R33 GTR AFR levels at cold start, cruising and WOT....please help

[judasentinel]

Do you think this means all the rings in cylinder 5 are shot? Otherwise, how would that happen, right?

And this might also mean that there might be no point in taking the head off...the mechanic doesnt want to do a wet compression test, and says that he feels its the top end. I will explain to him today that Ive been getting oil in the turbos. However, having siad that, up until 2 weeks ago, the engine ran smooth, the plugs were clean and no oil on them. I installed the LS2 coils over 2 weeks ago and everything was perfect until then. The oil in turbo issue has been happening for over 3 months now, so not sure if there is a correlation between the two. But then I can be wrong as usual.

Let's see what the mechanic says after he checks under the valve covers.

[future_R34]

Thank you, Bruizer and future_R34.

When I looked at the gauge, it showed 60 psi and the needle stayed there. When I asked him about it, he said that his gauge has some kind of a valve that keeps the needle where it is supposed to be, even if compression drops to zero, to be able to record the max compression the gauge registered.

check valve keeps the pressure trapped. If your still getting some compression, it could be rings, if you pour in oil and try again and it gets better, that's your problem. If there is no change after oil in the cylinder than its a valve issue.

Hopefully you get it sorted out



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[hp44incgtr]

Bro I had the same issue, it's definitely yo ls coils some of them are weak not working to full potential Iv spend an week testing this issue nothing worst having an rb26 running on 5 cylinder. So after swapping an few coil still had same issue. So I replace all of them at night I could see spark leaking out cylinder 2 even after I put new one which I pay 80$ each at cost from work. The oem gm coil. Come to think of it most people do the swap to save money and raid of the igniter. I'm gonna save some $ do the r34 swap .

[judasentinel]

@hp44incgtr - man that is alarming. People are swearing by how much better LS2 coils are, but you are sharing a different story. I dont know what to believe. It would be quite a challenge to put the stock coils back on, because I had to cut up the stock harness to connect my LS2 coils.

I did swap the spare coil in, and it ran fine with all cylinders, in that it was sparking even for cylinder 5. I doubt it is the coil, unless the dwell time is messing it up. Someone commented that you have to readjust the base timing after putting the LS2 coils. And I wasnt made aware of that before.

[caliber676]

Unless I'm not understanding you correctly I would say your mechanic is wrong. A compression test that fails should always be followed by a leak down test to isolate the compression leak, I'm not sure how he's saying he can't tell where it's losing compression from.... There's no point touching the head unless your sure it is the valves that are causing it.

[judasentinel]

I agree with you, caliber676. I just cant seem to get a hold of him now, since Saturday. Calling him and leaving messages hasnt helped and he hasnt called back to let me know what's up. My work wouldnt let me leave before 6:15 pm and I start before his shop opens.

I am getting to the point where i will just go and pick up the car and drive her home and then put her away for the winter. The only thing is that the only way I can do it is by leaving early, which creates an issue with work, and then I dont know if he is even there...he could be sick, for all I know.

I think what I will do is buy a compression tester and do a wet compression test myself. If the reading improves, I will put in a can of Restore in it and drive it until the compression climbs back up and put the car away for the winter. If it doesnt improve, I know the head is coming off.

[GTRADDICT]

Dont put restore in the car!! FFS might as well put some sand.

Caliber676 is dead on with the compression test/leak down test.

[judasentinel]

Dont put restore in the car!! FFS might as well put some sand.

Caliber676 is dead on with the compression test/leak down test.

I do intend to do the wet compression test, as caliber676 suggested, once I get the car back

Is there a reason for your comment on Restore? I have been doing a lot of reading on it, and seems that it does not affect turbo-charged engines negatively, nor does it clog up the turbos. I am sure you have reasons for saying what you said, and would love to know them, so I can make an informed decision and not do it if it is bad for the RB.

[future_R34]

Dude, find another mechanic, or just do it yourself. Products like reatore are like a bandaid on broken leg, useless. Lol 'nuff said.


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[GTRADDICT]

If you have low compression there is a mechanial reason behind it... There is not 1 product out there that can add metal where is needed just but adding some magic oil in a can. You must find the reason behind your low comp. I do not have any experience with the product, but my judgement behind my reasoning is this: You have low comp from either carbon deposit on valve seal or metal is missing somewhere (rings, valve seal etc.) No additif will fix the problem. I would hate for you to block an oil passage somwhere in the block. It would only cost you more $$ in the end.

Retire the car for the season.
Talk to knowledgable people
Buy the tools to do the comp test
pay a shop to do a leak down test (if needed)
and go from there.

Edit: The only place I would use restore would be in a beat down car that I would like to give it new life for a couple of months... Or if I would be deep in the woods and that can would bring me home... And you can be sure that I would flush my engine with varsol the second I get a chance.

[judasentinel]

I know it can be frustrating to deal with someone like me, who seems to be trying to cut corners and identify any ways to save money and not have to pull the engine out to get it fixed.

I did find out from the mechanic when he did another compression test that cylinder 5 cold as around 20 psi. Let's see what he says now. He was supposed to call me today, but nothing thus far.

[judasentinel]

Convinced the mechanic to do a leakdown test....he put cylinder 5 at TDC. He said he was sure it was at TDC, and then did the leakdown test with a pressurized hose connected to the cylinder. And we found that air was slowly seeping out of the MAF filter....seemed like the rear one only....I say that is intake. Or could it be the exhaust if the rear turbo was completely done? Seems that the issue is with the head after all. He will know for sure once he takes the head off.

I dont know if i should be relieved or upset, but oh well. At least leakdown showed that air is escaping. We shall see.

[future_R34]

Make sure it's not getting through the crank case breather, which (I think) gets plumbed back to intake.

Regardless, your going to have to take the head off.


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[steveo1502]

^^ this .... it could be leaking past the rings

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[future_R34]

⬆️ forgot to say that. If rings were bad, the air would leak into the crank case and make its way back to the intake.
Ask mechanic to try test again with the crank case breather disconnected. That way you can narrow it down even more.


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