GTX motor cutting back at 4.5k

[OCD-SPEED]

Fo, I think the problem is, that if youre thermostat is stuck open and it stays running cold then the ecu is still running in open loop. If your getting on it in open loop it probably would do that. Get that thermostat fixed! Does that sound right to you guys?

[Lex]

motor goes into closed loop once exhaust gases heat the O2 sensor to ~600degrees F

[FE3-323]

i've heard of people using the RX7 AFM instead of the BP26 "Y" code AFM they are the same size however. no gain is had there. think there is any benifit to changing AFM's?

i've got 1 of each "B" & "Y" code AFM's

[OCD-SPEED]

So lex, would my solution be right or wrong. Would the 02 stay below 600 if the car was running that cold?

[TurboProto]

If i accel slow it doesnt do it. But i know there is no way that im running 14psi to hit boost cut. I havent got a boost gauge yet, still waiting on it. But i know what 14psi feels like. Yea i have been reading that website.

See when mine was cutting out the only way to make it not do it from idle to redline was to stomp on the gas. And it would fly w/no fuel cut. But my fuel pump is hardwired to a shut off switch so I dont think its fuel cut. cause It has a stable voltage. So my afc saved the day. I think the ecu was tryin to adjust it's self at the wrong rpms. So go figure??

[Lex]

So lex, would my solution be right or wrong. Would the 02 stay below 600 if the car was running that cold?

Actually not entirely true ... the exhaust gas temperatures are quite separate from overall engine temp. They rise and fall very quickly depending on how you drive your car compared to overall engine temp. They also have a much larger range of temperatures (up to upwards of 1400 F)

I dont think its thermostat related. I can get in my car and turn her on and stomp on it and it wont cut back. This is not good practice as its good to let her warm up ... but none the less I dont think this is the cause of his problems.

Foescort, do you have an A/F gauge to give you an idea of what's going on?

[TurboProto]

And my buddies gtx setup his car was doing the same thing , so we put in his n/a ecu and changed the timing. The boost cut was gone and the rev limiter in fist gear was higher like we wanted. Also his fuel pump is wired the same way as mine.

[Foescort]

ok Lex, i want to see what the diffrences between our setups are.Because you say you never have that problem right?
what i have:
Full gtx oem setup
Stock motor, stock harness
stock intercooler pipes,
BP55 ecu
2.5 inch exhaust
and intake.
What do you have?

[Lex]

Right now I have:

Full GTX motor + injectors
GT harness with TPS and knock sensor wired in
BP26 ECU
RX-7 VAF
Walbro fuel pump
2.5 inch intake piping and Starion FMIC
3 inch exhaust
15-16 psi boost (more on the hwy)

I also ran the car with a BP55 and a BP10 ECU and an unmodified GT harness

[SgtRauksauff]

If I remember correctly (which I may not be) I think it's pin 1M on the GTX ECU involves some sort of fuel cut. I never had to change it with my setup, but a guy I know had to disconnect that pin because he kept running into a fuel cut for some reason. This was 2 years ago, and it's starting to get vague now. I seem to remember finding out about it either on 323gtx.co.uk or fordlaser.com, I don't remember which one.

--sarge

[FE3-323]

sorry sir pin 1M is unused.

[FE3-323]

this is a very worth while thing to investigate tho.

[Lex]

fordlaser.com ... that's where I read about it as well.

[SgtRauksauff]

Hmm.. It looks used to me...

Section B-2c of the manual (page 627 of 677 in the 1990_EA_4WD_Supplement.pdf) shows this. Black wire, it's a Harness Ground in the Emissions harness [EM], looks like circuit number 4 in that harness (at least that's what I assume the circled 4 means).

I wish that the ERDT forums hadn't collapsed, I had a very good bunch of quotes from different boards, but then they too had some incidents, and I don't know if the exact posts are around anymore.

--sarge

[FE3-323]

just going by my diagrams...
im going to make a sticky of the pin outs i have, would that help anyone else?