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549 RWHP and 569 TQ
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Discussion Starter #1
Here is the Reader's Digest version of my problem.

When my car was bone stock I could run back to back to back 13.6's all day long. I was pretty happy with that.

I had an LS1 tune put in a short time later. With nothing else done but a K&N panel filter and the tune my next outting produced 13.7, 13.8, and 13.9's even though the tune netted me about 15 hp on the dyno.

I then installed a TC and the Speed Inc. induction w/ Z06 MAF. I went to the track and things got worse. 13.8, 14.1, 14.3 etc. My mph fell from 102's to like 98. I auto tapped the last few runs and it showed my fuel trims were around 18% @ WOT and the timing was down to less than 10 degrees. The guy who tuned it was there and we figured out that we forgot to tune it with the new air box and MAF.

I went to his shop and after three hours of disasterous numbers we put the stock MAF back on, retuned it, and tried it again. This time the hp was the highest it had been and all the numbers looked right, finally.

Well, now that the car was fixed, I headed to the track to see what gains the TC really got me. It was like deja vu all over again. First run 13.6 @ 102. I was ok with that since I hadn't had time to cool the car down or practice launching much with the TC. Auto tap came undone so it didn't record that run. The next two runs were 14.0's @ 99 and 98. My fuel trims were back up over 10% @ WOT and timing was around 13 to 14. WTF?

I know the torque mgmnt. is zero'd out and the abuse mgmnt is also at zero. And yes, I had traction control off every time. Any ideas what is making it do this? More importantly, anyone know how to make it stop? Thanks for bearing with this long dissertation, any help would be greatly appreciated.

Dave
 

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Few random questions...

What size TC?

How long between passes?

The last time at the track was with the stock MAF right?

There are pllleeenty of abuse mode tables ..what software is he using? LS1edit might not have them all....

What was the KR?
 

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549 RWHP and 569 TQ
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414 Posts
Discussion Starter #3
DevilYellow said:
Few random questions...

What size TC?

How long between passes?

The last time at the track was with the stock MAF right?

There are pllleeenty of abuse mode tables ..what software is he using? LS1edit might not have them all....

What was the KR?
Yank SS3600

ABout 30 minutes this last time, line was moving quick, not a lot of cool down time, but previous nights were more like an hour with similar results.

Last time the MAF should have been right, it was the day after we "fixed" it.

It was LS1 edit.

Last week KR was there the whole run, as much as 4 deg. Last night it was zero all night. We seemed to have fixed that part of it at least.

Dave
 

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549 RWHP and 569 TQ
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414 Posts
Discussion Starter #6
Devil Yellow:
No, the last time was with the stock MAF, the time before that was with the aftermarket one. No KR with the stock one and the fuel trims were "down" to 10% as opposed to 18% the time before.

Nikivee:
It was slipping about 50 rpm on the dyno the day before. I don't know if that would cost me that much mph. The first run was close to what I had been doing, it seems to fall off as the night progresses.
 

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Wavydavy GTO said:
It was slipping about 50 rpm on the dyno the day before. I don't know if that would cost me that much mph. The first run was close to what I had been doing, it seems to fall off as the night progresses.
Dave, I'm with nikivee, I think your stall speed is too high for your current mods. BMR is running only a 2800 on their 11 second car. One temporary fix would be to install a lock-up switch to keep it from slipping and to lock it in 2nd and 3rd. I did this on my high-stall WRX and gained 2 tenths and 2 mph.

I did more than 150 passes with my WRX, and 9 times out of 10, my first run of the night was always the best. On the drive to the track, your car reaches optimal temps, but once you start running and sitting in the staging lanes, it'll go up - heat soak. Only way to fix this would be perhaps a lower t-stat, an electric water pump, or some way of manually activating the radiator fans.

Padre
 

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549 RWHP and 569 TQ
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414 Posts
Discussion Starter #8
PadreGTO said:
Dave, I'm with nikivee, I think your stall speed is too high for your current mods. BMR is running only a 2800 on their 11 second car. One temporary fix would be to install a lock-up switch to keep it from slipping and to lock it in 2nd and 3rd. I did this on my high-stall WRX and gained 2 tenths and 2 mph.

I did more than 150 passes with my WRX, and 9 times out of 10, my first run of the night was always the best. On the drive to the track, your car reaches optimal temps, but once you start running and sitting in the staging lanes, it'll go up - heat soak. Only way to fix this would be perhaps a lower t-stat, an electric water pump, or some way of manually activating the radiator fans.

Padre
I'll look into the lock-up switch, thanks. I agree about the temps being higher later on in the night, especially last week because I was running about every 20-30 minutes. But, to lose 4-5 tenths that quick seems to indicate something else is at play as well. I'm one of the lucky one's with the new version tstat so the Hypertech won't fit, I have to wait for one to come out. My fans do come on earlier but I am looking for a fan switch to manually do it at the track. I guess I can pretend I already have a supercharger and ice it down!
 

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Its easy to loose 3-5mph in the heat. Weather and vehicle temps can really change the way the car performs from one to the next.

I'm not so sure the converter is too big. Many F-Body guys run that or higher with no internal mods. Does the converter lock up at all? You really need it locking up at least in 3rd gear. If it does, then locking it up in 2nd might help also as suggested.
 

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549 RWHP and 569 TQ
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Discussion Starter #10
I know my guy tuned it to lock up at some point but this is my first experience with a converter so I don't know what all he programmed. I'll find out and ask about second gear if it doesn't already. Thanks.

My friend had a 99 Camaro with nothing but an open exhaust and an air box with a 3500 and had really good results with it. The one I have is a lot more efficient than that one was. I don't claim to know much about LS1's, yet, my experience was with GTP's before this car so I am relying on my friends who have been messing with these engines for years with good results.

I just think there are some unique qwerks to be figured out about the GTO's that are slightly different than F-bodys and vettes. I think Devil Yellow is probably on the right track about the abuse tables maybe not being all accessible on LS1edit. The guy who tuned it basically used his standard F-body tune for lack of anything else to go on.

I do appreciate all the advice being given, he may have already accounted for all of this but not everyone can always think of every possibilty so thanks for the brainstorming, keep it coming.

Dave
 

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It sounds like you are using poor fuel. Did you fill the tank after you reinstalled the stock MAF? The first pass after you reinatalled the stock MAF was 13.6 right? After that pass the computer may have detected a lot of spark knock and lowered the timing for the next passes. Try using better gas or adding octain booster. Everytime the computer senses spark knock it will lower the timing until there is a change in the level of fuel in the tank.
 

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549 RWHP and 569 TQ
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Discussion Starter #12
I showed no KR during any of the passes. I was using 93 octane, I didn't have time to get any race fuel but I will get some next time and see if that helps, thanks.
 
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