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Jimmy9190
Dodge Dakota
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11/11/2007
19:00:49
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 Subject: Spark plugs and PCM's
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I have a 2001 3.9 V6 with 5-speed manual, 79,000 miles. It had a slight ping in the engine, not too bad but I decided to do a tune up anyway. I usually do it every 20,000 miles and it was just about time. So today I replaced the cap & rotor with the brass ones from Napa and put in the NGK FR5 plugs with a new set of the Napa premium Belden wires. Did an oil change today too. I was using the Autolite 3923's but I had read that the NGK's were better for the 3.9. The truck does seem to idle smoother and start easier, and there is a noticeable improvement in power on the butt-dyno. But the truck still has a moderate ping under a light throttle. My question is does the PCM need time to learn the new plugs due to the difference in spark from the V-Power NGK's? I have looked down the throttle body and there is a very light film of oil which I read is normal so I don't suspect the belly pan gasket. If I'm wrong about that hopefully someone here can tell me so. I take very good care of my truck and I use Chevron gas just about all the time, #87 octane. Truck has been running fine with no ping until a few days ago.
Any help is appreciated.
Jimmy
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dakota49
Dodge Dakota
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11/11/2007
19:42:15
|  RE: Spark plugs and PCM's
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It could be that you have a little carbon build up causing the pinging, since its light I wouldn't get too excited, you can run some Seafoam through the throttle body with the engine running, then after you pour about a half a can through shut it off wait for about a half hour then take it out and run it pretty hard to blow out any built up carbon. Also the engine should be warm before you pour the Seafoam through it.
It can take a couple of hundred miles to learn the new spark plugs, if you want to wait to see if that makes any difference. Mt guess will be it probably won't. Oh yeah, you would need to do a hard clear on the computer as well. That's were you disconnect the battery and with the bat. disconnected hold the key in the start position for 2 minutes I think, that should clear the computer. The batt. needs to be disconnected for about 15 minutes.
Good Luck
Dakota49
1988 3.9 4X4 5speed
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Jimmy9190
Dodge Dakota
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11/11/2007
20:11:10
| RE: Spark plugs and PCM's
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Thanks Dakota49. I had thought of trying Seafoam anyway. Last year I paid a shop to do the BG fuel induction service and it seemed to help the truck run better, but from what I hear the Seafoam is just as good as the BG. I am not a big fan of additives or chemicals in the engine but I have heard good things about Seafoam. The only reservation I have about it is whether it can foul out any of the sensors on the truck. I'd appreciate it of anyone here can share any info on the Seafoam and whether it has worked for them? I'll do a search on it here too.
Thanks,
Jimmy
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Jimmy9190
Dodge Dakota
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11/12/2007
16:55:31
| RE: Spark plugs and PCM's
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An update to the problem: I took a better look down the TB today in the daylight with a good flashlight and the manifold is dry. There's no oil present there but there is a very light carbon dusting which I would think is normal. The dust doesn't even cover the entire surface of the manifold. I replaced the NGK's with new 3923's and went for a test drive. There's no ping at all now and the truck is running fine. I drove on straight flat roads and up & down hills too and there is no noticeable ping. The truck holds its speed in 5th gear climbing hills and will ping just a little if I gas it to increase speed going up hills, which I would also think is normal. I had considered using Seafoam in it but I am not a big fan of additives and/or chemicals. I'll leave it just like it is for the time being. I guess my particular Dakota just runs better with the 3923's. Maybe it's the difference in the amount of copper in the plugs or some other difference that caused the ping with NGK. The same kind of problem occurred with a serpentine belt tensioner from Autozone. Two different tensioners kept slinging the belt off and I had to get the one from Napa to finally fix it. But the Napa part was built exactly the same as the OE tensioner, and the AZ part was a different design.
Thanks again.
Jimmy
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Trev1
Dodge Dakota
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11/12/2007
19:44:35
| RE: Spark plugs and PCM's
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The NGK's are the best plugs out there for the Dak. They are.... I just wish I had the $ to buy a set....HA HA.
Glad you got it fixed..Just a little Humor
Trevor in SWMO..
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Jimmy9190
Dodge Dakota
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11/12/2007
21:06:06
| RE: Spark plugs and PCM's
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The NGK's might be good for some trucks but not mine I guess. This was an expensive lesson learned since I paid $15.00 for the NGK's but at least now I know what plug to use from now on. I guess I'll "always be right with Autolite".
Jimmy
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