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M D Nugent
Dodge Dakota
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3/01/2004
15:47:29
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 Subject: Odd miss and backfiring thru intake
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Message:
I took my '92 Dakota (with 121,000 miles on the 5.2) to a local performance shop with a good rep and they spent about 6 hours trying to find the source of this problem. When I left, it was better, but it went back to the old behavior in a week or so.
Symptoms:
- missing and backfires through the intake
- only around 2200-2400 rpm
- only on light throttle (e.g., flat freeway cruising at 60-65 mph or putting around town)
- a bit worse under load (e.g., up a slight hill)
What they did:
- removed and flow-tested the injectors (they're fine)
- checked all ignition connections (I'd just put on new spark plugs, wires, cap, and rotor myself)
- put dilectric grease in the spark plug boots
- had it hooked up to a scope while on the chassis dyno for several hours trying to trace down the cause
- re-routed the spark plug wires per the Service Bulletin (this seemed to make the most difference)
They warranty their labor, so I'll be going back. Is there anything Dakota-specific they should check next?
Thanks for any clues,
M D "Doc" Nugent
Renton, WA
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ticats
Dodge Dakota
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3/01/2004
16:19:00
| RE: Odd miss and backfiring thru intake
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Message:
Only two things come immediately to mind. A small vacuum leak or the O2 sensor's response time has slowed down enough to cause the misfire. Good luck!
ticats
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midnightmagic
GenIII
3/01/2004
16:52:07
| RE: Odd miss and backfiring thru intake
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Message:
or a coil?
You gotta ask yourself one question...That Thing Got A HEMI???
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Rob C
Dodge Dakota
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3/02/2004
02:45:58
|  RE: Odd miss and backfiring thru intake
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Message:
M D Nugent, Did you replace all those ignition parts because of the backfire? Make sure you gapped the plugs to spec not wide. Carefully inspect distributor cap for cracks. (Yeah, I know it's new but, you never know) If you look under the hood in the dark, you don't see any blue-ish glowing or arcing around the coil, wires or cap, do you? Finally, did anyone check your timing? It isn't way off or very advanced is it?
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RadioMan
Dodge Dakota
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3/02/2004
07:01:43
| RE: Odd miss and backfiring thru intake
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Message:
Anyone ever think it may be the timing chain and
or gears? At 121000 miles it could be time to
change them.
A lot of people think the computer or its inputs
are always the cause of problems. My Father in
law had a Ford car and drove all the back from FL
to OH on five cylinders. Every Ford dealer he
stopped at along the way said it was the computer.
I fould his problem five minutes after he pulled
up my driveway. Number one spark plug wire was
bad.
Remember, it's just a bunch of metal parts trying
to ware out. 99% of the time it WON'T be your
computer. All your computer is trying to do is
tell you what\where the problem is.
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Rob C
Dodge Dakota
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3/02/2004
19:11:06
| RE: Odd miss and backfiring thru intake
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Message:
That's why I asked about the timing. If the timing is way off it could be a sign that the timing chain jumped a tooth, especially with 121K miles. Besides, no one said anything about a computer problem, did we?
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M D Nugent
Dodge Dakota
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4/22/2004
21:18:05
| RE: Odd miss and backfiring - the fix?
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Message:
I took the '92 back to the same shop - the backfiring has been getting worse. They finally determined that the bushing that holds the distributor gear against the cam had an egg-shaped center (worn out). The tip-off to them was that the rotor tip, which is supposed to have less than 3/16" of slop was moving over 1/2" - the distributor was setting its own timing on the fly.
$18 for the "improved" bushing, $45 for the gear that wore abnormally as a result, and $400 for the labor to replace them (including new intake gaskets and an oil change).
Hope that does it . . . !
MDN - Renton, WA
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M D Nugent
Dodge Dakota
JOIN HERE
4/23/2004
20:14:16
| RE: Odd miss and backfiring - fixed!
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Message:
Replacement of the bushing seemed to eliminate the symptoms. The new improved bushing has oil grooves so it doesn't run dry and wear out as fast.
As it turned out, they were able to replace the bushing without taking off the intake manifold, so I saved a couple hundred off their initial estimate. That's as close to a good day as I've had for months!
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