LT1 tuning help
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Teching In
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From: Ontario
LT1 tuning help Just finished my 94 LT1 overhaul with fresh bottom end, stock heads & Lunati cam with complete valve train. Lunati 219/227 cam, 1.6:1 roller rockers, springs, lifters, push rods etc. Having a rich running problem, my BLM's at cruise are 108-115. Have stock injectors installed, new GM O2's, NGK TR55 plugs, new GM opti. If someone could give me some advice where to look I would really appreciate it. I have a DataMaster log I could send as well. Thanks, Jeff.
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Teching In
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From: Ontario
Hey, might have found the cause. Was looking through the manual about rich conditions and vacuum tested the evap purge solenoid(RH intake) with KOEO and it does not hold vacuum. I will log it tomorrow night and give an update.
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From: Maricopa, AZ
Post your data log up and I'll have a look see. Also need a list of mods. Stock TB? what do your BLMs look like at idle? Who tuned it? Are you using a MAF or SD?
Make a sig with all your vehicle info so when you ask a question like this you don't have to list your vehicle specifications.
Year, make, model, trans type, and mods all make a difference in how we respond to you. It'll either be nothing, like this case, or you'll have a bunch of people chiming in with assistance. I didn't chime in earlier because you provided little information for me to help with.
I see you provided most of it, but not everything needed. Post up your data log and I'll look it over.
Make a sig with all your vehicle info so when you ask a question like this you don't have to list your vehicle specifications.
Year, make, model, trans type, and mods all make a difference in how we respond to you. It'll either be nothing, like this case, or you'll have a bunch of people chiming in with assistance. I didn't chime in earlier because you provided little information for me to help with.
I see you provided most of it, but not everything needed. Post up your data log and I'll look it over.
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Verdad Gallardo TECH Addict
Joined: Dec 2010
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From: Maricopa, AZ
Was this tuned at all or no? Never mind, I just read your e-mail. And looked at the logs.
You need to adjust your throttle body blades to make sure they are fully shut. You have a split BLM at idle, then you are pretty much pulling fuel the entire time. Either you have a Vacuum leak somewhere or your MAF needs calibrated. What tuning software are you using? Also, is your MAF in the stock location? And what intake are you using, stock or CAI, if CAI what brand?
You need to adjust your throttle body blades to make sure they are fully shut. You have a split BLM at idle, then you are pretty much pulling fuel the entire time. Either you have a Vacuum leak somewhere or your MAF needs calibrated. What tuning software are you using? Also, is your MAF in the stock location? And what intake are you using, stock or CAI, if CAI what brand?
Thread Starter
Teching In
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From: Ontario
Idle did seem high but I thought it was to smooth it out a little. I didn't touch the throttle blades or adjust the TPS either. Have sprayed some brake clean around while it was idling but didn't seem to make a difference.
Thread Starter
Teching In
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From: Ontario
Idle vacuum is 16.5-17" Hg. Will have to do another driving log after the evap repair so it will probably be different. Also valves are set at 1/4 past zero lash, runs better at that setting. Thanks, really appreciate the help!!!
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From: Maricopa, AZ
It does look like 800 rpm idle is commanded. It doesn't have to be that high. Your vacuum at idle in neutral is 12 inhg, but in gear jumps to 16-17inhg. Your IAC counts correspondingly jump too, that tells me your car is tuned to idle at 800-850, but with 24 IAC counts at neutral idle your TB blades possibly aren't all the way closed.
If no vacuum leaks, then I'd start with adjusting the MAF calibrations after making sure the injector flow rates and offsets are correct. Take your time. Make sure you back up your original tune from Solomon in a couple places as not to loose it.
Calibrating the MAF can be tricky on an LT1 because it uses the VE tables while in MAF mode under some circumstances, and if those aren't adjusted correctly for your build then it could throw off the MAF calibrations too.
Adjusting the VE tables is no easy feat, and takes some time and patience to get them just right. This is best done on a Dyno, but isn't always feasible. I did mine while driving to and from work adjusting them twice daily for a couple of weeks at home and work until I got them just right.
Actually, I think your first step is to read this site and this site then keep reading them over and over again until you feel comfortable tuning your car.
I'm also going to assume this is the same cam card you have?
Last edited by hrcslam; Aug 7, 2014 at 11:57 PM.
Thread Starter
Teching In
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From: Ontario
Well the CAI is a no name ebay one with a K&N filter. I will adjust/check the throttle blades, then adjust the TPS if necessary. I am using DataMaster and just play back the log. Are you using something different? I was looking at the intake gasket and I will send a picture. Something odd on the pass side. On the drivers side you can clearly see the gasket between the intake and head. Pass side seems not as visible. Looked to me on Open Loop that LH bank went lean and RH bank was more rich. Maybe need to pull the RH bank plugs and have a look?
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From: Maricopa, AZ
What program are you using for tuning?
All of those are good idea's. Spark plugs are a bitch to access, but a good idea to monitor while tuning.
The left side did go lean at idle, but the right die looks good. I would make sure the TB blades are adjusted correctly (fully closed) before messing with and VE or MAF calibrations at idle.
If you don't already have Tuner Pro RT, download it (it's free) and the supporting files, then go to LS1LT1.com and look for Steveo, in his sig you'll see a link to an XDF file, download that and load it into Tuner Pro. Then you can pull your tune into that program and look at everything there. It's really a handy program, and it's free, uses 3D graphing and click and drag capabilities, and Steveo has taken the time to make that XDF file with most of the perimeters defined or explained if you hover over them, it's been a god send in my efforts to learn how to tune.
All of those are good idea's. Spark plugs are a bitch to access, but a good idea to monitor while tuning.
The left side did go lean at idle, but the right die looks good. I would make sure the TB blades are adjusted correctly (fully closed) before messing with and VE or MAF calibrations at idle.
If you don't already have Tuner Pro RT, download it (it's free) and the supporting files, then go to LS1LT1.com and look for Steveo, in his sig you'll see a link to an XDF file, download that and load it into Tuner Pro. Then you can pull your tune into that program and look at everything there. It's really a handy program, and it's free, uses 3D graphing and click and drag capabilities, and Steveo has taken the time to make that XDF file with most of the perimeters defined or explained if you hover over them, it's been a god send in my efforts to learn how to tune.