Not the usual missfire...

1007 Views 17 Replies 7 Participants Last post by kb277, Mar 11, 2010

I_<3_boost

Discussion Starter · Feb 6, 2010

Ok so I have a Rb25det in an s14, the problem seems to be when the car is warming up, judging by the water temperature guage, once the water temp is up I normally give it a few more miles before letting it see boost anyway, but the problem is an intermittent missifre when cold (not all the time) but once its warm and its seen a bit off boost a couple of times, it runs fine.
Also when the car is cold and it idles its lumpy, but again once warm its smooth as!
Now its doesnt seem to be related to revs, ive changed the plugs and the coilpacks are RSP.
Hopefully someone can help me out, its annoyinggggggg
Thanks, Jason.

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Yella

· #2 · Feb 6, 2010

Only time I've had a misfire when cold is when one of the plugs just wouldn't work until warm, but you've changed them. Does it happen when cold and given a bit of boost ? I know most people don't as its not the done thing but when I had the old turbo elbow fitted it would run lumpy as hell until it was boosted.

Once it had been boosted it was fine, I have now put this down to the turbo elbow and the wastegate catching slightly, as said once boosted it ran perfect.

Since going hybrid I have had to change back to the standard elbow due to the size of the wastegate penny on the hybrid, hasn't done it since.

I_<3_boost

Discussion Starter · #3 · Feb 6, 2010

If ive had to give it a little bit of boost then its like riding a 2 legged horse and its starts bucking all over the place! but only when cold :s

I_<3_boost

Discussion Starter · #4 · Feb 7, 2010

any other ideas?

I_<3_boost

Discussion Starter · #5 · Feb 9, 2010

any more help?

koh

· #6 · Feb 9, 2010

what other mods have you got?,could be an overfuelling related missfire

I_<3_boost

Discussion Starter · #7 · Feb 9, 2010

Well I used to run the Recirculator, but then got a HKS ssqv and a fmic and full ehxaust system and thats it.
but it used to missfire even when i had the standard recirc...

Hugh Jass

· #8 · Feb 9, 2010

What other mods do you have?

ecu, afm etc...

I know plugs were mentioned, but what gap did you set (0.8mm)

I had a very similar on my r33 due to plugs wrong gap.

See if you can borrow a standard afm to try too.

Another possibility is lamda sensor in turbo elbow, but usually that gets worse and car wont run at all.

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I_<3_boost

Discussion Starter · #9 · Feb 9, 2010

evrything else is standard apart fomr the above mentioned.
I had a set of plugs in there that were at .8mm then got some standard ones ie 1.1mm as im still running standard boost.
I may take the AFM out tomorrow and clean it best I can without damage.
The lamda sensor isnt that old I highly doubt its that, but will check it.
anything else?
It completely clears up once the car is completly warm though :\

SPEEDR33PER

· #10 · Feb 9, 2010

plugs should be 0.8mm mate regardless of mods

Hugh Jass

· #11 · Feb 10, 2010

SPEEDR33PER said:
plugs should be 0.8mm mate regardless of mods

^^^ indeed :dance:

Pete H

· #12 · Feb 10, 2010

My bet is the afm and just cleaning the elements may not solve the problem as it could be a dry solder joint on the afms cicuit board. When i had a problem similar to yours mine misfired when warmed up but ran perfect when cold and it was the afm.

Hugh Jass

· #13 · Feb 10, 2010

Pete H said:
My bet is the afm and just cleaning the elements may not solve the problem as it could be a dry solder joint on the afms cicuit board. When i had a problem similar to yours mine misfired when warmed up but ran perfect when cold and it was the afm.

^^^ i agree also.

Ask if some wonderfull skyline owner with the same afm, near to you, can do a quick swap ( 5 mins )

or re-gap plugs then try afm.

good luck

I_<3_boost

Discussion Starter · #14 · Feb 10, 2010

Ok the plugs that were in there were gapped to 0.8mm and it still done it, also you say about the AFM but my symptons are round the other way, missfiring when cold then when its warm its ok.

koh

· #15 · Feb 10, 2010

is there anywhere local you could have it checked for sensor error codes?

Pete H

· #16 · Feb 10, 2010

I_<3_boost said:
Ok the plugs that were in there were gapped to 0.8mm and it still done it, also you say about the AFM but my symptons are round the other way, missfiring when cold then when its warm its ok.

Well what i'm saying is that the circuitry allows for a cold engine and then adjusts for a warm engine it dosen't matter which way round the problem is it can do it either way depending which part of the circuit is affected by say something like a dry joint .... as said a working afm swap with someone will tell if it is that or not.

I_<3_boost

Discussion Starter · #17 · Feb 10, 2010

Ok I get ya sorry! so is there anyone local, Bromley/Kent?

kb277

· #18 · Mar 11, 2010

i have exact same prob now with my R32. Only when cold but once fully warmed up goes like a rocket. I mhave stripped and cleaned my AFM but might try this again. My plugs are gapped exactly 0.8mm used to do it all the time until i gapped them properly but now only when engine not up to temp... I think i read somewhere how to strip AFM and re-solder connections etc. might try this out.

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