undertaker

94 LT1 rings were shot so new motor went in and ran right for a while, year and half ago, trans crapped out, rebuild that, now its running like crap.

Motor was rebuilt with the tune with mildly worked heads, and a comp 306 cam, set for 30 lb injectors (I orignally had accels in it, was advised to swap to SVO's which I did) stock fuel pressure etc. Car is running lean on bank 2, tested all the injectors and resistance rings back even on all 8. Pressure is 43 with the vacuum line off the regulator, no vacuum leaks when checked with starting fluid, opti is replaced with a MSD unit, new plugs, wires, 02's, cat etc. Problem is the car at teh tail pipe rings out with a wideband around 19-1 after the cat. We pulled the 02's and threw the wideband in each respective hole and the driver's runs properly, the passenger is running 16.7 at idle, 16.4 at 3K. Car sitting at idle gets the cat (which was replaced less than 2 hours max, can't put miles with it running as is) glowing cherry red after 10 mins. Even with the exhaust dumped at a pre-cat cutout its lean as can be.

hooked it up to a scanner and this is the fun stuff we found.

idle rpm 900
tps .71v
coolant temp 180
battery volts 12.0
IAC 80
injector pw bank 1 2.5 ms
injector pw bank 2 4.8 ms
long term bank 1 108
long term bank 2 160
map 2.7
man 18in merc.
manifold air temp 107
MAF 10.0 g/sec
right HO2S .8-.4 mV bouncing around
short term bank 1 110
short term bank 2 135
spark 27 deg (idle)

Any thoughts as to why the passenger side is trying its hardest to fuel and nothing is happening? all 8 injectors ring out with equal (15ish) resistance. All have a solid 12 volt signal on the pink wires. The car has a stock intank fuel pump, is there an issue because of that even at idle? My 502 ramjet runs off a factory vortec (99) intank in my tahoe at 54 psi without complaint (this motor is tamer and its problematic at idle). I was of the opinion a factory pump could handle it, definetely at an idle. Obviously the inlet is on the driver's side so that rail sees fuel first. and the schrader test port is off the regulator area.

Injuneer

You mention the right side O2 (Bank 2) sensor reading "right HO2S .8-.4 mV bouncing around"..... what is the left side O2 (Bank 1) doing? In closed loop the O2 sensor readings should be swinging back and forth rapidly (9 times per second) between 0XX - 9XX millivolts (you appear to be posting "volts" and not "millivolts"). Is the left side doing that as well? Is the right side not dropping below 400mV?

You have a major case of "split BLM's" at idle. Bank 1 is pulling out 15% of the fuel and has bottomed out the BLM at 108. The right side is pouring in 25% extra fuel, and has maxed out the BLM at 160. Then the short terms are pulling out more fuel in Bank 1 and adding additional fuel on Bank 2. As a result, the Bank 2 injector pulse width is almost double the Bank 1 pulse width.

The fact that you have such severly split BLM's tells you it is not caused by any factor that could affect BOTH sides simultaneously.... e.g. it not the fuel pump, not the fuel pressure, not the MAF sensor, etc. Try "search" on "split BLM" for additional info.

Split BLM's are common at idle with aftermarket throttle bodies and large cams. You have to figure out if those two factors are causing the split. Then you have to look at what might be affecting the right side of the engine to make the PCM think its running lean and causing it to add all that extra fuel. Could be a faulty O2 sensor, could be a large vacuum leak that only affects the right side, could be a poor job of valve adjustment. The MAP reading of 18"Hg would indicate a possible vacuum leak, poor valve adjustment or just a poor tune for the cam.

Do you have any scan data (BLM's) for Cells other than the idle Cell (Cell 16)?

Injector resistance does not indicate uniform flow... simply that they will react electrically the same. It will not show if they are leaking or plugged. Sounds like the passenger side injectors may be plugged or not flowing rated capacity.

In the stock LT1 fuel rails (94-97), the Schrader valve is on the hard line into the back of the passenger side rail, not on the regulator side.

undertaker

well only scanner I have for this pre-obd 2 platform is an old genisys which does realtime.....from waht I remember the driver's side stuff stayed constant.

What essentially seems to be happening is the passenger side (bank 2) is trying to flood the motor with fuel......yet its still lean as anything when you remove the factory O2 from the hole and plug in a wideband in its place, meanwhile the driver's side is within reason. Vehicle does have an aftermarket 58mm (not sure which brand off the top of my head), I'd like to think the injectors are ok, there's 2 hours on them tops, bought last summer of 07. I've been told it could be something with the ECM in the car which was bought as a core a few years back and reflashed before the current rebuild, and flashed again by pcms for less. O2's are less than a month old, read the same as the old ones, but figured the old ones should go since the car had massive blowby. The rockers aren't locked, I'm almost wondering if they some how could have worked their way loose over time. (car was running decently for a while till I was nice enough to finish off the trans shortly after the motor went in)

I've just had this damn car for the last 2.5 year in my yard or in my shop because my buddy has lost most of his interest in it. and want it done and the heck out of my way. LSx stuff no problem I'm up to my elbows in them all the time but LT1's seem to fall thru the cracks. Both of my 96 b-bodies are high miles and untouched down to the optis (just plugs and oil) Never had to bother with LT1's till this everlasting headache.