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Old 08-25-2016, 03:24 PM   #1
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Random Misfire

On the way to work today I got the Random Misfire code. I was going up a pretty steep grade at 45mph and where it gets a little steeper I roll on the gas to maintain 45mph. This time, the speed kept dropping. It got to 40mph and I put my foot in it a little more and it just felt like I didn't do anything. I think it was in 4th gear. I had to step on it enough to downshift and then it took off like it should. I did it again to see if the converter locked and had the rpm super low or what, but it had it around 2200rpm and then the check engine light came on. It blinked a few times and then went back off. I read the codes when I got to work and it showed a random misfire. My entire commute is only 3 miles and I was just about at the top of the hill where I work when this happened. I vaguely remember getting a random misfire code years ago with a similar effect on performance and it just now came back. I only have 41k on this thing, so still on the stock plugs. I never felt any lurching or vibration from the miss, just no power when I rolled on the gas a little.

Has anyone on here fixed a similar problem? I am going to rule out coil packs and plugs since it is a random misfire. I am wondering if my fuel pump is going. A neighbor had his go out completely a while back, but he had a lot more miles on his. The way it recovers though makes me think it is a sensor with a bad reading. We'll see how it does on the way home.

Thanks!

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Old 08-25-2016, 05:09 PM   #2
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Spark plugs should have been replaced at 30K miles.
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Old 08-25-2016, 05:22 PM   #3
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My guess you need plugs and air filter. Cleaning the TB would also probably give results. 3 mile trips are hard on a engine.
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Old 08-26-2016, 09:56 AM   #4
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Ran fine home yesterday and back to work today. I'll do the plugs anyway. I guess I should have checked the maintenance schedule. They are going so far with plugs nowadays I didn't think they would need to be changed yet. What is the preferred plug to run in a stock Hemi?

I also want to get the trans serviced. I really don't feel like doing that myself. Is 40k and 10 years old a good time to get this done?

Thanks
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06 QC SLT Big Horn Hemi 2wd 20's,3.92's, Magnaflow, custom Y, Diablo, Edelbrock Shorties, modified K&N CAI.
14.64 @ 90.5 mph (short belt, no spare, 20's)
14.60 @ 91.50 mph (short belt, no gate or spare, 17" drag radials)
93 Stroked and Blown Mustang
10.84 @ 128.5mph
2016 Explorer Sport AWD with 3.5 Ecoboost
13.81 @ 98.2mph Tune Only
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Old 08-26-2016, 01:40 PM   #5
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This sounds exactly like a cool randomly cutting out under load or arching in the plug tube. This is a very common issue on COP vehicles. Try and duplicate the same issue again sometimes even driving steady at 45 and then pressing gas enough to accel without downshift will do same thing. The random part can either be a coil or the fuel pump starting but that's not very likely.
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Old 08-26-2016, 02:53 PM   #6
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I tried to duplicate it and it is running fine now. Also, this is the same commute I do every day. The way I rolled on the throttle when it happened is the same way I do it every day so it if was still bad, it will continue on my daily commute. I am pretty sure it did a similar thing 8 years ago when I first got the truck. I was going over the overpass though, so about the same rolling on the throttle but in 2nd instead of 3rd that time. It would have been under 10k on it at that time.
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Old 08-26-2016, 03:17 PM   #7
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'IF' fuel and / or plugs are the problem:
Just a suggestion IMO - try using some Lucas Ethanol Fuel Conditioner with Stabilizers...especially if you make short runs frequently. There are other fine products available as well .

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Old 08-26-2016, 04:34 PM   #8
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Well this is a weird one then. Gonna be tricky to since this issue.
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Old 08-26-2016, 07:11 PM   #9
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Quote:
Originally Posted by need-a-cage View Post
Ran fine home yesterday and back to work today. I'll do the plugs anyway. I guess I should have checked the maintenance schedule. They are going so far with plugs nowadays I didn't think they would need to be changed yet. What is the preferred plug to run in a stock Hemi?

I also want to get the trans serviced. I really don't feel like doing that myself. Is 40k and 10 years old a good time to get this done?

Thanks
I run the recommended spark plugs, SPARK PLUG 16EA CHAMPION COPPER PLUS 570
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Old 08-27-2016, 11:02 AM   #10
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If the weather conditions and engine temperatures were just right, it could have developed moisture in the spark plug holes. It's a reach but I get condensation at times that are unexpected.
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2003 RCSB, 2wd, "Pro-Street"
6.4L/cog driven V7-Ysi/46rh trans/HTH Truckarm coilover suspension. HP Tuning...

1956 Jeep Pickup Hemi powered "Street Rod project"

1# 2017 HTC FASTEST HEMI List....
Current 1/4 mile [email protected] (2018)
Current 60' PB 1.351 (2019) mechanical issue for 1/4m

HTC 2018 TOTY

Support vehicle- 2007 QC G56 4x4 diesel
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