1997 v70 10v tick over too high (12-1400 rpm) replaced iac and tps no change, replaced one rubber vacuum connector (which looked a bit perished), no change, with the iac disconnected it ticks over ok, with the new iac in place and the old iac connected to view its operation (as the old one was not faulty)you can see the valve open as it should when throttle is opened, but it remains too far open at tickover (the old one that is) I hope that makes sense, something is telling the iac valve to open up a bit at tickover speed, but what is it likely to be? can anyone shed some light on this please
it seems to me that the tps is working ok (opening the valve as the throttle is opened) so the signal is getting through from the ecu.
Oh yes, throttle body removed and cleaned (no change)
there must be another sensor somewhere which is telling the ecu to open the iac at tickover
any help would be much appreciated
no fault codes stored btw
Thanks
Roger

 

The quest continues, with new parts in place, engine running, idle too high, disconnect iac and idle becomes normal; connect old iac to plug and observe its operation, at idle speed, the old iac is being opened, does anyone know if that is the ecu thinking it is running too rich and therefore needs more air? if it could be, where does the ecu get that information from? bearing in mind that there are no fault codes stored.
I did disconnect the battery and pull the ecus reconnect everything and fire it up with the maf sensor disconnected, tick over much more like normal, reconnect maf and tick over stayed the same, kind of back to normal, that was last night, will try again today to see if things are ok, but, someone must have experience in this area and be able to say 'it is most likely to be.... this or this that caused it...'
thanks

 

continuing this saga, yesterday all I did was to pull the plug on the iac, idle speed went to normal, put it back in and it remained the same, [good good I thought] drove the car last night, I now find the idle speed too low and the car difficult to start when cold, just as if the control circuitry [the ecu] doesn't realise it is cold mind you once warmed up and running ok, it goes fine, and, but, the idle speed is really too slow.
I am beginning to wonder if the temp sensor is duff, ie telling the ecu that it is warm when it isn't giving a too weak mixture, I did have a temp sensor go previously so might have an old one to check resistances with
Roger

 

the new coolant temp sensor in the parts shop had a similar resistance to the old one at ambient temperature so I dont think it is that,
someone must have been down this road before.
Could it be the O2 sensor (I only have one after the cat)4 wire titanium I think
Help, dont know what to think any more
tick over still too low at about 500 revs

 

added new ambient temperature sensor, no different, changed the coolant sensor for an old one, worse, in fact when driving as it got hotter it got even worse, so finally today the new map sensor arrived, I also gave it a new coolant sensor and thermostat for good measure, and so far it is looking good, tickover (idle speed) about normal
will know more tomorrow when I will have driven the car.
It may well have been the coolant temperature sensor, but I don't recall the symptoms being similar when it failer before, however, at the end of the day, to replace what I have has not cost a fortune and probably needed doing anyway, a combination of sensors operating at the extremes of their tolerance could well have been ther problem

 

drove the car this morning and it is still a problem, idle speed too high 1400ish
but it was ok when first started, quite normal in fact,
so something is becoming a problem as it warms up
help,., I'm stumped

 

well here we are again march 2011 and I still have the problem, pretty much everything in the loop has been changed, ecu O2 sensor, coolant, ambient air, throttle position and manifold absolute pressure sensors all changed, and the problem still persists, it remains as something telling the iac valve to open a bit, rather than an air leak
as 360 + people have looked at this thread, presumably others have had similar problems
any help would be very welcome

 

hello many years passed but how did you solve the problem?