Aftermarket PCM results

[Sprucegagt]

Originally Posted by Vegeta

If you completely reset what the computer has learned, and then go down the track at WOT, you will have no real fueling corrections. You shouldn't have to drive 30 minutes to get the WOT performance differences figured out. We had a problem on the dyno with phil's car but that was probably due to the bad VE tables from DHP at the time.

You couldn't be more wrong. After you reset the PCM, all of it's learning parameters change right after start up. By the time you get to the line, your LTFT will be very far off causing a big effect on your 1/4 mile time. This doesn't matter if the PCM is tuned or not. Most tuners never change the PCM at the track. Instead they will only change the dedicated WOT parameters like PE and the high load portions of the Good Fuel Spark Table. That way they never effect the LTFT value.

[O1GAGT]

I am wondering if DHP with the 1.0 PCM made any changes to the VE table?

The DHP Powr Tuner VE tables were off pretty bad, and alot of people were wondering why they were fighting their tune. Thankfully that issue is now corrected.

In the top pic you can tell where the problem was. The bottom pic is the corrected VE table, so if you are using the Powr Tuner make sure you are running the 1.2.3 version for the corrected VE tables.

[Sprucegagt]

Originally Posted by O1GAGT

I am wondering if DHP with the 1.0 PCM made any changes to the VE table?

The DHP Powr Tuner VE tables were off pretty bad, and alot of people were wondering why they were fighting their tune. Thankfully that issue is now corrected.

In the top pic you can tell where the problem was. The bottom pic is the corrected VE table, so if you are using the Powr Tuner make sure you are running the 1.2.3 version for the corrected VE tables.

I have a feeling they didn't. Changing VE without scan data is to risky.

As for the new tables, I've already completed my VE tuning with them. Strange thing was it didn't make any major changes to the rest of my tune.

[lone_wolf025]

So roughly what kind of gain are we seeing in terms of HP after a tune w/100% stock setup?

[Blackbombshell9]

Originally Posted by Sprucegagt

You couldn't be more wrong. After you reset the PCM, all of it's learning parameters change right after start up. By the time you get to the line, your LTFT will be very far off causing a big effect on your 1/4 mile time. This doesn't matter if the PCM is tuned or not. Most tuners never change the PCM at the track. Instead they will only change the dedicated WOT parameters like PE and the high load portions of the Good Fuel Spark Table. That way they never effect the LTFT value.

One guy in my carclub ran a 14.0 in a 98 gtp with a dhp 1.5. He removed it and put in his intense pcm in a matter of 15 minutes and ran another 14.0. His best time once was a 13.7 but that was on a much colder day with better track conditions.

[Vegeta]

You don't have an idle cell for that ltft? Thats pretty sad that GM backtracked from OBD1 to OBD2 by eliminating the cells.

[slowbird]

I don't know about that other stuff but I know for sure the shifts on my car didn't firm up until the following day of my MMS PCM install.

[Sprucegagt]

Originally Posted by Blackbombshell9

One guy in my carclub ran a 14.0 in a 98 gtp with a dhp 1.5. He removed it and put in his intense pcm in a matter of 15 minutes and ran another 14.0. His best time once was a 13.7 but that was on a much colder day with better track conditions.

Those are 2 completely different tunes. So with the LTFT being off it will affect each one differently. Also how did he get a DHP 1.5 tune? Just an FYI, if this is an off the shelf PCM then you want the 1.0 tune. The 1.5 tune does not have nearly as much done to it as the 1.0.

Originally Posted by Vegeta

You don't have an idle cell for that ltft? Thats pretty sad that GM backtracked from OBD1 to OBD2 by eliminating the cells.

You do have an idle cell (0) along with decceleration (1), normal load (2), high load (3) and moderate load (4) cells. But that doesn't mean what happens in one cell doesn't affect the others.

[MMGT1]

Anytime I make corrections to the trans it takes a while for the VCM to learn. If I hit it too hard it will act kinda wackey for a while. I've found the Grand Prix's don't have this problem. (Bastads)
Using HP tuners BTW

[AaronGTR]

Originally Posted by Sprucegagt

I have a feeling they didn't. Changing VE without scan data is to risky.

As for the new tables, I've already completed my VE tuning with them. Strange thing was it didn't make any major changes to the rest of my tune.

As long as we're using v1.2.3 we'll have the correct tables though right? I'm hoping this is part of the reason I was having so much trouble last summer. I was using v1.2.0 last time I tried to VE tune and I couldn't even keep the car running long enough to get into gear and out of the parking lot with the MAF disconnected. Whatever the issue, my car needs a VE tune BADLY and I want to get it done this spring.

[Sprucegagt]

Yes, 1.2.3e does have the correct VE tables. 1.2.2 had them as well. But get 1.2.3e, because saving your scan data is faster with it.