Rough Fast idle
 

Is there anyone in NZ that is prepared to lend me (for a week) a MAF that is a proven good-unit? I have a problem with my '95 -Cold start fine, runs well for a few minutes, -as it warms up it develops a lumply idle -almost to the stalling stage. Hard acceleration fine. Have had 4 different 2nd hand MAF's in it (all give slightly different symptoms), changed the coils, plugs, run injector cleaner. Cleaned all ignition and injector connections. Altered TPS -exchanged fuel pump. Miss not confined to one cylinder.
No black smoke.
Auto electrician has looked at twice -plugged in to OB -no reported errors. Throws no codes.
I find it hard to accept I have had 4 bad maf's, but if anyone described the symptoms to me -first choice bad MAF. I hesitate to spend $$$ on a new one if that is not the problem -hence plea to borrow one. ( I will cover all postage)
regards Don Mac

Re: Rough Fast idle
 

What about the temperature sensor? Runs well when cold and then rough when warm seems to point in that direction.

Re: Rough Fast idle
 

What you need to check first is that the cold start idle bypass valve which is bolted to the coolant pipe isn't sticking open. The way to check this is to pull the pipe off the side of the snorkel when the car is hot, hold your thumb over the pipe and a thumb on the snorkel outlet as well.
Get someone to start the car. Check if the problem still exists.
Next issue could be a crease in the snorkle were it goes onto the throttle body. Single the biggest problem child.

3rd and strangest is there is a breather hose going into the sump of the engine which has 2 pipes coming off it. That pipe cracks down near the sump and you can't see it so as the car warms up the hose flexes letting air in which stuffs up the idle.

Never seen idle go high from a MAF sensor, generally the idle goes high due to air leak.

Re: Rough Fast idle
 

Hi All, and a Merry Xmas and a prosperous new year to you.

After having all sensors tested thrice, a minor descrepancy showed up on the Auto electricians diagnostic gear. It proved to be on Cyl 6 and changing the plug fixed the problem -yeah.
The Auto-el had never seen a spark plug give this kind of error. (fail at no load) -usually the other way round.
Even tho' it cost me several hundreds of dollars (to change one plug) I am still a happy chappie :-). Must take her for a blat tommorrow!!

Mechanics comment -should have resorted to base principles to start with -ie change the plugs as a matter of course. probably have to agree.

Thanks anyway for all the comments here and elsewhere.
At least I know all sensors/airways/waterways etc are up to spec (did all the suggested remedies)
regards
Don McAlpine