High Idle And Blocked Off Iacv Hose On Mpi
#1
Posted 17 April 2017 - 07:56 AM
My 1997 MPI has for some time now suffered with a high idle once the engine gets hot. It idles fine on cold start up, my usual method to remedy when driving is to lift the clutch a little in traffic but realise this isnt a very good way of solving the issue.
Have seen that the iacv might need a clean so was tinkering around with this when i noticed that the hose leading from the throttle body to the iacv had been taken off the throttle body and plugged with a dirty great bolt. Am i right to presume this has been done to bypass the iacv as the previous owner may have been to tight to sort it out if it is shot or couldnt be bothered to clean it?
I removed the bolt and reattached the hose to the throttle body, started her up from cold and the revs went through the roof, up to about 3500-4000rpm. Took the hose off again and and put the bolt back in to the hose and the revs went right back down to normal, just bellow 1000rpm.
Left it a while to heat up and right on cue when it was hot and i accelerated a little the revs started to rise and settled higher at somwhere between 1500 and 2000 rpm at idle. From what i have read on here so far am i right to presume an air leak of some kind? It has original plastic throttle body so maybe warping allowing air in when the engine gets hot? Electrics seem fine, no chaffing.
Please point out if ive missed anything or you can suggest anything else but im looking at cleaning iacv, if problem remains that it shoots to 4000rpm on cold start up then replace it. Also, swapping out plastic throttle body for new metal one?
Any help or suggestions would be very much appriciated on my iacv and thottle body issues and thanks for the patience of an MPI owner harping on about this seemingly common problem!
#2
Posted 17 April 2017 - 08:28 AM
big issues here. ive not read the whole post, but just the fact that the iacv is plugged off is a good indicatorthat there are issues with this one.
all i can suggest at this point is to put everything back to original, chase out any other bodges, get hold of a diagnostic service tool and get back to us
edit, replace the iacv and then get back to us
Edited by Sprocket, 17 April 2017 - 08:29 AM.
#3
Posted 17 April 2017 - 09:41 AM
#4
Posted 17 April 2017 - 10:02 AM
Edit - heres a photo of the offending bolt bodge
Attached Files
Edited by cheshuntmini, 17 April 2017 - 11:17 AM.
#5
Posted 17 April 2017 - 02:41 PM
My money is on air leak somewhere -
check for cracked hoses & inlet manifold gasket leaks
or cracked throttle body
best of luck - hope it's something cheap / easy
also is their a whiter spark plug than the rest ? (sometimes indicates which side the leak is on)
Edited by sledgehammer, 17 April 2017 - 02:54 PM.
#6
Posted 17 April 2017 - 05:20 PM
#7
Posted 18 April 2017 - 08:19 PM
#8
Posted 06 May 2017 - 09:26 AM
Replace the iacv with a new one from minispares turned over the obligatory 3 or 4 times for the car to sort itself out and all was looking good....until i tapped the accelerator pedal and boom the revs shot up to 4,000rpm! Turned off and on again the the iacv sorted it to a nice 850rpm on idle as it should. Took it for a little drive and boom, once again the revs were shooting up every time i pressed the clutch to change gear. I checked for any sticking of the accelerator, none present. Why else is this happeneing?
Please assist if you can as my knowledge has completely run dry.
Oh and i have reattached the hose to the throttle body too (the one that had the bolt blocking it before!)
Thanks in advance!
#9
Posted 09 May 2017 - 01:41 PM
I am wondering that with all the other "adaptations' that this engine has had, if someone has adjusted the throttle stop on the throttle body. This needs to be adjusted with a diagnostic tool. It is critical as it gets the airflow with in range for the IACV to do its work. The IACV needs to make adjustments within a certain range of "steps."
Now that the IACV has bee replaced, the diagnostic tool is the next step.
#10
Posted 10 May 2017 - 10:22 AM
#11
Posted 10 May 2017 - 02:24 PM
Just make sure the garage has the correct diagnostic tools for the Rover MEMS 2J ECU used in the MPi.
The service reset and adjustment components are only available in a few of the diagnostic tools, like the the original Rover Testbook, SP ACR and Crypton ACT.
Other diagnostic tools may connect, but the information may not be accurate.
#12
Posted 18 May 2017 - 02:52 PM
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