LT1 issues - PLEASE HELP!
10-01-2007, 06:05 PM
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LT1 issues - PLEASE HELP! Well, my Twin Turbo LS1 project is almost done, but now i'm having issues wiht my LT1...
Out of nowhere, it started with its current problem (i'll explain below) - i had hoped it was bad gas, but i was wrong. I'll give some of my ideas and see what u guys think.
As long as i'm in the low RPMs it runs fine - pulls the same as it alwasy has. However, if i'm anywhere above about 2500-3000, and above about 40% throttle, the car falls on its face - literally, it will actually fall forward like you just hit the brakes. It doesnt jerk and studder like its the optispark or something in the ignition - it feels like it just shuts 4 of the cylinders off... completely runs out of power, and the RPMS won't move above 3200 or so. And this isn't just in drive. If the car is in "P" and you just give it a little gas, it will rev the whole way to redline... but if you floor it, it goes up to about 3K, and just sits there and gargles.... Sounds like pure ****...
Now, for some time now i have had a pretty good size exhaust leak where the passenger side manifold meets the y-pipe. And i've been meaning to fix it but been soo busy with the LS1 project i havent got to it. So that's a little something to keep in mind.
The SES light isn't on, but if i scan the car, i get these DTC codes:
CODE 16 LOW RES FAILURE
CODE 55 FUEL SYSTEM LEAN
CODE 64 RIGHT O2 SENSOR LEAN
CODE 51 PROM/FLASH ERROR
I thought, if anything, the ehxaust leak would make the car run rich, so that's why i thought it might not have anythign to do with my problems... Plus its been there for quite some time (over a year) and this just suddently happened..
I'm thinkin the O2 sensor could be bad, or a bad fuel filter. Please, any help would be greatly appreciated!
Out of nowhere, it started with its current problem (i'll explain below) - i had hoped it was bad gas, but i was wrong. I'll give some of my ideas and see what u guys think.
As long as i'm in the low RPMs it runs fine - pulls the same as it alwasy has. However, if i'm anywhere above about 2500-3000, and above about 40% throttle, the car falls on its face - literally, it will actually fall forward like you just hit the brakes. It doesnt jerk and studder like its the optispark or something in the ignition - it feels like it just shuts 4 of the cylinders off... completely runs out of power, and the RPMS won't move above 3200 or so. And this isn't just in drive. If the car is in "P" and you just give it a little gas, it will rev the whole way to redline... but if you floor it, it goes up to about 3K, and just sits there and gargles.... Sounds like pure ****...
Now, for some time now i have had a pretty good size exhaust leak where the passenger side manifold meets the y-pipe. And i've been meaning to fix it but been soo busy with the LS1 project i havent got to it. So that's a little something to keep in mind.
The SES light isn't on, but if i scan the car, i get these DTC codes:
CODE 16 LOW RES FAILURE
CODE 55 FUEL SYSTEM LEAN
CODE 64 RIGHT O2 SENSOR LEAN
CODE 51 PROM/FLASH ERROR
I thought, if anything, the ehxaust leak would make the car run rich, so that's why i thought it might not have anythign to do with my problems... Plus its been there for quite some time (over a year) and this just suddently happened..
I'm thinkin the O2 sensor could be bad, or a bad fuel filter. Please, any help would be greatly appreciated!
10-01-2007, 07:26 PM
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LOW res failure is the signal from the opti spark...
Lean condition could mean unmetered air, or not enough fuel, or incomplete combustion. Im either looking at a bad opti, or a possible weak fuel pump/clogged fuel filter.
Since that low res code is there, im edging towards a bad opti.
also. if that leak is down that far, isnt it after the O2? so it really wouldnt effect the O2?
Lean condition could mean unmetered air, or not enough fuel, or incomplete combustion. Im either looking at a bad opti, or a possible weak fuel pump/clogged fuel filter.
Since that low res code is there, im edging towards a bad opti.
also. if that leak is down that far, isnt it after the O2? so it really wouldnt effect the O2?
10-01-2007, 08:58 PM
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bah... it might be time to just get rid of the car....
I told myself a long time ago that the next time the opti goes, i'm getting rid of the car...
it has 176K miles on it and just a month ago i had a lady crunch up the front end on the car.... so i've been driving it as is, and it may just be time to junk her... i hate to, but i might donate it to Wyotech and get the tax deductions
I told myself a long time ago that the next time the opti goes, i'm getting rid of the car...
it has 176K miles on it and just a month ago i had a lady crunch up the front end on the car.... so i've been driving it as is, and it may just be time to junk her... i hate to, but i might donate it to Wyotech and get the tax deductions
10-01-2007, 10:44 PM
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haha, i know... the only reason i havent gotten rid of it yet is b/c I absolutely love the car... even with all its flaws, it was my first "baby" ... worked rediculously hard to be able to get it when i was 18... however, with the TT LS1, i'll never leave the F-body crowd
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10-01-2007, 11:06 PM
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I wouldn't jump on the opti so quick, but alot of people like to. My car gave the lo res failure and also another one for the opti, can't remember what it was exactly but it was pure BS. I was also getting a prom error. Mine would completely shut down past 5000 rpm and the only way to get it started again was to turn the key off and sit for a minute and it would fire back up. Changed the opti because it had 145,000 miles on the original, and it still gave the same codes and still shut off past 5000 rpm. Ended up being a combination of the icm and ecm both crapping out.
Clear the codes, fix the exhaust leak, check the fuel pressure with a gauge while driving, or at least in a good rev, then move on from there.
Clear the codes, fix the exhaust leak, check the fuel pressure with a gauge while driving, or at least in a good rev, then move on from there.
10-06-2007, 03:54 AM
#11
Well, my Twin Turbo LS1 project is almost done, but now i'm having issues wiht my LT1...
Out of nowhere, it started with its current problem (i'll explain below) - i had hoped it was bad gas, but i was wrong. I'll give some of my ideas and see what u guys think.
As long as i'm in the low RPMs it runs fine - pulls the same as it alwasy has. However, if i'm anywhere above about 2500-3000, and above about 40% throttle, the car falls on its face - literally, it will actually fall forward like you just hit the brakes. It doesnt jerk and studder like its the optispark or something in the ignition - it feels like it just shuts 4 of the cylinders off... completely runs out of power, and the RPMS won't move above 3200 or so. And this isn't just in drive. If the car is in "P" and you just give it a little gas, it will rev the whole way to redline... but if you floor it, it goes up to about 3K, and just sits there and gargles.... Sounds like pure ****...
Now, for some time now i have had a pretty good size exhaust leak where the passenger side manifold meets the y-pipe. And i've been meaning to fix it but been soo busy with the LS1 project i havent got to it. So that's a little something to keep in mind.
The SES light isn't on, but if i scan the car, i get these DTC codes:
CODE 16 LOW RES FAILURE
CODE 55 FUEL SYSTEM LEAN
CODE 64 RIGHT O2 SENSOR LEAN
CODE 51 PROM/FLASH ERROR
I thought, if anything, the ehxaust leak would make the car run rich, so that's why i thought it might not have anythign to do with my problems... Plus its been there for quite some time (over a year) and this just suddently happened..
I'm thinkin the O2 sensor could be bad, or a bad fuel filter. Please, any help would be greatly appreciated!
Out of nowhere, it started with its current problem (i'll explain below) - i had hoped it was bad gas, but i was wrong. I'll give some of my ideas and see what u guys think.
As long as i'm in the low RPMs it runs fine - pulls the same as it alwasy has. However, if i'm anywhere above about 2500-3000, and above about 40% throttle, the car falls on its face - literally, it will actually fall forward like you just hit the brakes. It doesnt jerk and studder like its the optispark or something in the ignition - it feels like it just shuts 4 of the cylinders off... completely runs out of power, and the RPMS won't move above 3200 or so. And this isn't just in drive. If the car is in "P" and you just give it a little gas, it will rev the whole way to redline... but if you floor it, it goes up to about 3K, and just sits there and gargles.... Sounds like pure ****...
Now, for some time now i have had a pretty good size exhaust leak where the passenger side manifold meets the y-pipe. And i've been meaning to fix it but been soo busy with the LS1 project i havent got to it. So that's a little something to keep in mind.
The SES light isn't on, but if i scan the car, i get these DTC codes:
CODE 16 LOW RES FAILURE
CODE 55 FUEL SYSTEM LEAN
CODE 64 RIGHT O2 SENSOR LEAN
CODE 51 PROM/FLASH ERROR
I thought, if anything, the ehxaust leak would make the car run rich, so that's why i thought it might not have anythign to do with my problems... Plus its been there for quite some time (over a year) and this just suddently happened..
I'm thinkin the O2 sensor could be bad, or a bad fuel filter. Please, any help would be greatly appreciated!
10-18-2007, 04:29 PM
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Optispark..... bullshit......! BSBSBSBSBSBSBSBS! It could be but not likely. Schematics say a code 16 low resolution signal has to do with the optispark. The fact is your fuel injectors, optispark,pcm and guess what you Mass AIR FLOW SENSOR all coincide with each other. code 16 is telling you that you have a bad sensor straight up. Your MAF determines how much fuel to put in based off of how much air your motor is receiving. My answer and I know i am right, is you have a bad Mass air flow sensor. I've gotton this code on many times before and schematics do show that it is the opti, but with all the other codes......... follow the trail man. MAF all the way. I just had this problem a week ago. MAF is bad. It is sending the wrong signal to your PCM, the PCM is shutting down your fuel becuase that part of the MAF is not working. Your car is running... the optispark is good. If it was bad, it would either not be working at all or, backfiring and missing like crazy and showing that stupid code if it wasnt working or running at all.
Similar simptoms happend to my 3000gt when my MAF went out.
MAF went out b/c i cracked the housing and washed my engine compartment, water got into the housing and fried my MAF
10-18-2007, 04:34 PM
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I suppose every individual car is different. I had a very slight miss once that I could not seem to track down and finally got a code 16. Put in a brand new AC Delco opti and miss was gone.
10-18-2007, 11:54 PM
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i also say hook up a fuel pressure gauge like mentioned above before you go pulling and replacing parts. maybe try driving it and testing it right after you start it up while it is still in open loop. does not the computer bypass the maf when in open loop? or even unplug the maf and test it out. i may be wrong on the maf thing so maybe someone can correct me on that.
