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M D Nugent
Dodge Dakota
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3/01/2004
15:39:02
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 Subject: Odd miss and backfiring thru intake
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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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M D Nugent
Dodge Dakota
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3/01/2004
15:49:02
| RE: Odd miss and backfiring thru intake
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Sorry - wrong forum (again!). I need a new glasses prescription!
MDN
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J and J Auto
GenII
3/01/2004
16:57:58
| RE: Odd miss and backfiring thru intake
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Anyway
A bad leak on the intake pletem gaskit will cause
a lean out problem and a popping and backfire
will happen
Larry
J&J Auto
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Ron T.
Dodge Dakota
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5/11/2005
01:56:29
| RE: Odd miss and backfiring thru intake
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My 2001 Quad Cab (3.9L, 5sp man.) has been doing almost the same thing as yours the past 2-3 months. In addition to unexpected hesitation during acceleration at highway speeds, its also done it during take-offs from stops, and has sometimes idled very rough. It doesn't always do it, and I'm having a hard time pinning down a clear pattern to describe to the service techs. Since March I've taken it in and the following "fixes" have been made. 1st, a fuel-injector/system flush, and they diagnosed the rough idling problem as a "idler control motor" (or valve) which I then had replaced. Problems soon returned, and they suggested a tune up, which I had done yesterday. Today the problems are all back, so I'll be returning with the truck and a heaping pile of nice things to say to them. I'll post again if they come up with a real cure.
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OBIO3
Dodge Dakota
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5/11/2005
14:53:30
| RE: Odd miss and backfiring thru intake
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M D I think you may have answered your own question > (rerouting the plug wires) > You said the wires are new > You did not say if they was cheap wires and even at that they can be defective quality wires > It happens > Try Looking at the wires in total darkness while the truck is running > See if there cross firing on you > Good luck
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Wadak
GenIII
5/13/2005
00:43:38
| RE: Odd miss and backfiring thru intake
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Ron T.,
Two other possibilities, as Larry posted above, it could be a leaky plenum gasket above. Are you using oil, if you are using oil at the rate of a quart or more per 1000 miles it could be the plenum gasket on the intake manifold. Take the air cleaner off and open up the throtle plates on the throttle body and shine a flash light down th throttle body bores, if you see oil film build up its the plenum gasket.
A partially bad or intermittent distributor pick up (fuel sync pickup) could cause problems. A bad O2 sensor will cause hesitiation, loss of performance and gas mileage to fall off.
How many miles on your truck and has the O2 sensor ever been changed?
92 and 97 Daks both with many mods.
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Ron T.
Dodge Dakota
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5/14/2005
00:51:59
| RE: Odd miss and backfiring thru intake
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Message:
Wadak,
My Dakota just passed 40k miles on it, and no, the O2 sensor has not been replaced. I've had a GM or two that had those go out on them nearer to 100k miles, and that was usually accompanied by the "Check Engine" light. So far the "Check Engine" light has never lit up during any of these bizarre episodes in the Dakota. It's not using oil either as far as I can tell. The levels stay fine, there's no sign of leakage anywhere, and it's not burning any in the exhaust. One other thing though, this engine has had the 3.9L "spark-knock from hell" almost from the day I got it. I made several trips to the dealer to try and get that cleared up, with zero luck. I'm just hoping and praying that all that detonation didn't totally screw something expensive.
Thanks for the advice.
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Three.9HP
Dodge Dakota
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5/25/2005
18:49:02
| RE: Odd miss and backfiring thru intake
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I have a 93 Dak and I had the same problem. The thing is , is that nobody ever thinks about the distributor gear and bushing going bad. I went through almost 900 bucks and three meachanics before I found out what it was. It happens a to a lot of early 90's models. Good luck buddy!
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J and J Auto
GenII
5/26/2005
07:00:05
| RE: Odd miss and backfiring thru intake
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A coil going bad will also do that and not trip
any coil circuit codes
Larry
J&J Auto
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G
Dodge Dakota
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8/22/2005
14:35:26
|  RE: Odd miss and backfiring thru intake
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I also have the same problems with my 01 3.9L Dakota Quad. I have had 3 diff. O2 censors replaced (only 1 left to replace), the fuel pump, plugs, caps, wires, a supposed Broken vac line and still the truck occasionally runs like s---. the problem is it only seems to do it with me and never while it is at the dealer. I've had the truck a year and it has been in the shop over 35 days on 8 seperate occasions for the same reason. I bought the truck to tow my camper, but I don't want to take a chance with it until I get it fixed properly. I spoke to a mechanic on the side who told me about the same problem he had with his Dakota and it was caused by a damaged intake plenum gasket. He said that it could cause the O2 censors to go bad as well as other problems. I am trying to get the dealer to replace it.
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bigdave
Dodge Dakota
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8/23/2005
17:43:53
| RE: Odd miss and backfiring thru intake
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One more thing to check. The wires that go to the bottom of your coil, wiggle them while at idle and see if your motor hesitates or backfires. Mine was doing the same thing and after replacing mostly everything I stumbled on it by accident.
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G
Dodge Dakota
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8/24/2005
08:34:46
| RE: Odd miss and backfiring thru intake
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I'll try that as well. My check engine light came back on again. Back to the shop it will go..
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