[Gmecm] 749 ECM

Wed Mar 14 11:12:22 UTC 2007

 Yes, you need to adjust the BPW vs Desired EGR table to affect fuel delivery.  The 0% EGR entry is the main cell.  It may help to set egr enable temp to it's maximum during initial stages of tuning.

The $58 calibration spark values come from the lowest RPM row of the main spark table when the throttle is closed.  Sometimes this can cause issues.

Idle can be tricky in $58.  It helps to isolate closed loop issues from open loop issues by setting closed loop enable temp very high.  It's often easier to make the engine idle well in open loop, especially if you have a bit of a cam.  O2 parameters can be important as the ecm will calculate the time required for the O2 signal to get back to the ecm.

You can also force the ecm rich or lean in closed loop to see what happens.

Zaphod

-----Original Message-----
From: romans at starstream.net
To: gmecm at diy-efi.org
Sent: Tue, 13 Mar 2007 12:29 AM
Subject: Re: [Gmecm] 749 ECM

I don't know where the injector constant is on a 4.3 Turbo $58 file, I remember it has something to do with the 
EGR... BPC vs EGR? 

The two tables I'm referring to are the VE Table - in idle 
and VE Table - not in idle. 

Since you say you are idling for 3 minutes before it dies, it would indicate to me that it's too rich, but when it goes 
into close loop it does something bad. 

You need to scan it to see what it's doing.. The VE Table, - in idle goes from 20 kpa to 100 kpa and from 600 RPM's to 1600. 
The 600 rpm and 20 kpa setting is 28.08. If it's idling at 50 kpa due to your cam and 600 rpm's, the be at 50kpa is set at 36.66 
You need to reduce this number to match up with what fuel it needs, smooth the map.... Run it on as many cells as possible and keep 
going until the corrections are very small, try to keep it pulling out about 5% fuel. 
Mark 
----- Original Message ----- From: "James Panter" <9jim30 at charter.net> 
To: <gmecm at diy-efi.org> 
Sent: Monday, March 12, 2007 3:28 PM 
Subject: Re: [Gmecm] 749 ECM 

> Mark: I have the injector set at 7 for 42 lb injectors which should be > correct. The engine dies within two or three minutes after starting > which, I believe, is due to the rich condition. That constant was about > 4.5 before so the new consant may help. 
> What line items are you referring to on the VE tables? The only line item > that I see with VE and closed throttle is F30. 
> Your help and suggestions are greatly appreciated/ 
> Jim Panter 
> ----- Original Message ----- > From: "Mark Romans" <romans at starstream.net> 
> To: <gmecm at diy-efi.org> 
> Sent: Monday, March 12, 2007 9:43 AM 
> Subject: Re: [Gmecm] 749 ECM 
> 
> 
>> Hi Jim: First make sure that your injector constant is set properly. 
>> 2nd. A stock engine idles at about 35kpa, so what kpa does your engine >> idle at? 
>> Past the VE setting from 35 kpa to the kpa your engine idles at. Copy >> that kpa from the 
>> colume where it idles all the way to the smallest kpa settings on the >> map. (Closed Throttle). 
>> This will get you started. 
>> Mark 
>> ----- Original Message ----- >> From: "James Panter" <9jim30 at charter.net> 
>> To: <gmecm at diy-efi.org> 
>> Sent: Monday, March 12, 2007 6:22 AM 
>> Subject: Re: [Gmecm] 749 ECM 
>> 
>> 
>>> Mike: Good point you make particularly on the injectors. I doubt >>> whether the small block is a 350 or 355 would make much difference in >>> the larger picture (a stroker would). I'm using a very mild Isky cam >>> and 45 lb injectors and was just really surprised at how rich the engine >>> is intially after just changing the bin to reflect a V8 rather than the >>> V6 because the actually cyl volume is very similar. And, yes I have an >>> LM1 and all the Moates stuff. I was just hoping to get close on the >>> settings and save time. The car hasn't been driven yet, just started >>> and it's far too rich to drive. 
>>> I appreciate you response. 
>>> Jim 
>>> ----- Original Message ----- >>> From: "Mike V" <efi at dyakron.com> 
>>> To: <gmecm at diy-efi.org> 
>>> Sent: Monday, March 12, 2007 7:48 AM 
>>> Subject: Re: [Gmecm] 749 ECM 
>>> 
>>> 
>>>> Hi Jim, 
>>>> it's unlikely that there will be a bin that is ready made for your >>>> combination of 
>>>> cam, injectors, etc. Do you have a log file from your ALDL >>>> datastream? 
>>>> Also, what are the specifics of the engine? There are other factors, >>>> but 
>>>> the camshaft specs and injector size are two big ones that come to >>>> mind. 
>>>> Datastream monitoring is critical for addressing this sort of thing. 
>>>> mv 
>>>> 
>>>> ----- Original Message ----- >>>> From: "James Panter" <9jim30 at charter.net> 
>>>> To: <gmecm at diy-efi.org> 
>>>> Sent: Sunday, March 11, 2007 7:34 PM 
>>>> Subject: [Gmecm] 749 ECM 
>>>> 
>>>> 
>>>>> Hey Guys Is there anyone who has done a small block Chev (twin >>>>> turbos @ 8 psi boost) using the $58 program that has it tuned?? I >>>>> have my project running but very rick and was hoping to find someone >>>>> who could send me a corrected bin or give me line items changes they >>>>> made that worked. 
>>>>> Thanks for any help--- 
>>>>> Jim 
>>>>> 
>>>>> _______________________________________________ 
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>>> 
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> 
> 
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