So we got a car in that came with a blown motor and overall the car is in terrible condition. Everything just seems to be destroyed or blown that I put in my hands...

The car has a new built engine now - just regular forged stuff, 2.0, 9:1 CR.. China intercooler 3", HKS 280 cams (the old ones) and a random K&N small cone filter - on the stock rubber tube and MAF location. Evo metal dump valve. Fuel system is still stock by the looks of it - we didn't check the fuel pump if it's stock or not tho, injectors are however...

Running the stock map - it's lean at low rpm and idle. Idles at 18ish AFR and stutters. Touching the gas raises rpm and reduces the condition but still nowhere near the 14.7. At ~1300 rpm the afr is at 16 or so... However when going out for a cruise and driving slowly the cruise afr bounces from 14.4-15.0 so that seems normal.

The car does not have the rear o2 sensor at all - just chopped wires hanging there.

I haven't pushed the car yet so can't comment on anything wot related, the new motor has 5 miles on it or so now.

Things checked:
- no boost leaks
- no exhaust leaks
- front o2 sensor replaced with a working one

I can't log fuel trims - just 0's on all trims. Injector latency, scaling etc is stock.

Anyone has an idea what could the reason for the lean running be? What can I do to log fuel trims without the rear o2?

Cheers in advance!

 

Anyone?

 

An exhaust leak maybe? Are you running a rear 02 simulator, since it is not hooked up?

 

I guess a good question is why can't you log fuel trim? Don't fuel trims come from the front O2 sensor? Your working front sensor may be working but if that work's not reaching the ECU you have a problem. Broken wire maybe?

 

If the ECU was not flashed to allow for the rear o2 to be deleted then he will not get fuel trims.

 

I flashed it with tephra mod and deleted the rear o2. Same thing.

 

He should still have a STFT, or front o2 sensor voltage.

 

What did you find with the O2 sensor sir?

 

Replaced the front one, simulated the rear one with tephra mod.

 

I have seen people do this mod but incorrectly and still would not get readings. Care you post up the actual tune for the car so were all not blind?