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fabracator
GenIII
1/04/2003
16:17:10
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 Subject: #7 Misfire
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Message:
Ok, check engine light came on. Took it to Pep Boys. Code said Cyl. # 7 mis-fire. What could have caused this, and were do I go from here.
Why buy what you can make
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Red
Dodge Dakota
JOIN HERE
1/04/2003
17:09:37
|  RE: #7 Misfire
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what year and how many miles....
It could be as simple as a tune up, or maybe you need to clean your fule injectors....a lot of bad gas these days. When was the last time you had a tune up? If you have over 25-30000 miles on it it, it is probably time. I had similiar misfire on *8 all I did is tune it up and clean my throttle body and I havent seen it since.
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fabracator
GenIII
1/04/2003
17:30:34
| RE: #7 Misfire
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She is a 99 with 75000 mi. on her. Did a tune up abut 4000 mi ago, also ran a fuel system cleaner and took my TB off and cleaned it vary well.
Why buy what you can make
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Hurl
Dodge Dakota
JOIN HERE
1/04/2003
18:15:24
| RE: #7 Misfire
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Message:
Rule #1: Don't go to PepBoys for anything which requires thought.
Misfire; well, you could have any number of things happening. You need a few things in order to fire a cylinder.
A. Compression
B. Fuel
C. Spark
D. Air
E. Clear exhaust path (if you intend to fire more than once)
So, since you (and apparently PepBoys) do not have an engine scope to look at the ignition you'll have to do a few things.
Pull the #7 plug wire. Stick a screw driver into the boot and (while holding the insulated portion of the handle) have someone crank the engine while you hold the conductive part of the screw driver about 1/8" from a metal part of the engine. Does it spark? Hook the plug wire back up and start the engine. Do you see a spark from the #7 wire arcing to ground?... might be best to do that at night where you can see an errant spark. If you know what you're listening for you'll hear it arcing. Be sure to check the cap/rotor for any carbon tracks which could be shorting the spark (do '99's have cap/rotor?).
Pull the plug and look at it. Does it look wet? Does it have build-up on it? While the plug is out, do a simple compression check (purists will want you to pull all plugs and check all cylinders). Ensure you have the proper compression per spec.
If you're confident you have spark and that your plug is okay, then you have to move on to fuel. Since the rest of the cylinders appear to be working you'll need only focus on #7 injector. An exhaust gas analyzer would be helpful here. If you're misfiring and your HC's are not high then it would likely be a matter of an injector not firing... no fuel in the cylinder no unburned gas and no high HC's to go along with the miss. Anyway, make sure #7 injector is firing. You can put a screw driver against the injector and put the handle to your ear and see if you can hear a "clicking" from the injector. If you're not sure, then listen to the injector while the car is running, then disconnect the electrical connector from the #7 injector... see if it sounds different.
Perhaps there is a vacuum leak at #7 cylinder. take some carb cleaner (be sure to have the red tube on the nozzle so you can pin-point spray it) and spray around the intake seal near #7. Does the misfire go away? Is the EGR or any other vacuum accessory (like the brake booster) ported near #7 cylinder intake?
There are lots of things to look at. I'm not sure about what systems the Chrysler OBDII looks at in order to fault a particular cylinder, although I would suspect something with the ignition.
By far your best bet would be to take a cursory look at the simple things. If that yields no results then take it to a professional (NOT PEPBOYS). Your diagnosis will be done pretty quickly.
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Jason Teague
Dodge Dakota
JOIN HERE
1/04/2003
23:53:51
| RE: #7 Misfire
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On your truck, being 96-newer, all it takes is a little hick-up to set a misfire code. You said you just tuned it up, do you mean you changed only the plugs? Does the engine have a constant miss? More than likely it is an intermitent miss. Possible dirty injector, plug, plugwire, distributor cap. Has the engine been consuming any antifreeze? If so it could be a cracked head. Very common on Mag motors. If a constant miss, look for low compression problem (i.e. bad piston, burnt valve, busted valve spring or other valvetrain problem). Also don't overlook the intake pan gasket. Open the throttle body and look down into the intake with a flashlight and look for oil in the intake. If the intake pan gasket hasn't been replaced yet yooou are past due for it to need replacing.
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Goldberg
Dodge Dakota
JOIN HERE
3/30/2006
15:01:00
| RE: #7 Misfire
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I have a 02 Dakota V8 and i am having that #7 misfire as well. i took it to a shop and they replaced the plugs (don't have plug wires, replaced the injector, and still not fixed. They checked the intake and supposedly cleaned the fuel rail. When the engine is cold i have a compression of 185 to 200 in all cyl. when it heats up i get the bad idle and the compression in #7 drops to 105. The don't do head work so i have to bring it else where. They think i may have a head gasket leak. Hope not, but thank god for that extended warenty if it is.
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OBIO3
Dodge Dakota
JOIN HERE
3/30/2006
15:31:32
| RE: #7 Misfire
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That sounds like a tight valve. But I don't think that's possible......or is it guys???////Head gasket is your best guess but have it checked
So many problems .... So little time
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Goldberg
Dodge Dakota
JOIN HERE
4/13/2006
13:52:32
| RE: #7 Misfire
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Brining it to the shop on Monday before i leave for vacation. Hope it will be done by the following Monday and will let ya'll know what they found/did.
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jasonsdakota
Dodge Dakota
JOIN HERE
4/14/2006
00:33:35
| RE: #7 Misfire
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Message:
could be bad coil pack. try swapping it with cylinder number 1 and see if you get p0301 instead of your current p0307 code. if so, there's your trouble.
jasonsdakota
04 ext cab 4.7 2wd auto
ho cams
exhaust
4.10 gears
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brad
Dodge Dakota
JOIN HERE
4/16/2006
11:19:39
| RE: #7 Misfire
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maybe you should take it to the dealer and we would have it figured out in no time dealers have the tools and the smarts
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Relf
Dodge Dakota
JOIN HERE
4/18/2006
20:54:13
|  RE: #7 Misfire
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Message:
Hey Hurl, Fabricator didn't go to Pep Boys to get his truck diagnosed, rather he took advantage of using their scanner for free. I know which Pep Boys he goes to and I use their scanner sometimes too. I've got the same problem, but on my V6. Thanks for reminding us about checking the cap & rotor, I forgot that.
Relf.
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