11 replies to this topic

[cheshuntmini]

Hi everyone, i understand that this topic has been discussed lots on here but im struggling to find the answer to my particular problem, so bare with!

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!

[Sprocket]

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.

[cian]

Bizzare why someone would block it off as that would only make the problem worse! What about getting another iacv

[cheshuntmini]

Very strange indeed, think the next step might be to get a new iacv. Engine idles well on cold start up with the 'modification' to the iacv hose strangely though!

Edit - heres a photo of the offending bolt bodge

Attached Files

•  20170417_121601.jpg   62.02K   13 downloads

Edited by cheshuntmini, 17 April 2017 - 11:17 AM.

[sledgehammer]

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.

[cian]

That's a new one on me! I've a good used iacv in stock if your interested

[cheshuntmini]

Thanks cian for the offer, popped into minispares on the way home from work (very handy that its nearby!) and picked up a new one from there, ill update on the issue when i can fit it! Thanks again!

[cheshuntmini]

Hi all, update on the iacv sitch.

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!

[tmsmini]

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.

[cheshuntmini]

I agree...it was steady as you like all be it reving its plums off! Sending it in monday to a garage so hopefully that will sort it out! Thanks for all your help so far!

[tmsmini]

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.

[cheshuntmini]

Hi all. Thanks for all the input and advice on the problems my car has been having. Got it back from the garage today and the inlet manifold was the issue, cannot pinpoint exactly what but new one has been installed and it runs like a dream (for now!) Lets see how it deals with this weekends L2B!