I decided to go for a run in the car tonight and took it for a blast down the motorway and whilst driving through town on the way back, the revs started hunting when I was pulling up or sat at idle (in neutral and in gear), after a few minutes of this the engine stalled. The car restarted straight away and I drove off but the revs were hunting again and eventually stalled again. It did this several times until I was able to pull into an area that wasn't obstructing the road.

 

I swtiched every thing electrical off that wasn't necessary and after about 5mins, I restarted and the revs seemed to be holding and drove off. About 1 mile later it did it again. This time I switched off for about 10mins, restarted and drove the 5miles home without it happening again. Once home I left it running for a few minutes and the revs held fine.

 

The revs at neutral had been at the 1100-1400 mark this past month, it seemed a bit high but it never hunted. When stationary and in gear the revs were around 8-900.

 

The standard boost gauge is reading as normal. The car was warmed up before I'd gotten to the motorway.

 

Anyone shed some light on this? Fingers crossed it's not something major.

Have you done an ECU diagnostic. Could it be the PTU?

I don't have access to a conzult. the PTU is a series 2 one and fairly new, prob a couple of years old.

Probably not that then! You don't need a conzult to check out fault codes though - http://www.twinturbo.net/ttnetfaq/FAQpages/ECUdiagnostics.html

cheers Dave. do you just count the number of times the check engine light flashes?

If you have access to a multimeter you can check the TPS very easily. With engine running, connect -ve probe to a suitable engine ground [battery –ve] & insert +ve probe into the back of middle wire (white) on the grey connector. If you see a reading of around 0.44v at closed throttle then I'd say your TPS is OK. I believe it should rise to somewhere around 5V with the throttle wide open.

 

Of course if you don't have a multimeter then this won't help :(

 

 

Gaz

thanks Gaz. I'll borrow one tomorrow to check.

You cleaned up your throttle bodies? If you haven't then do it, and while you're at it, pull the hose off the Idle air valve and spray some carb cleaner in there too.

 

Other than that, a conzult or datascan is the way to go. Hook one up, set the TPS to 0.44v at idle, and make sure the 'closed throttle switch' is ON, if it isn't then unplug the connector on the front of the TPS for a short while and put it back on, it will reset.

After that, use the base idle adjustment, and adjust the screw on the side of the IAV so that the rpm is about 650/700. After this, the idle should sit steady at 750 with the a/c off and 800/850 with the a/c on. If it doesn't, then a vacuum leak is likely.

cheers Dave. do you just count the number of times the check engine light flashes?

It'll do a number of long flashes (which is the first digit of your code) and then some short ones (the second digit). No errors is code 55, so 5 long then 5 short. The list of codes is here - http://www.ttzd.com/tech/diagnostictech.html

thanks Clarkey. wheres the IAV on here? http://www.300zx.co.uk/forums/showthread.php?t=26120

 

edit: forget that, just realised the IAA unit is the same thing :)

It'll do a number of long flashes (which is the first digit of your code) and then some short ones (the second digit). No errors is code 55, so 5 long then 5 short. The list of codes is here - http://www.ttzd.com/tech/diagnostictech.html

 

ta