Hey all, just wondering possible causes for an irregular idle could be..?

Most of the time it idles fine, but sometimes its at around 2k.. this isnt just when its cold either, I was in traffic, at some points the idle is 2k 2 minutes later its normal..?

Is this anything due to the fact it has a viscus fan and the engine was hot? (never had a viscus before)

I did have some issues a few days ago regarding some bucking and juddering when driving normally, but these stopped during the same journey, I have since cleaned the airfilter too, but in an attempt to take it off sheared one of the 4 bolts (the fixings are all horribly rusty in there), so its possible its recieving a little more air than usual... possibly....

 

What does everyone think?

 

Cheers

 

Sky

Sounds like mine. Does it suddenly go from normal then up to 2k and sit there? And then later without any rhyme or reason back down to where it should be?

That would be an accurate description!

If its because of the viscus requiring more revs to give adequate cooling, I can accept that and just let it do its thing from now on, but I'm just not sure at the moment if thats fact, im still very new to the Z and dont know it's quirks and processes.

 

Cheers

 

Sky

i had a similar issue and it was the idle valve . needed a clean .

i never done the job so i cant offer any advice on how to do . jeff at zedworld did mine and was much better afterwards

Mmmmm I have that too on my 94 uk manual. It seems to hunt a bit then go up and settle down. Strange there seems to be a few cars with the same issue, It must be a common fault so hopefully someone can come up with a solution!

That would be an accurate description!

...

Sky

 

OK. My S1 TT Manual never did this but my S3 NA Auto does it all the time. So far it has stumped three known Zed specialists. Throttle bodies cleaned, all linkages checked and greased. Throttle Position Sensor was checked. There are a couple of valves IACV and AAV which have been replaced, first with s/h and then with new (sometimes they can stick so when tapping one with a hammer sent the idle back to normal, we thought we'd found it. But no.) Then wiggling the water temp sensor connectors did the same so those were cleaned up. Partial success but it all came back a few weeks later.

 

ConZult doesn't show anything.

 

It seems breathing or sensor related. I'm pretty certain it's not the viscous fan. Sometimes when cold in the morning it's gutless and sometimes it's fine and sometimes it accelerates on its own into 2nd.

 

It's in the garage again so if there's a cure, I'll post. Otherwise anyone else got any bright ideas?

Mine does this occassionaly too. The Senators and Carltons I used to have would do this regularly.

 

It was invariably down the the IACV needing a clean out. Fill with carb cleaner and shake vigorously until the stuff that comes out is clean then lube with a bit of WD40 should do the trick.

IACV was replaced with new. Still happens!

right so as an initial check.. throttle bodies should be lubricated, and sensors checked, where are these sensors you've been talking about (im really not familiar with the engine yet), and how should I proceed once i've found them.. removal and a clean up?

 

Cheers

 

Sky

There are squillions of sensors all over the place. The Z32 engine and ECU were very advanced for their day. To get to grips, you'll probably best start with the fault codes for the ECU. Here's a guide to how to get them (or find someone with a ConZult) http://www.zmods.org/index.php?page=ecu_diag

 

And a useful page with pics of where a lot of stuff is http://www.z32photoguide.com/

 

And here's a very comprehensive page of how to troubleshoot and check hesitation/stumbling which gives a good overview of fuel/air type probs, how to clean stuff etc http://www.zhome.com/ZCMnL/PICS/hesitation/hesitation.html

 

 

Good luck :)

Edited July 27, 201015 yr by Gio
speling 0/10 chiz chiz

Hey, thanks very much!

I'll have a good old read then, I do need to do some geeking up on the engine.

I'll let you know how I get on.

 

Cheers

 

Sky

Meant to update this a while back.

Since the fault in the injector wiring was fixed and the injectors themselves were replaced, my strange wandering idle doesn't seem to have come back. Mr F's theory is that the ECU was getting strange signals or not seeing an injector or something when the fault occurred which made it do something that increased the revs.

Not conclusive but a reasonable theory.