Quoting einstein:
It also has md 165531 ecm in it which according to the tage is for a auto transmission with a manual trans would that be the main cause of the issue?
Matt,
There's a few factors related to running a dsm automatic ecu in your vr4 that may make things a little funky untill things are warmed up and in closed loop.
The dsm automatic cars ran a smaller fuel injector (I *believe* they were 390's vs. the 450's in the manual trannydsm/vr-4's) and they ran them at a higher fuel pressure (I *believe* the auto's run 41-46 psi vs. the manual dsm/vr-4's at 36-38 psi, (vacuum hose disconnected))
The two factors almost cancel each other out, but the size/pressure difference will alter the amount of fuel the ecu "thinks" it is delivering versus what is actually being delivered to the engine, especially when you apply a varying load on a cold morning drive.
In addition, the vr-4's had the lower honeycomb in the airflow meter removed from the factory, and the dsm did not.
That probably skews the fuel trims a meaurable amount.
The two factors working together will definately affect the actual vs. targeted warm up mixes the ecu is shooting for and make for a wonky idle/funky driveability when cold.
It will especially affect the base idle because the ecu is targeting 800rpm on the vr-4, versus the 750rpm of a dsm)
Prior to the engine warming up and the ecu allowing closed loop fuel control, it's just using simple temp/rpm/load look up maps (with no feedback control,) and the occasional lean stumble/rich bog may result when it's recieving erroneous info on airflow from the maf, and shooting more/less fuel at the injectors.
It will be able to trim most of those problems out when the engine is warmed and the system is in closed loop.
Quote:
Where is a good place to get a manual ecm?
All may not be lost!
Is this an e-prom ecu?
If so, the old chip can be removed, the board can be socketed, and then a new chip can be made to bring things up to the vr-4 spec programing, (or you can even add/modify a few features for a better match with your set-up.)
A pic of the ecu board you're working with will tell many tales. /ubbthreads/images/graemlins/smile.gif