2zz ge lean idle and misfire

[Duncan M]

This is going to be a bit of a long one just to save people from suggesting things I’ve already done. My bottom end went last year so decided to rebuild the engine, during the rebuild I did the following modifications: light weight flywheel, egr delete, air-con delete, cone filter on custom intake pipe and a full set of samco hoses. Upon starting the engine for the first time it had a poor idle, always changing revs, running lean and misfiring along with the sound of the intake ‘chuffing’ (basically inconsistently drawing in air). I didn’t try and really solve the problem at the time as the car ran and that’s all I wanted. Once the car was driving it behaved okay, it drove smoothly and I wore in the engine for 1000 miles. After 1000 miles I then took it to redline and my bottom end went again to my disappointment. I now believe that this was due to the constant misfiring putting strain on the bearings from cold and on a regular basis. I then bought a second hand engine, dropped it in, with all the same modifications now with a MWR oil pump and morosso sump to protect the bottom end for future abuse/track days. After finding my earths were poor I got it started and it ran fine for the first 15 mins, no misfires, a consistent intake noise and constant idle. It then started making the chuffing noise again (having not revved it or even driven it). I don’t want the drive it like this as the bottom end will probably go again. So far with all my spare parts I’ve switched out the coil packs, injectors, cleaned the maf, unplugged the lamda all to no change. I also switched out the crank position sensor which got it running nice again for about 20 seconds, it then returned to its usual poor idle. I also tried running an extra earth to the old and new cps but that made no change. I feel like I’ve exhausted all my options and can now only think there’s an issue with either the loom or the ECU as they haven’t been changed and were sat somewhat out in the elements while I rebuilt the first engine. I’ve also checked for vacuum leaks and haven’t found any. Once again it runs fine once going and pulls hard to redline this time. Any suggestions or ideas as to how to get it running nice are welcome, I’m all out of ideas. The OBD code coming up is the random misfire one so doesn’t really say much.

[Rob2zz]

I'm having the same problem same situation, i cammed my Celica and upgraded the internals same problem also **** idle and misfire sometimes it also shuts off, apprently its the sprocket (vvtli timer)