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NJ 3.0lt idling high

Posted: Sat Dec 11, 2010 4:46 pm
by hudson44
Hey boys, its been a while. I'm having drama's trying to get my 3.0lt Paj to idle below 1100rpm. I have tried replacing both the IAC and Throttle body. The IAC tests ok and is working as it idles up with steering and A/C. I have heard of the wax pallet within the throttle body playing up and i have replaced this with another one from another engine but to no avail. (that's not to say they are both not faulty). I am thinking maybe the ECU is my next port of call? I have set the base idle screw as per factory specs and the idle air screw is wound all the way in. I have poured water over the throttle body etc and that is indicating no air leaks. Has anyone come across this before or have any suggestions?

Re: NJ 3.0lt idling high

Posted: Sat Dec 11, 2010 5:51 pm
by -Scott-
hudson44 wrote:Hey boys, its been a while. I'm having drama's trying to get my 3.0lt Paj to idle below 1100rpm. I have tried replacing both the IAC and Throttle body. The IAC tests ok and is working as it idles up with steering and A/C. I have heard of the wax pallet within the throttle body playing up and i have replaced this with another one from another engine but to no avail. (that's not to say they are both not faulty). I am thinking maybe the ECU is my next port of call? I have set the base idle screw as per factory specs and the idle air screw is wound all the way in. I have poured water over the throttle body etc and that is indicating no air leaks. Has anyone come across this before or have any suggestions?
Hi Gabe - wotcha bin up to?

Have you considered temp sensors? If the ECU thinks it's cold, would that make it idle high?

Re: NJ 3.0lt idling high

Posted: Sat Dec 11, 2010 7:13 pm
by hudson44
Been busy Scott. Bought a new house and just had our 3rd (and last) kid. The old Paj has been a little neglected. She needs new rubber, so i'm going up from a 32" to a 33" on a 15 x 8 rim with 0 offset. Am tossing up between the KM2's and the new MTR kevlars. I want to get her back in ship shape form and get back out there again...

I think you might be on to something there. When i think about it, it has idled high since i put the new jap import motor in, and the coolant temp sensor is about the only thing i didn't use from the old motor. I have one lying around. I'll give it a try tomorrow.

Re: NJ 3.0lt idling high

Posted: Sun Dec 12, 2010 2:38 pm
by hudson44
No good. Damn. this one really has me stumped. Anyone in Melbourne have a spare 3.0lt Ecu they can lend me to diagnose?

Re: NJ 3.0lt idling high

Posted: Wed Dec 15, 2010 6:29 pm
by hudson44
Just an update if anyone has any ideas. I blocked off the fast idle valve on the throttle body to rule this out. I was able to set the idle at the desired RPM with more to play on the idle screw. Went for a drive and all was good. Turned it off then on again and what do ya bloody know, Idle at 1100 rpm again. If i wind the IAC motor all the way out by hand (idle at its lowest) and start the car, it will idle really low. Every time i restart, the idle creeps up until eventually it settles at 1100rpm again. I am thinking it has to be either the IAC or the ECU. Anyone got any suggestion?

Re: NJ 3.0lt idling high

Posted: Wed Dec 15, 2010 6:52 pm
by -Scott-
Exorcism?

Re: NJ 3.0lt idling high

Posted: Wed Dec 15, 2010 7:07 pm
by NJV6
I have read somewhere I can't remember where that a poor earth will cause a high idle, and this can be in the ECU....

Poor earth in ECU is my guess but since you didn't pay me its worthless and probably wrong :finger:

Are you able to source another ECU? I have two here that are no use to me as they are quite different to the 3.5's but they are along way from you :P

Here are two companies here in NZ that offer them repaired, its a pretty common thing with the ECU's

http://www.trademe.co.nz/Trade-Me-Motor ... 553608.htm" onclick="window.open(this.href);return false;

http://www.trademe.co.nz/Trade-Me-Motor ... 908093.htm" onclick="window.open(this.href);return false;

Re: NJ 3.0lt idling high

Posted: Wed Dec 15, 2010 7:54 pm
by hudson44
Yeah i will look at getting an ECU Glen. It has a high tide mark on the circuit board from when i drowned it, so I'm thinking if its not shagged now, it will be sooner or later. Damn why haven't they invented solid particle e-mail yet so you can e-mail me an ECU over!