[jaz]

as some of you may know my car has playing up recently and has steadily got worse.

symtoms are, its got a terrible misfire. sometimes wont rev over 4k. continously back firing, absolutely no power when pulling off, hardly any power when driving along but turbo is whistling its nuts off and boost guage is at the max. because of all this it wont go over 60mph and takes a year to get to it.

now, 2 weeks ago i booked it into a garage that specializes in evos and other jap performance cars. so far they have tested the ecu, coilpacks, plugs, plug gaps, cas, afms, cam timing, air fuel ratio, pressure in the boost system. and probably a few other things i cant remember. all this has turned up a ok. so we are scratching our heads a bit now.

last thing we thought of is wether part of the exhaust system has collapsed forcing the pressure back up to the turbos. now i dont know what the outcome of this was as they broke up for xmas and are back open again on the 4th. so im just waiting with fingers crossed now.

what you guys think?
cheers
jaz

 

[General Banter]

I know what you just said but all symptoms point to a boost leak bud.

 

[MARKPRIOR]

blown headgasket? dosnt have to loose oil or water, can just cause crap compression

did they do a compression test?

 

[jaz]

yeah i still think its a boost leak too. but i dont know how they checked the system for leaks.
im not sure if they have done a compression test. il ask them once they are open.
its doing my head in now. just want my car back working properly

 

[Twill]

mmm i had this fault on my rb25 and it was the afm plug on the loom so i would check both the plugs that fit to the afms and check boost leaks

 

[jaz]

keep these ideas coming guys

 

[Twill]

do you still run the standard boost control valve ?

 

[jaz]

engine is completely standard. even has original airbox

 

[archaeic_bloke]

boost leak

 

[j_jskyline79]

afm or a boost leak

 

[RXXXIV]

Have you checked your inlet manifold gasket? Or just the area around it? Spray some brake cleaner there while engine is idling. If revs go up you have a leak there somewhere.

Apart from that check what people above have said.

 

[DazzaGTRVspec]

Dont rule out lambda sensors or clogged fuel filter and all the above

 

[jaz]

fuel filter is ok ive just serviced it. and yes it had the problem before and after service.

whats the deal with this brake cleaner? ive heard about this before but dont understand what happens.

can someone tell me why its backfiring though because ive never heard anyone mention that on a boost leak before.

cheers guys
jaz

 

[Boostjunkies]

Have you checked your inlet manifold gasket? Or just the area around it? Spray some brake cleaner there while engine is idling. If revs go up you have a leak there somewhere.

Apart from that check what people above have said.

This is where I would be looking too, either that or your intercooler is leaking

I had a simular issue once before on another car and it was over fueling due to the AFM registering the air flow, the ecu shoving fuel in but the charge from the turbo not getting back to the inlet due to the leak, the extra unburnt fuel was igniting in the turbo compressor housing almost sounded like anti lag, ie backfireing... thats my take on it anyhow, I sorted the inlet gasket and it was fine after ?? could be a similar thing??

 

[jaz]

well il try the thing with the brake cleaner.

but they reckon theyve measured the air fuel ratio and its spot on?

 

[convert]

check the plug at the back of the coil pac amplifier is well pushed on, give it a wiggle, and otherwise im with jay, if you leave one of the afm's unplugged has the same effect, unplu one and drive it, then the pother if its just the same, its the plugs have breaks in the wires, or damp in the socket or similar

OR a tub could be screwed, so is it smoking its ccok off?

 

[jaz]

no smoke at all. the only time i see stuff coming out of the exhaust is when its a really cold morning, but then every car in the street is the same

 

[RXXXIV]

If there´s a leak the brake cleaner will get sucked in due to the vacuum resulting in your revs going up slightly. If it does that there is a leak somewhere. These gaskets are know to fail after all the years of being in. If your on boost air that has been measured by the AFM would get pushed out through the leak resulting in your AFR going down, meaning that it would be running rich. Normally runs way to rich then resulting in the mixture not being ignited anymore, misfiring/backfiring and unburnt fuel even exploding in your exhaust if exhaust is up to temp already.

Whatever garage you took it to, if they checked your AFRs they would or let´s say they should have noticed unusual low AFRs on boost if you really have a leak somewhere in your system, i.e. inlet manifold gasket or intercooler piping and hoses.

 

[jaz]

see i agree with all that and when i booked it in i said it has a boost leak and told them the symptoms and they agreed. but with them saying the afr is spot on, what do i do?

i cant really tell them how to do thier job because im not a mechanic. im in a bit of a pickle

 

[GETGREDDY]

We have just bought a system for checking leaks off the snap on man! It pumps manmade smoke into the intercooler, manifold and piping under pressure and obviously where there is a leak, smoke will appear. A few tuning garages have invested in them mate, so i'd have a ring around and see if you can find a place with one!