Ive been having a problem with the car being down on power, the last week or so. Every so often, it will go back to normal and pull well for a few minutes and then go back to lacking power.

 

I have also noticed that the enginebehaves oddly when the throttle is 'blipped'. The revs will drop for a split second before going up.

 

Also I've noticed that the boost pressure will only go to 3/4s of what it normally would.

 

 

Can anyone suggest anything to check, would the TPS cause anything like this? PTU also?

 

Injectors appear to be OK.

 

Video to follow in a few mins

Here's the video

http://youtu.be/NKQHYPzzrZ0

Sounds like your car is dropping into safety boost mode.

First off try running a basic ECU check using the following guide

 

http://www.zmods.org/index.php?page=ecu_diag

 

I would guess you might get a code 13 with the symptoms you describe. Probably wrong though!

Cheers for the reply, my car has a nistune ECU, which doesn't allow you to flash up codes, as I found when I tried to look! You think it may be coolant temp sensor? Would that be worth replacing as a precaution?

I don't have why having a nistuned ecu would stop you fron getting fault codes. I have one and I can get them. I generally use the data scan or something though.

 

What have you checked so far mate? Slight Hesitation like that is fairly common but could be a few things so might help to advise what you've tried if anything. If you need to start from scratch I'll list some possible for you to try

Any info on the the workings of a nistune ECU and how to read codes would be great as I'm in the dark on that one! Is it an RS 232 lead that's is needed?

 

I've checked the injectors, and one was reading around 20 ohms when hot, so I have changed that for a good one, but the problem didn't change. Coil packs appear to meter out OK, about 0.7 ohms.

 

I will check the plug on the TPS for corrosion. Any advise would be welcome!

 

Cheers guys!

I would generally check for corrosion on most plugs and stuff. Maybe do a boost leak check. If I'm honest, I very much doubt there'd be any fault codes for what you're having.

 

I'm guessing you don't have data scan or conzult or anything?

I find this quite helpful...

http://www.300zx.co.uk/forums/attachment.php?attachmentid=48699&d=1244586707

Does sound like your dropping into safety boost as said above, its possible you have a faulty thermostat that is jammed open and the engine temp is dropping below the threshold and triggering safety boost, this will lower the amount of boost and retard the ignition until the temp rises slightly again and so will full power, if this is the problem it will NOT give a code either, did a tech thread about this in the past see here: link ( back in a second)

 

Jeff TT

Does sound like your dropping into safety boost as said above, its possible you have a faulty thermostat that is jammed open and the engine temp is dropping below the threshold and triggering safety boost, this will lower the amount of boost and retard the ignition until the temp rises slightly again and so will full power, if this is the problem it will NOT give a code either, did a tech thread about this in the past see here: http://www.300zx.co.uk/forums/showthread.php?126426-Thermostat-tech-tip&highlight=thermostat+tech+tip

 

 

Jeff TT

Does sound like your dropping into safety boost as said above, its possible you have a faulty thermostat that is jammed open and the engine temp is dropping below the threshold and triggering safety boost, this will lower the amount of boost and retard the ignition until the temp rises slightly again and so will full power, if this is the problem it will NOT give a code either, did a tech thread about this in the past see here: http://www.300zx.co.uk/forums/showthread.php?126426-Thermostat-tech-tip&highlight=thermostat+tech+tip

 

 

Jeff TT

 

Out of curiosity Jeff, how often is a sticking thermostat likely to occur?

Say 1 in 10 of us or 1 in 100?

Is it a possibility that some people may have this issue and not even realise it?

Out of curiosity Jeff, how often is a sticking thermostat likely to occur?

Say 1 in 10 of us or 1 in 100?

Is it a possibility that some people may have this issue and not even realise it?

 

Its a very common problem and yes lots have the issue and don`t know, as a sort of litmus test when at JAE one year we did around 35 ConZults and 9 had jammed open thermostat problems!!

 

When we do new owner assessments it is one of the items we look for, but my main decider is when doing cam belts, so to date I have completed around 1,400 documented belt swaps, in those at least a third had jammed open stats, of course the stat is changed anyway but as is often the case when done at a "normal" garage the stat remains untouched and hence 24 year old cars with 24 year old stats despite the belt service been done, imperative in my view that any cam belt service includes photo proof, no excuse with digital camera`s these days, unless of course the work has not been done as charged for ??? on a side not I have never come across a stat stuck closed on a zed, not saying it cannot happen but not seen it in 15 years.

 

Jeff TT

Cheers guys, Jeff my car had some work done at zedworld before I owned it in 2010, including Cambelt.

Cheers guys, Jeff my car had some work done at zedworld before I owned it in 2010, including Cambelt.

 

Just looked and replied with the details of work done in a pm, still worth checking the running temp just to be sure on a ConZult.

 

Jeff

Jeff how can you tell if its the thermostat? On a conzult or what ever

Jeff how can you tell if its the thermostat? On a conzult or what ever

 

Yes what you basically looking for is the full working temperature it achieves, should be around 80c typically a faulty stat will see anything between 58c and 68c which can cause safety boost, ( lower boost and retarded ignition) sometimes when the problem first starts the working temp will creep up to 72c and full power will return, however when the extra air passes through the radiator at a the higher speed the temp will drop and safety boost will cut in again and the cycle continues..

 

 

Jeff TT

this is something that i found when i replaced my engine, and in the end i found the culpriut, it was the fact that when i was putting the engine back in i also plumed in a fmic but placed two of the pipes aroud arrse about face. put then were there ment to go and proplem sorted it was like a major air boost leak i guess. u never know.

So after some more tinkering and cleaning of electrical contacts, the car seems to be running much better. The PTU connections were particularly bad, and so I think that may have been the culprit. The spark plugs seem to be quite black, so I will be putting new ones in as a matter of course anyway.

 

There is some black splattery soot from the exhaust, which seems to be unburnt fuel, but as I say the engine is pulling much better now...