Bill, you may be experiencing the same misfortune I had. There was a bad batch of exhaust springs that got built into some of the later 2g 3.5liters. It caused the exhaust valves to stop rotating allowing carbon buildup which eventually prevented the exhaust valves from closing properly. It caused a loss of power and the CEL to light up. They had to pull my heads off and clean the valves and install replacement springs. Warranty work btw
2004 SXT random misfire
As the title says, yet another random misfire.
I've yet to get any other code than P0300 as of yet, but here are the things that I have noticed and tried as of yet.
First thing I did was sea foam. No luck.
Then I tried cleaning up the coil packs. When I pulled the boots off of the coil packs I noticed quite a bit of corrosion (rust) or white buildup on the springs at the coil end, so I pulled them all out and cleaned them thoroughly.
I noticed that the car runs much smoother at idle now, but the random misfire remains when under acceleration. I figure the white residue was the remains of dielectric grease, so I reapplied some to each as I reassembled them.
I've noticed that the miss is most noticeable at just above 2000 rpm under very light acceleration, or very hard acceleration. Under very very light acceleration, the miss is constant when the RPM's are just below 2100 RPM's, while under hard acceleration, the miss is more random, but noticeable.
Cruising along at a constant speed, I cannot notice any misfires, unless the RPM's are just barely above 2000 RPM's..
I'm leaning towards a bad crankshaft sensor, or camshaft sensor.
Any other ideas??
I've yet to get any other code than P0300 as of yet, but here are the things that I have noticed and tried as of yet.
First thing I did was sea foam. No luck.
Then I tried cleaning up the coil packs. When I pulled the boots off of the coil packs I noticed quite a bit of corrosion (rust) or white buildup on the springs at the coil end, so I pulled them all out and cleaned them thoroughly.
I noticed that the car runs much smoother at idle now, but the random misfire remains when under acceleration. I figure the white residue was the remains of dielectric grease, so I reapplied some to each as I reassembled them.
I've noticed that the miss is most noticeable at just above 2000 rpm under very light acceleration, or very hard acceleration. Under very very light acceleration, the miss is constant when the RPM's are just below 2100 RPM's, while under hard acceleration, the miss is more random, but noticeable.
Cruising along at a constant speed, I cannot notice any misfires, unless the RPM's are just barely above 2000 RPM's..
I'm leaning towards a bad crankshaft sensor, or camshaft sensor.
Any other ideas??
1 - 20 of 20 Posts
hmm this is faintly similar to my misfire i had caused by a broken flywheel, very very rare however and i doubt thats your problem..
does the car get better under heavier acceleration? above 2500 rpm?
is your tachometer dancing at all?
make sure 100% that its only under acceleration i thought mine was, until i went down a hill where the rpm was around 2000 and i saw the tach dancing all over the place...
i know for 1st gen at least that the timing is controlled by the crank up to 2500 or so RPM then switches to the cam.
does the car get better under heavier acceleration? above 2500 rpm?
is your tachometer dancing at all?
make sure 100% that its only under acceleration i thought mine was, until i went down a hill where the rpm was around 2000 and i saw the tach dancing all over the place...
i know for 1st gen at least that the timing is controlled by the crank up to 2500 or so RPM then switches to the cam.
Balls to the wall acceleration I feel random points of misfires with high RPM's, but at just over 2000 rpm with very light acceleration you can feel it non stop. That's why I'm wondering if it is a sensor issue. In the last several months I have run quite a few high dollar fuel system cleaners through it, including seafoam, lucas Slick 50, and rislone, so I can't see how it could be carbon buildup, but I don't know everything there is to know about cars, so at this point anything is possible.
Also I always use 93 octane religiously because I live in a state that has cheaper gas prices than most.
I was thinking about the sensors mainly because it is close to the 2500 RPM change over point that perhaps it could be the issue.
I'm basically otherwise clueless, which is why I'm hoping that the details I posted will jog someones memory with a past experiences they had in the past.
I haven't seen any tachometer dancing around, it has been smooth and steady as far as I have been able to tell, but I will have to go out for another test drive on the highway to see if it twitches at all during the misfires.
Also I always use 93 octane religiously because I live in a state that has cheaper gas prices than most.
I was thinking about the sensors mainly because it is close to the 2500 RPM change over point that perhaps it could be the issue.
I'm basically otherwise clueless, which is why I'm hoping that the details I posted will jog someones memory with a past experiences they had in the past.
I haven't seen any tachometer dancing around, it has been smooth and steady as far as I have been able to tell, but I will have to go out for another test drive on the highway to see if it twitches at all during the misfires.
^^^This may have some merit^^^Bill, you may be experiencing the same misfortune I had. There was a bad batch of exhaust springs that got built into some of the later 2g 3.5liters. It caused the exhaust valves to stop rotating allowing carbon buildup which eventually prevented the exhaust valves from closing properly. It caused a loss of power and the CEL to light up. They had to pull my heads off and clean the valves and install replacement springs. Warranty work btw
The problem spilled over into the LX and CS 3.5L engines as well in subsequent years. The initial fix was a dose of upper engine cleaner. Probably similar to the popular Seafoam treatment. But, since you've already done that, I would be taking compression and cylinder leakdown tests.
When I first started using the fuel system cleaners, the car was running perfectly. I simply used them as preventive maintenance.Warranty work btw
Are you saying that if that turns out to be the case, it will be covered by warranty, or that it was covered by a warranty for you?
It could also possibly be a malfunctioning spark plug. In low rpms the spark plug would run fine, but once into the higher rpm it could be struggling to keep up
Also, my car was switched over to Mobil 1 about 4 months ago.
I put in new plugs a few months ago, but I can pick up a couple more and try swapping them out. The factory recommended plugs.
Perhaps one went bad.
Perhaps one went bad.
Only reason I say that is because we had a random misfire in our truck around 3000+rpm and it ended up being a bad spark plug. Hopefully it's a cheap fix!
Just got back from another test run.
RPM's are rock solid throughout the entire range, idling, cruising and balls to the wall acceleration. (No dancing or jerking needle.)
The misfires are most pronounced between 2000 and 2500 RPM. Higher speed acceleration from 75/80 and up smooth with no noticeable misfires.
I put about 60 miles on it on brand new road surface on the nearby interstate.
RPM's are rock solid throughout the entire range, idling, cruising and balls to the wall acceleration. (No dancing or jerking needle.)
The misfires are most pronounced between 2000 and 2500 RPM. Higher speed acceleration from 75/80 and up smooth with no noticeable misfires.
I put about 60 miles on it on brand new road surface on the nearby interstate.
I just found out that my PVC valve hose has a split in it. Not sure if that could cause the problem or not, but worth replacing.
I stopped at advanced auto to get a new one, and another champion plug for it, but they carry neither in stock.
What kind of useless parts supplier doesn't carry Champion Spark plugs for gods sake. I can understand them not having the hose in stock, but they don't even freaking carry Champion spark plugs at all according to the guy at the counter.
I'll try again tomorrow, when my normal parts supplier is open, Carlson's Auto Parts. I've dealt with them for so long, that they gave me in house credit to get whatever I need, even if I don't have the cash on hand..
I stopped at advanced auto to get a new one, and another champion plug for it, but they carry neither in stock.
What kind of useless parts supplier doesn't carry Champion Spark plugs for gods sake. I can understand them not having the hose in stock, but they don't even freaking carry Champion spark plugs at all according to the guy at the counter.
I'll try again tomorrow, when my normal parts supplier is open, Carlson's Auto Parts. I've dealt with them for so long, that they gave me in house credit to get whatever I need, even if I don't have the cash on hand..
Did you replace the cam sensor like you planned in earlier posts?
I'll be getting that Wednesday from the dealer, along with a new crankshaft sensor. When two or more parts work together like they do, I tend to replace them together also.
You don't need 93 octane. The SXT is not programmed to take advantage of if. Just good quality detergent gas. It is your choice though.
PCV valve hose split is not influencing misfire.
Stock plugs for 04 sxt are not champions. They are NGKs
Not sure if your constant use of fuel system cleaner would counteract the carbon buildup from a faulty exhaust valve spring or not. If the valves have stopped turning, there might be a spot that the cleaner isn't hitting. IDK.
PCV valve hose split is not influencing misfire.
Stock plugs for 04 sxt are not champions. They are NGKs
Not sure if your constant use of fuel system cleaner would counteract the carbon buildup from a faulty exhaust valve spring or not. If the valves have stopped turning, there might be a spot that the cleaner isn't hitting. IDK.
It's the Fetzer valve!
J/K! Good luck getting the PCV hose from anywhere other than the Dealer. And then you can only buy it as part of the complete heat Exchanger package to the tune of $150 or more!
I went to Napa and purchased hose and plastic elbows to make this work on my 2000 R/T. The bend in the OEM hose means if you just buy a plain piece of hose it will kink at the "bend". Used to be you could buy the original non-heat exchanger hose for like $13 from the dealer and cut the section off and use it for heat exchanger equipped cars. The part number for that hose still exists in parts catalogs online and at the Dealer but it's discontinued. If you go to the Dealer they'll tell you it's been superseded by the complete heat exchanger assembly(expensive). When you go to the online Mopar dealers the part is listed as available and when you order it....you'll get an email or phone call a few days later saying you need to buy the superseded complete heat exchanger!
Good luck!
I also think sealing up the PCV hose might solve your random misfires. If nothing else try a complete section of hose from the head to the PCV valve and bypass the heat exchanger. The hose might cost you a $1 and might clear up your problem.
J/K! Good luck getting the PCV hose from anywhere other than the Dealer. And then you can only buy it as part of the complete heat Exchanger package to the tune of $150 or more!
I went to Napa and purchased hose and plastic elbows to make this work on my 2000 R/T. The bend in the OEM hose means if you just buy a plain piece of hose it will kink at the "bend". Used to be you could buy the original non-heat exchanger hose for like $13 from the dealer and cut the section off and use it for heat exchanger equipped cars. The part number for that hose still exists in parts catalogs online and at the Dealer but it's discontinued. If you go to the Dealer they'll tell you it's been superseded by the complete heat exchanger assembly(expensive). When you go to the online Mopar dealers the part is listed as available and when you order it....you'll get an email or phone call a few days later saying you need to buy the superseded complete heat exchanger!
Good luck!
I also think sealing up the PCV hose might solve your random misfires. If nothing else try a complete section of hose from the head to the PCV valve and bypass the heat exchanger. The hose might cost you a $1 and might clear up your problem.
Also....isn't your SXT a non-original engine? I seem to remember you buying it and the engine taking a **** shortly after? What code engine was installed? Got more than one member on here that did engine replacements either as a straight 3.5-3.5 swap or 2.7-3.5 swap where there were misfire issues.
The engine came from another 2004 SXT.
I temporarily patched the cracked hose with rubberized electricians tape and wire ties. Car runs much better, and I can't feel any misfires at all. Will hold final judgement though until I can get another hose for it, but I really do think that has fixed it.
I temporarily patched the cracked hose with rubberized electricians tape and wire ties. Car runs much better, and I can't feel any misfires at all. Will hold final judgement though until I can get another hose for it, but I really do think that has fixed it.
x2 Anything else doesn't seem to run as efficiently supposedlyStock plugs for 04 sxt are not champions. They are NGKs
Maybe they were NGK, I forget now. DOH!!!
I know that they were the ones that the parts book recommended. I always bought Champions for cars in the past, so my mind must have switched them up on me.
I know that they were the ones that the parts book recommended. I always bought Champions for cars in the past, so my mind must have switched them up on me.
1 - 20 of 20 Posts
- This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
DodgeIntrepid.Net Forums
A forum community dedicated to Dodge Intrepid owners and enthusiasts. Come join the discussion about performance, modifications, specs, parts, classifieds, troubleshooting, maintenance, and more!
Full Forum Listing
Recommended Communities
