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!

I'd put my money on the MAF or CAS anything else would be a constant problem.... this is intermittent

I'd put my money on the MAF or CAS anything else would be a constant problem.... this is intermittent

 

half agree with you... those two aren't the only things that can cause intermittent issues.. :) particularly as warming up.. could also be the IAA system...

 

I've also and intermittent issues that were due to vac/boost loss but only some times...

Thanks guys, I really appreciate the help.

 

The thing that makes the problem strange is the fact that when starting from cold, I could run the engine for hours perfectly. It's only when it restarts from warm that the problem occurs. The car is difficult to start when warm, idles perfectly then starts stumbling/hesitating at RPM above about 2500rpm or so.

 

I have already replaced the MAF, and checked the filter etc. I have checked the relays and the contacts seem good. I have checked the contacts on the TPS, PTU (I will be trying a known working PTU tomorrow morning) and the small sensor on the metal pipe at the front (couldn't remember the name.).

 

As I say, the strange thing about this is that the problem doesn't introduce as I'm driving. It's only when I restart the engine when hot/warm.

that does sound like injectors to me (from what I've heard on other posts)..

 

might be time to so a full check on them (resistance) and balance test...

 

FSM will give you the correct readings.

that does sound like injectors to me (from what I've heard on other posts)..

 

might be time to so a full check on them (resistance) and balance test...

 

FSM will give you the correct readings.

 

Awesome, thanks for the help. This gives me a more solid direction to look.

The ptu is known to cause starting problems when hot, could also cause irratic running as it controls the signal to the coil packs.

 

At first i thought MAF, injector terminals can cause misfire and lumpy running and loss of power, but would be constant rather than when warm.

I would change out the PTU at least to eliminate that end of the coil pack.

The ptu is known to cause starting problems when hot, could also cause irratic running as it controls the signal to the coil packs.

 

At first i thought MAF, injector terminals can cause misfire and lumpy running and loss of power, but would be constant rather than when warm.

I would change out the PTU at least to eliminate that end of the coil pack.

 

I do have another PTU, so I'll go ahead and do that as it takes seconds.

 

The thing I find odd about it though is the fact that if I start the car from cold, it seems completely fine and stays like that until I turn the engine off and start the car again. Any idea why this would be the case?

The only thing that springs to mind for that scenario is the aicv. When cold the ficd acts as a choke and once up to temp it turns off, so could have a sticky ficd (fast idle control device) which is attached to the aicv. To do an initial test when the engine is warm turn on your ac and see if the revs change or you hear a click.

The only thing that springs to mind for that scenario is the aicv. When cold the ficd acts as a choke and once up to temp it turns off, so could have a sticky ficd (fast idle control device) which is attached to the aicv. To do an initial test when the engine is warm turn on your ac and see if the revs change or you hear a click.

 

The revs do change, I have noticed this earlier. They increase.

You could do with plugging in to consult or datascan, if its electrical it should give you a more definitive place to look

Thanks groover. I'm thinking of taking it to Jeff, he is pretty close by.

 

I took out my coils to give the plugs a once over because after restarting my engine warm this morning it was firing on five.. I noticed one of them was different to the others. Most of the coil packs on the inside had what looks like a spring they use to make a connection to the plug, but one of them looked like it had a black nub. Is this what they're meant to be?

They have a spring with a tip on the end akin to a bush in an alternator to make contact, have you pinpointed which cylinder is down?

 

Dont say 6, Dont say 6,Dont say 6,Dont say 6, :lol:

Unfortunately not as it was getting dark. How would you identify which one? Pull the tension lead and see if it gets worse?

Yes basically pull each pack one at a time and the revs will drop, if they dont then you can target that cylinder for further investigation

So this ended up being the coil pack, for some reason when warm the coil pack doesn't spark - checked the pack on other HD leads and doesn't work.

 

So, where is the best place to buy a single coil pack?

on here for second hand... should do the trick (get two to make sure)

or new from Zcentre ..

 

http://www.zcentre.co.uk/index.php?page=shop.product_details&flypage=flypage.pbv.tpl&product_id=96&category_id=67&keyword=coil&option=com_virtuemart&Itemid=7

 

but I'd go for second hand before paying that much.. you could also try MJP on this site (for new)

 

http://www.300zx.co.uk/forums/forumdisplay.php?38-MJP-Eastern-auto

put a post in the wanted section... :)

 

I've got spares but wouldn't be able to post until mid next week.. I'm sure there are heaps on here with spares.. :)

How much would you want for them medallion man? I'm not gonna be able to fix it until after the new year anyway!

How much would you want for them medallion man? I'm not gonna be able to fix it until after the new year anyway!

 

Pop to my unit bud you can have a coil pack

Give me a call on 07921238496.Lee:santa:

LOL.. you won't get a better offer than that.. top man Lee..

Pop to my unit bud you can have a coil pack

Give me a call on 07921238496.Lee:santa:

 

Nice Xmas offer, nice one lee can`t beat a bit of loss leading offers.

 

Jeff TT

Pop to my unit bud you can have a coil pack

Give me a call on 07921238496.Lee:santa:

 

Great club spirit Lee.

Nice Xmas offer, nice one lee can`t beat a bit of loss leading offers.

 

Jeff TT

 

cool..can i have a new engine please,my sleighs knackered

cool..can i have a new engine please,my sleighs knackered

 

I don't think you're the real Santa :2guns:, as he would know that his sleigh is powered from reindeer and Xmas spirit :biggrin:.

Engine is my last reindeer bless him..donner`s got a bit of a eggnog problem so i`ve had to relieve him till he sorts himself out but Engines not far from retiring you see. Oh ye of little faith.., this is why its getting harder to fly..first it was the elf petrol stations & now disbelievers..