[Gmecm] Re: +AFs-Gmecm+AF0- How to wire Timing Bypass on 4-Cyl 151 Iron Duke?

[Aphelion79]

Thanks... however, are all the GM-ECMs similar in their wire colors on
the distributor?  On mine the four wires are the same colors... but do
they do the same things as the diagram for the 7747 indicates?

Thanks again to all on this list!
-Matt

David Allen wrote:
>   Both my GM-ECM controlled cars have the "set-timing" connector you describe.  It's simply a break in the "bypass" signal wire.  Doing exactly what you said (making your own inline connector that can be disconnected) would be what you need to do.
> David
>
>
> ----- Original Message ----- 
> From: "Aphelion79" <aphelion79+AEA-cox.net>
> To: <gmecm+AEA-diy-efi.org>
> Sent: Thursday, August 03, 2006 11:13 PM
> Subject: [Gmecm] How to wire Timing Bypass on 4-Cyl 151 Iron Duke?
>
>
>   
>> Hey, remember me? The newbie with the 4-Cyl 151 Iron Duke and the CJ7?
>> Well anyway, I'm finally able to start working on my Heep again... and 
>> am curious as to how to set the timing on this thing...
>>
>> Now, all vehicles have some sort of timing advance... on carburated 
>> engines (just spilling out how I understand it... correct me if I'm 
>> wrong with anything) you unplug the vacuum advance hose and plug the 
>> port as to not cause any vacuum leaks... and set the timing... on a 
>> TBI'ed vehicle... there is a special wire that has an in-line coupler 
>> that allows you do disconnect the signal sent to the Distributor for the 
>> electronic advance... unplug that, set timing.. yadda yadda
>>
>> But here's my problem:
>> On a 88 Chevy S-10 Pickup, "there is a black/red wire under the 
>> passenger's side floorboard that you can disconnect and then set the 
>> timing"... well... I obviously do NOT have an S-10... nor any wires 
>> inside of the firewall as I just spliced most of the wires off that went 
>> to the fusebox... and I've followed diagrams of the ECU pins and could 
>> not find any mention of this special wire... However... on GM-ECM I 
>> found a schematic for the 7747 ECM 
>> <ftp://ftp.diy-efi.org/pub/gmecm/manuals/1227747/747ecm6.jpg>
>> (ftp://ftp.diy-efi.org/pub/gmecm/manuals/1227747/747ecm6.jpg) -which is 
>> NOT the ECM I have... (if this information is current, got this from an 
>> old post I made a while back on a different forum:) mine is:
>>
>> SVC+ACM- 16198445
>> Barcode:
>> 866647W643273117
>> Chip Inside:
>> ACKD 4890
>>
>> The previous link to the 7747 indicates the TAN/BLK wire right off the 
>> distributor controls the timing bypass... now I've disassembled my 
>> wonderfuly sexy wiring loom and traced all 4 wires that come off of the 
>> distributor...and each one of them goes DIRECTLY into the ECM... none 
>> have any splices in them as well or any disconnects in-line... Would 
>> splicing into the wire, and creating my own quick connect/disconnect 
>> in-line plug right at the 4-pin connector off the distributor be a good 
>> way to do this or am I missing something? I could simply "just try it" 
>> but I wanted to run this by you all first... you guys seem to know more 
>> about this stuff than any of us on JeepForum
>>
>> Thanks again... !! By the way... the Jeep runs... haven't started it up 
>> in 2 months and it fired right up... however it idles a bit rough and 
>> doesn't have very much power at all... so I figured timing would be the 
>> issue! I previously set the timing by luck by putting it at top dead 
>> center... unplugging the whole entire 4 pin connector off of the 
>> distributor -which doesn't allow the engine to run- and had a helper 
>> eyeball it to 0+ACo- and plugged it back in...
>>
>> Anyway, enough length on this... any other questions or things I should 
>> look at let me know!
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