I have installed new splitfire coils. New serie 2 ptu and fuel pressure regulator and new stainless fuel filter (40 micron)

 

I have a problem with misfire that starts at about 4000rpm at full throttle.

 

The fuel pressure is at just above 3 kg/cm2 at idle.

 

could the coils be bad?

Could be a plug(s) breaking down under load, id try a new set if they haven't been changed for a while as the new coils could be putting them under extra load.

hmmm... I'll check the plugs. Just ohm'ed the coils. 0.9 ohm on all.

and ohm'ed the injectors exept number 1. Need to loosen the plenum a bit to get to it. But all the other injectors ohm was 12.5

Plugs seems fine. NGK iridium bkr7eix. Done about 10.000km on them

is it an after market fuel pressure reg ... or just a new standard one ?

aftermarket fuel pressure regulator. now adjusted to 2.6-2.7 kg/cm2 at idle. Helped a bit.

 

Have another problem to. Don't know if it is revelent. When I just toutch the speed the car almost stalls/dies then jumps back up again to normal. A bit difficult to make still starts because of this.

put your standard fuel p-reg back on and see what happens u may find all probs will go

Have you checked the timing?

MAF faults start around 3000-4000 rpm....... remove the MAF sensor and inspect the wire for fault indications.

 

Alz.

I had a similar problem in my old prelude, as mark says put the stock fpr back on until you can get it to a dyno and check fueling

MAF faults start around 3000-4000 rpm....... remove the MAF sensor and inspect the wire for fault indications.

 

Alz.

 

i'm curious what fault indications should he be looking for please explain in detail which may help other members

It could be a turbo issue here........ Have you had the standard turbo's changed and fitted uprated tub's from a mechanic that think he knows what he is doing, but clearly does not......

Edited March 16, 201213 yr by AlanZ
Spelling.....

Funny thing that........... uprated turbo fitment..............

Edited March 17, 201213 yr by AlanZ
Spelling again... doh... or is it double doh!! ;) "Jimmer!!"

The turbos is fine. This backfire problem happened after i replaceed coils,ptu,fpr and fuel filter.

I'll check the timming as soon as the shop opens on monday. (Don't trust the old one. Worked kinda last time I checked the timming. So though I should recheck the timming, Nothing. So buying a new one)

 

And I'll se if I can find the old FPR and test that too. And check the MAF of course and get back to you all.

 

Appreciate the help :)

The turbos is fine. This backfire problem happened after i replaceed coils,ptu,fpr and fuel filter.

I'll check the timming as soon as the shop opens on monday. (Don't trust the old one. Worked kinda last time I checked the timming. So though I should recheck the timming, Nothing. So buying a new one)

 

And I'll se if I can find the old FPR and test that too. And check the MAF of course and get back to you all.

 

Appreciate the help :)

 

Have a read of this, http://www.300zx.co.uk/forums/showthread.php?152683-Timing-light-tech-help I set my timing the way you would expect, using the induction loop on the PTU, but after reading Jeff's write-up, I did it his way, it was 13 degrees out, made a huge difference...

Thanks for article Tudor. Checked timming and it was 15 ad idle (750-800rpm, 80-90 engine temp)

Changed to stock fpr. Made no difference.

Checked Maf and seems fine.

Next step changing back to the old serie 1 ptu...

Going to buy new plugs to see if it helps. got ngk iridium heat range 7. Maybe I should try 8 since it's e85?

Just out of curiosity, have you had a manual conversion done? And I would go for NGK platinums for the plugs, the proper ones for the VG, actually developed for it, as I remember Jeff doing a write up about plugs, and iridums cause all sorts of problems, and he can tell if a car has them in just by listening to it on tick over...

No manual conversion. It is and have always been a manual TT.

Spark plugs... always a question... Done some web searching and every site that sells plugs for the 300 seems to recommend the iridium plugs. It's only Z1 that still sells the standar spark plugs. I'm leaning towards iridium and heat range 8. Any reason I shouldn't

Short Spec:

Nismo 615cc

GT600R turbo

Boost: 1 on gasoline (ash-spec download with nistune from old chip). 1.2bar on e85 (422rwp) Need to map the gasoline so proberly going up on boost there too.

and other supporting specs

i'm using those plugs u have .... no probs up to now ...

u can swap them see if ...

Yeah, many mixed opinions on spark plugs, you can get colder platinums tho. Sorry cant be of much more help without getting down and dirty with it...

found the problem. bad gasket on the turbo. and some other small stuff like bov that had rustet shut and one open. ooohhh, and air comming from the small hole in front of the gearbox. Need to get that fixed before tuning the car. Not looking forward to it :( By the way. Is the oilcooler on the gearbox of any use? Do I need it? (can't be any good after 22 years)

is the auto oil cooler plumbed in to the rad like stock or does it have 2 small rads in front of the main/ac rad ?

 

as u should have

 

Engine oil Rad

Auto Oil rad

Ac Rad

Main Rad

The car is a manual and I think the diff and gearbox have sa shared oil cooler at the back somewhere around the rear wheels. I would just like to know if that rear cooler is necessary?