I am new to the forum and have a question regarding a 97 Northstar that I have installed in my Fiero based Lamborghini diablo replica. I have spent 5 years building this and now have it on the road (www.lambobuilder.com). My Nothstar was a brand new 97 that I bought from Gary Zumalt. He went out of business before he supplied my axles. I did the usual pontiac 6000 spindles, alante hubs, shorten axles etc. and it is now drivable. I swapped out the 97 throttle body for a 95 throttle body. I also bouth a modified 95 computer from Howell Engine Development. It has a super chip that is supposed to give me 300HP. Most of the time the car will run just fine, when I step on it it has good acceleration. However, after driving it for a while, it will begin to idle up and down and get real boggy, when I step on it it will barely accelerate. Stopped in traffic, it will begin to idle up and down and requires firm pressure on the brake not to move into the car in front of me. The check engine light will stay on until the next time I start it. The Howell computer came with an ALDL connection to plug in a tech II to read the codes. unfortunately, they have confirmed that it was never funtional so I cannot read any codes to do any type of diagostics. I am considering the Holly Commander from CHRFAB that is fully programmable but I'm not sure it I will have issues with the automatic (I'm using the stock NS transmission). Has anyone installed a Howell computer on a NS and been able to find a way to read the serial data from the computer? If not does anyone have any experience with CHRFAB's Holly commander?
Any feedback would be greatly appreciated.
------------------ Dale lambobuilder.com
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02:43 PM
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Will Member
Posts: 14252 From: Where you least expect me Registered: Jun 2000
Welcome! Glad you finally found us. I have been following your Lambo build up for a while and I would like to say I am a big fan of it.
Concerning the N* auto tranny, I have had no experience with it at all, but hopefully some of the super smart people that are members of the forum will be able to help you out.
--Will
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03:29 AM
Dennis LaGrua Member
Posts: 15526 From: Hillsborough, NJ U.S.A. Registered: May 2000
I am new to the forum and have a question regarding a 97 Northstar that I have installed in my Fiero based Lamborghini diablo replica. I have spent 5 years building this and now have it on the road (www.lambobuilder.com). My Nothstar was a brand new 97 that I bought from Gary Zumalt. He went out of business before he supplied my axles. I did the usual pontiac 6000 spindles, alante hubs, shorten axles etc. and it is now drivable. I swapped out the 97 throttle body for a 95 throttle body. I also bouth a modified 95 computer from Howell Engine Development. It has a super chip that is supposed to give me 300HP. Most of the time the car will run just fine, when I step on it it has good acceleration. However, after driving it for a while, it will begin to idle up and down and get real boggy, when I step on it it will barely accelerate. Stopped in traffic, it will begin to idle up and down and requires firm pressure on the brake not to move into the car in front of me. The check engine light will stay on until the next time I start it. The Howell computer came with an ALDL connection to plug in a tech II to read the codes. unfortunately, they have confirmed that it was never funtional so I cannot read any codes to do any type of diagostics. I am considering the Holly Commander from CHRFAB that is fully programmable but I'm not sure it I will have issues with the automatic (I'm using the stock NS transmission). Has anyone installed a Howell computer on a NS and been able to find a way to read the serial data from the computer? If not does anyone have any experience with CHRFAB's Holly commander?
Any feedback would be greatly appreciated.
While there are many knowledgeable people here on this forum; the GM ECM forum is where all of the programmers hang out and share info. While it pays to have knowledge of programming ECM's to participate, anyone is free to join and ask questions. To my knowledge there are few if any people that have been able to adapt the Northstar and OEM electronics to another vehicle and have the N* engine perform in full power mode. This may be because a full disassmebly and definition of the N* ECM code has not been done as yet. Many folks claim to have reprogrammed the N* ECM but IMO few have fully succeeded. If I were to do a Northstar I would consider using the F.A.S.T. lap top reprogrammable ECM. It's a bit expensive but so is the N* engine.
Thanks to some of the information, I will be trying some things. I will be happy to post the results once I've found a soulution. I talked to dynatech motors and they suggested that I get a stock 95 computer and defeat the VATS system as a start. He seemed to feel it was a chip issue. If I can find a 95 computer that has the diagnostic port, I may go that route just so I can read the codes. Although I believe all the codes were displayed in the AC display on the cadillac. I'll keep you posted.
The cal listing for the NS is out there but it's closely held like some of the other applications, so making an editor available to the masses is left to the hacks. The GM programmers of the pre-96 code did some specific things to make it a bit trickier to disassembly (they obviously knew the tricks we use) but once you're past those little hooks it's fairly standard (other than being split over two eproms).
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12:20 PM
vortecfiero Member
Posts: 996 From: Toronto Area, Canada Registered: Feb 2002
As Dennis said, the GMECM list is a good place to start. I know little about programming ECM's, but I lurk there and pick up quite a bit of useful information.
If you go with CHRFab's Holley, you'll lose the transmission side of the ECM since the Holley doesn't do that. You'll have to come up with some other way to control the thing. Probably the easiest is to use one of the aftermarket controllers. TCI sells one that's almost infinitely adjustable and programmable by laptop, but you can expect it to set you back close to $1,000. You'll also have to do some minor re-pinning of the connector to the transmission as it's made for the 4T80E instead of the 4L80E and there are some wiring differences.
Another possibility is the TCM from an early '90's GM Diesel that came with the 4t80E. These controlled just the transmission and nothing on the engine. Unfortunately, the shift points aren't exactly going to be optimized for a Northstar since it came from and application that redlines at about 4,000 rpm.
Ideally, it would be nice to have someone that knows and wants to play disassemble the chip in the GM unit and burn a new one with the proper shift points and pressure settings for the Northstar. Then we'd have a plug it in and go unit that costs less than $300 and needs just a simple chip change. I haven't found anyone to do that yet, so it's still a dream.
No. The TCM from those trucks controls JUST the 4L80E and nothing else. What would need to be modified is the shift points at various rpm, kickdown points, TCC lockup, line pressure, etc.
IIRC from the service manual, the only thing going anywher but the transmission is a TPS and maybe a MAP, as well as the SES light and ALDL port. But I'd have to get the book out and look again.
John Stricker
quote
Originally posted by TK:
You mean just remove Vats and disable some error codes?
No. The TCM from those trucks controls JUST the 4L80E and nothing else. What would need to be modified is the shift points at various rpm, kickdown points, TCC lockup, line pressure, etc.
IIRC from the service manual, the only thing going anywher but the transmission is a TPS and maybe a MAP, as well as the SES light and ALDL port. But I'd have to get the book out and look again.
John Stricker
I asked the wrong question. It would be nice to have a TCM that could be used for other applications.
