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1995 R33 Gtr - Cylinder 5 Fouling Up After Ls2 Swap

judasentinel

By judasentinel,
in Engines & Forced Induction

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judasentinel Explorer

judasentinel

Posted
Posted

Hello all,

I have a 1995 R33 GTR and I recently completed an LS2 coil swap on the car. It ran great until recently, when I started noticing a slight shudder and rougher idle. Thought it was a MAF issue so I cleaned them up, and resoldered them.

I also decided to clean up the plugs and to my surprise, found that plug no. 5 was completely black, and oily. Now I dont know if this is a sign of a blown cylinder or low compression, but I decided to swap out coil no. 5 and changed the coil wire, but no change.

I am at my wit's end, trying to figure out what is wrong with that cylinder and would really appreciate if someone could shed some light on what to do here. I live in a remote town in Canada, and do not have access to most things people do in larger towns, so have to depend on myself to carry out any tests or check things. This has gotten worse over the last 2-3 days, as I drove the car on a 200 mile trip, which was great until I got back home and it started to show signs of running stupid rich while cruising and lean when boosting.

I have checked the coils, the wires and the plugs are all good. When I disconnect the coil wires no. 5, there is a very very minor change in the revs if at all. I can hear the coil ticking and the spark is there. If the injector wasnt firing, would it foul up the plug with black oily stuff?

How do I check without the car running if the spark is strong enough? Could it be faulty injector or a weak spark? Is it also possible that cylinder 5 has lost compression?

Please help me :(

Thank you.

GTSBoy Grand Master

GTSBoy

Posted
Posted

Possible that the injectors is buggered and pissing too much fuel in. Also possible that it's buggered, not put enough fuel in, you have run that cylinder lean and it is now rooted. Also possible that the rings on that cylinder have just died on their own.

Injectors out and flow tested are probably the on only way to tell if either of the 1st 2 are true.

sonicz Rising Star

sonicz

Posted
Posted (edited)

Could be a injector doing that for sure. Stuck open or not right. Has the car ever been run on Ethanol gas?

Ive had this exact same issue with ethanol many a few times. I Learned Stock R33 injectors just seem to die on ethanol within a few months, no idea exactly why.

Edited by sonicz
STATUS Grand Master

STATUS

Posted
Posted

Could be a injector doing that for sure. Stuck open or not right. Has the car ever been run on Ethanol gas?

Ive had this exact same issue with ethanol many a few times. I Learned Stock R33 injectors just seem to die on ethanol within a few months, no idea exactly why.

odd never had an issue in 7 years... unless they were highflowed std items then yes nearly every set of ive had through have failed.

sonicz Rising Star

sonicz

Posted
Posted

odd never had an issue in 7 years... unless they were highflowed std items then yes nearly every set of ive had through have failed.

Nope, I've had 2 completely stock sets die, each set lasting about 2-3 months of E85 use. The original + a stock used set, all died a slow one by one death.

I think I read something about the Series 1 constantly sending 12 power to the injector loom even when the car is off, which i turn causes corrosion of the internals of the injector, but was later changed not to do this in later series, maybe series 2?. If anyone can confirm or deny would be great.

I have a set that were on their way out to the point the car barely ran, i.e at least 3 of them will be dead. If you have the means to found out what is wrong with them I can send the entire set of 6 you free of charge, bar the cost of postage. Maybe we can split that as I very curious to know what the cause of death is. I never bothered to find out.

judasentinel Explorer

judasentinel

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Nope, I've had 2 completely stock sets die, each set lasting about 2-3 months of E85 use. The original + a stock used set, all died a slow one by one death.

I think I read something about the Series 1 constantly sending 12 power to the injector loom even when the car is off, which i turn causes corrosion of the internals of the injector, but was later changed not to do this in later series, maybe series 2?. If anyone can confirm or deny would be great.

I have a set that were on their way out to the point the car barely ran, i.e at least 3 of them will be dead. If you have the means to found out what is wrong with them I can send the entire set of 6 you free of charge, bar the cost of postage. Maybe we can split that as I very curious to know what the cause of death is. I never bothered to find out.

Were you offering this to me or to STATUS?

Secondly, on the issue itself, if the cylinder was toast, wouldnt I smell fuel on the plug no.5? All I see on the plug itself is that it coated with black oily stuff and its not like it is covered in oil...just a complete oily blackness.

If the cylinder was toast, would the car still rev high? The AFRs are erratic, but lean out under boost/WOT. I dont have a compression tester, but assuming the compression is zero, what symptom(s) would the car have? There is only a slight drop in performance under load. It does spit black soot out of the exhaust upon cold start, mixed with water. But there is no blue or black smoke coming out.

judasentinel Explorer

judasentinel

Posted
  • Author
Posted

Just checked compression. 70 psi in cylinder 5.

I drove the car to a shop and it drove fine, even with this low compression. Injector was firing, and so were the coils. Seems either the bottom end is fried or the top end is messed up - could be a partially stuck valve/lifter/ faulty spring, or do you guys think it is the bottom-end?

This is devastating. I dont know what to do....

Dale FZ1 Veteran

Dale FZ1

Posted
Posted

Sounds like the head gasket is shot.

Worst case, you may have had a piston ring land fail.

Head off, investigate further.

Annoying, yes. Devastating, not really.

It's probably seen some service, and presume you're happy to give it some stick?

judasentinel Explorer

judasentinel

Posted
  • Author
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The mechanic who did the compression test says that it is unlikely anything within the bottom-end, although I have my doubts. It could be the rings or ring land, but I am not an expert to comment.

There is no oil-coolant mixing in the radiator or the oil pan. The car doesnt smoke black, blue or white. The AFRs on my wideband are kinda spot on when itdling, but are erratic and go up and down quite a bit, and running leaner under WOT. The plug for cylinder 5 was covered in oil/petrol mix, totally black and oily. He thinks it is the head/valve/springs, etc..

The car still pulls strong even with this issue, and boosted fine. Just that I can see the rear turbo doesnt spool as well as the front, possibly due to loss of exhaust pressure from cylinder 5 coming in, which makes me think that perhaps the exhaust valve is burnt or messed up?

He says that there is no need to do a leakdown test as we cant really ensure the cylinder 5 chamber would be completely sealed.

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