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My Ford 2001 F150 4.6L V8 is missing and has never turned on the check-engine light, or produced a code. It has 114,000 miles.It runs ok cold, misses slightly at idle and at almost any speed, although 35-45 seems worse. It’s not bad, it’s just constant. A few times is seemed serious, but then is settled back into annoying.I have an Autozone handheld OBD tool, and it seems to work ok, but the handheld reader has never shown a code, hard or pending. The Check Engine light is off.I’ve replaced the plugs, COPs, and Injectors – the truck still misses. I’ve Cleaned the MAF (with MAF cleaner) and all the filters have been changed regularly.What product would I need to diagnose, or at least be able to read the Ford data?Thanks
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Under load can be simulated on an Automatic Transmission vehicle by putting your foot hard on the brake, shifting into D and revving the engine up without moving.
As far as I know you can safely start a car with the scanner connected.
Quoted From pcmdjason:As far as I know you can safely start a car with the scanner connected.
Awesome, thanks
Quoted From dreamer2355:
2k RPM should be enough C8-)It is irregular, but misses reliably at higher RPMs. I will give it a go.
On a related note, I would like to pick up a PC based scanner – it might help in situations like this. Anyone seen a site where they review the scanners? All software based scanner reviews I have found are outdated.
Poster pcmdjason had a nice review but I would like one with vendor support.
My wifes car gets the hesitation from stop issue a lot and it seem always turns into a P030x type code over the course of a month.
Taking the coils off and on almost always makes it better and clears the code. Both coils have been replaced but one got slightly burned when it blew a plug last year. So that one still causes occasional issues.
Ok, update.
I found a shop that will hook up their high dollar Verus computer for $40. They found nothing out of spec, which was disappointing.
For another $40 they pulled all the COPs and plugs, and found nothing out of whack except I’d been too generous with the dielectric grease. I thought second opinion (other than my own, plus they know what their doing) was worth $40.
It actually did seem to run better, but had a slight “from dead stop” hesitation. The mechanic suggested the engine mount can simulate a takeoff miss, but those and the transmission mounts looked ok. The truck always starts right up, no prolonged cranking, good engine pickup.
Later that night the truck returned to its old pattern, once warm 45-to-55 bucking with occasional misfires at lower speeds.
Any idea where I might look next?
Take it to someone who knows how to use a Verus to start with…
$40.00 wont cover the hour it will take to use that tool correctly to find the misfire.
A visual inspection won’t reveal anything unless it is so obvious it’s stupid.A guy needs to plot all 8 ignition coils for signature ramp, all 8 injectors for signature ramp and a relative compression test without ever going into the enhanced vehicle data and without ever turning a screw or bolt.
That would take about 20 minutes to do and would leave a balance of 40 minutes if the problem goes deeper or for pinpoint accurate confirmed conclusions.If you don’t have any codes it’s most likely something basic, considering it misfires under load I would be looking to the ignition system especially since they found something of an issue there, here is a video that might help.
After reviewing this video “No code misfire” from “Real Fixes Real Fast”
http://www.youtube.com/watch?v=CR32Lpt623M&feature=player_profilepage
I went back to the repair shop (under warrantee) asking them to reconnect the computer, and asked them to look at Mode 06, test ID 53. The first time they scanned the truck, I stood back and let them do their routine, this time I hovered over his shoulder and told him what I wanted to see. Guess what, $53 showed misfires on one cylinder.
Replaced the COP and the plug, and that fixed it.
I am one happy camper!
Awesome! Thats why i love forums like these. They can empower people with knowledge!
I would have loved to see that techs face C8-)
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