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Idle Problem

robwright

robwright

New member
Right long time since I have posted a problem. I remember when that was what this forum was all about. Car has started idling rough. Dropping to around 800 RPM and showing really lean on the AFR. Idle adjustment on throttle body makes no difference but when I clamp off the hose from the ICV to the inlet manifold it returns to somewhat normal. I am thinking definitely ICV. Help me out here guys ??
 
Should have said mate. TPS is definitely working. Disconnected and goes into a very high idle as if TPS was not working.
 
I've got an AFR gauge fitted, and my turbo had all the symptoms you've described, I blanked off the ICV, replaced throttle body seals, checked fuel pressure, checked vacuum lines, changed the AFM, and things I've probably forgotten. The only thing that seemed to work was disconnecting the TPS and adding some fuel. AFAIK the turbo TPS has an idle circuit and a potentiometer, I think disconnecting it makes the DME revert to a default setting, so your idle going high seems a bit odd. As you've got Jon's chips I'd ask him for some advice perhaps.
 
The revs will go higher if the TPS is disconnected as if it is not working. It also won't turn off the injectors when coasting because it stays in running map. I have a fuel pressure gauge fitted and that shows good. Preliminary check of vacuum lines looks OK. My thought of the ICV being stuck wide open seems logical hence the really lean readings on my AFR because far too much air is being supplied. Running is perfect as normal. I may even consider deleting the ICV as I only run the car in summer anyway so starting in cold weather is never an issue. Stuart thanks for the offer. Had no time to look at it really because the bread knife has me fitting a new kitchen.
 
Drown the ICV in carb cleaner and it should unstick, if that's the problem. I'm sure you can do that in situ via one of the pipes. I've done it before, although in the end it wasn't my issue, mine was a bad connection to the MAF. Mine was super rich and I thought the ICV may have been stuck shut.
 
robwright said:
The revs will go higher if the TPS is disconnected as if it is not working. It also won't turn off the injectors when coasting because it stays in running map.
Click to expand...
My car runs OK with the TPS disconnected. No lean Idle, fuel leans off on closed throttle, extra fuel added with boost. Good luck finding your issue.
 
Yes the car will run fine with TPS disconnected. That is one of the points of the TPS. When I said revs increase when disconnected it is to a more reasonable idle speed. The car will not coast properly with no TPS though because the DME does not know it is in idle and will continue to run on normal running map. That is what the micro switch does. It tells the DME to switch to idle map.
 
Rob...can you hear the ICV click when turning the ignition on to position 2.....you'll need someone to help with this as you need to be close to the ICV to hear it. If no click then you know it's stuck,..... if so try spraying in some carb cleaner as scam75 suggested..
Pete
 
Or giving it a hit with a stick ?? To be fair I have a spare ICV. When I get done with SWMBO’s kitchen then hopefully I can get to it.
 
robwright said:
That is what the micro switch does. It tells the DME to switch to idle map.
Click to expand...


I know the theory, I gave you my first hand experience. Let us know if you find a new TPS.

 
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