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caulk04
GenIII
 
1/08/2006
21:50:34
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 Subject: High speed misfiring and low power
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Message:
Ok...so when I did my intake manifold swap, I got a little bit of antifreeze on a couple of the plugs and had a misfire on 2 or 3 cylinders, bad. Replaced the plugs (originals at around 47K) with 3923's. Now I occasionally (well more than often enough to drive me nuts) get a p0300 (random/multiple cylinder misfire) above 5000RPM in 2nd gear. When it trips this code, it is always preceeded by a flashing MIL. Sometimes, however, I get the flashing MIL and no codes afterwards. Manual says flashing MIL means emissions problem that can cause heavy power loss and cat damage.
I haven't yet pulled any plugs to check anything, but its only at high RPM where it struggles to pull to 3rd gear. Once I clear 5000-5100, I have no nuts to pull 2nd gear which really hurts passing performance and general playing around :)
I just installed my SC 3715 tuner and don't notice a whole lot of gain (though it is cold here so fluids are thicker) on the butt-dyno. Also, why no RPM limiter option for my truck? Not that it matters, I have no power above 5K, much less 6K.
The manifold I installed was for an 02 HO engine, direct match. My intake is stock with a dropin K&N, recently cleaned.
Thanks guys!!
'02 CC 4x4 4.7 HO
http://www.cardomain.com/ride/2147050 <- Check it out!
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davec
Dodge Dakota
JOIN HERE
1/09/2006
20:19:22
|  RE: High speed misfiring and low power
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Message:
Sounds like a plug problem to me. Seems like they don't hold up against high rpm.
I have my o.e. Champions in with 36k miles on em'. I have plenty of power until about 6200rpm. Gotta love those O.H. cams. ('02 4.7 RC 2wd)
Dave
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caulk04
GenIII
1/09/2006
21:22:08
| RE: High speed misfiring and low power
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Message:
Funny, you have the same initials as my father. :)
Ok, I'll look for some NGK 2262's locally and work on that this weekend maybe...
What mods do you have on your 4.7?
Thanks!
'02 CC 4x4 4.7 HO
http://www.cardomain.com/ride/2147050 <- Check it out!
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davec
Dodge Dakota
JOIN HERE
1/10/2006
08:41:15
| RE: High speed misfiring and low power
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Message:
I've installed headers and made a custom exhaust. That's pretty much it for the mechanics.
Dave
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caulk04
GenIII
1/10/2006
18:48:21
| RE: High speed misfiring and low power
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Message:
I wish I had the resources to build an exhaust...I think I'm gonna have the local shop build me a system when I get my return this year. Need to do something with that y-pipe.
Well, I reset the PCM before going to work last night (which I've done several times to clear the code) and on the way home today it definetly had more nuts. Maybe it finally adatped to the SC tuning?
I'll give it some time and see how it works out.
'02 CC 4x4 4.7 HO
http://www.cardomain.com/ride/2147050 <- Check it out!
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jayfitzy
Dodge Dakota
JOIN HERE
1/17/2006
12:57:40
| RE: High speed misfiring and low power
IP: Logged
Message:
caulk04,
I did the 218 cams and the ho intake manifold and the plugs all in one day. I have the same problem at about 5100 rpms. It sounds like I am hitting the rev limiter. It only happens once in a while. I though it might have been due to the fact that I didn't replace the valve springs. Let me know if you find the fix. I am getting a new computer this month from mike leach. I hope that and new plugs will solve my problem. oh btw I have a 2001 4.7 rc Motor Sports dakota.
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caulk04
GenIII
1/17/2006
15:47:45
| RE: High speed misfiring and low power
IP: Logged
Message:
I wish I had gone with the 206 cams...was too much money at the time though.
I was thinking about trying the 5224 plugs since its cheap, but the misfiring went away now with my Superchips tuner...occasionally now it will lose power at high RPM but then minutes later it will pull pretty well all the way to 6K.
Sorry I don't have anything for sure for you, but maybe try the plugs and let me know.
'02 CC 4x4 4.7 HO
http://www.cardomain.com/ride/2147050 <- Check it out!
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Old Member
Dodge Dakota
JOIN HERE
1/17/2006
17:22:00
| RE: High speed misfiring and low power
IP: Logged
Message:
Intake Leak
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caulk04
GenIII
1/17/2006
19:19:20
| RE: High speed misfiring and low power
IP: Logged
Message:
Nah...not happening.
4.7's use rubber seals molded into the manifold and steel sleeves around the bolts so you can't overtighten them.
I think its more of a fuel/spark timing issue. I may try the 5224 plugs come spring when its easier to work on the truck. Dad's garage is a little cramped. :)
'02 CC 4x4 4.7 HO
http://www.cardomain.com/ride/2147050 <- Check it out!
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GraphiteDak
GenIII
1/17/2006
23:26:29
| RE: High speed misfiring and low power
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Message:
Weird. I run mine to over 6k RPM's all of the time. That's with the HO cams and stock (2003) intake, ported 68MM TB, etc.
I also wanted to try the other cams. Now with my gears and dual exhaust I think if I do any more mods, it should be full length headers and some bigger cams yet.
Oh. The only problem I've had since doing my custom exhaust, is it smells a tad rich at start up. But no codes.
Let us know if the problem stays gone...
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caulk04
GenIII
1/18/2006
02:32:44
| RE: High speed misfiring and low power
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Message:
Either with my profit sharing or income return this year, I think I'm gonna have the local shop build be some exhaust from the pre-cats back. Probably a single 3" all the way back, with a Magnaflow muffler of course. :)
Should help free up some high RPM power...
'02 CC 4x4 4.7 HO
http://www.cardomain.com/ride/2147050 <- Check it out!
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Slow4x4Dak
Dodge Dakota
JOIN HERE
1/19/2006
17:13:22
| RE: High speed misfiring and low power
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Message:
I got some radiator fluid on my plug wires when I did my engine swap. It burned through the wire pretty good and the misfiring happened same as yours. Around 5k rpm 3rd gear but didn't start puttering until over 100mph. Went under the hood, replaced the wires and no problems since.
I only had a misfire on 5 cylinder though.
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caulk04
GenIII
1/19/2006
20:00:27
| RE: High speed misfiring and low power
IP: Logged
Message:
I'm assuming you have a 3.9/5.2/5.9 then...us 4.7 guys don't have plug wires per se. :)
I'm still open to any ideas on freeing up a little high RPM power.
'02 CC 4x4 4.7 HO
http://www.cardomain.com/ride/2147050 <- Check it out!
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Dan
Dodge Dakota
JOIN HERE
1/21/2006
01:06:16
| RE: High speed misfiring and low power
IP: Logged
Message:
Antifreeze! sounds like the intake manifold is not lined up right.
Could also cause a small vaccum leak. Maybe you didn't have the
right thickness of gaskets?
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caulk04
GenIII
1/21/2006
09:26:32
| RE: High speed misfiring and low power
IP: Logged
Message:
There are no gaskets for the 4.7...its all o-ring'd and you can't mess it up unless you don't snug the bolts down. The bolts that attach the 4.7 intake are also studs that extend upward to secure the individual coil packs. I check the tightness of those every time I change the plugs. No intake leaks.
BTW - I reinstalled the air-box snorkel (the thing that points to the fender) to quiet the intake down after I did the hardware store intake. Seems to have actually helped a little bit. I also JUST finished installing AL 5224's this morning and I will go drive it around some today after I install a new wheel bearing in my GF's car.
One last thing...there is no antifreeze in the plugs this time. All were blown out very well and I smeared a little bit of dielectric grease in the coil packs.
Thanks for the help, we'll see how it runs today.
'02 CC 4x4 4.7 HO
http://www.cardomain.com/ride/2147050 <- Check it out!
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jayfitzy
Dodge Dakota
JOIN HERE
1/23/2006
08:15:36
| RE: High speed misfiring and low power
IP: Logged
Message:
Let me know how your truck is running. I wanted to change the plugs as well but we are getting 6-9" of snow today. Winter sucks for working on the truck
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caulk04
GenIII
1/23/2006
08:24:18
| RE: High speed misfiring and low power
IP: Logged
Message:
Ahh...forgot to post back in here.
I drove the truck after a surprisingly easy wheel bearing/hub swap in the Stratus and I really do think it helped the mid-range a little, maybe even a bit in the top end. Mis-fire is still gone, will give it some time.
All in all, unless your plugs need changed, I wouldn't mess with it since there is a fair amount of screwing around to change plugs in the 4.7 (at least you don't have to crawl underneath or contort yourself though).
Gonna try to get an estimate this week from the exhaust shop on y-pipe back 3" exhaust with an 18" long Magnaflow...should really help to get rid of that stock 3rd cat for a hi-flow.
'02 CC 4x4 4.7 HO
http://www.cardomain.com/ride/2147050 <- Check it out!
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