!Gn|T|0n

The 5.0 stings me again. I have an idle problem. I first noticed it a few days ago when I pulled up at a gas station after 2 hours of faultless highway driving. The motor was hunting badly with a rev swing of roughly 500 rpm from memory - perhaps more. It stalled a few times too. There were no problems with the car at all prior to this trip.

Upon further diagnosis it seems that it can take anywhere between 0 and 3 minutes or so after starting for the problem to become evident.

I've replaced the IAC motor and housing and have cleaned and replaced the EGR valve and verified that it opens and closes by applying external vacuum to it. Unplugging the IAC seemed to improve things slightly during the 1st day of diagnosis but now it makes very little difference to the idle. I've cleaned the PCV valve and can hear it clearly rattle. No noticeable difference can be detected when the engine is run with the oil filler cap off.

I've cleaned the battery earth. I've verified that all the leads are firing using a test lamp at the spark plug end but the car seemed to run smooth(er) when each cylinder was tested. Perhaps the fault wasn't evident when these tests were done as I performed them cold and only ran the motor for a few seconds each time observing that the lamp was firing. I've cleaned and roughly checked the gaps on each spark plug. I've also cleaned the dizzy and rotor arm. Lower TPS has a dynamic range of 0.75Vish - 4.2Vish and the upper TPS has a dynamic range of 0.8Vish - 4Vish. Swapping the TPS plugs over makes no difference.

The hunting is like a lumpy cam... quite periodic actually with a frequency of about 2 "surges" per second. It even hunts / surges at slow driving speeds. The fault is not constant. I can pull up at a set of lights and it will sometimes idle well, sometimes a little rough but mostly quite poorly.

There are no new KOEO codes (I still get the MAF and EGR codes I've had for some time) and I can't seem to extract slow KOER codes, only the fast codes so I need a reader. I don't know why this is. I discuss my inability to extract KOER codes and the two KOEO codes in this thread.

Weird observation during EEC-V code extraction

Any ideas? Temp sensor?

Thanks.

PigDog

It sounds like your tps is over 1.00 which causes the engine to think the throttle is open at idle and dump in fuel, but you say you already checked that..

I sorta lost track of this forum for a bit, since the manifold change are you still using your stock injectors?

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svo347

I take it your using a FMS 65mm t/body?
If so you'll have to remove it & drill a "Small" hole into the butterfly, Im talking about a very small hole here, I once had the same problem & tis been fixed for sometime now

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Rollin

he has a T/B from an XR8 Sprint...we fixed the problem today, kind of embarrasing that it stumped me considering the fix :S i will let igntion tell teh story, he has a much more interesting way of telling the story IMHO :s6:

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dodgie

Did he forget to plug the MAF in?
I did this the other day....and Im a dick.

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ED Fairmont Ghia 5.0L

!Gn|T|0n

Almost.

One of the clips on the MAF plug had broken off and the plug must have sagged enough during my long highway stint to break electrical contact whilst still appearing to be plugged in upon visual inspection. I feel like such a thunder-turd. Rollin was kind enough to let me bring my car into his work yesterday for a look-see and how red I was when a holden tech took all of 4 minutes of playing around to fix the thing. At least it sounded tough on the way in! In my defence, the "MAF voltage low or grounded" code which may have normally been a give away has been logged by the computer before without any drivability issues at all... Perhaps it had briefly broken contact before causing the fault to be logged and little more. I had assumed it had something to do with my use of 55mm MAF electronics on a 70mm aperture and had not diagnosed the cause further.

... perhaps the sonic boom I created on my way back from the coast was enough to permanently dislodge the plug.

Rollin

ROFLMAO!!!!! was that while you were racing a certain white NL whose owner kept insisting it's a six!"?

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