Hey everyone. I will try to provide as much detail as possible.
I have searched and searched and tested and tested, and now Im at wits end. I need some help figuring this out.
car: 89 turbo with a jdm 7mgte swap cause the PO was an idiot who thought it easier to swap than fix a BHG.
engine: post 89 7mgte with no emissions stuff
current modifications: turbonetics 62-1 hifi turbo with ported wastegate hole, BIC divorced downpipe with motorcycle muffler on wastegate pipe, minor head porting, lex AFM with K&N filter and Sonic Screw, 580cc injectors with clips, 4 inch MDC downpipe back exhaust, no emissions equipment (egr, canister, cat), no boost controller, Tial BOV with 11pound spring, 2.25" upper intercooler piping, 2" lower piping, Jtube bypass, electric cooling fan, autometer boostgauge in the dash.
The diag process starts back several months ago. While on the stock turbo with BIC downpipe and stock injectors and stock AFM I found fuel cut with a boost controller. No problem, back down the controller and Im good at this point. so good so far. Went to the dyno and saw my top end falling flat. MDC was nice enough to build me a one of a kind 4" exhaust to help resolve the lack of top end power and from this point I cannot get away from fuelcut. As soon as the exhaust was installed I removed the boost controller and was hitting fuel cut and running extremely rich.
Remedy #1: Lex AFM and 580CC injectors
still hits fuel cut.
Remedy #2: back out the Sonic screw to try to trick the AFM out of fuelcut so low
still hits fuelcut. Then I opened up the bov port on the accordion pipe to let in some unmetered air. no dice, still hits fuel cut.
Remedy #3: boost leak test.
found one small leak, fixed it. I drove the car all of about a mile before the stock turbo shat itself. so I never got to see if this actually fixed it.
At this point I already had the turbonetics turbo so I swapped turbos and installed the muffler on the downpipe so as to not get arrested every time I floored it. get the car back on the road and BAM, fuel cut. only now its atleast alot of fun right before it hits it. Boost comes on very strong at 3500rpm or so. Im thinking this car would be alot of fun if I could rev past 4500rpm... now it hits 14-15psi and slams fuel cut at that point without a boost controller.
remedy #4: boost leak test.... again
minor problem found air coming out from behind the compressor housing. I read on "the all knowing internet" that this is ok since it held pressure for a couple of minutes no problem. I also couldnt get the manifold to hold pressure, but this also appears to be normal.
remedy #5: replace 7pound Tial BOV Spring with 11pound tial BOV spring just in case the BOV was leaking
waste of time, still hits fuel cut and now has some surge to boot.
remedy #6: replace injector seals and upper manifold gaskets hoping they were leaking boost
no dice, still hits fuel cut.
remedy #7: remove J tube (Im reaching at this point guys)
still hits fuel cut, still runs rich.
remedy #8: pressure test intercooler
nope, no boost leaks found here. still hits fuel cut.
remedy #9: loosen up wastegate actuator.
It dawns on me that the car should not be hitting 14psi when the guy who sold me the turbo said the actuator was hitting 10psi on his car with the same actuator and no controller with the same dp and a 3" catback... got the wastegate actuator loose then adjusted it open a bit and set it so it was just barely loose. Looked inside the downpipe at that time to see if it might be hitting the wastegate flapper, nope, no interference found. Put the thing back together with a big smile on my face thinking I finally figured it out and went for a test drive and guess what?!?!?!?! The freaking thing still slams into fuel cut at 14psi with no boost controller.
Like I said, I need some help here guys. I have a dyno commitment at a meet in Indy on the 10th and Id really rather not dyno the Scion...
Im hoping someone can post something simple Im forgetting.
Summary: fuelcut sucks, been troubleshooting for months please help.
AP
