I would love to use a Commander 950 ECM to tune my engine.

I am curious, could a burn a prom, and take out everything, so it just runs my air pump, egr, fuel canister (if that's computer controlled), and Torque converter lockup?

This way I could run the commander 950 for the engine, and tuning, and I could leave the stock harness in place, controlling my emissions. Can this be done?

 

That's an interesting question, and it may work, but I could see a lot of flags needing to be turned off.

I wonder how the ECM itself would react to an empty PROM as far as fuel and ignition are concerned.

Just curious as to why you would want to burn a PROM to control just emmisions and tranny, when you could use the same ECM to control the engine too.

 

Well, to me it looks like the Holley Commander 950 is a billion times easier to learn, plus it can be changed on the fly with a laptop.

Id rather spend a month driving the car, while tuning it, than a few months running inside, burning a prom, running back outside, plugging it into the ecm, etc, etc. The Prominator sounds good, (from the other thread) but I would really like to use the Commander 950. (plus it has it's own documentation and instructions. I would rather rely on that, then having to constantly post here, gmecm, etc etc to get answers to a billion questions)

I need to keep my emissions equipment here in Colorado, so I was trying to figure out a way to run the 950, yet retain all of my emissions equipment. I would need to fabricate the EGR into the Stealth Ram intake, but if I can keep the stock ECM controlling the air pump, tcc, and everything else the 950 doesn't, I don't see that as being a big problem.

Thanks for the reply. Does anyone think this would work? Since so much would be turned off, it wouldn't matter if the prom went into limp-home mode even, unless that changes emission controls, and tcc lockup.

 

You need to investigate the ROMULATOR and TUNERCAT R_T.

Real time just like the aftermarkets, and just when your done you burn a chip. And you only save 400-500 bucks.

If you think the documentation on any aftermarket is perfect please send me a copy, I really like to see that. I just read thur a an ----- --- -- manual. What it said was interesting and informative. Trouble is I could think of a hundred guestions it didn't give the remotest clues about. Any sort of complete documentation is going to a thousand pages. Min..

Have a tech problem with the Commander and where do you go for answers?. yep, the net. Ever call tech support for an aftermarket ecm?. Some of them are just flat laughable.

To make an ecm simple and easy to use means compromises. To make it easy to learn, means not many adjustments. ALL the newer aftermarket ecms are getting more complex, why? because they want to approach the oems for drivibility. It's easy to get an engine to run, the trick is giving it good manners.

I'd love to hear an aftermarket ecm manufacturer claim they can do BETTER then an oem, in all reguards.

Not to mention that you might find this all really interesting and with the aftermarket, your locked into just doing what they want you to be able to tune. With the oem ones, most all the popular ones have pubic domained code listing ALL the changes possible.

Needless to say, I don't see any advantages to what you want to do.

BTW, the aftermarket ecm may use a different strategy for reading temps, and you might not be able to share senders. So you really make sure you get this right, I'd suggest you build an ecm bench, and run both ecms at the same time, and monitor there outputs individually, and then together to see what's really going on.

http://www.diy-efi.org/gmecm/project...cm_tbench1.jpg

Here's what a dual ecm bench looks like. Granted this is primitive compared to what's available today, but to get things done correctly without risking having it take a dodo on a public street this is what I'd suggest you do.

 

I will check those two programs out.

My biggest problem is this. I bought a ALDL cable pre-made, and tried running craig moates software, and also win ALDL. Craig's didn't run at all, and winaldl, while it ran, it didn't update any of the BLM, or spark fields.

I don't really know what I could expect from either field, but I wasn't able to figure out why neither updated, and also what each ment.

I hesitate to stick with the factory ecm, because I don't see a point in doing so if I can't even scan it. I thought scanning my stock ecm would be a good way to start understanding more so I could get into prom burning. This has turned me off to it.

Also, I'm worried about dropping in a new engine, and having a stock, or incorrectly modified chip to run the engine at first. Couldn't that ruin an engine quickly?

I know that the Commander 950 seems much more friendly to initinal tuning then the stock ecm. While the documentation for the 950 shows that it can't do as much as a oem ecm, it also has documentation explaning how to tune, and explaining what to look for. So even if it can't configure as well as a prom re-program, to me, it can, because it has the information for at least basic tuning. I don't see that with prom burning, I wouldn't know where to begin, and there isn't a tutorial anywhere that I know of, which says, "Scan this, if the reading is this, add fuel" or "adjust this until the reading is this".

 

So since you couldn't get any freeware to work on the stocker your jumping to a $900 aftermarket ecm that MAY have a better intial starting point.

And just for grins how well does the commander do self diagnostics?, and pick defaults for when a sensor fails?.

I'd seriously suggest you reevaluate where your at, and what you want to do. If your ready to quit over not getting a scanner working, what are going to do when you get something as rare as a Commander and then need help with that?. You seem to think the Commander is a magic bullet, and while it MIGHT turn out that way, there is a 50/50 chance that it won't.

Setting the stock ecm for continual open loop, and turning off all the diagnostics will get you close. You would really need to read thru some commented code, to be sure everything functions as you want thou.

 

Grumpy, that is a good point.

Thank you for stepping in here and giving me some suggestions. I will research into oem ECM prom programming more.

 

I work for an aftermarket fuel injection company, and I believe I just did what you are talking about. I installed our ECU in between the factory harness and the factory ECU. I only intercepted the injectors, ignition ref & EST, and IAC and ran a MAP sensor (I have an 89 MAF), spliced into the TPS, and EGO (could have tied into stock MAP if it were there 90-92), and ran a second coolant temp sensor and air temp. I have them all switchable on the fly (IAC requires tranzorbs to be switchable on the fly (stepper motors spike out voltage when quickly disconnected and reconnected)).

I can run with stock timing, and my own fuel, or stock fuel with my own timing, or my own timing and fuel with stock IAC, or all my ECU or all GM. It only took a few days to make the wiring interceptor and get everything plumbed in, and there was even a 3/8" NPT plug in the front of the intake manifold for the coolant temperature sensor.

There are a few catches, make sure to tie the new ECU's sensor ground to the stock sensor ground; don't try to share temp sensors; don't try to tie the +5V sensor powers together; and don't start the car on the aftermarket ignition because the stock ecu will set a code.

All it takes is a GM ECU connector (the part that is built into the ECU) and a short section of wiring harness with the ECU connectors. It can also be done with the stock wiring harness, but that is an uncomfortable way to do it.

I wouldn't recommend doing any of this on a car with a CAT, unless you use OUR ECU with block learn, decel fuel cutoff, and calibrated on a dyno. And be ready reset the stock ECU every once in a while if you are calibrating (block learns on stock will likely max out if too much time is spent rich or lean). Also don't switch IAC control with the car running, or else it'll likely lose track of where it actually is.

If you are seriously wanting to do something like this, and you want me to make the harness thing, it'll cost you, because I only have the one prototype. We also haven't began selling our ECU in the states, and are currently developing a new one. Our current ECU is ugly and made in China, and is geared towards meeting emissions in China, and lacks some of the aftermarket bells and whistles. Our new one should be much better, but it is down the road a ways.

If you want me to draw out exactly what I did so you can do it yourself with a Holley (eh), or Accel DFI (OK), or Electromotive TEC 3 (OK), I could. I'm waiting on my boss to finish the software for my car so that it can have block learn, and injectors firing once per revolution (we deal mostly with 4 cyl, TBI - think about it). I have prototype software in it currently that has the right injection mode, but no block learn, so I have done only a halfassed calibration on it and am exceeding stock torque by about 12 ft-lbs, and am within a hp of stock. This could potentially be for sale, but I have absolutely no idea how much it would cost (but it would be cheaper than just about everyone without the harness).

Anyway, if I had a choice, I'd still stick with a stock ECU and modify it, if I knew how (I'm trying to learn, because everyone keeps asking if we can do it). If you think about it, it is the better way to go if you have time to learn it. You already have the stock ECU and wiring, and you have to pass emissions. As long as you don't mess things up too bad, it should still pass.

I can be reached at jschmidt@injectionlogic.com and am always willing to give advice on tuning aftermarket ECUs or fuel injection engineering questions, so feel free to ask away.

Good Luck,
Jeremy

 

That tech-9 seems like a neat product though..

-- Joe

 

gm high tech performance magazine did this with their project magnum, using the stock computer to control emissions and an accel gen 7 dfi. in the article, they give the name of the company that markets the harness. i've been to their site and saw the harness, but can't locate the bookmark now.

if someone were to do this, would it be better to go with the holley commander, accell gen 7 dfi or the f.a.s.t. software? from my perspective, i've been reading the stickys and tech articles on prom burning and i just don't believe i have the computer skills to make it work. i essentially need something that's "plug and play". i also like the flexibility of the aftermarket units for swapping. i have a tbi, but will definitely want to swap to an mpfi system at sometime in the future.

 

And the Magazine was probably given the ecm and expertise to make it work in order to sell their product, not that the product offered anything new, just another way of doing something. Another attempt at just prying money loose from customers.

Think about it, you say your short on computer skills yet you want to toss money at a system with even more unknowns. You're going to have to understand both systems to blend them together.

MO, It's easier to learn how to do chips for the oem ecm, and then decide based on actual experience what you want to do. ie Baby Steps, figuring out for $200 is alot cheaper then spending $900 if you just can't figure out EFI programming. The burning stuff you can always get your money back out of used, with the aftermarket stuff that varies alot.

Yes, Plug and Play is neat at times.
But, nothing bets learning the system, thou.