What I've got
97 lt1 stock bottom end
LE 2.2 heads / cam
58 mm tb


My problem
PCM is adding, on average, 10-15% more fuel(short term) on bank 2 and the long term fuel trim is maxed @+ 25% . Bank 1 is pulling fuel at idle as it always does and it's long term is -10 to-17%.
B1 injector pulse width is 3.3 ms at idle( p/w even out under throttle but fuel trims only improve by 60-70%)
B2 is at 5.8 ms at idle

This all started last fall when I threw a code for bank 2 high voltage. Figured no big deal swapped out both o2 sensors as preventative. Still there

What I've done
Cyl leak down. All within 5% of each other
Injector balance test. Perfect
Checked for good spark on all 8. All good
Readjusted all the rockers to be safe
Swapped out o2 extensions to see if there is a short. Good
Swapped plugs. Still there
I was getting an occasional high voltage spike on my bank 2 rear o2 sim. Disconnected both of them cause they're disabled anyways. Still there
Sprayed carb cleaner and traced vac lines with propane. Still there
fuel pressure is 38@ idle w/ vacuum and 45 without( old holly fpr)255lph walbro-7yrs old/20k mi on it
all injectors ohm out within .1 of each other.( 30lb svo)

My thoughts without throwing unnecessary parts at it

Possible maf
Possible PCM
Short in the engine harness
Pull the intake to visually check the intake gaskets for vac leaks

Here is a pic of the plugs from 2-8


Why 2 and 4 look decent and 6 n 8 look like **** is beyond me. Bank 1 look like I just installed them
my first thought when looking at the plugs, with the thought that all 4 cyl are getting the same amount of fuel, is 2 and 4 have a vac leak of some sort. To me, The added fuel explains 6 and 8 being rich.

Any other ideas?

 

Ok...just a wild guess here.....PCM grounds get checked/cleaned just to be sure? Sometimes a visible once-over is not good enough. I'd trace them down, and unbolt/clean all ground points leading to the PCM.

Just a though. Sorry to hear about your problems.

-James-

 

thanks. I was going to do that tonight along with checking the o2 and injector harness for resistance.

 

Did you change your dist cap? It looks like you arent getting full spark to those others, or you have a bad injector..

I would change cap, maybe even spark plug wires.

 

I'm with Jesse on this one. Lack of spark most likely the problem. Cap, wires, etc. If the cap is old, start there.

 

thanks for replying

the whole opti (delco) has maybe 500 miles on it. Not to say it's not possible but the injectors ohm'd and balanced out evenly on all 8. I've posted it up in lt1/4 section as well for addtitional ideas if you care to read .

https://ls1tech.com/forums/lt1-lt4-m...need-help.html

 

How did you test the injectors? Have you tested the power and pulse to them?

 

tested power with a noid light and pulse with a fuel injector pulse timer. it pulses the injector for 3 seconds at a rate of 10ms. I pressurize the fuel system, record the psi, pulse the injector, and record the drop in fuel pressure. did it for all 8 and they're identical.

 

Good deal. That's exactly how you're supposed to test them. I have the same flow tester/actuator.

Have you put the noid light in while the engine is running? Put the noid light in and started it? Does it blinky blinky?

 

Yes it goes blinks,blinky.. Lol

I think improper flow in my idle circuit is my cause. I eliminated my nitrous outlet plate and bolted the throttle body directly to the intake and my p/w on the injector dropped to 4.2 ms,short terms started to stabilize @+\-3 % on bank 2. Bank 1 was still slightly lower but I'm sure the fuel fouled spark plugs and possibly fouled o2 sensor aren't helping me.

Thanks for all the help and suggestions

 

How much of a nitrous shot are you using?

Those plugs are pretty cold. Have you tried and read a set of 6 range instead of 7s?

 

I was at 150 and I stepped up to 200 on a Nitrous outlet plate. I had a nitrous works plate on a 150 shot and to me it had a similar hit as the 200 N/O plate. When the car was dyno'd to verify A/F on spray I was running autolite 104's and it was fine. But I caved to the masses and I was told by many that I was going to have a melt down with the combo. I'm running the br7ef's If I remember correctly.