I've got a 1990 Z32 TT, and in the last couple of days I've noticed that when I touch the throttle at idle (hot or cold) the revs actually drop before rising again. This makes it very jerky moving off, and nearly cut me out once or twice. Normal idle speed is about 1200, revs drop to 1000 or less before rising.

 

It then stopped doing it for a bit, but this morning when I came to start she just wouldn't fire. Starter was running fine, fuel pump OK, but no ignition. I cleaned out the TPS connector, WD40'd various others but no luck. Gave it one last go and she started up, but idle all over the shop.

 

Idle settled down after a few minutes, but with the revs dropping again when I touched the throttle. Then after a few minutes that went away and she's fine (but it was happening when hot yesterday).

 

I've pored through the threads for idle problems, but I'm new to the forum and wouldn't know my AAV from my IIA, or where to find them! I don't have access to a Conzult and my nearest specialist is a couple of hours away, so can anybody out there help please?

 

Cheers,

 

Chris

Well there are quite a few things it could be unfortunately and will probably be down to a process of elimination.

 

When you said you cleaned the TPS, was that just the contacts or did you remove it completely. TPS would be a good starting point and if you have a multimeter it is very easy to check: with the car running you just need to test for a value between about 0.40v and 0.45v at idle and you can do this by sticking the +ve lead from the meter into the middle wire on the grey connector (should be a white wire). If you get a value much higher or lower then this could be your problem.

 

If you don't have a multimeter, get the Conzult on it and check the value with that.

 

Do a quick search on here for cutting out problems, you'll probably find more posts than you care to read on the subject.

 

Gaz

Thanks Gaz, will try that first - I just cleaned up the contacts before.

 

Is that 0.45V relative to Earth, or to the other wire on the TPS? (I guess the latter). And do I check it with the TPS connector on (tricky) or off? Sorry if these seem like dumb questions!

 

Chris

Connector on and meter to earth

Hi Chris, I had a similar problem to this about a year ago on my 1990 z32, would like to mention though m8, your car should'nt be idling at 1200 rpm, it seems a bit high, just a couple of things you can try though if you've not already sorted it, first of all the obvious like your air filter, just check thats its clean, also your engine temp sensor, its at the front of the engine and goes into the water inlet pipe, mine has a yellow plug attached to it, just whip it out and clean it up with some wire wool / brillo pad, this can cause bad problems with idle and also starting, might also be worth running a bit of redex through the tank aswel, just in case you may have any build up in the idle speed control valve, if not pal, depending on where you live , quite a few of the lads in the club do have conzult, and i'm sure they would help you out fella, good luck with it m8, let me know how you get on. :dance:

i had this exact same problem last week, cleaning the temp sender connector fixed it and it was all fine again :) well, until this week and now the Zed wont start :(

Thanks Guys, got nowhere with the TPS coz the probes on my multimeter won't fit in there with the connector on, but the temp sensor sounds likely - just had a new water pump so that sensor was disconnected last week and the plastic connector's cracked. Maybe it's dirty/not been re-seated properly.

 

Will give it a go and let you know how I get on!

You Guys Rock!

 

Just took off the yellow temp sensor connector, it was cracked and wonky and had all the crap in christendom inside it. Cleaned it up and reseated it and now she's running sweet as a nut.

 

Thankz a million!

 

Fingers crossed she still starts tomorrow - if there's one thing I've learned about Zeds, it's that they have an evil sense of humour ;-> :xxx:

nice :)

btw i notice you are in gloucester, you dont have a spare PTU lying around do you? :)

 

(I cant find how to check continuity to be sure mine is nackered so im after one to buy/borrow off somebody.)

Glad you got it sorted fella, your right about the evil sense of humour :)

Just be sure to make sure that its held in place with a cable tie or something similar until you can get a new one!

Sorry m8, that's one of the (few) bits I've not had to replace yet!

 

btw i notice you are in gloucester, you dont have a spare PTU lying around do you? :)

 

(I cant find how to check continuity to be sure mine is nackered so im after one to buy/borrow off somebody.)