well now i am the proud owner of a 91 tt 2+2 which i picked up on saturday and overall i am over the moon with but the problems have started allready? it has got 12 months warrenty but i live in the middle of nowhere and a fair distance from the garage i bought it from so with some help you lot might be able to point me in the wright direction...first problem is when hot the car has failed to start twice...it fires up eventually....the second prob is when on idle if you just touch the throttle and i mean just touch...the rpm falls ever so slightly "200 rpm" and there is a click around the engine when you do this..and finally when you give it some stick in third it gets to about 3500 rpm and then sometimes does not want to rev any higher virtually stalls but continues to accellerate in fourth? are these all linked or what any suggestions much appreciated?

 

done a bit of thinking and the motor has had a new timing belt? reading a previous misfire query this maybe the case for mine? any suggestions..

 

Your hot start problems could be down to fuel vapourisation. Z's don't normally suffer from this because they have a vacuum operated fuel pressure regulator. This might be your first point of call. Secondly, it could be a blocked fuel filter.

 

Next, your rev drop out could be the throttle position switch (TPS).This might need adjusting and you need a Nissan consult to check this. It should read 0.44v at idle. Alternatively, the connectors could just need cleaning.

 

Your 3rd gear acceleration problem could be safety boost. The ecu may detect a problem, ie. detonation sensor, and then cuts the boost level to a safe maximum of 6-7psi.

 

OR

 

This could be a problem linked with fuel pressure regulator.

 

Your warranty should cover these but if the company you bought the car from are just a trade dealer then your probably best getting a report done by a technician who knows the Z and has access to a consult.

 

Steve

 

thanks for the reply.....its has had a new fuel filter when it was serviced last week......boost could be a problem?how do you rectify,by adjusting the actuator??is the tps on the end of the throttle body small black box? i do not really trust anyone around where i live all apart from a mitsibishi dealer they service 3000gt's they might have some idea.....cheers

 

 

This one might be a shot in the dark. Is the fuel filter fitted the right way? ie. flat end towards the front engine direction.

 

The TPS is the little black box on the end of the passenger side throttle body.

 

Steve

 

I have this as an ongoing problem as you have probably read on the postings.

I am having a new timing belt fitted on Thursday and they are going to check the TPS at the same time. Please bear with me and I shall post my findings once the new belt is fitted.

Cheers

Stuart

 

thanks for the replys......yes the filter is on the right way checked it today...i went round all the conection blocks i could find yesterday and cleaned them and coated them with WD40 since then i have not had the hessitation problem "yet?" got to work today and there was a stong smell of petrol could not see any leaks though...but it has been raining ever since i have bought the car so its a bit hard to tell.....still getting what i think to be over boosting got to get it sorted.....cheers....

 

Hot start problems are often caused by a faulty fuel temperature sensor. The ecu thinks the engine is still cold and puts too much fuel in the cilinders. Check for corrosion on the connector of the sensor.

 

As for the fuel smell, check for leaking hoses between the fuelrail and the fueldamper and regulator. Try to tighten the clamps a little bit more.

 

the car has gone to the doctors today? will know tomorrow what the verdict is?

 

 

Mines gone in today to have the timing belt fitted and the TPS checked so hopefully this should solve the problem. Will let you all know later.

 

Here's my verdict;

 

jizz, you have a siezed turbo, probably on the driver side as these normally go first.

 

Stu, your cambelt replacement and TPS check up will not cure you hesitation.

 

Sorry to be negative fellas but this is just

IMO

 

Steve

 

Well if this doesn't cure it I have no idea what it can be. So far I have had:

Diagnostic check-found nothing wrong

New Power Transistor-old one died anyway

New plugs

swaped coils with another Z to check

Fuel pressures checked

New fuel filter

New PCV valves and pipes

New pipes where neccesary

compression check

I don't have much left to check but if you have any ideas Steve they are most welcome.

 

Let us know how it runs after the cambelt change.

 

I am giving this some thought but I'm not saying my opinion is correct! :-)

 

Do you know what condition your battery is in? The coilpacks take alot of power when they are providing spark under boost/load and it is possible the battery is not up to the job. The alternator cannot supply enough power by itself.

 

Steve

 

The previous owner had just fitted a new battery as I have the receipt in the history, it's also an extra heavy duty one.

The confusing thing is the car runs perfect past 1800rpm and pulls like mad with no hesitation right upto the red line.

I found an article on a Z owner in New Zealand that described exactly the same problem and had done all the same changes as me and his turned out to be the timing belt fitted wrong causing a misfire in a specific rev range. I don't know if the belt has been done and mine has just done 64K so I figured it needed doing anyway.

 

Stu, sorry I was thinking for a minute that your misfire was at the other end DOH!

 

Ok, here's another go.

 

The TPS voltage should be 0.44v as my previous post. This tell the car to be in idle mode where the AAC takes control of the air supply.

 

When the TPS voltage increases to over 0.46v the AAC is longer used and the MAS voltage is taken and used by the ecu (Henri or Adrie correct me if I'm wrong here!)

 

Therefore, if it's not found to be your cambelt causing the problem it must be linked to TPS, AAC and MAS co-ordination.

 

Steve

 

MAS being MAF

 

Steve,

 

I think you'll find the voltage should be between 0.45v and 0.50v for idle (acceptable tolerance) going all the way to 4.0v at WOT.

 

Anders

 

Thanks Steve, fortunately the guy who works on my car also has a Z so we swap parts to try them which is a great benefit.

The timing belt is done but hasn't solved the problem so the only thing I can think of thats left is the TPS?

 

well the car is back from the doctors and at least i know what is wrong? well sort of? first the car has several fuel leaks around the engine,thus when hot finding it hard to start and my 3500 rpm rev limit is down to the wastegates not working,they work when moved manually but on the road not at all?the car at the minute is producing way to much boost.apparently below 4000rpm the car can take as much boost as it likes but above this rpm there is a sensor that detects the boost presure and if it is too much it sends a signal to the ecu to cut the fuel until the pressure drops?and the rev drop at idle is down to the TPS,i have got to take the car back on tuesday to have all the fuel hose's replaced and the wastegates sorted out,also the idle will be sorted aswell,will let you know how things turn out?

 

i also found out a bit about the TPS apparently it sense's when for instance you are slowing down from say 3000 rpm the TPS sense's that you have closed the throttle,but the engine is still turning at a fair rate so it cuts fuel to the injectors until such a time that you need it again ....so as you are touching the throttle if this TPS is not set up correctly it can cut the fuel for a split second and there is you stumble in the rev range at idle..well so i believe anyway?

 

Oooops! DOH!!!

 

For those of you reading my post above and think I've gone completely mad. (your probably right)

 

jizz, I was referring to vijay when I mentioned a seized turbo. (see other post by vijay about 0-60 to long)

 

Just to put the record straight!

 

Steve

 

 

 

for anyone that is interested,i got my car back today........with new fuel pipes and now working wastegates? sombody in japan had removed what looks like a boost switch of somesort? and totally disconected the wastegates....so anything above 4000rpm and the computer was shutting the fuel off,before it blew up....but now it is all piped up as it should be and it revs all the way to 7000 with ease....and it now stars from hot aswell?....a job well done i think...