I had my car dyno tuned, but for various reasons I want to have my computer re-flashed back to stock programming. I went to the dealership and they tried to re-flash the PCM, but they said it would not work because it was already reading STOCK programing. I thought to myself, WTF, I had my car dyno tuned yet I still have stock programming. So emailed my tuner about this situation.

His response:
"As far as the dealer being unable to flash over the programming that is true. Your computer has the latest GM updates which have a "part number" associated with them. Tuning involves editing the tables in those files. The ID(part number) remains the same and therfore looks unaltered by the TechII scan tool that GM uses. The TechII can only flash over the PCM if it sees an update from GM."

Is this true that my computer can only be re-flashed if it sees an update from GM? Or can the PCM can be re-flashed regardless, and the GM dealership didn't know what they were doing? Please only accurate answers, im already confused enough.

Thanks...

 

His response is right.Ls1edit leaves the tables looking stock.Why not just go to the tuner and have him put in the stock program?I keep all my customers stock programs just for this.

 

I had Wester's Garage send me a totally useless update (waited 6 weeks) for my blower and my truck sounded like it was going to blow up. After him dicking me around for a few days and saying he wouldnt send me an update until I proved to him that I indeed had 43lb injectors I had to get a new tune ASAP. He locks his tunes so my tuner had a tech reflash a stock program over my locked EDIT program. Worked fine, well at least it got rid of the crap tune and lock.

 

Slowhawk...isnt it wise as a car owner to save the stock tune then in the first place?
Or get a sec CPU for a tune and in case something plays "windows" just plug in the stocker to get home?

Couldnt the GM Tech guy alter the Vin on the CPU and the reload a update on the cpu?

another sponsor Q:

in the old GM ECM days you had a ECM number and a code
Example GTA 88 with 350 and 7ooR4

ECM Number 1227165
Code AKXZ 3294

looked up the Number on my OTC Book and the code on our GM Fbody Part book!Found out what emission and trans and ratio axle it was set up for

WHERE CAN I CRAB THAT INFO ON A LS1 CPU???????????????????????

I got a 98 LS1 unit but would rather backoff the numbers before going to messwith the CPU/ Harness......HDW No. 16220610 CWJP

 

If you need to change a computer back to stock. all the dealer has to do is input a vin from a different year in the car say if yours is a 99 then you have them put in a 2002 vin. "it has a different operating system" then, when that is done, then they put your 99 vin back in and it will flash it to your stock 99 calibration. The tech 2 only allows flashing if the operating system has a different number then the current one. This can be verified by going to http://calid.gm.com/vci/VINEntryPre.do and entering your vin. That will tell you most likely what operating system you have in your vehicle. As for Saving a stock tune for safety, that is not really a big deal at all. It is very easy for a person to recieve a stock tune for any pcm. Heck i email them to people all the time. i just pull them out of sps and email them to guys on all the boards.. it only takes about a minute or so and is exactly how it comes from the factory...
And for the numbers on the pcm meaning anything, they dont really go off that any more. most of the info is in the vin number itself for options.. The broadcast code is really just a brief vehicle type and the hardware id and the service number can have multiple applications.

 

Ok thanx for the GM page and other infos!

I did left away the CPU number and after waiting yesterday for some replys i got the CPU out and Its:

CPU no 09354896 cwjp + hdw no 16220610

Looked it up at S&P and its a 99 and UP!
Happy me its not a 98!????

Again need to finally get this topic off the table:

Is the 98 CPU limited in its standarts or with its "function-output" compared to the 99 and up CPU´s?

In the 3rd gen Fbody world the 1226870 CPU change over to the 1227165 CPU was "THE Update"

The ECM that came in my 1985 Z28 Camaro with the TPI motor (VIN "F") is a series 1226870 (870) control unit (car computer). This model was used in the '85 F-body cars with TPI motors, Corvettes, and some 2.8l V6 (VIN "S" and VIN "W") (*Reference*) cars. One major problem when tuning an EPROM for this ECM is that the diagnostic data (ALDL) is transmitted at only 160 BAUD!. This works out to about a 1.25 second interval between the 25 Bytes of data. I have only been able to get about 6 to 8 data samples during a Quarter-Mile DragStrip run which you can imagine does not provide much feedback for tuning. (sample data are at the bottom of the page in PDF format)
The ECM that came in 1986-1989 TPI Fbody's and Vettes is a series 1227165 (165). The ALDL data rate in this model can supply diagnostic data at 8192 BAUD. The (expanded) data stream of 64 Bytes cycles through every 62.5 milliseconds (16 per second) at this BAUD rate.

I will send in the Harness and CPU to John to rework,tune and delete stuff of the CPU!
The car is a Hybrid : using a 2000 Z28 Ls1/4l40e

Does it matter then what CPU i send to John if the OS from any year can be put on the CPU with a vin change?
Or am i right when saying the 98 CPus are "slower" and it would be better to send in a 99 and up!
By reading lots of threads i was thinking its only the OS year that is important
and that the 2001 and up is better due to the VE tables and a later change to mafless car!
So do i care about the OS years or the CPU years? Its tuff getting LS1 parts here at all!
What would you suggest?
Plans for the future are a Magnacharger and a transmissionswap ( the 4l60e is a transmissions nobody over here can work on!the prices suck too so i was thinking of getting a build 350th)