LT1-LT4 Modifications 1993-97 Gen II Small Block V8

need help with supercharger and new injectors

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Old 09-26-2004, 10:23 PM
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Default need help with supercharger and new injectors

I have been restoring old cars for 15+ years but my 95 lt1 is the first "modern" car I have worked with. I have mechanical ability, but have not had experience with the computer stuff - although I am very comfortable with computers.

I installed an ATI 600b supercharger. The unit is freshly rebuilt by ATI.
I installed in on the stock 95 lt1 and had 2 problems.

1. The car would not shift out of 1st gear at WOT. - any suggestions?
2. I took the car to have it checked out - ran very lean. 14.2 at WOT. I could not adjust out the lean condition with the supplied FMU. The shop that dyno'd it suggested I switch to bigger injectors. The kit came with some lucas #42 injectors, PN 621031 - 42.29 lb/hr @ 43.5 psi

I installed the injectors - car runs and idles terrible.

I bought an Aeromotive LT1 adjustable fuel pressure regulator - set it at 43psi - still runs terrible.

I have the TunerCat program with the LT1 edit add on, but have no idea what to edit. How????????

I also have the TTS powersystems datalogger to monitor the results - what results am I looking for and where???

Any help is really appreciated - even if you can just point me in the direction of help.........
Old 09-26-2004, 11:15 PM
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sounds like you have a few problems.

first it sounds like the TPS is not working. Fix the electrical and then go for then rest. first things first

I have custom installed a ATI or two in my day and every thing should work before you tune.
Old 09-27-2004, 09:59 AM
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My understanding of the big injectors is that they will idle bad because of the flow. Perhaps now you are getting too much fuel with the injectors and the FMU? Would the big injectors be sufficient by themselves?
Old 09-27-2004, 11:36 AM
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Your first step will be to tell the computer that it now has 42lb injectors. Unless i missed somthing,You changed from the stock 24lb injectors and put in the 42lbs ones. This will casue huge problems. Car will be running very very rich.

After you get that adjusted with the lt1 edit, You will need to start logging your fuel trims. You want them to be close to zero. For more information on how to tune the ob2 i would go to the tunning/diagnostic area. And do a search. If you are still haveing difficulties you can email me And Ill help walk you through it.

Micah
Old 09-27-2004, 04:16 PM
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get the PCM reprogrammed. I'm running 42lb/hr injectors on mine but wouldn't even think of running it without a tune.
Old 09-27-2004, 09:19 PM
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Guys you are missing a very important point. the install rendered his transmision useless there is a problem. it needs to be adressed. YES it will need tuned for the injecters but first things first

BTW I ran 36Lh injecters with just a maf translator and stock tuning Then again I was only running 14PSI of boost to go with it
Old 09-27-2004, 10:04 PM
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Originally Posted by enisguy
get the PCM reprogrammed. I'm running 42lb/hr injectors on mine but wouldn't even think of running it without a tune.

how is your idle with these injectors? I have had folks tell me it will be poor.
Old 09-27-2004, 10:05 PM
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Originally Posted by TwoFast4Lv
Guys you are missing a very important point. the install rendered his transmision useless there is a problem. it needs to be adressed. YES it will need tuned for the injecters but first things first

BTW I ran 36Lh injecters with just a maf translator and stock tuning Then again I was only running 14PSI of boost to go with it

I am only running 8 lbs of boost.

What is TPS? If it is Throttle Position Sensor - why would this change with the SC install?? The car shifted fine at WOT before the SC install.
Old 09-27-2004, 10:08 PM
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Originally Posted by TwoFast4Lv
Guys you are missing a very important point. the install rendered his transmision useless there is a problem. it needs to be adressed. YES it will need tuned for the injecters but first things first

BTW I ran 36Lh injecters with just a maf translator and stock tuning Then again I was only running 14PSI of boost to go with it

I am only running 8 lbs of boost - would you suggest a MAF translator instead of editing my PCM??
Old 09-27-2004, 11:45 PM
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The reason I point out the TPS is it can cause many issue. many times during an inatal it will get struck/unplugged or even cut off. I saw one case where they some how managed to cut off both the TPS and MAF ends and then got them backwards.

At least now you get the injecters in the kit back then they told you to use stock injecter...that tended to lock up when subjected to more then 80Psi by the FMU

I would definately tune the car for the right injecters. I used the MAF translater until We got LT1 Edit. Andrew hooked us up early on that one Back then we did not have many choices for tuning. Back then I could tweak every sensor to rear what I wanted to get around the Stock Tune.

I would Check and make sure the PCM is seeing the correct TPS(throttle position sensor) signal and change the tune for your injectors. Changing the tune for the injectors is not going to fix the no shift issue.

If you would like I could make some changes to your file for you. I also have tune cat and LT1 Edit
Old 09-28-2004, 10:22 AM
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Originally Posted by real82it
how is your idle with these injectors? I have had folks tell me it will be poor.
The idle is totally fine. She's got a small blower cam too. Idle is close to stock sounding.
Old 10-03-2004, 09:15 PM
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Originally Posted by 96SCTA
Your first step will be to tell the computer that it now has 42lb injectors. Unless i missed somthing,You changed from the stock 24lb injectors and put in the 42lbs ones. This will casue huge problems. Car will be running very very rich.

After you get that adjusted with the lt1 edit, You will need to start logging your fuel trims. You want them to be close to zero. For more information on how to tune the ob2 i would go to the tunning/diagnostic area. And do a search. If you are still haveing difficulties you can email me And Ill help walk you through it.

Micah

ok - i edited my ECM constant table to reflect a 42lb injector flow rate. The car now idles good and my AF ratio looks good at partial throttel (no chance to log data in WOT yet - I am using tuner cat and a data logger program). What do I need to do/edit to get my trims in line?
Old 10-03-2004, 09:18 PM
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Originally Posted by TwoFast4Lv
The reason I point out the TPS is it can cause many issue. many times during an inatal it will get struck/unplugged or even cut off. I saw one case where they some how managed to cut off both the TPS and MAF ends and then got them backwards.

At least now you get the injecters in the kit back then they told you to use stock injecter...that tended to lock up when subjected to more then 80Psi by the FMU

I would definately tune the car for the right injecters. I used the MAF translater until We got LT1 Edit. Andrew hooked us up early on that one Back then we did not have many choices for tuning. Back then I could tweak every sensor to rear what I wanted to get around the Stock Tune.

I would Check and make sure the PCM is seeing the correct TPS(throttle position sensor) signal and change the tune for your injectors. Changing the tune for the injectors is not going to fix the no shift issue.

If you would like I could make some changes to your file for you. I also have tune cat and LT1 Edit


ok - i edited my ECM constant table to reflect a 42lb injector flow rate. The car now idles good and my AF ratio looks good at partial throttle (no chance to log data in WOT yet - I am using tuner cat and a data logger program). What do I need to do/edit to get my trims in line?
Old 10-05-2004, 09:17 PM
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Default still need help.

ok - i edited my ECM constant table to reflect a 42lb injector flow rate. The car now idles good and my AF ratio looks good at partial throttel (no chance to log data in WOT yet - I am using tuner cat and a data logger program). What do I need to do/edit to get my trims in line? I looked through the Tunercat info and searched the web but still can't figure it out.



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