'97 3800 L36 - tuning for boost

[scubasteve231]

I have a 1996 Firebird 3.8 5 speed manual. I got a great deal on a turbocharger and I've been looking at what it's going to take to tune the computer for boost. I want to make sure that HP Tuners will be able to tune my car before I make the purchase.

The car is a 1996 and from what I understand it has an early version of the ODBII computer which has no aftermarket support. However, I have found that the 1997 ECM is pin compatible and can be swapped into the car as long as the programming is correct. HP Tuners shows to support 97-02 F body 3.8 cars. Looking at parts catalog, the same computer is used across all 1997 3800 engines, both the L36 NA and L67 supercharged. Am I correct in thinking I can get any computer with the proper part number from any 1997 3800 car and reprogram it?

The stock MAP sensor is only 1 bar. A 2 bar MAP sensor from a 1997 L67 supercharged car should be electrically compatible with the ECM. L67 supercharged computers obviously had a 2 bar MAP table. Can HP tuners add a 2 bar table to any base tune?

In my situation where the car won't have the stock ECM and tune, what would be the best way to approach tuning? The 1996 ECM is incompatible and gets set aside. A 1997 ECM gets installed and the existing tune in it is probably for a naturally aspirated engine with an electronically controlled automatic transmission. Can HP Tuners simply build a tune for the computer based on the needs of the car? Do I need to track down a stock bin file for a 1997 F-body 3.8 5 speed since that most closely matches the car and has the proper transmission config?

[5FDP]

I think starting off with a 97 GTP computer would work, then just disable all the transmission codes for the auto.

I think you'd need to have DHP and or tiny tuner to put a L67 bin file into the L36 computer to support the 2 bar map sensor.

These computers don't even use the VE table when in boost anyway, it's a MAF based system to figure out fueling.

[scubasteve231]

So I take it HP Tuners can't simply flash any bin file to any ECM? If that is the case, it sounds like I would be dollars ahead searching for an 1997 ECM from a L67 supercharged car. Is there any difference between the ECM/software for Pontiac/Buick cars?

At first I didn't realize the MAP sensor didn't contribute to fueling under boost with these computers. I found another thread here where someone recommended to run the L36 ECM with some modification to the MAP sensor circuit so it didn't see boost, and then tune it for boost based on the MAF. Would this be a valid approach as well?

Starting with the L67 computer seems like a more attractive option since it is already tuned for boost, and I plan on running the same amount of boost as the L67 supercharged engines.

[507]

If u wanna know the truth if the car does use the VE tables, just zero out the VE tables start the car and and pull the plug to the mass air flow sensor and see what happens. Then put the file back in on the VE tables start the car again and pull the plug to the mass air flow sensor and see what happens. Then theorize what would happen if the mass air flow sensor dies in boost or high RPM. If it does dies in boost. Even with a n/a car try it and see what happen, the same will happen. Not knocking 5 Finger Death Punch or being rude. But i did does this to my car to learn and see what happens.

[5FDP]

HPT can write different files onto different computers but it's at the cost of 2 more credits for the file you wish to flash over and it's possible that something could go wrong and it brick the computer. Then you are out 4 credits basically.

The only thing I don't know is, does the 97 L67 PCM plug into your harness.

[5FDP]

Sure it uses the VE table, but pretty much only when the MAF dies. And half the time the car won't even run right and won't start if the MAF has completely failed. Lots of time the MAF gets over looked on a no start condition.

I've never tuned the VE table on a 3800, I don't really know anyone that has. Mainly just because it uses only the MAF readings to figure out fueling and the stock VE table ends at a low KPA value. Most cars run far above what the VE table reads.

[scubasteve231]

HPT can write different files onto different computers but it's at the cost of 2 more credits for the file you wish to flash over and it's possible that something could go wrong and it brick the computer. Then you are out 4 credits basically.

The only thing I don't know is, does the 97 L67 PCM plug into your harness.

Man that's awfully expensive.

Everything I've read tells me that you can take a 1997 L36 ecm from another f-body of the same transmission type and plug right in to a 1996 car and drive away. Looking at parts catalogs for remanufactured ecms, it appears the L36 and L67 ecms are all the same GM part numbers, just different bin files. Based on all that I am mostly sure that I can plug a 1997 L67 ecm into my harness, but no I haven't actually done it.

[scubasteve231]

Just thought or something else since the MAF is responsible for fuel under boost.

I had originally planned to leave the MAF in the throttle body and let the turbocharger push air through it.

The L67 motors are set up such that the supercharger is drawing air through the MAF instead of pushing air through it. Seeing as I want to use as much of the L67 tune as possible, would I need to relocate the MAF so it is before the turbocharger compressor inlet, in order to mimic the stock L67 arrangement?

[5FDP]

The MAF can stay in the throttle body, all the turbo kits for the grand prix's do not move the MAF sensor at all.

[KerchumA222]

Just throwing this out there: My computer could handle it differently since I have an 02, but it definitely uses MAP and MAF together. Just zeroing out the table for the map completely prevents the engine from running. It uses the MAP for transient fueling (again at least for my 02), which means that when you step on the gas it looks at the VE table and uses it as part of its fuel calculation. I have heard this was designed this way since the MAP sensor is more responsive than the MAF.

When just MAF tuning my car for boost My values were all +-20%, which is a really wide margin. Turns out it was because of the VE table.

[5FDP]

I know I never said you should zero it out, just saying that once you are in boost and above a certain KPA value. It does not use the VE table anymore, it then is only goes off of the air going past the MAF sensor.

It's why I've never needed to tune the VE before. I mainly focus above 6000-7000hz on the MAF table to control fueling. Perhaps if you stuck a huge cam in the motor and big injectors you'd have to work on the VE and transient fueling.