Hi, I bought my first ZXTT (Auto) a few weeks ago and I love it. It is running very well, boosting as it should and driving faultlessly with the exception of a slightly strange idle.

 

The car idles fine for exactly 11 seconds, then the revs drop to about 500rpm for 4 seconds then go back up to about 800rpm for the next 11 seconds. Yes you really can set your watch by it!

 

Any ideas anyone?

 

(I have already adjusted the TPS so it is putting out the correct voltage and cleaned the Throttle Bodies which has made a slight difference)

 

Thanks in anticipation..

Welcome to the forum. Sounds like it could be the idle control valve sticking.

Welcome to the forum chap, I had a similar prob and turned out to be twitchy injector and coilpack plugs as soon as i replaced them she ran sweet as a nut.

Thanks very much, I will check them out.

also could be the CAS as well as it seems very regimented?

YAY another Northamptonshire person with a Zed :D Welcome

Welcome matey :) hope you get your problem sorted.

Welcome to the Club :)

Thanks for a very warm welcome, I really appreciate it and thanks for you help so far. I have checked the coil packs by diconnecting them one by one with the engine running (to see if one doesn't make a difference) so I think they are OK.

 

I did discover one of the coil packs not bolted in properly, so I have gently tightened it up.

 

Not sure I have the skill to check out the injectors or the CAS (unless there is an idiot proof and I mean idiot proof guide out there?). May need a trip to ZedWorld.

 

Having said all this, I have just come back from a 30 mile trip and the idling has changed... it is now smooth for about 15 seconds and drops to about 500rpm for about 2 seconds. That's an improvement.

If you think the car will be ok then id suggest a trip to Zedworld, ill be making the same trip soon myself to get the car looked over.

 

Craig

might be worth resetting the ecu?

This might sound odd, and im not sure if its the same as on a 300zx as it is for the pug 406, but when you idle a pug with A/C every now and then it cuts the A/C compressor in, this drops the revs slightly and then the ECU compensates and corrects the idle.

 

Do you hear a click just prior to the revs dropping? could be a stiff A/C compressor clutch problem.

 

although this is just a ball park guess, but might be worth a look with the bonnet open, to see if you can spot what is happening when the revs drop.

Thanks for the advice. I have had a really good listen with the A/C on and off, when the A/C switches on I hear the click but the engine behaviour is exactly the same.

 

It is beautiful to drive and I use it every day on some fairly long journeys so a trip to Zed World sometime would be fine.

 

I have reset the ECU a couple of times over the last few weeks, but not since I adjusted the TPS and tightened up the loose coil pack. I will give it another go later tonight, it may help, thanks.

 

If there is no change, I think I will check the idle control valve as recommended above.

i say the cas as it sounds like my old R32 which ran fine for 30 seconds then just died, turned out to be a bent CAS disc so replaced it and ran perfect :)

Thanks. It never cuts out, the revs just drop to about 500rpm for 2 seconds (now), then it comes back up to around 800 rpm again...really strange. As soon as I drive it away it's really smooth and responsive.

I had very similar symptoms on my shorty.

 

Upon breaking the zed, i discovered that the air flow meter was knackered.

Thanks, I will take a look. I believe the import company replaced it, but I will check.

Hello and welcome to the club as funkysi has said the idle valve control looks to be playing up if you need to have a conzult just call the workshop and we can get you booked in

Jamiett

Thanks, I think I will!