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So... I recently bought a Supra, MKlll 1988 with the 7M-GTE in it. Being my first project car ever. I’ve chased down multiple problems with the car with the cash I can spare, I’ve added a Air Filter, New Fuel pump, New TPS, Did a coil on plug conversion to the car, with IS300 Coil packs and wires. Spark plugs are also brand new, each one gapped to ~.30. Also changed the original plastic intake piping out for wider piping.

Current problem has me stuck, I’ll just go into detail from here. Car starts fine have to start her up a few times, however there slight miss here and there when idling. While in park giving it a little throttle and holding it steady, the car surges almost, the rpms raise and drop all by itself, when just holding it steady. Same thing when I put it in drive and attempt to do the same. The rpms just bounce up and down between 1200~1400. Along with this problem. When attempting to drive the car, it breaks up slightly during acceleration, and when you attempt to build boost it breaks up badly, especially around the 3k RPM mark. I attempted to give it an attempt at a pull and it starts to suck air and build boost, but suddenly the rpms turn off. Then I have to build boost up again. And under load trying to do a pull, the car does the same surging when it DOES manage to pull, the rpms raise and drop at like 5000~5500.

A few problems I’m working on fixing on the car I KNOW of are, it is straight piped all the way out with no Catalytic converter’s (idk if this would cause any of this), along with a decent hold in the down pipe where it bends, under the turbo. Might have a plug broken at the TPS, (old wiring/plugs sucks.)

If you have any clue as to what could be causing my problems under boost. Any help would be much appreciated.
 

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So... I recently bought a Supra, MKlll 1988 with the 7M-GTE in it. Being my first project car ever. I’ve chased down multiple problems with the car with the cash I can spare, I’ve added a Air Filter, New Fuel pump, New TPS, Did a coil on plug conversion to the car, with IS300 Coil packs and wires. Spark plugs are also brand new, each one gapped to ~.30. Also changed the original plastic intake piping out for wider piping.

Current problem has me stuck, I’ll just go into detail from here. Car starts fine have to start her up a few times, however there slight miss here and there when idling. While in park giving it a little throttle and holding it steady, the car surges almost, the rpms raise and drop all by itself, when just holding it steady. Same thing when I put it in drive and attempt to do the same. The rpms just bounce up and down between 1200~1400. Along with this problem. When attempting to drive the car, it breaks up slightly during acceleration, and when you attempt to build boost it breaks up badly, especially around the 3k RPM mark. I attempted to give it an attempt at a pull and it starts to suck air and build boost, but suddenly the rpms turn off. Then I have to build boost up again. And under load trying to do a pull, the car does the same surging when it DOES manage to pull, the rpms raise and drop at like 5000~5500.

A few problems I’m working on fixing on the car I KNOW of are, it is straight piped all the way out with no Catalytic converter’s (idk if this would cause any of this), along with a decent hold in the down pipe where it bends, under the turbo. Might have a plug broken at the TPS, (old wiring/plugs sucks.)

If you have any clue as to what could be causing my problems under boost. Any help would be much appreciated.
I had the thought of replacing the stock 7M plugs with the IS 300 plugs you are speaking about because I own both a MKIV and a MK3 and I have piles of parts and thought it would be “cleaner” but some of the wiser members here pointed to others having difficulty under boost with those coils on the 7MGTE. I never tried them personally and went back with the big ugly OEM coilpack on top.
 
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