View Full Version : Stock ECM vs Performance ECM
Just sharing some results on ECM swaps. My truck was originally an S code. I changed the intake and ECM and converted it to F code. There was a notable power increase in the upgrade. I bought a used performance computer about a year later and have been running it for about 2 yrs. Big power increase on that swap.
Two weeks ago I decided to put the F code computer back in as I am going on a long trip not towing anything but a small boat. I was hoping for better mileage with the F code ECM.
To my suprise the mileage was a little worse than the performance ECM. I really noticed the power loss too.
So the moral of the story is you can have your cake and eat it too! (in this case any way) Just thought I would share my findings with all.
racedaymechanic
06-08-2012, 05:03
Just sharing some results on ECM swaps. My truck was originally an S code. I changed the intake and ECM and converted it to F code. There was a notable power increase in the upgrade. I bought a used performance computer about a year later and have been running it for about 2 yrs. Big power increase on that swap.
Two weeks ago I decided to put the F code computer back in as I am going on a long trip not towing anything but a small boat. I was hoping for better mileage with the F code ECM.
To my suprise the mileage was a little worse than the performance ECM. I really noticed the power loss too.
So the moral of the story is you can have your cake and eat it too! (in this case any way) Just thought I would share my findings with all.
Theres more to it than just changing Boxes, Get a Heath tune and youll be happy, More Power and better mileage
greatwhite
06-08-2012, 08:17
Just sharing some results on ECM swaps. My truck was originally an S code. I changed the intake and ECM and converted it to F code. There was a notable power increase in the upgrade. I bought a used performance computer about a year later and have been running it for about 2 yrs. Big power increase on that swap.
Two weeks ago I decided to put the F code computer back in as I am going on a long trip not towing anything but a small boat. I was hoping for better mileage with the F code ECM.
To my suprise the mileage was a little worse than the performance ECM. I really noticed the power loss too.
So the moral of the story is you can have your cake and eat it too! (in this case any way) Just thought I would share my findings with all.
The MPG and power is not too surprising.
Something as simple as a refinement of the stock timing curve can net nice gains in both arenas.
The electronic 6.5 responds very nicely to increased timing as the rpm's rise.
Toss in a little fuel curve massage and things start to wake up very nicely.
SSD used to get their PCM's from Westers IIRC. Lyndon is pretty good with these old beasts. I bought my .VDF from him.
He's in your home province too!
Down around Red Deer I think......
:cool:
Edit: just checked, He's in Tilley which looks to be halfway between Calgary and Medicine Hat.....you're close engouh to run down and have him tune it on the dyno if you wanted! Might get a bit pricey though....
Where can you tell what code engine you have? Also, which code is better? Scott
DmaxMaverick
06-08-2012, 23:05
Where can you tell what code engine you have? Also, which code is better? Scott
F and S refers to the 8th digit of the VIN. F is heavy duty, S is light duty. F generally means no or less smog equipment and a higher power rating. This applies to an original configuration vehicle and engine. If modifications have been applied, or the engine has been replaced (to a condition other than original), it could be either, or a combination of both.
To the OP:
You have not indicated if the TDCO relearn was ever done to your truck,does either ECM know the actual IP location?
john8662
06-11-2012, 10:22
IIRC, you usually to a learn with the Key On, Key Off Method on a 1996+ when replacing the PCM.
J
A TDCO relearn can be done as you say:
From a post by Turbine Doc:
"Same as above bring engine to coolant temp 170 or above, see that all codes are clear (clear codes before proceeding).
Shut off engine, then turn key to run not start and accelerator to floor minimum 45 sec,(this activates TDC learn), then key off 30 sec.
Restart truck if coolant is above 170 and rpm below 1500 PCM automatically relearns offset, may stumble on start 1st run until new offset is accepted"
A scanner that displays TDCO values is required to know the learned location/amount to determine if the IP needs to be physically moved to the desired location.
After each IP adjustment the TDCO relearn needs done again with a scan tool or the KOKO method.
Stock TDCO range: -0.25 to -0.75
Performance TDCO range: -1.50 to -1.94
greatwhite
06-11-2012, 15:53
IIRC, you usually to a learn with the Key On, Key Off Method on a 1996+ when replacing the PCM.
J
Sure can.
It's built in on OBDII.
However, you still need a scanner of some sort to confirm your setting.
Did a TDC offset relearn and it was -1.94 now it is -2.02. Guess that is a little steep for a stock ECM. Seems to run well though. What will I gain by putting it to .75? It also says in the manual you only need to do a relearn if you change both the injector pump and the ECM at the same time.
You must have a - value to have advanced timing.
The difference between -0.25 and -1.94 is fairly significant,the stock setting is a quieter cold start and normal running engine.
The -1.94 is much more rattle at cold start and a performance gain.
A relearn is required anytime you change the IP adjustment,when you change resistors or crank sensors.
greatwhite
06-13-2012, 19:03
-2.02 is the max available setting.
You might actually be over it. I've set a couple trucks that would go to -2.02, not code and wouldn't go any further.
I'd adjust it back to a setting more in the -1.50 range. That's a decent balance between "power" and clatter.
Personally, I run a little + to keep things nice and quiet for the missus. She doesn't appreciate the diesel noise that much.....
The OBD2 trucks will read TDC Offset to +/-2.46 as I recall.
The OBD1 max at +/-2.02
The drawback to having an aggressive TDC is that the light load timing can get to be a bit harsh. I try to account for this with my ECM programming.
greatwhite
06-14-2012, 01:40
You're probably right John, working on these trucks is a sideline hobby for me. I'm sar of the ch149 cormorant so I've got a lot of different bits of technical info rolling around this old noggin. Not to mention, mEmory doesn't seem to serve as well as it once did......
I may have gotten obdi and obdii mixed up.
Did a TDC offset relearn and it was -1.94 now it is -2.02. Guess that is a little steep for a stock ECM. Seems to run well though. What will I gain by putting it to .75? It also says in the manual you only need to do a relearn if you change both the injector pump and the ECM at the same time.
Setting TDC is like playing a vaguely loaded roullette wheel. Try again and it should fal on 1.76, 1.85, 1.94, 2.02, 2.11 etc. Just keep doing it until it lands on your number. If you want to fall outside this range you need to mov the pump and try again.
10-4 John. My son will bring the tech 2 home after work tomorrow and I will set it up on 1.76 if I am able. Also seems that mileage has picked up considerably on the second tank with the stock ECM.
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