Misfire In First Gear?

[Ep82jm]

Hi,

So the r33 has developed a misfire again. Strange thing about it is it's only in first gear and very very seldom it happens in second gear too but happens every single time in first when I boot it,but if I build the boost up slowly it's fine.

It isn't like the coilpack related misfire I had before where it just stutters,this time between 4-5k it splutters and pops and bangs

Doesn't happen in 3rd 4th or 5th at all.

I'm running stage 1 mods plus walbro pump,benchmark coilpacks and rsp stage 1 ecu.

Coilpacks were newly fitted in February of this year so I'd imagine it isn't them although I wouldn't rule them out.

Spark plugs wer put in around 5 months ago and are gapped correctly.

Today I took all plugs and coilpacks out and all look normal.

Changed air flow meter with no difference.

New lambda sensor yesterday which again made no difference.

Car is running perfectly bar the misfire and is going as well as I could expect power wise through the gears.

Any ideas on what to try next?

Think I'll borrow a set of coilpacks from someone local to try rule them out or so I can sent them back under warranty if needs be but I'd imagine if they were at fault I'd get the misfire in all gears and especially in higher gears at full boost due to being under more stress/load?

Should I be changing the plugs again even though they are only a few months old and have done less than 1000miles? Again I'd imagine plugs would make it occur in more than just first gear though?

Any suggestions would be great.

Thanks

[Ep82jm]

I should also add that I had the CAS out recently when checking the timing was set right by the previous owner. Is there anything I could have done wrong when refitting? Both the base and advanced timing are correct

[Ben C34]

What do you mean advanced timing is correct? First I've heard someone say that in relation to an efi car.

What's a stage 1 ecu?

Only in first is odd, but the rev range you mentioned is what a coil pack misfire would first become noticeable.

What gap plugs you running?

[Ep82jm]

What do you mean advanced timing is correct? First I've heard someone say that in relation to an efi car.

What's a stage 1 ecu?

Only in first is odd, but the rev range you mentioned is what a coil pack misfire would first become noticeable.

What gap plugs you running?

Ignition timing at idle.

Stage 1 ecus are made by a lot of different companies,it's basically a chipped ecu I suppose,company maps a skyline for x mods and then puts that map on multiple ecus. Obviously I know this isn't exact to my car but they are generally used to get rid of the flat spot from running higher boost etc on the stock ecu and the car has been fine for months whilst running this ecu. I have an apexi pfc lying to go on the car but no point fitting it while the car is misfiring.

Plugs are gapped to 0.8,heat range 7s.

Yea I just find it strange that a coilpack would only cause a misfire in first gear though,last time they went I had the 4-5k misfire in every gear. I'm going to fire a set of plugs in it tomorrow to check,again I'd expect them to show in more than just first gear and I'd especially think they would last more than 1000 miles.

Forgot to mention I also replaced the fuel filter incase it was causing a problem and still no luck.

Edited July 2, 2015 by Ep82jm

[Hadouken]

This is not gran turismo. We use big boy mods. We don't have stages of hektik modification.

And it sounds like spark blowing out.

[Ep82jm]

This is not gran turismo. We use big boy mods. We don't have stages of hektik modification.

And it sounds like spark blowing out.

LOL! it was bought just to see if it got rid of the flat spot I was experiencing when I first got the car. Have collected bits to run "big boy mods" and will be getting them all fitted during the winter while the car is off the road.

Thanks for the suggestion! So new plugs and gapped to 0.8 again or should I drop to 0.7/6?

[niZmO_Man]

Solder fixed the AFM?

[Ep82jm]

Solder fixed the AFM?

Swapped it out with a known working AFM which made no difference.

[Hadouken]

Yep drop them to 0.7/0.6 and see if the miss is gone. It would be a quick way to see if you have weak spark.
Then report back

[Ep82jm]

Yep drop them to 0.7/0.6 and see if the miss is gone. It would be a quick way to see if you have weak spark.

Then report back

Ok so i dropped my original plugs down to 0.6 there and the misfire is gone!

So should i just leave them at that or is that only masking a problem? E.g coilpacks breaking down and not producing a strong enough spark? im only running .85 bar so i would have thought 0.8gap would have been ok for that boost?

[Hadouken]

You need to get yourself a new set of coil packs then you should be able to run spark plugs at 0.8 gap again.

If it were my car running that little boost I'd leave it at 0.6 gap til you can get some new coils.

[Ep82jm]

You need to get yourself a new set of coil packs then you should be able to run spark plugs at 0.8 gap again.

If it were my car running that little boost I'd leave it at 0.6 gap til you can get some new coils.

Coils are only new 5/6 months ago too so ill fire them back under warranty.

Thanks for your help in getting it sorted,appreciate it!

[Ben C34]

I win this thread.

Yeah.