Changing either the engine or the electronics?

P

PHerder

Well-Known Member
Somewhere in the back of my mind is a note that if the engine or the electronics (PCM or BCM) is changed then something has to be checked/configured/? to make the electronics work with the different engine. (i.e. same type engine - 2.0 LSJ)

Anyone have any info on that? I do know that in the PCM, the VIN is entered into the memory so if that was changed, the VINs wouldn't match. But if the engine was swapped out (i.e. for a lower mileage version for example), is there something like a crank timing that the PCM needs to be configured for?

Inquiring minds want to know... :oops:
 
Last edited:
TheNuker

TheNuker

Goblin Guru
That is a question I also have, Because I'm going to plan to build a new LSJ for my goblin over the winter time. I need that 8200rpm head :D

Nuker-
 
RichN

RichN

Well-Known Member
Same question I asked for Frank. His donor is a 2007 2.2 but using a lower mileage 2008 2.4
 
TheNuker

TheNuker

Goblin Guru
Well Rich, We are wanting to replace the same engine for me the LSJ, Not switch engine models.

Nuker-
 
P

PHerder

Well-Known Member
TheNuker said:
Well Rich, We are wanting to replace the same engine for me the LSJ, Not switch engine models.

Nuker-
Click to expand...
Switching engine models would require a different PCM (or if they are the same model PCM, a program flash for the different model engine) would be the minimum.

Then there is the differences in the wiring for the engine... Unless both engines uses the same wiring harness, a different wiring harness or a rewiring the existing harness would be necessary. Not a problem if installing in a Goblin. ;)

When I put a Quad 4 (ancestor to the Ecotec engine) in a Fiero, I had to use an entirely different wiring harness AND had to rewire it to fit the Fiero chassis. I spend a LOT of time installing and removing the engine/trans/suspension assembly (8 total times out and 8 times back in!) before I found that my wiring was good... it was the Quad 4's injectors that were bad. :censored: I had changed to another year model PCM and wiring harness before finding that the injectors were bad. :oops: I was quite good and removing the assembly out of a Fiero. From everything connected BUT without coolant, I could have everything disconnected and the assembly sitting next to the Fiero in 30 minutes. :eek:

I learned a valuable lesson. If you are convinced it is a wiring problem, it is fuel related! And if you are convinced it is a fuel problem... yup, electrical! :rolleyes:

I will not go into the fun and games I had with my Stalker trying to get the mulit-port fuel injection working... Ended up with a Holley carb on it (and is still didn't run like I wanted it to but it was better.) :confused:
 
Silverback

Silverback

Well-Known Member
Another consideration is the gauge cluster odometer - at least on some Cobalts (later ones?) - validates the odometer mileage by matching the VIN stored in the BCM. I've been told that if you want to reset the odometer mileage, it has to be done on the BCM. But, as always, YMMV
 
Last edited:
Brian74

Brian74

Goblin Guru
There are inherent differences depending on the year and engine. Crank sensors changed tooth counts certain years as well as addition of VVT ect. Some PCM's, like the 2.2 PCM are different after a certain year (2007?). Same harness & PCM should work with same model year and same engine. I also recommend researching specific year PCM's prior to chosing a donor. Some year PCM's can be easily reconfigured with tuning software and some cannot. This becomes convenient when adjusting fuel and ignition maps, rev limits ect later on if you would like to perform future engine modifications.
 
SliderR1

SliderR1

Well-Known Member
Agree with Brian! The E67 PCM has much more tuning ability than the P12 Atlas on the LSJ cars. There are a few threads on hptuners and CSS.net where some people have actually modded an E67 to work on an LSJ to get more tuning options.
 
Silverback

Silverback

Well-Known Member
I've got a new chassis and a new crate engine, etc but the donor BCM/ECM will report that it has logged 92K+ miles. Can the trace to the OEM gauge cluster be cut to disable the inaccurate odometer? I'm thinking about using a digital GPS speedometer / odometer that will start at 0 miles to establish a true odometer reading. Any thoughts?
 
B

Briann1177

Goblin Guru
The only thing with that is that I think some states will require an odometer reading if you sell. Maybe that's only for dealers, though? I would assume that cutting a trace on your gauge cluster to disable the odometer would basically kill that entire display portion.
 
Silverback

Silverback

Well-Known Member
Briann1177 said:
...I would assume that cutting a trace on your gauge cluster to disable the odometer would basically kill that entire display portion.
Click to expand...
Yes, that's the plan to replace the donor mileage with the new GPS odometer status since - at least in Tennessee - it will be registered as the current year or MSO date.
s-l500[1].jpg
 
Last edited:
B

Briann1177

Goblin Guru
If you're going with GPS, then why not just leave the stock one intact? While I don't think turning off the display is really odometer tampering, but I personally wouldn't worry about it. It could cause issues down the road for some hard to predict reason.
 
SliderR1

SliderR1

Well-Known Member
There are people out there that can re-set your odometer. I think it just takes a Tech 2 module. Of course when you search online, most of the hits are regarding illegally changing, but there are valid reasons for being able to do this - example would be getting a new BCM for the car. I found a guy in Colorado, if I remember correctly, that said he could do after I explained the 'why'. I found him online - I'll see if I wrote his information down somewhere and post it.

Ramble off....

Edit: Found it - http://odo-pro.com/digital-mileage-correction.html
 
Brian74

Brian74

Goblin Guru
Silverback said:
I've got a new chassis and a new crate engine, etc but the donor BCM/ECM will report that it has logged 92K+ miles. Can the trace to the OEM gauge cluster be cut to disable the inaccurate odometer? I'm thinking about using a digital GPS speedometer / odometer that will start at 0 miles to establish a true odometer reading. Any thoughts?
Click to expand...

Have you given any thought to the new engine break in? I’m in the same boat. I cannot find any info on whether or not the LNF requires a crank relearn like the LSJ but I am concerned with properly seating the rings under load on initial start up and eliminating any extended idle times.

I do believe a dealership can reset the odometer, as they have to reprogram new ones with current mileage whenever the BCM is changed. I’m sure they charge at least an hour of labor to do so.
 
Silverback

Silverback

Well-Known Member
Brian74 said:
...reprogram new ones with current mileage whenever the BCM is changed...
Click to expand...
My understanding is that GM engineered the BCM's odometer to be initialized only one time and cannot be reset, not even with Tech 2. Maybe there is an unofficial method (hack) to overwrite it, but I haven't found it. A new BCM and an understanding GM mechanic might be the ticket, but disabling the mileage display and adding a GPS speedo/odometer seems cheaper and easier. After all - at least in Tennessee - the Goblin will have to be registered as a new vehicle, not as a Chevy Cobalt that merely donated some parts.
 
Silverback

Silverback

Well-Known Member
I haven't heard back from Powls yet, but I know the mileage is kept in the BCM's memory. It has to be over-written with the current mileage, so maybe the Tech 2 is just limited to establishing an initial mileage only when that data field is null. Perhaps it can be hacked by someone with appropriate knowledge and tools.
 
Last edited:
You must log in or register to reply here.
Top