A&Q about 350Z
Q:
Hi,
I hope someone can help me here cos I'm at my wit's end!
The problem is on a 90 valver which is modded (gasflowed, 2exh cams etc.)
It ONLY happens 1st thing in a morning when the car is dead cold. If you then leave it from warm (e.g. outside work for 8 hours) and restart it, it's fine. And it only seems to happen on cold days. Was doing it even on mild days originally but tried some things and now it only does it when cold days.
Car starts fine initially but then idles really rough, but if you leave it for 2 mins or so it sorts itself out and from then on it is fine OR if you set off immediately after starting up, as you dip the clutch to approach a junction the revs drop and the car stalls and is a pig to restart (have to press the throttle a little or it won't start)
Firstly I checked the ISV, works fine. I even bought a replacement to double check from ebay (after dealer wanted £240+VAT for one!!!) Replacement was actually worse so not the ISV.
Cleaned all the associated pipework and the ISV itself with brake cleaner. No different.
Next looked ar the WUR. Found some crap in it so cleaned that out and made a slight improvement but problem still persists.
Next set the idle and CO correctly. Asked a garage to set it at 2%. No different.
Next tried throttle cable (although surely it would also do it when warm if it was this). Looked a bit stretched so replaced it anyway. No different.
Next changed plugs. No different.
Next stripped down full intake system. Was a bit of oil in there but nothing major. Cleaned fully. No different.
Next changed the fuel filter in case it was crapped up and ran injector cleaner through the fuel. No change.
Car is always run on shell Optimax /v-power
I have also disconnected the cold start injector which didn't make any difference to the problem but at least it stops it flooding when I try to restart it so it makes restarting a lot easier and less embarrasing.
I am at my wits end with this and can't take it to a garage to diagnose as it would have to be left outside overnight to replicate the problem. If not left outside, it doesn't do it.
Only thing I haven't tried yet is the auxiliary air valve but I'm not sure where this is.
I posted on another forum for help and one guy said to get the car warm, disconnect the ISV and set the idle to 1000rpm. Did this and it did seem to improve things but now the real cold mornings have started to come it's back doing it again
Any assistance would be gratefully appreciated.
Thanks
A:
Anyone?
A:
sounds like a duff wur....or no power supply to wur
you need to get fuel pressure gauges on it and see what the pressure is doing
A:
Thanks I'll have a look at that then.
Cheers
A:
The ISV itself may be fine but have you checked the coolant temp sensor that the ISV control box uses?
It uses one of the three temp sensors on the right hand side of the head looking from the front of the car. The other two sensors are used by the water temp gauge and the ECU. IIRC all three sensors are the same and so should give similar resistance readings. If the one for the ISV has a high resistance then the ISV control box will think the engine is warm when it is cold. I think that is the right way round :D