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Slowing down stumble


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Hi All, 

As I've got my car back on the road, after a recent engine rebuild etc, everything works OK. However sometimes, when slowing down, before coming to a complete stop, while still in gear, the engine may stumble and stall. I restart the engine, keep driving and all is OK. Before the rebuild I don't recall that happening noticeably. 

I was told that it may be a IAC (Idle Air Control) valve issue, it may need to be replaced. Can somebody please advise on this problem and if it's related to iAC? 

I can provide more information on what has been done on the car during the rebuild. However the IAC is original. 

Please advise, thank you in advance. 


'95 Esprit S4s

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  • Gold FFM

Yup could well be. Rockauto is the place to get a replacement - about £20 and shipping only takes a few days.

before that though - it’s be worth plugging into a pc and resetting the ecu and doing a relearn cycle to see if that changes it. Also check the TPS is set correctly - that’s important 👍

Only here once

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Hi All, 

Thanks very much for your help! I have some further questions:

1) What's the procedure to check if IAC is working correctly (or not)?

2) Same question re: a procedure for TPS? 

BTW, I checked that Freescan has some TPS data; at least there is a TPS column in the csv log dump file. 

Please advise, thanks very much. 


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  • 1 month later...

Hi - my S4S did this after work on it - battery disconnected etc. It was just the ECU relearning and self remedied after about 20km or so......don't disconnect battery and keep driving.....I hope your problem is the same as mine

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