Any Ideas?

[GTR_NUTZ]

hey all....

I have a GTR 32 and for the last week my car has been back firing a fair bit with white/blue smoke just poring out the exhaust, but this only happens when the engine is under load, like whenever I put it down a gear to slow down (engine breaking), or when I have it in a gear, and I accelerate and come off, there is backfiring, but not straight away, and then the smoke appears... - before you all jump the gun and say I have blown a turbo, I can still get full boost. Can this happen with only a single turbo?

I have had a look on here if i can kinda self diagnose the problem my self.... but there are too manny gadgets and gizmoes on a Skyline that could cause this problem.

I think I have narrowed it down to one of these...

1 - One or both of my turbos are on its way out.

2 - Needs a tune like something chronic. I have noticed that the whitnes marks are slightly off, about 4mm, from where the orriginal marks are on the silver timing belt cover thing.

3 - There maybe a seal or something like that around the turbo that has cracked and leeks oil under load from the engine breaking.

4 - Either the rings or valve stem seals are worn and needs to be replaced. But if this was the case, it would be blowing smoke all the time.

Before you all make assumptions, my car is stock, apart from exhaust, boost controler - but thats been turned down by me, and then back to 1 bar of boost at race pace about a month ago. Thats all the engine/preformance mods. Also... about 3 nights ago my cat exhaust light came on for about a minuite so i stuck the car in manual and rolled for a bit which fixed it, then I sped up to see if it will do it ageain. but it didn't.

......So any ideas?

Any healp or sugestions would be much appreciated.

thanks

JUSTIN

[spikeman900]

I might not be the most knowledged person on the planet, but how many kays has it done? if its had a LONG, hard life then id say itd be the rings, but ya aint pouring out smoke all the time. But with aftermarket exhausts, the backfiring should be fairly normal.

[GTR_NUTZ]

When i got it ts said 1023?? now... It says it has done 1045?? its had a few oil changes since. But I just changed the oil on monday night. As in the 20-6.

I spoke to an old mechanaic at my work and told him about my car. He seems to think that it could be that the cam or belt has slipped on the exhaust side. And thats why it backfires badly(if there is a word...). And its not a normal backfire, its more louder and you can feel it thorugh out the car.

He also said if it was a turbo problem then I'd know about... as in smoke galore, and no power what so ever.

And to top it all off, im busy this weekend, and on night shift next week, and going to adelaide the next weekend. So if I can ill go see if JMS may know anything.

Any more sugestions would be grate right now.

thaks

JUSTIN

[NZM.031]

if it was the rings, it would be pumping out startup, once the oil starts to heat up and flow, and the engine heats up, the rings seal themselves. if its valve stem seals, then on idle at traffic lights or somewhere, it would be puffing out smoke, but then clear up as you drive off, unless you give it a big tromp.

it sounds to me like a turbo problem. you wont necessarily have no power and smoke galore. the turbo will still spool if its got an oil leak. backfiring could be due to alot of things. your plugs could be badly fouled up, but usually they arent bad enough to backfire that badly. if your cam belt has slipped, it would be backfiring off every fire as all cylinders are out, it wouldnt be just once or twice. you o2 sensor could be covered in carbon and not working properly, this will bring the cat light on aswell. it senses how much unburnt oxygen coming out the exhaust and adj. the fuel map to clear this up and burn all the oxygen for max performance. if its not working properly and dumping in alot of fuel, then it will backfire.

probs a good idea to get it over to the boys at JMS and let them have a look/drive... its hard for me to help you when i cant see for myself what the car is doing.

good luck with it,

cheers

Linton

[GTR_NUTZ]

Thanks Linton.

I live in VIC, but Im off to Adelaide next weekend, so Ill deffinatly get the 411 by JMS If I can.

After my little durnken episode on the weekend, I was speeking to some mates that reco engines and build high proformance engins and yadda-yadda... And they said that it is deffinatle a turbo issue.

They said that one or mabe both my turbos are shot and needs to be recoed. They also recon that if it is just happening just after a quick boot, or when the engine is under load e.g. putting it down a gear to slow down, then is it pumping oil arond faster because the revs are higher, then my turbos are "dumping" oil through the dump pipes and straight out the exhaust. It isnt burning the oil, just dumping it.

I am about to put my new head on, but now i dont know if it will be worth it, because now I still have to get the turbos fixed, and proper extracors too. So think Ill just put my money aside and blow it in one hit and get it all done.

Any one have any ideas on how much I would be looking at to rebiuld/reco my 2 turbos for? Or should I just pugrade?

thanks

JUSTIN