Ever since I have owened my z, the idle rpm has been fluctationg. I was told this is firly normal. It is gradually starting to get worse. I have notice the the rpm will fluctuate about 100RPM and any set RPM now, which it never did before. I was thinking this could be a problem with the throttle position switch, mine has been adjusted full one way to obtain a resonable idle as well. Nobody seems to be able to tell me why this would have been done. I was thinking it may be a vacuum leak as well, my engine seems to all ways run rich, and when the throttle position switch is moved to the correct setting the car won't idle below 1200 RPM, and the idle valve is at 60%, with conzult you can manually adjust the idle valve and the car will idle fine. Anyway is there any way to really test the car for a vacuum leak, like pressurising the maniflod? If anybody has any ideas it would be helpful. Thanks Jamie
If you have access to a conzult.....>> You should be able to correctly set your TPS so that it reads the desired ~.45volts. Adjusting the TPS to adjust idle is common metod of people who have no idea what they are doing to the car. I would suggest you do the following things in the following order. Check for boost leaks and fix any you find. Correctly set the TPS Unplug the TPS to allow the ECU to reset the idle position. Adjust the timing using the "base idle adjustment" feature of conzult. That should go a long way to fixing your problem, but if it persist, then there are a few more things you can try.
TPS part no.'s Do you unplug (both conectors?) with the car running or turned off. I romved my TPS to check the part no. after some reserch told me that NA's and TT'S have different TPS'S. the part no. opn my unit is A22-625 921, the part number I found for my car is 22620-12G11. Do these part no.'s align or is my car fitted with the wrong TPS.
You disconnect the grey plug....>> with the three wires that is slightly away from the TPS, not the one that plugs directly to the end. I always do it with the car running, although you could possibly get it to work with just the ignition on (not sure on that). The number writen on the unit is most likely the manufacturers part #, as the units are made by JECS for Nissan. The number on the back of a spare one I have lying around (from a TT) is A22-649 M00. If any body else can find a number then we might be able to see a trend.
i've also seen a fairly extensive tech document on the various causes of idle problems, but I don't have the link handy. might be an idea to add the link to that document into the Technical section if anyone has it.
Had the same prob with my Z Hi Jamie, it may be an unrelated problem but my TTZ had similar fluctuating revs at idle - especially when it was cold, but a thorough throttle body clean fixed it. I also replaced a couple of my Injector wiring connectors as well because they where quite corroded (as many imports are) so that may have helped as well. Anyway, they fixed that problem....
Re: i've also seen a fairly extensive tech document on the various Twinturbo hesitation FAQ Steve Chong There's a lot more but these are a great place to start
