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Discussion Starter · #1 ·
Hello again all.

im stuck with this problem ive tried most things.......

here the spec:
rb26dett:
fmic
k&n filters
turbo back 3" exhaust system
720cc injectors
apexi power fc ecu
twin hks dump valves + stock re-circ
1bar of boost 450bhp mapped by Rob @ perfect touch

i recently brought this with many problems and have fixed all the other issues (hicas/4wd/abs lights on) bleed and refiled the pot the the boot.

but the problem i have i just cant seem too fix is:

it is missing (think its cylinder 2) when cold its not so noticable but you can just about hear it. seems worse when warm.

yet if you turn on the air con for the 1st minite or so the missing stops even when reved but then returns.

and if you leave it ticking over after a little while it really becomes very lumpy and dies this lumpy-ness happens for about 1-2 seconds at a time then seems to idle agian still missing.

this were it gets more interesting, if you wriggle the 2ed air flow meter wire it becomes very lumpy again but wriggle it again a few seconds later and the wriggle of the wire does nothing?

when you drive it you cant really notice that it is missing seems normal and even under boost it really seems fine, not sure if it is still missing when being driven or on boost but if it is you cant hear or feel it, but the knock readings are between 70-90 when floor it??

so far ive:

* changed the oil and filter

of my mates r32 gtr tried:

* coil packs
* plugs
* box on top of rocker cover
* both air flow meters


ive noticed the fuel pressure regulator on mine (top half) is semi loose and can be rotated not sure this is any think too do with the problem but even with the vacum disconnected still misses and same has a little lumpy idle as expected when first pulled off, even if you suck really hard on it no change.

im not 100% sure if its down too a faulty injector but is there a way possible too check the injector other than swaping it with another to see if the missing changes cylinder?

the lad i got it from thinks its down too the mapping but even if i play with the inj/ing dont seem too fix the missing and im 90% sure this is the cause of the high knock readings

would it also be possible too be the fuel pump or filter?

any one local too biggleswade that fancys having a look?

any help or advice is well appriciated!!
 

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I would have suspected the AFMs, but if you've already swapped them around with your mate's GTR...

Try moving no.2 injector to a different cylinder and see if the miss moves with it. Not a big job and it would eliminate another suspect.
 

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Discussion Starter · #3 · (Edited)
you mean swap no,2 coil pack? cant swap injector as will put fuel in on the wrong stroke,lol

not sure if this has any think too do with it, but just went too the shop and when i come out and started it up the rev jumped too about 2500rpm (no missing) for about 2sec then it cut out then started again and just cut out straight away then started again and back too the missing on idle??? random or what,lol
 

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you mean swap no,2 coil pack? cant swap injector as will put fuel in on the wrong stroke,lol
What?

I don't mean the wiring/plug, obviously just the injector... You could try the coil pack too.
 

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Discussion Starter · #6 ·
update:

today i tried my mates :
fuel pressure regulator
cam angle sensor + checked timming and all ok with no change.
then tried his fuel pump ....again no change.

i check the voltage at the pump and got a reading of 6.8v so ive hard wired it via the ingnition but still no change.

up too now ive run the boost controller off (till i found the problem) but today was brave and turned it on, found that on low boost it misses on boost slightly and on high boost it misses really bad,lol so turned it back off,lol

ive also done a compression test
starting closest too rad
1: 152 psi
2: 153 psi
3. 152 psi
4. 152 psi
5. 153 psi
6. 152 psi

so all seems ok there.

i have noticed when i replaced the CAS unit that the cams are not standerd they have adjustble pullys on them. not sure if this has any think too do with it?

all my knock readings today have been around 25.

but it dose still die on tick over to 2000rpm runs very lumpy like lack of fuel but does this only when warm and runs very lumpy then dies rest of the time it idles but can hear a slight missing through the exhuast, but if you turn on the aircon it clears for 30sec or so then the missing returns?

any idea`s?
 

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Is the PFC set to O2 feedback or not? Could be a dodgy lambda sensor.

Could also try the normal disconnect battery etc... then start the normal self learn process, I believe the PFC still does some sefl learn stuff for off boost running.

Other than the above I had a similar problem when using big Cams and I was not getting enough vacuum pressure which led to erratic low down running like you have described.

I would suggest you get the car back to Tweenie Rob or have someone else have a proper look at it.

Kev
 

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Discussion Starter · #9 ·
exscoobyT - i dont know any one local with one and funds are tight at mo too pay a tuning garage too spend 3hrs at £55p.h,lol

kgleeson - ive tried turning off the o2 feedback off but dont stop the missing there is a change in revs but thats all, would take too tweenie rob but they want £55 p.h too look at it and said can take all day. not feeling the large bill, if funds were better i would defo take that route but as funds are ive got £25 too last me a whole week,lol spent £150 already on oils ect trying too find the problem should have gone straight there, but weres the fun in that,lol
 

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Hi Side,

Have you tried the Lambda sensors and do you have adjustabel Cam pulleys?

I would set O2 feedback to on to start with, you can check the sensors in the etc menu to see if they are varying too much from each other. I woudl still do the power off and self learn, process is to idle for around 10 mins, then put air con on leave for a few minutes, air con off etc... then go for a drive.

If you have adjustable CAM pulleys , I would mark the current settings on pulleys etc... so you can set them them afterwards. Then go to standard Cam timings and work out from there. Adjusting inlet first and then Exhaust.

Good luck
 

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Discussion Starter · #12 ·
souroull - if i unplug each coil pack 1 at a time there is a drop in revs untill you pop off number 2 coil pack then no change, but if you swap coils around with another cylinder it stays on number 2 ive also tried another set of plugs with no change.

kgleeson - yes tried unpluging the lambdas and has adjustable pullys, i just think its strange how if i turn on the aircon the missin stops for 30sec or so.
i think ill get the map checked at some point but i dont understand why it seems too have stages of going from a slight miss on idle too a patch of very lumpy idle and cutting out of witch still happens when driving under 2k rpm......
 

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If problem is stayign on cylinder 2 and not moving with coil pack I would ask your mate if you can try his coil pack loom. It i spretty easy to chnage to test

They have been known to breakdown.

Kev
 

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change injector number 2 to number 6 and listen again if the misfire moves you know what it is. If it stays where it is, it is the ecu or loom/coil packs
 

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Discussion Starter · #16 ·
ive spoke too rob @ perfect touch and he said it wasent mapped just dyno`ed but made 450bhp @ 0.7bar

and is running very rich under 2k rpm witch explains alot,lol the air con putting extra load on engine and with the over fueling.
 
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