Topic

I know there are a number of threads on this subject, but this might be a different problem.
TF is a 115 that had a water leak from the manifold gasket and has been cured with an alloy one from a 135. Complete manifold was used with the blue injectors but the throttle valve ,IAC valve and wiring loom were swapped from the plastic.
Engine started easily and warmed up, after a few seconds it started hunting between 1000 and 1250 RPM when fully warm it still hunts.
Tried IAC valve reset no difference
Tried disconnecting IAC valve when running still hunts
I noted the the carbon filter is ticking??
Idle speed used to be 850RPM solid
Fluctuation is rythmic and not random
Any suggestions much appreciated

Edit
Battery had been disconnected for about three weeks

Throttle position sensor reset, then replace IACV valve or clean it if its an older one.
Then I would start looking at the pre and post cat sensors. A plug in diagnostic may help.

Sundance

Hi Sundance
Thought about the cat sensors. Disconnecting the IAC valve makes no difference and the hunting continues. I've reset the throttle sensor by turning key to position 2 depressing the throttle 5 times waiting 15 seconds then turning off. Hunting remains.
I have a suspicion that the problem was there before I changed the manifold etc and all I've done is make the problem worse. The idle didn't seem to be rock solid but varied a small amount.
Tomorrow I'll put the original injectors in (if they'll fit) as they are the only component not transferred from the plastic manifold.

It sounds like you have an air leak

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Also check that the throttle body butterfly is returning to closed position. e.g. It is not being held open by a tight throttle cable.

Try disconnecting the cable if you are unsure.

Ian S3 wrote: wrote:

.....I've reset the throttle sensor by turning key to position 2 depressing the throttle 5 times waiting 15 seconds then turning off......

IIRC you should do the five depressions within 30 seconds, wait 30 seconds, start the car.

David Aiketgate wrote: wrote:

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Also check that the throttle body butterfly is returning to closed position. e.g. It is not being held open by a tight throttle cable.

Try disconnecting the cable if you are unsure.

Or it is sticking due to dirt, happened to me.

Changed injectors back to the original black, checked for leaks, started up and ......exactly the same problem.
Reset iacv exactly the same

I think there's an airleak resulting in the high idle and the mems is bringing the speed down by backing the ignition timing off and then returning it to the mapped figure. This would cause the rythmic hunting but.....

Whole manifold off tomorrow??!! hi

Problem solved.
Used the Torque pro app this flagged 4 faults cleared faults ran engine and then checked faults.
App reported tps and cam sensor faults
Swapped plugs around problem solved!!
Why aren't the plugs different??