Hey guys.

My friends car is currently being difficult.
The car will misfire around 4-5k revs.
He has a front mount, walbro 255lph fuel pump and a fuel cut defender.
We have literally tried almost everything we can think of.
We replaced and gapped the spark plugs, replaced the coil packs, replaced fuel filter, replaced battery, checked all the vacuum lines, cleaned the 02 Sensor, cleaned the IAT sensor, Tried another MAP Sensor and it still misfires. We have tried the coil pack test ( disconnecting while idling ) and its fine. We have yet to try another ECU.

What are the possibilities ? Could it be the ECU ? could it be timing ??

Thanks heaps !

 

it could easily be the ECU. open it up and look for leaky capacitors. It could also be a lazy fuel pump. Do you have a wideband to see if it is leaning out? Is this a stock 1jz, or is it singled? what boost level?

 

Okay. So here goes.

The car has
Stock 1Jz with steel wheel twin turbos( c12a's ), Front mount intercooler, aftermarket 3" dump pipes, hollowed out cat and a Fuel Cut defender. This is where it gets tricky.

We recently did a gearbox swap on it. It then started to misfire like crazy and it wouldn't kick down to first when the foot is planted to the floor. it stays in second and hesitates and misfires. It has thrown the error code
31 ( MAP Sensor )
41 ( Throttle position sensor )
and 47 ( Sub-throttle position sensor )

We recalibrate the TPS and it went from 3 codes down to 1.
(41 remained)
We have tried another ECU that has no known issues. So we are completely stumped. We have changed the following

Spark plugs(gapped to 0.7mm)
ECU
ignitor
Coil packs
Shift solenoids
Speed sensor 1 & 2.
Fuel PUMP ECU ( have tried 12V Bypass via diagnostics)
MAP Sensor

We literally have nothing else that we think it could be other than a damaged loom somewhere causing the error. The misfire has started to get better after a little TPS calibration but it is still there..

Here is a video of what happens at wide open throttle

Any help would be greatly appreciated