Eastern Iowa, looking to hack into a 1997 LT1 Firebird.

Hello, stopping in to say hi and introduce myself.


I live in the Eastern Iowa region and I am looking to pursue a few projects that require EFI tuning.


My wife has a 1997 Pontiac Firebird with the LT1 engine and OBDII. The previous owner installed full length headers and modified the shifting parameters. Now the car smells like a toxic waste dump when idling and shifts like a monkey mashing the lever with a brick. I'd like to clean that up a bit.


I have a 2005 GMC Sierra that is basically stock with the 6.0L V8 and a five speed manual transmission, wouldn't mind eliminating a few EPA regulated components. I also have some oversizzed tires and would like to recalibrate the speedometer.


I also have a 2012 Suzuki DRZ400S street-dirt bike that I ride to work. It is carbureted today, but I would like to put a microsquirt on it someday.


My main questions:
What hardware do you recommend to hack into my wife's firebird and my GMC? I would prefer something open source. I hope to find it somewhere in this forum, but would appreciate if you posted a few links to topics here I could read through.


My background:
I graduated with a BSME in mechanical engineering from General Motors Institute (now called Kettering University). I also have a MS in Automotive Systems Engineering from the University of Michigan. And for a kicker, I recently completed an MBA. I am currently a powertrain engineering supervisor for off-road diesel equipment.


I have experience programing ECU's but mostly with proprietary/corporate owned CAN loggers in the SAE J1939 and OBDII world. The equipment we use at work would cost several thousand dollars and is cost prohibitive for a private ECU tuning hobby enthusiast. So that is why I am here, looking for a cost effective way to reflash vehicle controlers.


I am very comfortable with Ohm's law, wiring harness design, operating milling and lathe equipment. I have extensive training on Air Fuel Ratio, knock, engine calibration, cam timing, spark timing, etc. I have rebuilt carburetors and engines, as well as tuned carbs to match custom exhaust and intake designs. Software is a bit more voodoo to me, but I can fumble my way around a bit.


Look forward to lurking about, hope to provide some sort of value someday as I get into my cars.

Welcome! It sounds like you might be able to give as much help as you get, if not more!

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My wife has a 1997 Pontiac Firebird with the LT1 engine and OBDII. The previous owner installed full length headers and modified the shifting parameters. Now the car smells like a toxic waste dump when idling and shifts like a monkey mashing the lever with a brick. I'd like to clean that up a bit.

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you sure these are tune related issues rather than a running or sensor issue? it's fairly hard to affect closed loop AFR at idle on an OBD-II LT1 with a stock cam.

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I also have a 2012 Suzuki DRZ400S street-dirt bike that I ride to work. It is carbureted today, but I would like to put a microsquirt on it someday.

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recently worked with a similar conversion that someone else did on a yamaha dirt bike, he gutted the stock carb and used it as a throttle body, with a TPS remotely mounted with a link rod.

it actually ran really well and seemed really reliable, but the fuel pump side of things was really hacky. that's where a lot of effort has to go for sure. a good regulated return line system requires a lot of chopping and plumbing.

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What hardware do you recommend to hack into my wife's firebird

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the enthusiast community has focused on the OBD-I computers (94-95). the 96-97 was a bitch to work with, mostly because the flashing routine was bizarre, from what i understand. two people did it; the tunercat guy (who sold his work to JET) and the LT1edit guy (who did a very limited hack that's missing lots of critical stuffs). unfortunately, you basically have to buy one of those to work with the ECM. this could change if someone reverse engineered the gm tech tool reflashing routine for that ecm....?

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Originally Posted by steveo

you sure these are tune related issues rather than a running or sensor issue? it's fairly hard to affect closed loop AFR at idle on an OBD-II LT1 with a stock cam.

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I have a few sensor issues to clean up as well. The intake temp sensor seal is leaking. It has an aftermarket intake tube that I cannot buy the seal. I plan to mill out the sensor port and re-machine it to match the GM seal.

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Originally Posted by steveo

the enthusiast community has focused on the OBD-I computers (94-95). the 96-97 was a bitch to work with, mostly because the flashing routine was bizarre, from what i understand. two people did it; the tunercat guy (who sold his work to JET) and the LT1edit guy (who did a very limited hack that's missing lots of critical stuffs). unfortunately, you basically have to buy one of those to work with the ECM. this could change if someone reverse engineered the gm tech tool reflashing routine for that ecm....?

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This is what I keep finding about the 97 Firebird. What if I started with the 2005 GMC? Could I use the same hardware for both, but maybe I can only monitor and log data on the Firebird while actually modifying parameters on the GMC? I think JET does both vehicles, I just hate that I am limited to three VIN's on the proprietary JET system.

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I plan to mill out the sensor port and re-machine it to match the GM seal.

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there's no GM IAT seal for that particular design of sensor that im aware of; it just sealed by being shoved into a hole in a rubber intake boot.

obviously a leak around the IAT sensor wont do much to the IAT readings, but the air leak post-MAF is a different story.

Easiest on the LT1 would likely be to convert ti to ODB1 by using a 16188051 PCM. Then Tunerpro works and it's basically better supported. I think the only thing that changes is the knock sensor is 100k on the ODBII and 4k on the ODB1.