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problem with chevy LT1 engine |
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TOM R 
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Joined: 23 May 2006 Location: VIRGINIA Status: Offline Points: 849 |
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 Topic: problem with chevy LT1 enginePosted: 05 Jan. 2007 at 9:42am |
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before i go through all the b.s. on this are there any LT1 experts on here?
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for mg42 talk goto www.mg42.us
46 CJ2A T24/m29 WEASEL 1954 m37 mvpa 31698 nra lifer my project http://www.thecj2apage.com/forums/forum_posts.asp?TID=7008 |
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lowenuf
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Posted: 05 Jan. 2007 at 11:04am |
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expert, no... rebuilt, installed, done high-performance upgrades, yes... shoot me the prob, we'll see how much i remember :) TBI, carb, fuel injected? year? solid lift, or mechanical? low
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45 #10012
45 #10033 ACM #47 45 #10163 ACM #188 57 CJ5 Dauntless V6, T-18 4-speed, D-44 rear/D-30 front, D-20 twin stick |
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TOM R
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Posted: 05 Jan. 2007 at 12:29pm |
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car is 94 roadmaster, engine is LT1 350 (same as corvette) multiport injected, flooding the left bank of cylinders, full tuneup with new distributer, new catylitic converter, new mufflers new o2 sesnsor, no trouble codes in computer, data stream looks normal
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for mg42 talk goto www.mg42.us
46 CJ2A T24/m29 WEASEL 1954 m37 mvpa 31698 nra lifer my project http://www.thecj2apage.com/forums/forum_posts.asp?TID=7008 |
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lowenuf
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Posted: 05 Jan. 2007 at 12:44pm |
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sound like a fuel rail sensor is going bad. i had this happen on a 96 Corvette i used to have. primary cause was a fuel pump about to croak. and that is why you are not getting a code, is because the pump is 1st to send a signal to the computer, and as long as the signal is strong enoug, the computer will not pick up on the rail sensors. and the sensor is staying open trying to deliver the needed supply. i would have it hooked up for diagnostics, or get a handheld scanner, and run an test on the sensors individually. the pump should be putting out between 50-75 psi. if it is on the lower end of that scale, the fuel management system will try to take over and compensate. my sensor cost me $100, the GM shop and computer readout cost me $500..next time i will run a test on my own..good luck
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45 #10012
45 #10033 ACM #47 45 #10163 ACM #188 57 CJ5 Dauntless V6, T-18 4-speed, D-44 rear/D-30 front, D-20 twin stick |
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TOM R
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Posted: 05 Jan. 2007 at 1:41pm |
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what are rail sensors? the rails on this 94 have only injectors on them, unfortunatly i am obd1 still so the diagnostics are not as good, also I have a distrubutor, isnt the 96 distrubutorless? not being a smart a#@ just makin sure we are on the same page
 the fule pump does sound like a reasonable problem car has almost 200,000 on it and i did replace the engine got no idea if it ever had a new pump
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for mg42 talk goto www.mg42.us
46 CJ2A T24/m29 WEASEL 1954 m37 mvpa 31698 nra lifer my project http://www.thecj2apage.com/forums/forum_posts.asp?TID=7008 |
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TOM R
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Joined: 23 May 2006 Location: VIRGINIA Status: Offline Points: 849 |
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Posted: 05 Jan. 2007 at 1:45pm |
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also regapped the plugs and noticed they look better after I did the o2 yesterday, the engine sounds like when you first start it it is ok while in open loop then when it goes to closed loop starts to miss
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for mg42 talk goto www.mg42.us
46 CJ2A T24/m29 WEASEL 1954 m37 mvpa 31698 nra lifer my project http://www.thecj2apage.com/forums/forum_posts.asp?TID=7008 |
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lowenuf
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Posted: 05 Jan. 2007 at 1:51pm |
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yes, the 96 was distributorless... even with the injectors to each cylinder, there are two fuel delivery sensors that control output pressure from the pump, so that you don't over pressure the injectors. if your prob is happening on the loop closing side, then the sensor is sticking open when the computer tells the sensors to restrict flow. again, i'd pull the pump feed line, and try to get a presure reading on the pump, and move out towards the engine from there.
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45 #10012
45 #10033 ACM #47 45 #10163 ACM #188 57 CJ5 Dauntless V6, T-18 4-speed, D-44 rear/D-30 front, D-20 twin stick |
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Lomar15
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Posted: 05 Jan. 2007 at 3:33pm |
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Did this happen after a repair? or after other work? Sounds like the ground side of the one bank of injectors is shorted to ground. |
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TOM R
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Posted: 05 Jan. 2007 at 5:36pm |
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i installed this engine and in doing so noticed the drivers cat was hollow, so it may have been doing this with the old engine for the po, my factory manuals only list the 1 fuel regulator and then the injectors, both rails are hooked together in a big loop with the 1 feed from the regulator, I am gonna guess your newer stule LT1 has a slightly different fuel delivery, where should I look for these fuel delivery sensors? It does boggle my mind why there is no code setting
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for mg42 talk goto www.mg42.us
46 CJ2A T24/m29 WEASEL 1954 m37 mvpa 31698 nra lifer my project http://www.thecj2apage.com/forums/forum_posts.asp?TID=7008 |
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lowenuf
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Posted: 05 Jan. 2007 at 7:12pm |
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the sensor should be at the rear of the plenum housing, just where the injector rails drop from the supply line, and it should have 1 wire to it. when you remove it, it should have a rubber gasket at the seat..
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45 #10012
45 #10033 ACM #47 45 #10163 ACM #188 57 CJ5 Dauntless V6, T-18 4-speed, D-44 rear/D-30 front, D-20 twin stick |
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lowenuf
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Posted: 05 Jan. 2007 at 7:21pm |
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let me go back a couple of steps, and ask a couple of questions..
1. did you plug the engine harness back into the new vehicle's PCM, or did you transfer the PCM that was original to the motor?
2. in either case, have you reset the PCM? '94 was the last year the PCM could be reset, and an owner could install high performance chips..
if you never reset the PCM codes, it may be trying to run bogus settings, and when the PCM is disconnected from a power source for any length of time, all the factory codes will be lost...
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45 #10012
45 #10033 ACM #47 45 #10163 ACM #188 57 CJ5 Dauntless V6, T-18 4-speed, D-44 rear/D-30 front, D-20 twin stick |
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TOM R
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Posted: 05 Jan. 2007 at 7:49pm |
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we cleared out the pcm at work, at first i reused the pcm that was with the car then installed the 1 that came with the motor no difference, yes all the injectors are plugged into the proper wires ( the connectoers are #) this engine has no sensor at the rear of the plentum or anywhere on the fuel lines or rails
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for mg42 talk goto www.mg42.us
46 CJ2A T24/m29 WEASEL 1954 m37 mvpa 31698 nra lifer my project http://www.thecj2apage.com/forums/forum_posts.asp?TID=7008 |
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lowenuf
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Posted: 05 Jan. 2007 at 9:29pm |
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sorry i wasn't much help then..somewhere, somehow, it really sounds like a fuel delivery issue, either an electrical malfunction, or relay somewhere in series not doing it's job. to lose a whole bank, i wouldn't think it would be a clogging issue.. only other thing i could offer, would be too turn the ignition to the on position, and use a multimeter to measure volts/ohms across all 8 injectors, then start the vehicle, and check the resistance one cylinder at a time..injectors go bad, i just have never seen a whole bank go at the same time..
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45 #10012
45 #10033 ACM #47 45 #10163 ACM #188 57 CJ5 Dauntless V6, T-18 4-speed, D-44 rear/D-30 front, D-20 twin stick |
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TOM R
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Posted: 05 Jan. 2007 at 9:40pm |
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well another suggestion was a bad knock sensor is retarding the timing and running the engine lean causing the cat to glow, problem is the plugs looked rich and wet
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for mg42 talk goto www.mg42.us
46 CJ2A T24/m29 WEASEL 1954 m37 mvpa 31698 nra lifer my project http://www.thecj2apage.com/forums/forum_posts.asp?TID=7008 |
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lowenuf
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Posted: 05 Jan. 2007 at 9:55pm |
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hmm.. i had a knock sensor go bad on an SS454 pickup i had, and it ran rich, and the cat almost melted out of it..actually warped the floor..
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45 #10012
45 #10033 ACM #47 45 #10163 ACM #188 57 CJ5 Dauntless V6, T-18 4-speed, D-44 rear/D-30 front, D-20 twin stick |
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TOM R
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Posted: 05 Jan. 2007 at 10:58pm |
 guess i need to goto the scanner again
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for mg42 talk goto www.mg42.us
46 CJ2A T24/m29 WEASEL 1954 m37 mvpa 31698 nra lifer my project http://www.thecj2apage.com/forums/forum_posts.asp?TID=7008 |
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