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01:28:09 - 12/20/2024
V8 Dakotas
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vothsc
Dodge Dakota
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1/23/2004
08:57:35
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 Subject: Engine misses over 2,500 RPM
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While driving to work yesterday the engine stumbled and after that it missed like crazy at 2500 rpm (like a rev limiter) and of course the check engine light went on. Fortuently being a V-8 I could drive it relatively normally to work. I put it in neutral and it cuts out at 2500. I turned it off and back on again and it reved normally but on the way home it did the same thing. I had a similar problem last year at this time but it was a one time event and the check engine light went out after 4 or 5 days. I had it checked out and the code was for the crank position sensor. Of course I got the old "couldn't reproduce problem" answer. Does this sound like CPS again? My guess is that if the sensor gives a bad reading, the computer takes over and puts the engine in limp home mode keeping the rpms to 2500.
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vothsc@ptd.ne
Dodge Dakota
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1/23/2004
09:00:01
| RE: Engine misses over 2,500 RPM
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I forgot to give a little more info - it's a 2000 4.7l V-8.
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Guitar Player
Dodge Dakota
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1/24/2004
14:02:50
| RE: Engine misses over 2,500 RPM
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I have been reading these forums for about a week now. I am having similar problems as many others on this site. I have a 93 318 automatic 4x4 LE w/305,000 miles. I love the truck. It was a speed demon a month ago. I rebuilt the motor from the heads up this past summer. Problems started about 1 month ago: Around the time we had 3 feet of snow and I drove thru it working the motor and tranny pretty hard. a day or two after the snowstorm I noticed a loss of power while stepping on the throttle. I couldn't pass anyone. It would backfire thru the throttle body. As time went on the loss of power got worse until it does what it does now.
note: I took a good look under the truck when I noticed the power loss problem(looking for bad wires) I noticed that the pigtail to two sensors were sheared off. One I think was to the tailshaft end of the tranny (I believe it's the VSS and has the speedo cable)and the other was about 12 -18 inches in the direction of the motor just below the transfer case breather tube.
It starts up quick and idles fine. If I slowly step on the throttle I can get it to almost red line and then seems to back off (while holding throttle steady) until it reaches around 300rpm and repeat. If I stomp (as if baking the tires) on the peddle it will die anywhere from 1000 to 2500 rpms. It seams to be directly related to how hard I step on the throttle. When in gear it does the same thing. I can't get over 10-15 mph with out it cutting out completely as if the fuel was shut off. Happens when engine is hot or cold!
No check engine light on!
Key on/off/on/off/on: 1-2, 2-1, 5-5
I am aware of the O2 sensor, but I don't believe I would have the problems in open loop.
I have checked:
Battery voltage, Removed cat and muffler, MAP, Fuel Pressure, moving rotor back and forth with very little play, pulse ring is nice and tight, cleaned pick-up coil, Cleaned throttle body and replaced gasket, removed and cleaned fuel rail and injectors, Checked for airleaks with a stethescope and water mist, EVAP, fuses, swapped relays, (checked wires for corrosion: red wire with white stripe fine, however black wire with yellow pinstripe was corroded:FIXED)
I would like to further check the pick-up coil in the distributor but I'm not sure what the readings are supposed to be. It doesn't explain it in the Haynes book. It has three wires from the pickup coil (pigtail). I only get a ohm reading on two wires on the left(must be the actual coil and not the plate). Don't remember off hand what the reading was but it wasn't infinate: Maybe like a few hundred ohms. Normal?
I have replaced:
Coil, wires, cap, rotor, ISC, TPS, EGR + Transducer, Manifold air temp, coolant temp, Fuel Filter.
I am guessing it might be one of the sensors underneath the truck, but the tech at dodge doesn't think so. He tells me to bring it in. I live 30 miles from the nearest dealer and the truck only does 10-15mph (much less up hill!).
Any ideas would be greatly appreciated.
Brian
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vothsc
Dodge Dakota
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1/25/2004
09:53:40
| RE: Engine misses over 2,500 RPM
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I put over 100 miles on the truck over the weekend and it ran fine and the check engine light went out so I'm almost certain it's the crank sensor that glitched. I have an appointment to take it in on Wednesday but if it behaves itself through the Monday snowstorm I'm going to cancel since it was probably a once a year thing. With the cold and all the salt on the road it's amazing these things run as well as they do.
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Guitar Player
Dodge Dakota
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1/25/2004
13:40:19
| RE: Engine misses over 2,500 RPM
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Is this how the truck would behave in limp mode? I thought limp mode would limit you to second gear. Cutting out at 2000-2500rpm is like you posted earlier, "the rev limiter". If it isn't "limp mode", or this "rev limiter", I am assuming the problem is a fuel/air/timing issue. I know it has a base timing signal because it starts up and idles fine. It's as if the timing isn't being retarded under acceleration.
As far as the cold and snow goes, this is when all my problems started. So I wonder if you may have something here and the problem will "cease to exist" in warmer temps. Let me know how you make out with your problem. Unlike you I had no engine light. I have no other codes but the o2 sensor. I might change the crank sensor for #%its and giggles. I have a spare motor and haven't changed that yet. Been -20F-50F below zero lately. Makes it rather difficult to work on the truck.
GP
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Guitar Player
Dodge Dakota
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1/25/2004
23:39:15
| RE: Engine misses over 2,500 RPM
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I was just thinking: My fuel pressure (with vacuum at regulator)is 31, and without vacuum is 40. This is what the haynes manual says is correct. However it doesn't tell me what my fuel pressure should be at different rpm's. Does it stay at 31 thru all rpm's? What should it be at say...3500 rpm's. Can someone answer this for me? It may help me solve my problem. In the meantime, I am going to do a search on it.
Later,
GP
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zorba
Dodge Dakota
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1/24/2005
07:11:32
| RE: Engine misses over 2,500 RPM
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vothsc:
I have exactly the same symptoms in my 2004 v6-
The only time it happens is when it's cold. The first was after it had been sitting for 2 weeks over x-mas. I started it up and the MIL came on, and, seeing as I was ~1k miles from home, and had to work the next day, I chose to ignore it. The 2500 rpm rev limiter kicked in, and the MIL went from solid to flashing. We limped back to where we were staying, and I started digging on this forum. I reset the computer by disconnecting the neg lead on the battery for 20 min, and it started the first time- no MIL, no limp home mode, not so much as a stutter for the whole trip.
Yesterday, we got 3' of snow, so I shoveled out, and pulled the truck into the street. I left it running while I shoveled out where it was parked. After about 10 min at idle, it died. I re-started it and sure enough, MIL came on, can't rev over 2500 RPM. This time I got the code P0339 via turning the ignition switch on-off-on-off-on. I once again disconnected the battery for 20 min, re-started, and it was fine.
Then this morning when my wife was dropping me off at work it happend again. So we reset it, and now just 5 min ago- my wife called and told me it tried to die on the way around a corner, and the MIL came on, so she pulled over at a gas station- sure enough 2500 RPM is the limit, so she now has to "limp" her way to her first day of work. Now it's sitting in a parking garage, and MIGHT make it home again- meanwhile, I have to leave on a business trip in 3 hrs which means my wife will have to deal with 3' of snow and a truck that doesn't run.
- Why is it that I bought a BRAND NEW truck? so it woudl be reliable? - HAH!
I'll be contacting the dealer as soon as they open.
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vothsc
Dodge Dakota
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1/25/2005
00:16:51
| RE: Engine misses over 2,500 RPM
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My problem was the Crank Angle Sensor. It got progressively worse and when I took it in they replaced it and no more problem - although I always had a slight sensation of a miss from new with this truck - maybe my imagination - anyway I traded it on a Ram 1500 Hemi last Summer while the deals were good. Great truck except for the gas mileage. - it sucks literally.
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