Intermittent miss up to 2k and idle when warm NA-T

[pwpanas]

Originally Posted by Travis89Turbo

Well I have an update for everyone. Unfortunately this problem is not gone, however i do now have proper compression, and a TT headgasket giving me a more boost friendly compression ratio of 9.2-1.

So... the problem still is it runs rich at start up avg. 12.5+/- It will run in that range for a while approx 5 min. Then drop off carzy lean 17+ at times my AEM AF gauge wont even read it. I have only ran the car for few mins at a time and is not off jack stands so im not going to drive it and do damage with the 17 AFR. The time frame in which it starts to bog and miss (when it falls to anything more the 15 AFR) has gone down drastically from when the problem very first started. Im out of options other then swapping parts. Which luckilty have a friend with a 2jzge in his mk2 that is nice enough to let me use his good parts. Im hoping for a bad MAF

I have a friend coming by the house in a couple hrs to let me try his MAF. If that is not the problem what else would you reccomend swapping to try and troubleshoot??

NEW O2 sensors as well.

1) Thanks for the update - much appreciated!
2) For what it's worth, I wouldn't call 9.2:1 "boost-friendly". Oem 2jz-gte is 8.5:1, and even that is only good for 15psi or so on 93 octane pump gas.
3) Ime, 12.5:1 a/f isn't really all that rich for cold-start. *shrug* However, I agree with you that 17:1 is crazy-lean - I'm guessing that's where your problem is (i.e. not the 12.5:1 on cold-start).
4) If you can obtain some sort of fuel controller to modify the maf signal (eg. APEX'i S-AFC or MAP ECU), you could try richening the fuel curve that way (above idle) - just as a troubleshooting step.
5) Guesses: Test for vacuum leaks. Bad IAC. Dirty injectors. *shrug* - I'll ponder it some more and re-post if I think of anything else. In the meantime, please do keep us updated.

Note: You can pressurize the intake with an air compressor to test for vacuum/boost leaks.

[Travis89Turbo]

Originally Posted by pwpanas

1) Thanks for the update - much appreciated!
2) For what it's worth, I wouldn't call 9.2:1 "boost-friendly". Oem 2jz-gte is 8.5:1, and even that is only good for 15psi or so on 93 octane pump gas.
3) Ime, 12.5:1 a/f isn't really all that rich for cold-start. *shrug* However, I agree with you that 17:1 is crazy-lean - I'm guessing that's where your problem is (i.e. not the 12.5:1 on cold-start).
4) If you can obtain some sort of fuel controller to modify the maf signal (eg. APEX'i S-AFC or MAP ECU), you could try richening the fuel curve that way (above idle) - just as a troubleshooting step.
5) Guesses: Test for vacuum leaks. Bad IAC. Dirty injectors. *shrug* - I'll ponder it some more and re-post if I think of anything else. In the meantime, please do keep us updated.

Note: You can pressurize the intake with an air compressor to test for vacuum/boost leaks.

Okay have a few more updates. And they are not good news.

I pulled off my MAF, Coil, and igniter and tried them on another 2jzge together and individually and it ran great no miss or hesitation at all.

So I got thinkin about the compression again. I do know that the GTE is at 8.5 but there has been gray success running 9.2 on the ge at lower boost levels. I'm only shootig for 350hp with a t70. Anyways. I ran the car for a bit a couple different times to burn any oil from assembly out of he cylinder. Re dis compression test and wouldn't you know. 145 across the board until #6 which is 129. Now I know the compression would go down with the 1.3mm headgasket but everyone else says they are around 170 with the thicker gasket.

What I did to originally repair the compression is pulled the head off. Replaced rings in 6 cylinder all others were 170ish. I also replaced valve seals on all valves. However me not thinking did not pull the valves out to inspect them. I am wondering if I have slightly bent valves possibly?? I am almost to the point of pullin the motor and swapping to another GE. Or would u suggest just a head change? I really don't think its in the bottom end myself. But I am out of ideas.

I do have a map.ecu. But I would much rather get it running properly on factory ecu. Although I may try it. But the compression numbers are depressing. I am picking up a leak down tester to find out where i am loosing my pressure.

I have done the pressure test at 50psi. All checked out okay. I will wire up the map.ecu and try to play with it.

[pwpanas]

Originally Posted by Travis89Turbo

Okay have a few more updates. And they are not good news.

I pulled off my MAF, Coil, and igniter and tried them on another 2jzge together and individually and it ran great no miss or hesitation at all.

So I got thinkin about the compression again. I do know that the GTE is at 8.5 but there has been gray success running 9.2 on the ge at lower boost levels. I'm only shootig for 350hp with a t70. Anyways. I ran the car for a bit a couple different times to burn any oil from assembly out of he cylinder. Re dis compression test and wouldn't you know. 145 across the board until #6 which is 129. Now I know the compression would go down with the 1.3mm headgasket but everyone else says they are around 170 with the thicker gasket.

What I did to originally repair the compression is pulled the head off. Replaced rings in 6 cylinder all others were 170ish. I also replaced valve seals on all valves. However me not thinking did not pull the valves out to inspect them. I am wondering if I have slightly bent valves possibly?? I am almost to the point of pullin the motor and swapping to another GE. Or would u suggest just a head change? I really don't think its in the bottom end myself. But I am out of ideas.

I do have a map.ecu. But I would much rather get it running properly on factory ecu. Although I may try it. But the compression numbers are depressing. I am picking up a leak down tester to find out where i am loosing my pressure.

I have done the pressure test at 50psi. All checked out okay. I will wire up the map.ecu and try to play with it.

I'd assume you didn't notice any cracks in the #6 piston's ring lands (this is common when compression is low). A bent valve is unlikely, unless your previous config was interference? A bent valve on the top side almost never happens with the OHC+bucket config. A leak tester is an excellent next step. Good luck with it, and please keep us informed. If I were to just guess (which I don't like doing), consider replacing your #6 piston (i.e. not the head).

[Travis89Turbo]

Originally Posted by pwpanas

I'd assume you didn't notice any cracks in the #6 piston's ring lands (this is common when compression is low). A bent valve is unlikely, unless your previous config was interference? A bent valve on the top side almost never happens with the OHC+bucket config. A leak tester is an excellent next step. Good luck with it, and please keep us informed. If I were to just guess (which I don't like doing), consider replacing your #6 piston (i.e. not the head).

Okay. Results of leak down.... I have only done cylinder 5 and 6 for the time being due to the cross over intake mani. And it was gettin late.

#5= an average of 25% leak. No leaking out of valves with small blowby past rings.
#6=an average of 85% leak! Blowing pressure out of intake and exhaust with very very little blowing by piston.

The ge is still Non interference motor but I'm assuming the added pressure from boost and high compression. May have tweaked them. It's not a massive bend cause it looked flush. I had done quite a bit of research before my tear down just tryin to find troubled areas on the GE. And like you said the cracks in the piston ring glands is a common problem. So I inspected the piston thoroughly and it besides the slight carbon (more then I expected at only 70k) the piston looked flawless as did the rings I pulled and measured within limits per factory manual. Although I replaced them anyways. The GE pistons are coated just as the GTE so I stayed away from the wire brushes.

I forgot to add that I found Volume 1 and Volume 2 of the factory service repair manuals on eBay for an insane deal of $45 shipped. Some were sellin for over 100+ These manuals are great. They cover everything you could think of and then ten times more! Thanks for the advice to pick those up!

[interested!]

Originally Posted by Travis89Turbo

Okay. Results of leak down.... I have only done cylinder 5 and 6 for the time being due to the cross over intake mani. And it was gettin late.

#5= an average of 25% leak. No leaking out of valves with small blowby past rings.
#6=an average of 85% leak! Blowing pressure out of intake and exhaust with very very little blowing by piston.

Hi! , The high blowby through the in and ex ports makes me believe the valves are on overlap - exhaust closing and inlet opening , may be an idea to retest with the crank in different positions to thoroughly test cylinder no 6 pressure .

[Travis89Turbo]

Originally Posted by interested!

Hi! , The high blowby through the in and ex ports makes me believe the valves are on overlap - exhaust closing and inlet opening , may be an idea to retest with the crank in different positions to thoroughly test cylinder no 6 pressure .

Only thing I can think of that is left would be ECU possibly. Hopefully I can talk my friend with the mk2 to let me swap ecus.

[interested!]

Hi! , No problem ! Question ? : is the engine a high miler from new without top-end overhaul ? -- The valve seats and valves may have some pitting and this is letting the pressure through , my 7MGTE head needed an overhaul ,the seats and valves desperately needed recutting/refacing following a BHG as they were severely pitted ,a leaking ( oil ) turbo and general clean-up . I've had two engines where the inlet valves have split at the seat and burnt away , one was nearly new , the other a high miler . both were misfiring .

[pwpanas]

Originally Posted by Travis89Turbo

Only thing I can think of that is left would be ECU possibly. Hopefully I can talk my friend with the mk2 to let me swap ecus.

How is your valve shim clearance?

Originally Posted by interested!

Hi! , No problem ! Question ? : is the engine a high miler from new without top-end overhaul ? -- The valve seats and valves may have some pitting and this is letting the pressure through , my 7MGTE head needed an overhaul ,the seats and valves desperately needed recutting/refacing following a BHG as they were severely pitted ,a leaking ( oil ) turbo and general clean-up . I've had two engines where the inlet valves have split at the seat and burnt away , one was nearly new , the other a high miler . both were misfiring .

True. I've seen a VERY badly pitted head from running higher boost on pump gas. In fact, (among other damage) it punched right through from one combustion chamber to the next! Lots of welding and machining was required to get that head back in shape.