Per my post above, have you checked for boost/vacuum leaks yet via pressurizing the intake yet?
One potential issue is a split vaccum (or charge air) hose that weakens with heat. A boost leak check will detect this (and an ordinary smoke test won't).

Here's another thought (while we're on the topic of split hoses):
http://autos.groups.yahoo.com/group/mkiv/message/230604

I have not yet pressurized the system I will do that this evening after building an adapter.

I pulled the code ==== 25 lean condition?? Fuel pressure is within spec.

I am starting to think possibly a bad MAF. I am running out of money fast throwing parts at it. Do you kno how to test the MAF on a ge??

Also at lunch today the check engine light went out on its own. At times my afr are perfect idling at 13.9 then all of a sudden just fall on its face down to 16-17. I unplugged the maf and it did not change the way it was missing???

I am also goin to ohm out the injectors this evening as well.

The easiest way is to swap it out with another Supra. I agree this is a possibility. One of my Supra buddies did have a MAF go bad.

Do you have the TSRM? I know it's a few bucks, but it's money well-spent that will pay itself back over and over again. The MAF test procedure and thousands of other useful procedures are detailed in it.

I do not yet have one but do plan on buying one.

Update- I pulled the turbo system off and put the stock na header back on with the sane 4runner dist cap and msd wires. Car runs AMAZING so far it made it all the way to work and didn't skip a beat for the first time in a while!

So two things I'm goin to do. In order to run my afr gauge I am only running one o2 and jumped the wires for the second into it. I am goin to switch it to the rear bank after work to confirm I ge the same results. If I do then I will be doin the pressure check on the intercooler piping. If that checks out the I will install the turbo and check it through the intake of turbo pressuring the entire system.

My question to you is should I dis connect it at the throttle body or will it hold 50psi??

Update :(

I switched the o2 sensor to the rear bank and what do ya know it started acting up again stumbling on idle just like before afrs drop lean.

So I ohm'd the injectors they all checked out within limits.

So tomoroow I will be gettin a new leak down tester and an adapter for my compression gauges as I didn't receive it back after I loaned it out.

Fluid levels still look great. No mix in any fluids so I am starting to wonder about my piston rings. ??

Everything should hold about 50psi bone cold. This is the equivalent of about 25psi running hot under boost. If things pop apart at 50psi or less, it just means you need better t-bolt clamps & couplings.

Maybe a silly question, but if it runs great using the O2 sensor to the front bank then maybe the problem is related to the rear O2 sensor (i.e. not anything else like the piston rings)?

I used the same o2 sensor for both tests just switched locations with my wideband afr.

I did a pressure check on the intercooler and piping but with the turbo pulled off I couldn't do it through the intake of the turbo yet.

Could still possibly be a clogged injector but the compression test will let me kno that tonight.

If it is rings I won't be rebuilding the GE. The limits are so tight on these motors I don't trust it with just a plasti gauge and don't have any better or special tools for that. So I will be looking into a 2jzgte swap with my single on it and pull the jdm twins. But would much rather not have to do that. Hopefully its not a compression issue in the bottom end. I will keep you posted!

Okay, but which O2 sensor was the oem ecu using to regulate the a/f curve? Since it ran fine when you flipped the wideband...

1. Quote:

   Originally Posted by Travis89Turbo (Post 104368) ...I pulled the turbo system off and put the stock na header back on with the sane 4runner dist cap and msd wires. Car runs AMAZING so far it made it all the way to work and didn't skip a beat for the first time in a while!...

2. Quote:

   Originally Posted by Travis89Turbo (Post 104368) ...I switched the o2 sensor to the rear bank and what do ya know it started acting up again stumbling on idle just like before afrs drop lean...

...then it seems that troubleshooting should focus on something to do with the O2 sensor?

If this is a dumb suggestion, please ignore. It's REALLY hard to provide third-hand advice over the internet...