Runs lean to hell!! please help me.

[mazdasly75]

Ok to make a short story...

I bought an 89 turbo wich the precedent owner had to change the engine cause of blown head gasket + leaking turbo. The change has been done by a garage and when he got back the car, it was running very terribly, so I bought it for cheap...I just took 2 runs and the engine could not enter in boost as it was hitting some kind of fuel cut. The check engine was there, but didn't threw out the code. The car is 91 000km, yeah it's a canadian supra

It was late in the last fall, so I deceided to upgrade the 7M. Since I knew I had to diagnose the source of the problem, I started the work. I change the headgasket for HKS one + ARP stud. Bought huge FMIC with IC piping, got new stainless downpipe, 3" stainless exhaust catless, AEM wideband + TRU boost controller, HKS BOV, I also put new timing belt, water pump, NGK plug wire....

While playing on the engine, I found that the Cam sensor plug had 2 pins out of the connector, wich probably threw a code. I also found 2 broken wires from CTS and another one that i don't know what it's function. Overall, I repaired all of those and earlier this week I started back the engine. Now it runs, still lean. So much lean that the wideband dosen't show anything till I'm pumping the gas and when the engine decelerate, I see 17:1 of reading due to momentary enrichment situation when the ECU shut off gas while acceleration/deceleration. (enrichment? really?) As far as I know the car won't move as it has no power and I don't want to run anyway. Right now, there's no code, I even tried to pull off, nothing. It start right off, no hesitation, but once idling, there's some misfire. I revs up once to 3000rpm, and I got a check. After reading the code, it was 51-52 knock sensor issue, wich was normal due to backfires and misfiring. The timing is adjusted, I ordered an AFPR. I was about to do a fuel pressure test when the electricity went down...damn snow storm.

Do you guys know what could make a 7M running lean? As far as I know if the CTS or IAT were broke or had an open circuit, it would runs rich. I'm thinking of low fuel pressure, bad fuel pump, clogged injectors, bad AFM...anything else to check?

Thanks
Sly

 

[Poodles]

Code 52 isn't caused from detecting knock, it's from a fault in the knock sensor circuit. It would not cause your problems.

 

[theKnifeArtist]

Your A/F will read lean if you're misfiring. Could be from a timing issue, ignition, compression, fuel.
Recently, I had a bad intake manifold gasket leak. It ran as lean as 21:1 at idle. What's your A/F at idle?

What's it at 2000RPMs in neutral?
What's it at cruising speed?

When running my leaky car, it of course ran like shit and the A/Fs were all over the place.

With a bad vacuum leak, you're running lean under boost, but trying to subtract fuel from the lost air in boost.

 

[kamikazemkiii]

Have you recalabrated the wideband?

 

[mazdasly75]

The AEM wideband dosen't need calibration, also it's brand new. I can't move the car as it's runs lean as hell. I'll do vacuum test leak with propane kit, thanks for the idea. Timing's good, I'll take a compression test, maby test leak too.

Again, the wideband shows no reading until I pump the throttle, then it shows some very lean condition. The AEM stops reading passed 18:1. It could be 1 or more cylinders not injecting or firing. Each cylinder would act as an air pump...?

 

[mkiiichip]

you said your car is misfiring, this means you can take your wideband sensor readings and throw them out.

all that is telling you is there is allot of oxygen in the exhaust. so your either its misfiring or lean or both.


i would start looking for which cyl is missing and why.

 

[jetjock]

^ This. Why anyone would use a WB to troubleshoot closed loop fueling is beyond me...

 

[mazdasly75]

I did not installed wideband to diagnose, my next step is to change turbo/injector and installing megasquirt. At that point, I'll need a wideband for tuning.

I got some cylinder pumping air for sure as I can put my hand on the downpipe without getting burned, after few minutes of running. The engine came from japan importer, so it sit there for at least 10 years before the precedent owner bought it. I'm thinking of clogged injectors. If the fuel pressure test shows nothing wrong, I'll take the injectors out and will bench test/clean'em.