I quickly hit the gas, it will drop down to 600 rpm, sit there for a bit then go back up to 2500 rpm. When the car is idling (for a short period) at 1000 or so, the engine is shaking a bit like it is idling at 600 rpm. There were some suggestions to check the hoses for leaks or that there could be a vacuum leak. This all started pretty suddenly. I noticed a tiny bit of something burning or exaust emitting from under the engine. I'm going to check again to see if I can locate it. Any thoughts on the rpm thing? I tried to adjust the rpm adjust screw just under the turbo pipe but it doesn't seem to make a difference.

Is your crossover piped cracked? Maybe it cracked right where it connects to the turbo.

Is your crossover piped cracked? Maybe it cracked right where it connects to the turbo.

 

Would that cause the idle to be so crazy? I'll take a look at it, thx. Where do I find that? Is it the Turbo pipe that run overtop everything?

 

thx in advance,

Simon

any exhaust leaks before the O2 sensor (immediately after the turbo) will cause a funky idle pattern - it causes the O2 sensor to get funky readings and therefore it causes the ECU to screw around with the engine's fuel/air mixture - check for exhaust leaks using the method of your choice, and if you find any, they are probably what is causing your problem

if you have a vacuum leak, your hvac will be screwed up too. you wont really be able to control where air blows from (ie: floor, vent, defrost). i read in a book if this happens, the default is supposed to be the defrost vents, but i had a vacuum leak in the buggy and iirc, it blew air from the regular vents.

have you tested the aux. air control valve?

 

This valve is what the ECU uses to control the idle when

 

the engine is cold.

 

Mounted on the upper rad hose "goose neck"

 

It has a line going to the intake manifold

 

pinch this line closed when it is idling high

and see if it affects the idle speed

 

There is also a idle speed compensator used

when the AC is on.

It compensates for the drag from the compressor

the reason why its rough at 600 rpms is because thats 200 rpms lower than the reccomended idle. the firing and ignition of the motor becomes inefficient which makes the rough idle.

 

I'm with 85Sub4WD on the exhaust leak. We had a turbo at work that did that.. changed out exhaust gaskets and turbo gaskets, problem solved.