1st gear is WAY slow

[ABC-Boostd-1]

Hello everyone, I seem to be having a bit of trouble with my car. It's a 1998 Pontiac Grand Prix GT with the L67 top end swap on a stock GT tranny.

***On the 3.25 pulley, I did not notice this problem***

Once I swapped balancers and put on the 3.0 pulley, this is when things started feeling...odd.

In first gear floored, it feels like the car just does not want to go at all when you ease into the gas. When you put it into first gear and floor it, it pulls extremely hard. But during the times that the car feels like it's not going anywhere, soon as it hits second gear, it flies.

I was told this is a Torque converter setting issue. Not too sure...it's becoming very frustrating.

A few factors that I think it might be -

Brand new 18" wheels (Heavy) with 245/45/18 BFG's that hook pretty well
The 3.0 pulley (something with the MAP maybe?)
Time for a tranny flush
Bad tune (Please look at it)

Check out my scan as well, it may show something that I am missing.

Thanks for all of your help, it is greatly appreciated.

[boogieq]

You might want to post a few mods that pertain to this forum, such as your injectors and maf setup, etc.

[ABC-Boostd-1]

Pretty new to tuning and such...I am running the stock L36 MAF sensor, the stock GT MAP sensor and L67 Injectors. I don't believe I am maxxing out the MAF because I am at 6000 feet elevation and only see around 11-13 psi boost. Sometimes 14 on cold days.

[murphinator]

ok I am still learning myself but here are some observations from looking at your scan & tune

why did you change your stoich afr to 15.09 ? my understanding is that should typically be left around 14.7

did your pcm start life as a zzp 1.0 , or was it copied from another 1.0 file ? reason I ask is you are adding 4*timing when your IAT's are -22* zzp does that for people that buy their "race pellet"

on your scan the 02's switching rate looks real lazy - not much activity there

your narrow band o2's are pretty lean when at 100% tps ( frame 2050-2060 )

your pcm is having to add a lot of fuel according to both your long term & short term histograms

your kr histogram is showing kr in an awful lot of cells

you are seeing as little as 11-12* timing at wot , you would probably b making more power on a larger pulley with more timing

[ABC-Boostd-1]

Thanks for all of that, I will look into all these factors.

[Russ K]

Why are you using a L36 OS on a L67 engine?

Russ Kemp

[ABC-Boostd-1]

It is an L36 with the L67 top end swap.

Thanks.

[n0dih]

Honestly, go with a full L67 flash on it, there is not near enough parameters in HPT to do a L36 to L67 swap without it. Sorry, just lacks a LOT to do that. The OS is not the issue, the issue is lack of HPT's tuning ability on V6's.

If you can get HPT guys to change your existing .hpt file to a .bin, send it to me and I can fix it up for you and send it back, and then I think you can import the .bin back into HPT and save it as a .hpt and do a full flash into the car and you will be good to go.

You need to turn on Supercharger option, turn on 2 speed fuel pump, add the 2 speed fuel pump, and a bunch of other things. You can make stock file a SC, but it does take some work to do. It IS best to start from a stock L67 tune as a base, as there is sooo much in HPT missing you will miss a lot, even in other programs that have a ton more, you will be missing things.

[n0dih]

Things of note:

You have a 1 bar MAP, so the PCM doesn't know you are in boost, can't work with it properly. You need to get the 2 bar MAP sensor in there.

KR isn't too bad, I have seen much much worse.

Log MAF Freq too, this will tell you if you are closer to maxing MAF out. Can you record gm/cyl air too? That will tell you where you are on the timing table. Only then can you dial in timing.

Your fuel trims are pretty off. Need to do some MAF tuning there. Don't worry about replacing it, you aren't close to maxing MAF out yet. Stock MAF maxes around over 2x where you were on this run. Record MAF Freq and when you are regularly seeing over 11000 Hz, start shopping....

[ABC-Boostd-1]

Things of note:

You have a 1 bar MAP, so the PCM doesn't know you are in boost, can't work with it properly. You need to get the 2 bar MAP sensor in there.

KR isn't too bad, I have seen much much worse.

Log MAF Freq too, this will tell you if you are closer to maxing MAF out. Can you record gm/cyl air too? That will tell you where you are on the timing table. Only then can you dial in timing.

Your fuel trims are pretty off. Need to do some MAF tuning there. Don't worry about replacing it, you aren't close to maxing MAF out yet. Stock MAF maxes around over 2x where you were on this run. Record MAF Freq and when you are regularly seeing over 11000 Hz, start shopping....

Thanks man. You think I need a 2 BAR MAP? I'm not anywhere close to 14.7 PSI...but does it read Absolute MAP? That would explain that.

I have scanned and changed the settings to read Mhz on the MAF, and WOT was only about 9800-9900 Mhz.

Fuel trims problem were fixed...it was a vacuum leak between the blower and the intercooler core. LTFT's are @ 0.0% at idle...not 16.3% like they used to be.

Thanks for the help man

[n0dih]

You need a 2 bar MAP (0-2 bar) anything over 100 kPA. Which 0 kPA is -1 Atmosphere, 100 kPA is 0 (or outside pressure), +1 bar is 200 kPA, etc.

So you are pegging your stock 0-1 bar MAP anytime you punch it. But you DO need a stock L67 program to make it right.

Glad you found the leak!

[Andy0x1]

In manual "1" a band applies, in "D" only the clutch is used, your 1st gear clutch is likely fried. But I'm sure you've already resolved this seeing as your post is over 4 months old.