1uzfe Starts good, then hunts and misses when at operating temp.

[Mikebratty]

Hi
My name is Mike.
I have a 1992 toyota surf with a 1uzfe in it. Its running a standard ecu and manual gearbox.
It starts beautifully and runs rely well for about 10min but when it gets up to operating temperature it starts to hunt/surge when idling, it also starts to miss and will occasionally stall.
If i give it a little bit of revs it stops missing and hunting.
I have already replaced the ISCV and put some throttle body cleaner through the throttle. I have tried unplugging the AFM and it continues to have the same problems. Any help will be much appreciated.

I would have thought if it was a coil bank it would fail under load?
Is it likely to be an ECU problem?

 

[Bushwhacker]

What year is the engine?

Have you tried replacing the EFI coolant sensor? (Green plug sensor near the IACV)

 

[Mikebratty]

Not 100% sure what year it is, think its an earlier model.
No i havent touched the EFI coolant sensor, But ill give it a try. Do you think it would be ok to unplug it and see if it still surges and misses when its unplugged.

 

[Yotarip]

I had the same problem. Turned out to be one of the primary o2 sensors.

Engine ran fine in the enriched warm up mode (bypasses signals from o2) but stumled and missed bad immediatley after.

 

[gloverman]

I would recommend getting a scan tool onto it. Cheers

 

[samsdad]

You have the main relay trigger wire and B+ around the wrong way

 

[MaccyD]

samsdad can u give a bit more detail on this please? thanks