1GGTE weird fuel/lean/rich problem

[LeaThaL]

hey all

im having a problem ATM with my ga70 and need some advice, ive asked friends and co-workers and anyone i can to help me and im slowly getting nowhere

its a 88 1ggte supra manual and has
-60mm radiator
-large oil cooler
-3' cat back

and everything else is pretty much stock

what it does exactly is mainly when first cold started i can drive up my street/minor hill and the car will makefull boost while at roughly 1/2 throttle but go nowhere as its hitting a massive flat spot, keep it at this level of thottle and it will stay the same but go a little thurther with the thottle and the car will jerk forwards as if getting the required fuel and take off.

it will do this at first and get better as i drive but unless i go full throttle constanly it will always hit this flat spot at 2500-2900rpm, and seems alot worse when started up again from hot. you can feel it while cruising at 60k as it will start pulling back as you hit the flatspot and the car sounds as if its running out of fuel and with a touch more pedal it will jerk forwards again and even when its feeling good you can feel just the smallest amount of hesitaion at whatever speed while crusing.

BUT! somedays its completely gone! but a hour later its shithouse again! and at the same time i do get good performance out of it when giving it the stick and puts the usual amount of fuel out the exhaust and all over my bumper but will still give a white residue on my plugs indicating lean running....

now ive tried 2 AFMS, 2 dizzys, 2 rotor buttons, 2 caps, new sparkplugs gapped to 0.8, full pro on-car injector cleaner, always 98 fuel, checked the resistance of my CTS and its fine, ive checked for boost leaks and seems alls good, replaced all breather hoses and vaccum lines, timing is correct, valve train timing is correct.

fuel pressure is roughly 220kpa on idle but when it hits this flatspot it will rise to about 300kpa! tried another FPR and same deal. tested on a hoist off the ground so no underload values but yeah.

I do have a spare coil/ignitor here but i dont think its that, and i do have a spare set of injectors to try with clean filters but not sure how they will go as their older and will need a clean themselfs once installed but im running out of ideas

[dnegative]

Try another TPS if you can

[SumKid]

Cold start injector playing up?

[LeaThaL]

I'll disconnect it and try but I don't think it could be but who knows

[LeaThaL]

Ok so i got on the gas analyzer at tafe today and had a play, this is my inital find...



this tells me im running really rich but im getting problems with surplus air in the exhaust, i do have one small exhaust leak but it seems its not the problem.
after trying a few things, doing a full smoke/pressure boost check i found no air escaping anywhere so thats good so we came to the conclusion that there is an air leak between the head and the 02 sensor so ill have to remove the exhaust manifold and turbos and see whats mesed up there!

[dnegative]

I need to think more

[LeaThaL]

i already have, i get a solid 220kpa which is pretty much fine

thats not an accurate AFR reading, under boost it goes up to 15/16:1 and the rest reads accordingly, but the o2 sensors getting way too much air from somewhre around the turbos, the motors getting drowned in fuel, whats what my fuel flatspot seems to be.

plus when it dumps fuel clean out the exhaust the way it was it cant be lean, we spent 40mins doing loads of tests and thats just one idle shot

[dnegative]

I'm guessing you have a working cat...... disregard

[LeaThaL]

Yeah intact stock cat still I'm still a tad skeptic still but the teachers got loads of experience and also got the same answer from another teacher

[cresslux]

tried a new ecu?

[LeaThaL]

Nah I'm trying to find one to fit atm