Bad Missfire Under Boost / Not Coils

[SevenAngryPenguins]

Hi, was after a few ideas of things to check with my r33, the problem is soon as it starts boosting up it missfires to the point it just doesn't run, just coughs and splutters, this happens at about 4 psi, as soon as i back off runs perfect. Things i have tried to do to rectify the fault is change, ecu, spark plugs (all came out totally black), afm, cas, ignition relays checked, igniter (the earth seems good too, I asume its the one that goes under one of the coil holding frame bolts), JJR coils went in about a week before this happened aswell. I haven't yet pressurised the system to check for air leaks yet but all the cooler pipes seem well sealed.

cheers

Edited December 16, 2007 by SevenAngryPenguins

[sidewayssam]

im having same problem aye, did urs start doing it suddenly? me mate put 95octane in his skyline and the thing just startn to get worse and worse missing, we changed the plugs and fuel filter but thinking mayb the injectors are screwed

[SevenAngryPenguins]

yeah happened straight up ran fine one day crap the next

[murrayis]

What new plugs did you put in?

[TTT]

Can you confirm the JJR coils are working (don't care if they are new)

plug them in to a mates car with same motor and test them out.

or use his ones on your car to test out.

[SevenAngryPenguins]

dont know anyone else with a 33, but i chucked the old coils back in and the problem is still there

plugs are bcpr6es

Edited December 17, 2007 by SevenAngryPenguins

[johnbarry88]

check ur fuel pressure mines dont the same thing b4 on my old skyline

[SevenAngryPenguins]

ok will do, how did you go about testing the fuel pressure i have a fuel pressure gauge...did you test it at idle or on load

[johnbarry88]

hook it into the fuel rail if its a standard pump at idle it should see around 40psi if this is the case then its alright but under load if it doesnt make anymore than that I would think your fuel pump would be dead.

[SevenAngryPenguins]

i put in a walbro a few months back and when it primes it sounds strong but i will still check it, how did you look at the gauge under load, i will have to get my little brother to sit on the engine while i boost down the road.

Edited December 17, 2007 by SevenAngryPenguins

[johnbarry88]

just feed it through the gap in the back of the bonnet and sit it under the wiper arm so u can read it

[SevenAngryPenguins]

after lots of stuffing around ended up buying a supercheap aircompressor to check for boost leaks and found a massive one so problem solved!!

Edited December 19, 2007 by SevenAngryPenguins

[TTT]

where was the leak?

just so others can check this as part of their diagnostics for similar problems.

[ZENNON]

front bottom IC pipe where it goes onto the FMIC

[SevenAngryPenguins]

it was where my first pipe off the intercooler joined with the crossover pipe just after it goes though the engine bay wall if that makes sense, it was joined with a silicone joiner it appeared as if it was perfectly sealed but the clamp was done up right on the edge of the metal pipe inside with a bit of air pressure it leaked like a siv. I'm a bit annoyed at myself that I didn't check the hoses more closely the first second and third time that i did it. Would of saved alot of stuffing around.

a picture speaks a thousand words so they say

[ZENNON]

ah wells - now u got it i can use it to see if i have any leaks

[SevenAngryPenguins]

haha yeah, so when you wanna move that fridge.....

[ZENNON]

lol - *me opens msn*

[TTT]

GET A ROOM!!!