[Gmecm] Re: Stumbling '7730

Wed May 30 19:18:26 UTC 2007

Thanks for the suggestions folks, I'll clean the whole IAC and throttle body, see if that helps.  

As to VSS, I do want one, so I installed an optical VSS (fit right onto my AMC speedo), but I haven't got the goodies together yet to tell the ECM to look for optical instead of magnetic!  I was hoping it might half work, even though the pulses per mile are wrong.  AT least the ECM would know when I was moving or not... Apparenly though, it made no difference hooking up the optical VSS.  When I transfer the whole business into the MGA next spring, it'll be coupled to a T5 from a Camaro, so the T5 should have a magnetic VSS (I think). 

**********************END TRANSMISSION**********************

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Sent: Wednesday, May 30, 2007 10:20:09 AM
Subject: Gmecm Digest, Vol 27, Issue 14

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Today's Topics:

   1. '7730 Stumbles at cruise (Cowen)
   2. RE: Too quiet? (Craig Moates)
   3. RE: Too quiet? (Mike Wilson)
   4. Re: Too quiet? (Programmer)
   5. Re: '7730 Stumbles at cruise (DV Fagan)
   6. Re: '7730 Stumbles at cruise (Programmer)
Hello folks,

It has indeed been quiet, so here's a question to generate some discussion.

I've got a stock '730 ECM from a 3.1 running, a 3.4, with injection parts from a Fiero 2.8, with DIS.  This setup has been going almost flawlessly for about 2 1/2 years now, and I love the power, mileage, low emissions, and year-round easy starting compared to the carb it replaced.

Unfortunately, it has picked up two small issues in the last 6 months or so.  First, it stumbles a bit at very light cruise. I have no VSS yet, so I'm pulling a code for that, but nothing else.  I have the (digital) EGR vacuum plugged too, but I don't think it enables without VSS anyway.

Secondly, when the engine is cold, the there's a bog coming off idle unless it's revved up.  This feels like the IAC is closing in response to throttle input.  I had this problem when I first got things going, because the throttle plate was adjusted for a 2.8 and the IAC had to overcompensate for the air in a 3.4, so properly adjusting the throttle body completely cured it, until now.  I've tried increasing the throttle at idle slightly (reducing IAC counts required), but it hasn't affected the mild bog.

I know my setup isn't perfect with no VSS (I'll be transplanting the whole shebang again into an MGA next year anyway), but the thing is it didn't have this stumble for more than a year of operation.  I've done a quick check for loose connections at the TPS and IAC and they look good.  I can't find any vacuum leaks and it still runs wonderfully otherwise.  

Any suggestions on what I should focus on?

Thanks!

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Yeah, somebody decided to attack our site. But we got it sorted out. I still
don't know what drives that sort of thing.

Best regards,
Craig Moates 

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On Behalf
Of David Allen
Sent: Monday, May 28, 2007 8:59 PM
To: gmecm at diy-efi.org
Subject: Re: [Gmecm] Too quiet?

It's been quiet.  Hey I tried to access your site yesterday and got a not 
found error.
Thanks,
David

----- Original Message ----- 
From: "Craig Moates" <craig.moates at cox.net>
To: <gmecm at diy-efi.org>
Sent: Monday, May 28, 2007 8:21 PM
Subject: [Gmecm] Too quiet?

> Folks,
>
> Did I accidentally unsubscribe, or has it been that quiet lately?
>
> Best regards,
> Craig Moates
>
> _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/gmecm
> Main WWW page: http://www.diy-efi.org/gmecm
>
> 

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Probably an unemployed carburetor salesman with too much time on his hands.

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On Behalf
Of Craig Moates
Sent: Tuesday, May 29, 2007 11:22 AM
To: gmecm at diy-efi.org
Subject: RE: [Gmecm] Too quiet?

Yeah, somebody decided to attack our site. But we got it sorted out. I still
don't know what drives that sort of thing.

Best regards,
Craig Moates 

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On Behalf
Of David Allen
Sent: Monday, May 28, 2007 8:59 PM
To: gmecm at diy-efi.org
Subject: Re: [Gmecm] Too quiet?

It's been quiet.  Hey I tried to access your site yesterday and got a not 
found error.
Thanks,
David

----- Original Message ----- 
From: "Craig Moates" <craig.moates at cox.net>
To: <gmecm at diy-efi.org>
Sent: Monday, May 28, 2007 8:21 PM
Subject: [Gmecm] Too quiet?

> Folks,
>
> Did I accidentally unsubscribe, or has it been that quiet lately?
>
> Best regards,
> Craig Moates
>
> _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/gmecm
> Main WWW page: http://www.diy-efi.org/gmecm
>
> 

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You guys, too ? Seems to be a rampant thing over the past two weeks...

Lyndon.

----- Original Message ----- 
From: "Craig Moates" <craig.moates at cox.net>
To: <gmecm at diy-efi.org>
Sent: Tuesday, May 29, 2007 12:22 PM
Subject: RE: [Gmecm] Too quiet?

> Yeah, somebody decided to attack our site. But we got it sorted out. I 
> still
> don't know what drives that sort of thing.
>
> Best regards,
> Craig Moates
>
>
> -----Original Message-----
> From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On 
> Behalf
> Of David Allen
> Sent: Monday, May 28, 2007 8:59 PM
> To: gmecm at diy-efi.org
> Subject: Re: [Gmecm] Too quiet?
>
> It's been quiet.  Hey I tried to access your site yesterday and got a not
> found error.
> Thanks,
> David
>
> ----- Original Message ----- 
> From: "Craig Moates" <craig.moates at cox.net>
> To: <gmecm at diy-efi.org>
> Sent: Monday, May 28, 2007 8:21 PM
> Subject: [Gmecm] Too quiet?
>
>
>> Folks,
>>
>> Did I accidentally unsubscribe, or has it been that quiet lately?
>>
>> Best regards,
>> Craig Moates
>>
>> _______________________________________________
>> Gmecm mailing list
>> Gmecm at diy-efi.org
>> Subscribe: http://lists.diy-efi.org/mailman/listinfo/gmecm
>> Main WWW page: http://www.diy-efi.org/gmecm
>>
>>
>
> _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/gmecm
> Main WWW page: http://www.diy-efi.org/gmecm
>
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> Gmecm at diy-efi.org
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Cowen,
Check your IAC passages for carbon or gunk.  Check
your TPS for proper values.
Dennis
--- Cowen <captain_krill at yahoo.com> wrote:

> Hello folks,
> 
> It has indeed been quiet, so here's a question to
> generate some discussion.
> 
> I've got a stock '730 ECM from a 3.1 running, a 3.4,
> with injection parts from a Fiero 2.8, with DIS. 
> This setup has been going almost flawlessly for
> about 2 1/2 years now, and I love the power,
> mileage, low emissions, and year-round easy starting
> compared to the carb it replaced.
> 
> Unfortunately, it has picked up two small issues in
> the last 6 months or so.  First, it stumbles a bit
> at very light cruise. I have no VSS yet, so I'm
> pulling a code for that, but nothing else.  I have
> the (digital) EGR vacuum plugged too, but I don't
> think it enables without VSS anyway.
> 
> Secondly, when the engine is cold, the there's a bog
> coming off idle unless it's revved up.  This feels
> like the IAC is closing in response to throttle
> input.  I had this problem when I first got things
> going, because the throttle plate was adjusted for a
> 2.8 and the IAC had to overcompensate for the air in
> a 3.4, so properly adjusting the throttle body
> completely cured it, until now.  I've tried
> increasing the throttle at idle slightly (reducing
> IAC counts required), but it hasn't affected the
> mild bog.
> 
> I know my setup isn't perfect with no VSS (I'll be
> transplanting the whole shebang again into an MGA
> next year anyway), but the thing is it didn't have
> this stumble for more than a year of operation. 
> I've done a quick check for loose connections at the
> TPS and IAC and they look good.  I can't find any
> vacuum leaks and it still runs wonderfully
> otherwise.  
> 
> Any suggestions on what I should focus on?
> 
> Thanks!
> 
> 
>        
>
____________________________________________________________________________________Building
> a website is a piece of cake. Yahoo! Small Business
> gives you all the tools to get online.
> http://smallbusiness.yahoo.com/webhosting 
> _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org
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> 

____________________________________________________________________________________
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Provided fuel pressure, ignition, and everything else is fine,

Without VSS, the ECM 'assumes' a couple things related to IAC strategy...so 
you might want to get that working....even though its been flawless for 2.5 
year, you can make it even more flawless.

LW

----- Original Message ----- 
From: "Cowen" <captain_krill at yahoo.com>
To: <gmecm at diy-efi.org>
Sent: Tuesday, May 29, 2007 12:05 PM
Subject: [Gmecm] '7730 Stumbles at cruise

> Hello folks,
>
> It has indeed been quiet, so here's a question to generate some 
> discussion.
>
> I've got a stock '730 ECM from a 3.1 running, a 3.4, with injection parts 
> from a Fiero 2.8, with DIS.  This setup has been going almost flawlessly 
> for about 2 1/2 years now, and I love the power, mileage, low emissions, 
> and year-round easy starting compared to the carb it replaced.
>
> Unfortunately, it has picked up two small issues in the last 6 months or 
> so.  First, it stumbles a bit at very light cruise. I have no VSS yet, so 
> I'm pulling a code for that, but nothing else.  I have the (digital) EGR 
> vacuum plugged too, but I don't think it enables without VSS anyway.
>
> Secondly, when the engine is cold, the there's a bog coming off idle 
> unless it's revved up.  This feels like the IAC is closing in response to 
> throttle input.  I had this problem when I first got things going, because 
> the throttle plate was adjusted for a 2.8 and the IAC had to 
> overcompensate for the air in a 3.4, so properly adjusting the throttle 
> body completely cured it, until now.  I've tried increasing the throttle 
> at idle slightly (reducing IAC counts required), but it hasn't affected 
> the mild bog.
>
> I know my setup isn't perfect with no VSS (I'll be transplanting the whole 
> shebang again into an MGA next year anyway), but the thing is it didn't 
> have this stumble for more than a year of operation.  I've done a quick 
> check for loose connections at the TPS and IAC and they look good.  I 
> can't find any vacuum leaks and it still runs wonderfully otherwise.
>
> Any suggestions on what I should focus on?
>
> Thanks!
>
>
>
> ____________________________________________________________________________________Building 
> a website is a piece of cake. Yahoo! Small Business gives you all the 
> tools to get online.
> http://smallbusiness.yahoo.com/webhosting
> _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/gmecm
> Main WWW page: http://www.diy-efi.org/gmecm
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