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V6 surging on idle and drive

944 Views 5 Replies 2 Participants Last post by  7089police
Wifey noramlly drives the V6 so dont get to spot any problems, borrowed it tonight and just noticed that there ia a slight surge on idle and when driving, on idle revs go from about 800 to 1100 then drop back about every 2 seconds, when doing normal town driving if the throttle is kept in a constant position there is a slight noicable periodic surge in engine revs which then fall back, thinking TPS? as they sufer from track wear or idle control valve, any ideas please.
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It could be either of those 2 parts that you mention.
It could also be other things.
Have a read at some of these threads.
KAZUYADOG thanks for the reply, ill have a look at the TPS and valve later today plus the pipe work shes almost ten years old so would expect a little hardening of rubber pipes, i will update ASAP
Ok Update as promised - all hose appear OK one was a little suspect so its been replaced, cleaned control valve and refited, ran engine and same thing either hot or cold, surging from 800 to 1100 every few seconds. After several other investigation have managed to track it down to a particular situation, it is only doing it when the Aircon is on, if there are any other eletrical loads the RPM is rock solid with the aircon off, switch on the Aircon and hey presto the surging is back, any ideas whats casuing it just to be when the aircon load is applied?
I think there is a sensor that increases revs a little bit when the aircon is on,also could it be related to a temp sensor problem.
If it was an A/C sensor would it cause the regular surging as in my case? I would have thought that the sensor would simply detect the aircon being on then ramp up the revs to compensate fo=r the additional load in normal operation or not up the revs if it has failed. in my case it is a very rythmic in cycle, if it is the A/C sensor that is causing the surge it as if it has decided "oooh Aircons been switched on, thats not enough revs, yes it is, no its not, yes it is, not its not, etc, etc" - Man I'm baffled by this one, it did seem like air leaks before i checked the hoses, but now they have been tested and are no longer a suspect in this case. As i said in the original post i can have any electrical load on in any combination, but as soon as the aircon comes on, surge away city.

In what way would you mean by a "temp sensor problem" the engine temp appears OK if it had a temp sensor problem would this not show up in the guage? or would it just manifest itself in this way.

Back to the aircon sensor, can anyone tell me where it is please and if it can be Ghetto tested at all, if it is just sensing the A/C status then it should be a basic on/off swith afair like a reverse lamp switch telling the ECU "more power Scoty, aircons on".

Knowing my luck the A/C sensor will be 2 miles inside the engine bay I'll have to sell one of my kidneys to pay for it and it will be on back order from Frauds until the next mellenium!!
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