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I have info regarding my misfire issues in multiple threads and its time to consolidate it in one place so some sense can be made.
The vehicle in question is a 1999 Dodge Ram 1500, 5.2L V8 4×4 Automatic, with 260,000 miles.
In November I had the plenum gasket replaced with a Hughes plenum kit. This ended about 6 months of misfiring, extreme oil usage, and bad mileage. I got 18 mpg after the fix as opposed to 16 before the gasket went bad, and 11 directly before the repair.
A few weeks later it began performing poorly again. It would knock at idle and flash the CEL under heavy load. I discovered that the wires, cap, and rotor were in need of replacing and this fixed it.
Roughly a month ago, the idle knocking returned. It got progressively worse, to the point of shaking the vehicle in park. I replaced the spark plugs, and this time it got worse instead of better. About a week after, I got a constant CEL with misfire codes for 6 out of 8 cylinders. It almost wants to stall when idling in drive or reverse. The RPM drops from 600 to 400 and there’s an audible “tick” and pronounced shake when it happens, which is every few seconds.
Realizing that the coil was the last old part of the ignition system, I tested it, and it’s within spec. We know this doesn’t mean much though, so I went to the U-Pull-It and got one off an 01 V6 Dakota with 2013 inspection stickers that wasn’t wrecked. (not sure why it was even there) It was the only one out of all the Rams, Durangos, Dakotas, and Magnum-engine Grand Cherokees that I was able to remove. (they all share a coil)
I have not seen a noticeable improvement with the “new” coil. I can’t remove the old coil because the screw heads are stripped, so until I can get a screw extractor, I won’t know how it handles actually being driven with the replacement coil. But at idle, I noticed no improvement.
To clarify, All of my symptoms:
1. Somewhat poor mileage (14 mpg)
2. Knocking at idle in park/neutral, felt in steering wheel especially
3. Shaking at idle in any gear
4. Almost stalling in drive/reverse, with a “tick” sound (like a relay) when it misses and the RPM falls by 200 accompanied by a shake
5. Noticeable exhaust smell inside and out when idling
6. Noticeable dead misses in exhaust note at idle
7. Jolting when TCC is locked up (normal for misfire, as it happened before when plenum was bad)
8. If you spray carb cleaner in the TB, it will run absolutely perfect for a few minutes
9. CEL with misfire codes P0300-307, but not 08. No other codes, and most are pending.Relative compression test sounds good (aka clear flood crank). I have fuel pressure. Coil does not appear to be the issue, but I will know more about that next week. I am not burning excessive oil. (but at 260k without a rebuild, I am burning some, no doubt)
I really am at my wits end here, and I need to get this thing running right. The 4 mpg I’m losing is enough to hurt the wallet, and it isn’t very enjoyable to drive since every time I stop, it shakes enough to drive me crazy and every time I get up to speed it kicks me in the rear.
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what sticks out for me here is when you spray the carb spray
and the truck runs good. you created a rich condition at the
o2 sensor. which tells the pcm to cut fuel back to lean out
the fuel. can you read live data to see the front o2 sensor.
I would also like to fuel trims and parameters.I am buying a live data scanner with my next check. I had planned to do so anyway.
Just to clarify, I didn’t spray the carb spray while it was running. I cleaned the TB with it and then noticed it ran great immediately afterwards, but then a mile down the road it went bad again.
So you think it is running so rich, it can’t burn all the fuel?
It goes bad again because the carb spray burns off and the
o2 should be coming down from .900 volts which is rich.
sounds like the truck is running rich to much fuel. it
seems to like it when it leans out. subtract fuel.There is a TSB on the 5.2 and 5.9 liter to re route and bundle plug wires due to cross firing of the plug wires make sure they are not touching the headers or any other metal. You can accomplish this by bundling them up with a wire tie
Here is the TSB http://dodgeram.info/tsb/1998/18-48-98.htm
The valve covers have plastic clips for the plug wires, and now we know why! I’ll reroute my wires tomorrow when it’s not 8 degrees F.
I moved the wires according to the TSB and there is very little, if any improvement.
I sprayed a bunch of carb cleaner in the TB again and it did NOT run better directly afterwards, which may or may not impact the overfueling theory. Since I had the carb cleaner out I checked for vaccum leaks again, and couldn’t find any, again. I pulled on the throttle a bit and I can definitely hear one, though.
I really hope my mechanic didn’t screw up my intake manifold gasket change. But, if he’s too lazy to change the hardest to reach plug, I have to wonder.
By the way, there’s a god awful binding noise when I put it in neutral. Loud enough to drown out the engine. I put the brake on and got out, and it’s definitely coming from the transmission area.
I’m about $1500 away from swapping in a Cummins 4BT and a 5 speed manual.
Out of curiousity, I see when you replacd the plugs it got worse, did you use champs? I’m no chrysler expert but I think they’re pretty picky about that.
[quote=”LJ11194″ post=47157]Well, no. But Champs didn’t come out of it either.[/quote]
The OE plugs for this Ram are Champion Copper Plugs. They should be number 436 I believe. Just like Hondas, Dodges don’t really like anything other than OE plugs for the long term. The plugs should also be copper, not platinum or iridium.
How I know: platinum or iridium plugs – ran poorly, $1.00(on sale)copper plugs, ran great. The only aftermarket plugs I’ve found that usually run acceptably are E-3, but that changes by car!
Autolite coppers were in it, (I didn’t put those in) except for #8 which was an Autolite double platinum (I didn’t put that in either). I’ll get a set of champion coppers, if it will satisfy you all. I got platinums because this is a 30,000+ mile a year vehicle.
I highly doubt that replacing old, worn out and damaged plugs with brand new ones would result in no change of symptoms, even if the plugs are “wrong”. People on the Dodge forum recommend everything from OEM to Autolite, to Bosch to NGK. Depends on the person.
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