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Discussion Starter · #1 ·
Okay, I have been addressing a few issues on my H/C car to make sure all my peripheral mods are up to snuff.
When I had a great running 340/350 (through 3.91s) bolt on tune I had no tune troubles. I was given a Tbyrne ported MAF and tossed it on, but kept the factory maf between the tbyrne ends. No problems noted, no codes. Ran fine for a year.

Put the fat cam and heads on, broke it in for a few days, went to tune. Hooked straight onto dyno, started doing pulls and tuning. My tuners reputation is good and he is experienced without a doubt.
#s came in a bit low, but in horrible (100*+) conditions. We pulled with lid open, and concluded a little vacuum was still present in the intake, but only 2hp gained with lid up.
After, we went to road tune. HERE is the ??
The tuner noticed my car wouldn't run in SD mode. We sat for 20 minutes while he tinkered and toyed with the idle/maf settings, and commented that he didn't know I had changed the MAF ends and descreened. Took quite a bit, then we went and did road logging etc.
Would doing the pulls before setting up the MAF settings effect the dyno pulls and tuning we did?
Could more timing/fuel or whatever have been added if the MAF cal had been done first?
Just looking for what effect this would have had on the big picture.
Thanks.
BTW, HPT used on the latest tune, LS1edit on the original, which ran great with that MAF. Car runs strong, no codes in a few thousand miles, but now looking for every extra tweak.
 

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From Chris at HPT

We don't support 1bar SD for the 2005 GTO, we only support 2bar. What are you trying to achieve on the vehicle? The LS2 doesn't default to the low octane table like the LS1.

Chris...
 

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Sorry, I missed that.
 

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Objects in mirror dont matter
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Discussion Starter · #5 · (Edited)
Sorry about the unclear use of "SD" in my post.
The goal is to have the car run with MAF, NA, with as much as hp possible, then hit it with a small dry shot (50-75) to get a little push now and then.
When I state in the first post that "he went to SD mode" maybe I used wrong words.
The tuner had me make the pulls and his adjustments, then realized the MAF calibration was "funky" and that I had put ported and descreened MAF in the car after we were done with dyno time. When he asked me to pull the MAF plug and start it, the car would not run.
He doodled with his laptop a bit while connected to the car with the MAf plugged back in and running, then indicated the MAF change had things sorta screwed up. Then he pulled MAf off, we drove a bit. Hooked Maf back up, then did a bunch of part throttle acceleration driving.
He declared it as good as it was gonna get and we were done.

Did the MAF port and descreen changes NOT being compensated for BEFORE the dyno WOT tuning leave HP on the table at WOT?
Should I retune?
I have added cutouts, am porting the TB and bypassed the PCV now and will retune as soon as I can afford my N2O kit and install it otherwise.

MOD INFO: Stg 3 243 ceramic coated heads flowing >[email protected] .650
cam 234/240 @.050, .598/.608 112*LSA
CAI, LTs, no cats, cutouts, UD pulley etc
3.91 gears.
Will add 42# green top bosch with dryshot. @ 80% inj now (stock LS1)
 

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Swampgoat said:
Sorry about the unclear use of "SD" in my post.
The goal is to have the car run with MAF, NA, with as much as hp possible, then hit it with a small dry shot (50-75) to get a little push now and then.
When I state in the first post that "he went to SD mode" maybe I used wrong words.
The tuner had me make the pulls and his adjustments, then realized the MAF calibration was "funky" and that I had put ported and descreened MAF in the car after we were done with dyno time. When he asked me to pull the MAF plug and start it, the car would not run.
He doodled with his laptop a bit while connected to the car with the MAf plugged back in and running, then indicated the MAF change had things sorta screwed up. Then he pulled MAf off, we drove a bit. Hooked Maf back up, then did a bunch of part throttle acceleration driving.
He declared it as good as it was gonna get and we were done.

Did the MAF port and descreen changes NOT being compensated for BEFORE the dyno WOT tuning leave HP on the table at WOT?
Should I retune?
I have added cutouts, am porting the TB and bypassed the PCV now and will retune as soon as I can afford my N2O kit and install it otherwise.

MOD INFO: Stg 3 243 ceramic coated heads flowing >[email protected] .650
cam 234/240 @.050, .598/.608 112*LSA
CAI, LTs, no cats, cutouts, UD pulley etc
3.91 gears.
Will add 42# green top bosch with dryshot. @ 80% inj now (stock LS1)
If you disconnect the MAF and the car does not run the cranking VE table and/or the regular VE table is not calibrated correctly. We you guys running with a wideband to see what what happening when the MAF was unplugged? Descreened and MAF ends should not hinder you from tuning the car properly.

Tim
 

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Discussion Starter · #7 ·
Tim05GTO said:
If you disconnect the MAF and the car does not run the cranking VE table and/or the regular VE table is not calibrated correctly. We you guys running with a wideband to see what what happening when the MAF was unplugged? Descreened and MAF ends should not hinder you from tuning the car properly.

Tim
Thanks Tim. The wideband was only used while on the WOT dyno pulls. The MAF issue/tuning VE and whatever else was done in the parking lot afterwards and before road tuning.
 

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Swampgoat said:
Thanks Tim. The wideband was only used while on the WOT dyno pulls. The MAF issue/tuning VE and whatever else was done in the parking lot afterwards and before road tuning.

So your tuner did the WOT stuff and "then" proceeded to mess with the MAF and VE? If you are doing it correctly the proper flow should be set the PE where you want it -> VE (SD/OL mode) -> MAF (OL mode) -> verify fuel trims is CL mode. The last step isn't critical but if your O2 sensors and widebands don't agree exactly on what is 14.7:1 then you may see some skew. This will generally be more prominent in the low flow rate areas (idle, etc.) What I do to correct that scenario is histogram LTrims against MAF Hz. This will tell you what areas of the MAF curve might need some tweaking.

Tim
 

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Discussion Starter · #9 · (Edited)
Thanks a lot Tim. I have a feeling my ratio may be bit on the rich side now, especially on the part throttle stuff.
I was thinking that the order of the tuning may have been a mistake. I am starting to understand how the VE helps the MAF at low rpm, throttle tip in and more. My low rpm surge/lugging may improve with tweaking, but am I correct in thinking that the WOT probably not effected?
 
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