1JZ Swapped 82’ Supra No Idle

132 Views 3 Replies 3 Participants Last post by Sam_Smiles, 4 d ago

Chriqs

Discussion Starter · 4 d ago

Hey everyone! I’ve got a 1982 Celica Supra 1JZ swapped but it won’t idle, just starts and stalls right out. It’s been sitting all winter long with the battery removed and the only thing i did was replace the oil pressure sender with a 7m and a driftmotion braided line extension.
Before first starting it, I also had some fuses and relays pulled. EFI relay, EFI fuse and MAIN relay just to crank no start on purpose. After putting the fuses back in, it started up and idled no problem. I then disconnected the battery again and let it sit like that. 2 days later I hooked the battery back up and went to go start it, started but won’t idle. Started it multiple times, sometimes it will idle very very low at maybe 400rpm. I can rev it no problem and i can keep my foot on the gas to stay steady at any rpm without issue. but once i let off the gas, it stalls out and shuts off.
Any ideas? Could it really be the ECU needing to relearn? Just a liiiittle worried about if it’s okay to drive to relearn the ECU if that’s all it is. Or maybe a stuck IACV? Seems like a big vacuum leak but i’ve been told maybe it’s just the ECU needing to be relearned. Any help would be much appreciated thank you!

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Funkycheeze

· #2 · 4 d ago

Stock ECM and IAC system? Valve could be stuck for sure. A vac leak would cause high idle. Id remove it and clean it out etc.

On the swap harness where does the IAC get its 12V power from? You can confirm the middle 2 pins of the 6 pin connector should get 12V when the car is keyed on.

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Chriqs

Discussion Starter · #3 · 4 d ago

Funkycheeze said:
Stock ECM and IAC system? Valve could be stuck for sure. A vac leak would cause high idle. Id remove it and clean it out etc.

On the swap harness where does the IAC get its 12V power from? You can confirm the middle 2 pins of the 6 pin connector should get 12V when the car is keyed on.

Yup, stock as far as I know. I wasn’t the one who did the swap unfortunately. Will check out the IACV when I get home! Seeing a decent amount of info on how long it sometimes takes the ECU to relearn after leaving the batt disconnected for a long amount of time.

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Sam_Smiles

· #4 · 4 d ago

When shutting off the car, you should hear the IACV valve "home" itself after about a few seconds. On the 1J it sits at the rear of the intake manifold. There's ways of testing it by Appling voltage to certain pins. It typically gets gunked up.

If you simply unplug it or unbolt it, your idol should skyrocket. You can put your hand over the hole and see if you car reacts. It should die.

A more simpler explanation could be your idol set screw at the throttle body. I've had mine come loose, but mine was stuck open.

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