Fiat Coupe Club UK

Randomly high idling

Posted By: X19_pilot

Randomly high idling - 06/06/2018 19:09

On the way to work this morning, as soon as the car got up to temperature, I noticed the revs climb at junctions and stay there as if I had my foot resting slightly on the accelerator, not revving through the roof, just up to 15-2000 rpm (guessing as rev counter not working at the mo)
It also seemed to do it when in gear and crawling in 1st/2nd gear too. Although it was intermittent, sometime a blip on the throttle would see the revs fall to normal tickover, sometimes not.
I noticed it on the way home too, but traffic wasn’t as bad and therefore not as noticeable

Just wondering where to start with this one? Airflow sensor maybe? Someone at work suggested spraying some carb cleaner into the throttle body. Any and all ideas welcome...

Thanks in advance.
Posted By: szkom

Re: Randomly high idling - 06/06/2018 19:33

Idle control valve needs a clean. That said I had issues with the wiring. You might want to try cleaning and reseating the ICV wiring plug, and doing the same with the large multiplug behind the battery.
Posted By: X19_pilot

Re: Randomly high idling - 06/06/2018 19:39

Thanks Sokom thumb

Where abouts is the ICV located? And will carb cleaner do the job?

I will take a look at the multi plug in the morning. Cheers!
Posted By: X19_pilot

Re: Randomly high idling - 20/06/2018 19:02

Since my last post, the car seemed to fix itself for a week, but then the same issues arose.
Having tried a few times to clean the ICV with wd40 and carb cleaner, I ordered a non-oem replacement from eBay, fitted it at work and it doesn’t seem to have made a difference.
I can control the revs if I slow and almost stall in a high gear at a junction, or really rev up through 1st and 2nd gears to clear it for a few more miles, but this is obviously not the way forward and the detour to the road that safely allows 60mph on the usual commute through town is a bit of a detour.

Am I now right to think that it could be a MAF sensor issue? I unplugged it whilst it was ticking over at higher than normal rpm and the revs dropped to normal straight away.
Posted By: X19_pilot

Re: Randomly high idling - 23/06/2018 18:56

MAF sensor has been cleaned, but made no difference. Could an air leak be the cause of this and if so, what pipes are likely to be causing it? There is no lack of power, so unlikely to be a boost related pipe?

Any pointers appreciated as it’s getting to be a PITA detouring to work to avoid traffic. frown
Posted By: Gunzi

Re: Randomly high idling - 23/06/2018 20:08

There are a couple of boost leak How to index.

Common culprit is the large pipe just before throttle body can split on the underside.

I had a big issue where the engine would cut out and it turned out to be an inlet donut.
Posted By: X19_pilot

Re: Randomly high idling - 26/06/2018 05:59

I have had a look for boost leaks, but there’s no lack of power and the car runs fine other than the revs raising up at a stand still.
Could it be a throttle position sensor that is at fault? I am clutching at straws now, hoping to get it down to JBTs in the very near future if I can’t sort it in the next day or two.
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