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art m
Dodge Dakota
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2/15/2006
20:50:26
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 Subject: random misfire
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Message:
new trouble - mil dtc shows P0300 random misfire and P0303, P0304 cyl 3 & 4 misfire...
just installed new plugs but cap and rotor have not been changed out - maybe fuel injector trouble, but I ran a couple of bottles of Textron fuel injector cleaner a couple of wks ago, mil went out for a while. Ran rough at idle and start up but then settles down.
Any thoughts? Thanks to this great board...
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LilRed01
Dodge Dakota
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2/15/2006
20:58:28
|  RE: random misfire
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Message:
Start with the cap and rotor, could be moisture under that cap. Spark plug wires would be a good investment aswell.
Don't worry about your injectors yet unless you run really dirty fuel they rarely cause problems.
Also when you put the new plugs in did you gap them to the specified gap? It is on the Engine sticker under the hood.
Did the Missfire start after the plugs were installed? if so then you may have cracked a plug during installation.
LilRed01
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art m
Dodge Dakota
JOIN HERE
2/15/2006
21:18:00
| RE: random misfire
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Message:
LilRed01 -
the plugs were at .040 when installed about 2 wks ago, the salesman checked the gap on all 6 plugs...
the P0303 mil code popped first, I thought it may be the plugs and had them changed them out at the garage about a week later. Funny, this mil code appeared after I had a new cat converter assembly installed at a different shop.
The wires were changed out about 80k miles ago as well as the cap and rotor after a cyl 5 misfire code - bad plug.
Only today did the random misfire and cyl 4 misfire codes pop.
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daddio
Dodge Dakota
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2/15/2006
21:33:06
| RE: random misfire
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Message:
"The wires were changed out about 80k miles ago as well as the cap and rotor after a cyl 5 misfire code - bad plug."
time to change them again. get a cap and rotor with brass inserts. if that doesn't work you could check all the electrical connectors on the injectors. make sure they are clean and no corrosion.
if that doesn't work you could try swapping injectors from cylinder to cylinder and see if the miss follows. if it does you found your problem.
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art m
Dodge Dakota
JOIN HERE
2/15/2006
21:36:29
| RE: random misfire
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Message:
daddio -
8mm wires, right? Any recommendations?
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daddio
Dodge Dakota
JOIN HERE
2/15/2006
21:41:08
| RE: random misfire
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Message:
if you're still all stock you don't need 8mm. just a quality brand 7 or 7.5mm will be just fine. some on here have posted good reviews using Bosch plug wires. i need to do mine but haven't looked at any yet. i'll probably go with something from o'reilly's. and i have had good luck with Bosch single platinum plugs 1 range colder than recommended for stock. they helped get rid of the slight ping issue i had.
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daveshotdako
GenIII
2/16/2006
09:55:22
| RE: random misfire
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Message:
i just installed a set of 8mm accell wires. they do not make a kit for the 3.9 though. i had to buy a universal v8 kit and cut them to length and put the connectors on. i noticed that my truck idles a bit smoother now and i noticed a little increase in pick up. in a week or so, i am going to be ordering a accell 45,000 vlot coil as well. like daddio said, if you dont plan on other upgrades like i do, then 7 or 7.5mm wires are fine.
GET IN, SIT DOWN, SHUTUP, AND HOLD ON
custom 48mm tb, tps @ .768, relocated IAT, 180 t-stat, autolite double platinum, accell 8mm wires, flowmaster 40 delta flow single in/dual out, CAI, superchips tuner
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art m
Dodge Dakota
JOIN HERE
2/16/2006
21:19:42
| RE: random misfire
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Message:
update - replaced the rotor & cap with NAPA brass and replaced mopar wires with Borg Warner 7mm ...
the cap did show trouble on one post and wire, don't know which number it was ...
when I first started it up, no MIL, but after a couple of minutes, it threw the same 3 codes - I hadn't left the garage yet, took it back in, the tech put the OBDII diag unit on, verified the DTC's, and we reseated the wires on the cap and rechecked - then cleared the DTC's. MIL stayed off and I drove about 15 mi back home - MIL is still good but the truck idles a little rough. I'm gonna drive about 400 mi tomorrow round trip job related and we'll see how it does. Maybe the onboard computer needs to relearn.
Thanks to all for your comments.
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daddio
Dodge Dakota
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2/16/2006
22:48:50
| RE: random misfire
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Message:
a weak battery can cause a rough idle. what year is your truck and do you have the original battery? if so you may want to have it load tested or at least clean the connections good. then start it with no accessories on and let it idle by itself for a couple minutes.shut it off for a couple minutes then restart. that will get it to re-learn the idle.
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LilRed01
Dodge Dakota
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2/17/2006
18:39:53
| RE: random misfire
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Message:
If the Idle is still rough and there is no codes double check the fireing order.
LilRed01
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art m
Dodge Dakota
JOIN HERE
3/06/2006
12:49:38
| RE: random misfire
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Message:
update - reset the PCM per procedures, and ran the truck for about 100 mi and the P0303 DTC tripped again. Then ran some injector cleaner thru, ran the truck for another 200+ mi, the code cleared.
The idle is smooth at 600rpm and stays that way today, no code either. Actually feels as if the truck is 20k mi on it, smooth accelleration and trans shifts good thru all gears.
I'm suspecting fuel injector problem on cyl 3...
Thinking of upgrading all injectors to the Bosch/FMS 21#...
I'm going to run this week and see how it performs. Also thinking of running some Champion concentrated cleaner with the next tank of gas.
01 Dakota 3.9L V-6
168k mi
NAPA brass cap & rotor
Champion plugs & Bosch 7mm wires
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Shatto
Dodge Dakota
JOIN HERE
3/15/2006
15:12:00
| RE: random misfire
IP: Logged
Message:
My Amsoil dealer showed me a document that said Magnum engines sometimes miss because the plenum leaks.
I just looked. Nasty job, but you can look at your camshaft.
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