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  #1  
Old 04-13-2004, 10:42 PM
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Join Date: Nov 2003
Location: Minnesota
Vehicle: 2004 Ford F150
Posts: 777
Disconnect Battery to reset PCM?

Quote:
quote:
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You unhook the battery while leaving the head lights on to drain residual power. Let it go for 10-15 minutes. Come back and hook the battery back up, turn the truck on and let it idle for 10 minutes. That will allow it to "learn" the new mods. Then take it out for a 15-20 minute spin to "learn" a little of your driving habbits. Nothing much to it.

TJ
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If I leave the lights on when I disconnect, they automatically go out. How will that drain any residual power? Am I understanding this right?

I turned lights on and disconnected battery. I will leave it like that until morning. If I let it idle for 10 minutes and then go, that's it?

Have I missed the point or did I get it...

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  #2  
Old 04-13-2004, 11:06 PM
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Join Date: Sep 2003
Location: Texas
Vehicle: 2004 Ford F150
Posts: 253
Our trucks do not have rectifiers in them or electronic tubes that have to have time to drain all power out of them. However, it appears that the "rule of thumb" to force an ECM to clear info that can be cleared is to leave the battery disconnected for approx 10 minutes. The base code will not be impacted by a power cycle.

Screwdrive
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  #3  
Old 04-14-2004, 12:25 AM
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Join Date: Feb 2004
Location: Oklahoma
Vehicle: 2004 Ford F150
Posts: 1,020
So say I am going to slap on a Borla cat back system this weekend.....

It would be pointless to reset the PCM on my truck by diconnecting and fooling with the battery cables, or does that PCM really figure out "Hey I got new exhaust let me adjust to that now"?

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  #4  
Old 04-14-2004, 12:46 PM
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Join Date: Nov 2003
Location: Minnesota
Vehicle: 2004 Ford F150
Posts: 777
Well, I disconnected the battery last night. I drove 191 miles today to give it a run. I also put 89 octane fuel in instead of reg unleaded. I got 14.861 mpg on all highway with no city driving.

Would that 2 mpg increase be the PCM or would it be the octane?
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Old 04-14-2004, 02:28 PM
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Join Date: Sep 2003
Location: Texas
Vehicle: 2004 Ford F150
Posts: 253
According to the experts (whomever they may be), increasing octane will not increase mileage and in fact my hamper it unless the engine has been tuned for the increased octane. I am from the era when muscle car engines needed all the octane they could get and then some and thus this line of thought is difficult for me. In modern vehicles calling for 87 octane I have always alternated between the middle grade and premium grade instead of using the 87. This was the case from day one with my 04, and was the case from day one with my 00 as well. After a long talk with Mike Troyer about octane and tuning I filled my “stock” (no fancy air filter, no performance chip, & no after market exhaust at this time) 04 up with 87 (just about killed me since again, my mental model dictated that 87 = bad, 89 = better, & 93 = good). Well low and behold, within 50 miles I noticed my mileage increasing according to the Info Center and the truck actually started running better. In addition, the truck was easier to start. This was my experience and may not be what is experienced by others.

As far as your mileage goes – I have no idea how you drive, IE, whether you peddle the gas, ride the brakes, punch it every time you leave from a dead stop, cruise at 80, etc. I do non of these things, well I do punch it now an then, and get over 4 mpg more than you on the highway. My truck is a 2 wheel drive with 3.55 gears and a bed cover however.

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Old 04-14-2004, 02:28 PM


 
 
 
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