Problems bracket racing LS2.

[SSinTN]

I'm a newbie here with a '06 tbss and I'm having trouble with consistency while drag racing. My mods are as follows: Mail-order tune, LS7 throttle body, efans, Maf moved inside air box. I have HP tuners but I haven't done anything with it except for a case relearn. My problem is this: When I go to WOT at the starting line I get a delay in throttle response (but not every time). It doesn't seem to matter if I leave from idle or torqued to 1,000 or 1,500 rpm. My ET's are very inconsistent. I was told to convert to speed density and unplug the Maf. Will that work? Will it hurt to zero out the IAT? Help please and thanks in advance. Sorry for the long post.

[EC_Tune]

DO NOT unplug your MAF to go SD. The IAT is integrated into it. Do you run with stabilitrak on or off? I would run with it off. Log some data while making runs and compare the data. You will be amazed at differences between runs. Don't change anything until you can confirm that the runs are giving you the same data unless of course the engine is knocking it's brains out...

[SSinTN]

I do run with the traction control and stabilitrac turned off. I was thinking more like relocating the IAT sensor away from the maf. How would that fit in?

[Scooter70]

If you think IATs are your issue, check out the Vector Motorsports IAT relocation kit. It's a new IAT sensor that reacts more quickly than the stock one. Since it's separate from the MAF, you won't have to worry about the "heat soak" of the MAF housing radiating to the sensor. I haven't bought one yet but I plan to do it this spring.

Note: there are other (read: cheaper) ways of building your own faster-acting IAT but this kit is plug and play so there's no need to splice any wires. I think Casper Electronics also talked about making a PnP kit but I haven't heard whether they did or not. If you look around ls2gto.com you should find plenty of info on the IAT/heatsoak issue and the various things that people have done to try to limit and/or eliminate its bad readings and their effects on timing.

[MNR-0]

I'm a newbie here with a '06 tbss and I'm having trouble with consistency while drag racing..

What are the inconsistencies? (and no, ET is not enough. What ET? What MPH?)

My mods are as follows: Mail-order tune, LS7 throttle body, efans, Maf moved inside air box.

Why did you do that?

When I go to WOT at the starting line I get a delay in throttle response (but not every time). It doesn't seem to matter if I leave from idle or torqued to 1,000 or 1,500 rpm.

Got any logs?

[PurplePiss]

I'm having the same problem. I bracket raced a cable driven TB 1998 WS6 for 3 years. I was deadly in that car. Now with the TBW TB, my reaction times are all over the place. Anyone know how to improve the response or atleast make it consistant?

[SSinTN]

What are the inconsistencies? (and no, ET is not enough. What ET? What MPH?)
60'=2.241, 660'=9.157, MPH=79.82
60'=2.258, 660'=9.182, MPH=79.74
60'=2.289, 660'=9.250, MPH=78.98]
60'=no time, 660'=no time, et=9.31, MPH=77.80
Density altitude hovering around 450', Temperature 55*F.
Why did you do that?
I did the pcmforless.com tune so I'd have something to start with
I did the Ls7 throttle body because I thought it might respond better than stock and it does, just not good enough.
I did efans so I wouldn't have the clutch fan dragging and possibly engaging at the wrong time.
I moved the maf inside the air box hoping it wouldn't get heat soaked as much as it will being next to the radiator hose.
Got any logs?
No.

Is that enough?

[MNR-0]

Well your times aren't that inconsistent at all. Looks like its all in your 60'.

I presume you own an A4 with stock converter?
Do you have the drive-by-wire TB or cable actuated TB?
Were you wheelspinning off the line?
You really need to go get some logs of launches, using the default configs.

Moving the MAF into the airbox will likely cost you, as the throttle response wil be less than more due to the extra plenum volume between the MAF and the valves. The MAF will be slower to respond, as launches take momentarily longer for the MAf to start reading increased airflow.

Also, the MAF need a certain length of pipe nefore it to laminate the airflow and deliver accurate readings. Did you stuff with the MAF at all? Like port it and remove the screen?

Whats you IAT like at launch?

Without logs, a tune file, we can only guess...

At a guess, I would say you are too lean at launch, caused by the MAF relocation and perhaps not compensating for the larger TB in your tune. but thats just a stab in the dark.

[PurplePiss]

So your saying by mounting the maf infront of the tb will get you better response?

[SSinTN]

I have the drive-by-wire setup A4 with a stock converter and I will run some scans and post them. I've ordered a CAI kit and IAT relocation kit so I'll wait till I get those installed before doing the scan...The CAI will locate the maf back to the stock location. I have not mofified the maf at all. I read where the LS7 TB is more responsive and that's why I bought one; it is the same diameter as the stock TB. The only real difference is the motor that opens the butterfly. I'm not experiencing wheel-spin at all but I do agree that the 60' times are the problem and I believe the delay in response is causing this. Unfortunately this is too inconsistant to be competitive at my home track. I've been racing with carburetors for 32 years and can tune them to run much more consistantly than this. I hope that with a little help from this forum I'll be able to do the same with EFI. Thanks.

[MNR-0]

Locating the MAF in front of the TB is equally as bad as mounting at the end of the intake pipe. PurplePiss, where did you come up with that one?

Some things you could try...

The TB could be your problem. Check if the diameter is the same. If it is, then move on. If not, you need to rescale your ETC Area Scalar.

Remove all ETC torque management limits, found under "Torque Management|General". Read the Help File on these tables to understand what you should set these values to.

You should then do a scan to check if any codes are being thrown after a hard launch.

Stock converter will yield at best 1.9x 60', but typically 2.0-2.2 60'.

[SSinTN]

Locating the MAF in front of the TB is equally as bad as mounting at the end of the intake pipe. PurplePiss, where did you come up with that one?

Some things you could try...

The TB could be your problem. Check if the diameter is the same. If it is, then move on. If not, you need to rescale your ETC Area Scalar.

Remove all ETC torque management limits, found under "Torque Management|General". Read the Help File on these tables to understand what you should set these values to.

You should then do a scan to check if any codes are being thrown after a hard launch.

Stock converter will yield at best 1.9x 60', but typically 2.0-2.2 60'.

As I said in the previous post the TB is the same diameter as the stock one. I will perform this test though. The stock throttle body did not respond as well as this one.

[PurplePiss]

So can anyone confirm that the LS7 throttle body will fit and work on an LS2/E38?

Is the motor different and therefor truely make it react faster? Any body test it?

[ScarabEpic22]

From what Ive heard the LS7 throttle body is the same as a LS2 car throttle body. There is a difference between a LS2 truck tb (TB SS, SSR) and a car one (Vette, GTO).

The LS2 car throttle body does indeed react faster than the LS2 truck tb, and is much better suited than the stock truck tb for boosted applications on the TB SS. I dont think you need to retune for the tb, but I may be wrong.

So, the short answer is, YES, the LS7 (aka LS2 car tb) will work on a LS2 truck manifold.