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Ecu help

creeping_death

Active member
Joined
Jun 8, 2009
Messages
37
Location
Spring, Tx
Hey, I bought a galant and have had lots of fun /ubbthreads/images/graemlins/frown.gif fixing the problems that keep popping up. Now it seems I have run into a stumper. I just recently found out that my ecu isn't the stock gvr4 one although the previous owner was kind enough to put it in the orginal case /ubbthreads/images/graemlins/banghead.gif Well I sent my car to a local shop to tune the bugs out of it and they're having a problem with the fuel trims. It was explained to me like this..... "Went for a couple pulls today and once I got on it the ecu screamed lean! lean! lean! while the wideband screamed rich! rich! rich!" So..... the number I got off the ecu was 0878m which I was told belongs to a 93 dsm ecu #md193299. Is this correct and if so is it compatible/could this be the source of my newfound vehicular headaches. Thanks
 

fivestardsm

Well-known member
Joined
Sep 8, 2006
Messages
1,699
Location
Middle, Michigan
Yes check it out here. click
 

creeping_death

Active member
Joined
Jun 8, 2009
Messages
37
Location
Spring, Tx
Nice. Thanks fivestar. Ok now to the next issue. Keep in mind that I have been a good new owner and done MOST of the critical/regular maintenance stuff.
 

Muskrat

Well-known member
Joined
Jun 13, 2004
Messages
2,107
Location
Lexington, KY
To answer your question, if you weren't sure. no that ECU should not be causeing you any issues, based on being out of a 1g turbo DSM. An AWD has the same programming as ours, a FF is slightly different, but will work.

If you still suspect ECU issues, the first step is to check your capacitor's to see if they are leaking and have damaged the circuit board.
 

As Muskrat said, the DSM Turbo ECU is very similar to the GVR-4, so they are usually interchangeable. The only issue might be a very lean idle, since the GVR-4 MAS doesn't have the lower honeycomb.
But, what do you mean by "the ecu screamed lean! lean! lean! while the wideband screamed rich! rich! rich!" ???
My ECU has never screamed at me. /ubbthreads/images/graemlins/dunno.gif In what way did the ECU scream? And, what was the "rich" wideband reading at the time? What octane and how much boost are you running?
 

creeping_death

Active member
Joined
Jun 8, 2009
Messages
37
Location
Spring, Tx
I have a 2nd gen maf running on 93 octane and I believe 15-18psi, and that was the quote by the mechanic im sure it didn't actually scream at him. I just wanted to get some kind of feedback from the boards if anyone had seen this happen to help speed this along. They're in the process of trying out another ecu to see if that fixes the problem.
 

Ok do you have anything to compensate for the 2g mass air??? like a chip or an AFC of some sort??
 

creeping_death

Active member
Joined
Jun 8, 2009
Messages
37
Location
Spring, Tx
I guess I forgot to mention but yes I have a safc2. I upgraded to a e316g ofh tube inline filter 560's mbc afpr yadda yadda. Its during the final tuning that the ecu is sending mixed signals with the wideband.
 

turbowop

Well-known member
Joined
Apr 29, 2001
Messages
11,971
Location
Yakima, WA
So what part of the ecu is showing a lean mixture? Is the knock sensor going crazy? Is the narrowband sensor reading lean?

Fuel trims have no bearing on WOT tuning and the wideband should be one of the most important tuning tools to be looking at. Either your mechanic isn't very good at communicating the issue to you, or you need a new mechanic.
 

creeping_death

Active member
Joined
Jun 8, 2009
Messages
37
Location
Spring, Tx
Yes turbo im sure I got the laymans explaination. As I was blessed with the ability to take stuff apart and reassemble, I know nothing of tuning. I do know they're using a datalogger, he told me that upon acceleration and cruising, even though he keeps adding fuel the ecu thinks its running lean and when he looks at the wideband it says hes running rich. I'll ask some more detailed questions come monday, they're swaping the ecu today to see if that makes a difference. Oh and the caps look fine. Thanks
 

1. The FUELTRIMS are only useful for tuning the closedloop operation of the ECU, when you are idling, or cruising under light load. You want to tune them using the AFC LOW settings only. I actually prefer to start by setting all the AFC sliders to zero, and then cruising around lightly for a while, watching the HIGH TRIM. If you have an AFPR, use it as a "rough adjustment" for the HIGH TRIM. Once you have the HIGH TRIM staying stable at 100, you can finetune the LOW TRIM if it is very far off. The stock O2 sensor tries to maintain a 14.7:1 AFR in closedloop, but it actually swings back and forth a few times per second, which makes it hard to read the closedloop AFR on a wideband. Just use the fueltrims. Only once you have a good base tune in closedloop should you attempt to tune the openloop/WOT operation of the ECU.
2. If you run good 92/93 octane, you want to adjust the AFC HIGH sliders for a target AFR of roughly 11.0:1, maybe slightly leaner, but no more than 11.5:1. In openloop the ECU's fueltrims are ignored, and the ECU goes strictly by the maps.
 
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