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Newbie Question: How do I reset the ECU?

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Old 07-19-2007, 12:58 PM   #1
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Default Newbie Question: How do I reset the ECU?

I'm new to the site; reg'd cuz I have Q's for which I need A's. I'll get to that.

I drive an '01 4x4 Supercrew, 6' bed (?), with the 5.4L, bone stock besides oversize tires. Got it used at ~80K miles, and I've made it to ~113K. I personally have had to replace 2 coils, at different times. I don't exactly take it submarining or even mudding, so how water continually gets atop the plug I'll never know. Whatever.

I've discovered that winter gas in Houston, TX (where I live...) tends to give me knock--we have mandatory 10% ethanol mix down here--during which I mix 50/50 93/87. (Why? Because with normal gas stations' equal increments from 87/89/93 that gives me 90 for the price of 89! Don't know if that extra 1 does jack for me, but I'm too busy to do a thorough test.) As a undergrad chemist, I do know that it's not that my truck's knocking on 87, but it's that the gas I'm getting is sub-87 sometimes, and that by mixing at least what should be 89-90, I solve this. I studied this in great detail, so if anyone's had similar issues, I'd be more than happy to give all the detail you need on the problem.

Another interesting thing is I bent my frame after putting too much dirt in my bed, evidenced by the cab/bed body panel separation on the top of each side farther (~2 fingers' worth) than it once was. Luckily I got rear-ended a few weeks ago (how often can you say that?) and blamed it on that, and got it fixed for free... along with my steering-wheel electronics which had spontaneously quit working (CC, horn, but curiously, not the button lights). This was also convenient, cuz I had my inspection in March and had to pay off the guy to not fail me for the horn not working. (The fix was the rotating contacts which had gone bad, and I was too wallet-conscious to pay for all that.)

That's pretty much my history with the truck. My actual problem is not so much a problem exactly, just a question. I want to reset my ECU. I am attempting to see if mixing 1:500 acetone\gas does anything for me. There's anecdotal evidence supporting an increase in mileage (which would be nice, as I get between 10-13 depending on how "nice" I drive or how much highway time I log in a tank... although there is also evidence that late-model Detroit cars have the ECU deliberately set so that any mileage above a certain point is out-of-range, and the fuel mix is richened... we shall see) in addition to a "smoother" feel aka less non-knock shake (not a misfire per se but more a "weak" fire) at idle and even slight increases in power, along with measured decreases in hydrocarbon emissions.

Anyway I've got it in my tank now, 6.25 oz. added to my 25-gal tank. Issue is, as I understand it, to take advantage of any supposed benefits but the correction of weak-fires and lessened HC emissions, which should happen simply by acetone's presence, I must reset my ECU. I've never done this, but I now see alot of support--at least for other makes--for the benefit of doing this regularly anyway... something about while it will learn to be less aggressive in the face of detonation, etc, it doesn't always attempt to regain that lost power when the conditions go back to "good."

Is it a simple battery disconnect? Is there an easier way? Is it more complicated? If it's just the batt, how long to leave off the cables? Thanks a bunch everyone.
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Old 07-19-2007, 01:19 PM   #2
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Disconnect battery(neg battery cable) for about 30 minutes. During this wait it's a goor time to clean the MAF.Check the TSB's for pcm/driveability problems.
My 05 5.4l 3v with Volant CAI & Edge tuner on level 2 ,I get 5-19 mpg combined.
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Old 07-19-2007, 06:05 PM   #3
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With the new OBD2 systems pulling the battery dosen't always re-set the computer as in older EEC4 systems. They retain a mempry. IT will reset the adaptive transmission and might reset the adaptive fuel curve. The Acetone might get better mileage because it tricks the o2 sensors into readingtoo rich so it leans out the mixture. What you have to be careful of is running too lean. Especially using higher than 87 ocatane fuel. The higher the octane the slower it burns. What I would do rather than risk putting chemicals in is find someone with a sniffer and see what the Mixture is from the tailpipe now. Ideal mixture is 13.0 to 1 for a NA engine. 12.0 to 1 for a Forced induction engine. If you are running higher than that you are already running lean. Usually a Dyno is the best place to check this. If you are running under these numbers you are too rich and I would recommend a programmer..Actually I would recommend a programmer anyway. Some ppl on here like the Edge. I personally like the Xcal2 tuner. Being an 01 you might be able to chip it. I know you can the mustangs. With a good tuner you can retard your timing a little bit and run the 87 even if its not actually 87 without the engine pinging. I would also look into doing a BG induction service, because your truck is designed to run on 87. You might be getting a pre ignition causing it to ping. This is because of carbon buildup on the intake valves, the top of the piston and the combustion area of the head.
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Old 02-28-2009, 04:54 PM   #4
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I just had my 05 F150 5.4L tuned up- plugs and gas filter, trainy service. She ran fine before the tune up at 108,000 miles. Now she pings and knocks when I drive over 30 mph or when going up hill. The engine runs smooth as silk reving to 4000 rpms when in park.
Ford diagnostics detected everything was fine. Anyone with any suggestions.
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Old 02-28-2009, 04:54 PM

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