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Hesitation issue...

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Hey guys,


Having trouble with the engine on my 94 Z.


The engine is struggling to rev properly. When accelerating it struggles to reach/go above 2500rpm. When in neutral it will reach around 4000rpm and will start to miss/splutter pretty badly anything past that. Unfortunately I had to drive the car like this 100 miles as I was away at the time.


During my drive back, the issue got steadily worse to the point where the car was struggling to hit around 1600rpm. Once the engine has cooled down, it's back to trying to get to 2500rpm.


Any ideas?


I have already tried replacing the MAF, PTU and disconnecting the TPS today with no effect.


Cheers lads!

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It sounds like a throttle position sensor issue (ie, it needs adjusting, not just cleaning of the contacts). Do you have access to ConZult or anyone with it near you? There is a way of setting up the TPS via voltmeter.


Just as an added note, it idles without any issues and doesn't sound rough at all until about 2500rpm. When accelerating anything past this it will judder and hesitate like hell.


I did disconnect the TPS completely - wouldn't this have made some sort of difference to how it was running when I did this?

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yeah, good call....


but if it's not then these might help...










also make sure you check all connections for corrosion and good contact (and clips) and do a Boost / vac test...


make sure you check the PTU relay as well.. (main engine bay fuse box marked EGI)

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Also worth a quick check - Unplug your MAF under teh nose cone. may find it is the sensor going faulty. Although the car will be limited to 2.5k when unplugged you may be able to notice a different - or borrow someones MAF locally?


I've already tried fitting a spare MAF buddy. Doesn't seem to have resolved the issue and the car still acts strangely when in limp mode.

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So, the problem is back again after an hour of being turned off. Checked all of the tension leads again but no luck.


The car was running perfectly for the 30 minutes or so we were testing it. Turning it off and coming back to it an hour later and back to having the exact same issue. Car when cold will reach 3000rpm normally, this gets progressively lower as the car warms up and eventually can't even get to 1300-1400rpm.


Checking coil resistance tomorrow - does this sound like it could be the issue?


When the car was working okay earlier, it literally didn't miss a beat for about half an hour. Can't think of what it could be.

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sounds like its coil pack related if playing with it made a difference. try measuring the resistances but it could be breaking down under temperature and be difficult to trace the duff one.


strange how it struggles so much to reach over 1.4k. Even running on 4 or 5 cylinders it would reach that easy enough.

does it sound like its running on less than 6 cylinders or is it smooth but not revving?


sounds like you need a conzult on it to see exactly what is coming in and going out.

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Well to start with it's smooth up until about 3-3.5k but as time goes on over a short period it gets worse. Above that it immediately starts sounding rough like a switch and refuses to go any further. Possible it could be firing on less than 6 cylinders but I'm not really sure what that would feel like

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Okay, so this problem is now quite a bit stranger.


Had a good look at it this morning, checked earths relays unplugged various sensors etc. Car was running perfectly, thought I had sorted the issue.


So, I stop the car then start it again and it starts missing again, at around 2000rpm. What would cause it to run perfectly, then turn the engine off and on again and start missing again. As I said the RPM gets lower that the missing starts the warmer the engine is.


I am completely lost here. Is there anyone in the Telford area that would be willing to pop over and give me a hand? I would really appreciate it.

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