LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Fuel trim cells ?, car acting odd

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Old Feb 18, 2004 | 05:29 PM
  #1  
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Fuel trim cells ?, car acting odd

idles in cell 16, and on snap throttle transitions (0-80,100%) it goes to FTC 18 up to 9 ms pulsewidth, and bogs. Slow transition is better, fast will kill the car when its cold. Way to rich.

Cruise at cell 15 at 40% throttle 2500-3500. Going from the info I have shouldnt that be more like cells 7 or 11?

Cruising it shows retard a little bit once the Charc Can. Purge gets to its peak. The snap throttle is FTC 18 which some said has something to do with CCP

Any ideas?

Overall car runs horrible on cold starts, open loop is rough idle, closed loop it pulls 15% on both banks out and idles a bit better
Old Feb 18, 2004 | 06:47 PM
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TTT here, this is my car that the questions are about. Someone chime in please.
Old Feb 19, 2004 | 07:50 AM
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I'm also trying to read the fuel cell readings on my Datamaster log, but not sure where I would look to see the breakdown of the cell readings or if I can even do that.
Old Feb 19, 2004 | 09:18 PM
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Originally posted by slider
I'm also trying to read the fuel cell readings on my Datamaster log, but not sure where I would look to see the breakdown of the cell readings or if I can even do that.
zzz
Old Feb 19, 2004 | 10:12 PM
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what are your BLMs at idle in closed loop? both sides?

and at 1500 rpm?
Old Feb 20, 2004 | 01:43 PM
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I switched it to read percent idle is -15.6%/-15.6% at 1500 +25/-15
Old Feb 20, 2004 | 05:07 PM
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Originally posted by LTOne4Fun
I switched it to read percent idle is -15.6%/-15.6% at 1500 +25/-15


Ok, I never noticed it going lean on the one side.

I'm wondering though, if the -15.6% is the bottom end of the barrell, being 108 LTerms, how much it's actually subtracting. Couldn't it be more, since the 108 is the reading limit for the computer??
Old Feb 22, 2004 | 01:58 PM
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Originally posted by LTOne4Fun
I switched it to read percent idle is -15.6%/-15.6% at 1500 +25/-15

your engine is runnin extremely rich!

check for too much fuel pressure
faulty MAF
injector leakin


at the 1500 rpm........that bank with the -15%.......I would suspect that bank to have a leaking injector.
Old Feb 22, 2004 | 03:59 PM
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Originally posted by JDBlaze85
your engine is runnin extremely rich!

check for too much fuel pressure
faulty MAF
injector leakin


at the 1500 rpm........that bank with the -15%.......I would suspect that bank to have a leaking injector.
Fuel pressure is set to 40 PSI at idle, 46 with the vacuum line off the AFPR.

No maf, my car is a 93 Speed Density setup.

No leaking injectors. There's absolutely no signs of a leaker, I.E. hard or long start condition.
Old Feb 22, 2004 | 04:05 PM
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pressure regulator getting gas sucked out?
Old Feb 22, 2004 | 04:08 PM
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Nope. Been there, done that.
Old Feb 22, 2004 | 04:10 PM
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have u pressurized the fuel system........check the fuel press. gauge for psi drop?
Old Feb 22, 2004 | 04:11 PM
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should hold pressure, no drop off


the MAP sensor working fine? around 1.5v at idle?
Old Feb 22, 2004 | 04:14 PM
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Yup, yup.

I've been from one end of it to the other, and can't find anything. Took it to the shop, who started this thread.
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