My buddys Camaro makes me crazy......

Here the hard facts:
1992 Camaro Z28, L98 engine, TPI MAP Setup, 1227730 AUJP, completly bone stock, emission systems so far as I see Smog pump, Evap, EGR.

the symptoms:
rough idle but not stalling, bad fuel mileage, bad acceleration with part throttle opened

what we use for diagnostic:
self built 8192 aldl cable with MAX232, TunerPro RT, handheld vacuum pump, voltmeter, fuel pressure gauge

what we did:
we changed spark plugs, spark plug cable, distributor rotor and cap, pick up coil, ignition module, ignition coil, O² sensor, ECM with prom
All parts were new and came from sealed boxes, except the ecm.
We checked the fuel pressure (41psi with engine off drops down to 38 psi by 2500 rpm). All vacuum lines were checked for cracks, puncture and proper seat. Firing order were checked also. Ignition timing, checked 0° with EST bypassed. TPS and MAP were checked and works fine.

what wee see:
no trouble codes were stored, in cloosed loop the O² hang around 0,6-0,8V and BLM and INT get in the low 80's. With tranny in 2 and foot away from pedal (decceleration, cut off mode) the O² dropped down to 0-0,02V and BLM/INT go to the default 128.

Actual, I have no more ideas what we can checked or fixed.......

Any help is welcome from a frustrated guy......

 

This wouldn't affect your BLMs, but I thought base timing (with est disconnected) was 6 deg BTDC, at least on MAF cars.

 

Ok, I will check this. The emission label under the hood is missing, but I will find the exact value.

 

Update:
I have checked the EGR Valve for dirt in the passage. Nothing. The valve moves freely and is in good working condition.......

 

My 91 Z28 with a 305 TPI is also 6 BTC, hopefully someone w/ 350 could verify it's the same.

 

305 and 350 have 6 Deg BTDC