Octane Adjust Shorting Bar Questions

[85 Coupe 5.0]

Spark Knock on Accel

I had recently done a PI headswap on my '96. I haven't had the chance to get a flash/tuning device yet to fully optimize the setup. I have read that you are suppossed to back your timing down a few degrees because of the bump in compression. I have ran 91 octane fuel even since the conversion, but had some pinging issues at part throttle when it gets hot out.

My question, has anyone ever tried removing the Octane Adjust plug (located by the MAF sensor). According to everthing i've read, this removes 3 degrees of timing, but will also set a DTC, although i don't believe it will turn on the MIL.

anyone got some info on this??

 

[85 Coupe 5.0]

BUMP

Anybody think this is a good work-around for the timing issue? or has nobody ever thought of trying this?

 

[85 Coupe 5.0]

geez, i can't believe this is such taboo to all the resident gearheads here. has nobody thought of this before? I pulled my connector and ran the car, the ping is gone and seems to have more power, being as I was over-timed with the compression i have. I always run 91 octane, but used to get a part-throttle ping on a hot day. guess we'll find out if it helped, test and tune is next week...

 

[Kilgore Trout]

Never heard of no "octane adjust plug"...

 

[85 Coupe 5.0]

me either Kilgore, but it is there. looks like it's only present on the '96 to 98 or so cars. I was at work the other day looking at the wiring diagram for my '96 and found it. it was located on the front of the passenger side strut tower, down low. just a little plug, looks like the SPOUT connector used on the older 5.0's.

Octane Adjust Shorting Bar

The Octane Adjust (OCT ADJ) shorting bar is used to retard spark timing. Removal of the shorting bar from the in-line connector will typically retard spark three degrees.

The purpose of the OCT ADJ self-test is to check the state of the OCT ADJ shorting bar. A Diagnostic Trouble Code (DTC) will be present if the shorting bar is removed or if there is an open circuit. The OCT ADJ shorting bar is similar in shape to the SPOUT in-line connector. On some applications the Power Steering Pressure (PSP) circuit will also have a similar shorting bar connector. DO NOT remove the shorting bar unless directed by a Technical Service Bulletin (TSB).

If you don't have the bar, your timing has been retarded.
Attached Images


and it works. I removed mine today, and the ping i've had at part throttle is gone, and it seems to have more power and better fuel economy now. I have read some ford TSB's about removing it, although mustang has none they still put the shorting bar on our cars, at least for the first few years. It's really only for troubleshooting purposes, and it does set a DTC but doesn't illuminate the MIL light. I can live with that, with my PI headswap and the 10.5 compression that comes with it, i was getting a slight ping even with 91 octane. it's completely gone now, with the bar removed.

anyone else found this?

 

[85 Coupe 5.0]

here is a thread on another site with people talking about this plug. I know it's a Ranger forum, but the purpose of the plug is the same on the mustang.

http://www.ford-trucks.com/forums/162016-octane-adjust-shorting-bar-c110.html

i can't believe nobody here has found this plug, it's completely obvious on the pass strut tower, it looks like something is suppossed to be there but they just put a plug in the end of the connector to keep stuff out, but it's actually a shorting bar.

 

[stangGT97]

That's very interesting. I've never heard it called that, but I have seen that connector under my hood (I think anyway). You said it fixed your pinging though? Thats great to hear, as long as there are no negative side effects. Out of curiosity, what are you gapping your plugs at? Stock 0.054"? In my PI headswap research, I found that people recommended a narrower gap, around 0.035"... someone correct me if I'm wrong, I actually believe it was tomustang that used that gap, and his car ran great even w/o a tune.