Hi recently my car has started to hold back when I'm on boost in first gear
It just feels very flat and only boost's to about .9 bar but second third gear
is OK boosting right up to 1.4 bar only some times holds back in second or third at high rpm and also the idle gets a bit lumpy when hot.
plugs are new ngk 7 with .6mm gap. can this be my z32 maf starting to fail.

 

Not 100% but dont think it'll be your MAF as it would hold back in every gear and wouldn't make it run rough at idle. Could be the lamb. sensor giving dodgy readings hense it being ok then not and cause rough idle. Or it might even be MAP sensor but again dont think this would make it run rough at idle.

I had a problem with my '99 turbo 2000 hesitating under boost and this was the plugs, in fact one of them had come loose in the head! I put some denso plugs in and it cured the hesitation.

 

hi its got new plugs and new coils ?

 

boost solenoid sometimes get oil in them worth checking as this was a problem on my legacy


AllanB

 

You've definately got the correct plugs n gaps? If so I would get the lamb. checked out as these are common on all vehicles.

 

Check inlet manifold for air leaks,If you have vac-boost gauge on tickover you should show 19 hg vac,if it is low- manifold leak-low flickering-inlet valve.Plugs-HT Contacts

 

Same here - I changed my plugs and it sorted the problem.
If your car is highly tuned try shortening the plug gaps - one of my mates had a similar issue and this cured it.

 

what will be the best gap for ngk 7 running 1.4 bar boost ?

 

With that amount of boost, I'd plump for 0.6mm if you're unsure of gnition system's condion. If you have new leads/coilpacks, etc. then opt for 0.65mm.

 

man i could sit and watch your avatar all night!!

 

Your username gives that away

 

Thanks i will try another set of plugs and see if that takes care of the problem
but i still suspect some thing else ?