Hunting idle

Scenario: NA to TT rebuild
Problem: As car warms up, idle hunting increases. At normal operating temp RPM varies between 300 and 1500 RPM, with about 1.5 seconds to complete the hunt cycle. At that point the car will die.

TPS is set to 0.44v
Timing hasn't been adjusted yet
Tune is someone else's, but injector sizing is correct.

Need to get this sorted so I can get the car to the exhaust place, and then subsequently to the tuner.

Edit: Advice I have already is that it's the tune at fault, and the tuner will fix it on the dyno.

 

Maybe you should pull the temp sensor wire and see if the car goes into failsafe mode enough to drive.
If you can drive her to the tuner it will be sorted.
Assuming that your diag software (Nikoz or ecutalk etc) is not showing an error code.

 

I have an occasional temp sensor error, but if I jiggle the cable it works. I have a spare sensor, I'll probably change it tomorrow.

As for the tuner idea, that's ok except its about 100 kms to him, so id rather have things sorted a little better. And the last thing I want to do is get someone else to fix something I can do myself.

 

I have an occasional temp sensor error too.
I jiggle the connector. But I know the back half of the connector is broken off, so whenever I experience that idle hunt I check that. You might have the same minor issue.

 

It will be your idle control solenoid, check connections, check solenoid, clean valve. To get yourself going, disconnect idle solenoid and using the manual idle screw, increase rpm to say 800 - 900rpm

 

So, I believe that I have found the problem. The boost line to the EBC was disconnected, which would not have helped, but now that's fixed, I can see the revs drop and then the pump starts up, works for a second or so, stops, then the revs start to drop, then the pump starts up, the revs rise again and so on.

The FPR should handle this quicker I am guessing.

Any thoughts?

 

What do you mean " the pump " is your fuel pump stopping and starting?

Cause it aint spose to do that..

 

Yes, it is stopping and starting, and I agree.

 

If your fuel pump is stopping and starting it is a good possibility a loose/bad connection wire or the relay is shorting out or the pump is giving up the ghost.

Check the wiring/relays first clean and reconnect or try another pump. Could it also be the leveler in the tank.

 

Replaced the pump, bypassed the FPCU, now looking at IACV. Will check ECUTalk

 

This is a bit slow going. Bare with me whilst I wait for the car to cool down. It won't start or run very long when it's hot.
Pulling the temp sensor plug helped at first, but not now.

Can't see any leaks.

 

I had the same weird hunting issue a month ago.

Turns out the ficd and AAC connections were swapped.

(Ficd has a white Male plug on mine and one of my female plugs had tippex on it) figures white plug for white plug. Screws entire engine idle system :lame:

 

I'll have a look the next time I am out there. Mothers day tomorrow, so don't know if I'll get out there tomorrow (worked on it all day today).

 

90%, dropping slightly, and then back to 90.

Interestingly, when I do the base idle adjustment, the hunting stops completely.

 

When I do the base idle, I was right in the middle of the green, around 750.

 

base idle set to low dave !! also be aware that na and TT ficd idle control units are actually different !! the TT one has a larger surface area compared to the smaller Na version !! i had issues with this before with hunting ! set your idle 800 and see how that goes