High idle and hunting. Please help.

[CMF_dreny]

Hi Everyone.

Here is the story. My little K11 was running pretty well until I decided to clean the throttle body and change the spark plugs. I sprayed carby cleaner into the throttle body to make sure it would not do damage.

After doing this the car proceeded to have a high idle (1100 rpm - 1900rpm) but seemed to run ok under throttle.

I read the forums and proceeded to resolder the AFM according to the guide and also cleaned the Idle Control Valve. This did not help but seemed to make it worse as it hunted for idle and rev'd higher.

I adjusted the idle control valve to make it more central within its adjustment as it was set to one side. This lowered the idle but still around the 1100rpm.

I also adjusted the idle screw near the TPS but this did little.

I have ordered a new throttle body with sensors in the hope that this will fix the fault.

In the meantime. Does anyone have any suggestions??

P.S. Can a smaller spark plug gap cause issues like this??

 

[CMF_Danvillan]

Similar problem occurred on here not long ago

https://micra.org.uk/cmf/message/81746

Seems the k11 doesn't like carby cleaner for some reason.

Looks like you tried the suggested fixes, but I'm interested in suggestion as to why this occurs when cleaner is sprayed into the throttle body.

No doubt someone knows why this is occurring.

 

[CMF_frank2]

its not gonna be the plugs eh,
the maf contains a very sensitive heated element, and spraying it with a solvent will probably result in a thermal shock as it evaporates away !

 

[CMF_asdame]

usually suggest
removing the old seized waxstat mechanism off the pre-face TB,
clean & configure the IACV,
adjust throttle cable till its just slack when closed,
adjust TPS,
synchronise the ecu IGN timing with the crank,
and then adjust the idle speed screw.

the IACV is a precision valve and configuring it properly requires a consult software to tell the motor "go to 0deg" and you then adjust the position of the motor housing relative to the IACV body till it just about blocks the flashlight shining though the slot.

http://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-19#post-446256

 

[CMF_dreny]

Ok, I had a bit of a play with the IACV valve today. I adjusted it in small increments and lowered the RPM to around 900-1000. This all seemed to work well until I put on the aircon and the RPM dropped to about 100rpm.

After the car idled for a while it then increased its idle to 1100-1200 RPM. Putting on the aircon again dropped it to 100rpm.

I thing I am just going to wait until I get a new Throttle Body assembly and get someone to calibrate everything properly.

So annoying.

 

[CMF_Danvillan]

I have a secondhand TB if your interested, not sure about the quality of it (was working fine when I took it off and has been sitting around for a couple of months now) but would only want $20 plus postage if you interested. I'm using a SR20 TB so I don't need it any more. Just PM me if your keen.

 

[CMF_dreny]

Ok. I think the problem is solved.

I removed the waxstat mechanism as suggested by asdame and then had another look at the IAC valve. It appears that i assembled the mechanism the wrong way around (180 degree out) so when the AC was turned on the IAC valve was opening the wrong way, giving me a extremely low idle.

After assembling everything correctly the idle sits at 800rpm and with the AC on it raises to 850rpm = perfect.

When driving the idle still seems to sit at 1100rpm when coming to a stop but then drops after a few seconds to 800rpm. This all seems normal and I am happy it is resolved.

Thanks again guy's for your help. I'm having a beer to celebrate.