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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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I’m getting a live scanner soon so I can find out if this is a fuel problem. It really just seems like an ignition issue but I’m out of things to change in that regard.
No. When the plenum gasket was done, my mechanic claims to have checked the timing and it was fine. The ignition timing is computer controlled so, if I understand correctly, a stretched or jumped chain wouldn’t affect it.
I didn’t really know if I was misfiring all of the time or only at idle or under specific loads. I can’t feel anything when driving unless the TCC is locked up, but I wanted to see if the knocking was still audible. Road noise generally drowns it out so I couldn’t tell. After watching alot of realfixesrealfast, I decided to brake torque the engine like Duane recommends. Unfortunately, at about 2000 RPM my brakes let go and I spun the wheels up in my driveway. Up until it happened though I DID hear knocking, but not as persistently as at idle. It would knock once every few seconds, instead of constantly. Just thought I’d share.
[quote=”LJ11194″ post=45885]Today, when COLD it decided to almost stall out at a red light. Idle dropped to about 400 every few seconds. I cycled it into park and back to drive and it stopped.
So just for grins I decided to check the transmission fluid. It’s fine, but what’s weird is when I put it in neutral (Chrysler recommends you check it in neutral w/ brake on as opposed to park), I hear a strange humming sound. (doesn’t do it in park, it makes a knocking sound then) And more interestingly, when I leaned on the vehicle it creaks very loudly. I turned off the engine, and… it didn’t do it anymore. Didn’t do it at all in any other gear other than neutral and only with the engine running. The engine itself appears solid, it doesn’t move or shake visibly by itself in any gear at any RPM. But now I suspect the transmission may be loose. Is this a reasonable conclusion?[/quote]
Hi. Glad to hear you’re making progress.
OK for the loud creak I’d check suspension bushings and shocks.
For the trans sounds, is there anyway you can record and post them? That would help a bunch.
It sounds as if you’ve done the common items for ignition misses. Let’s do a compression check and vacuum test next. Also if you can get short and long term fuel trims that will give more evidence to look at.Really sounds as if we’re looking at multiple problems, so lets take them ‘one bite at a time’.
I had one a couple years ago that had the same symptoms. Different year but same engine. It ended up being a opening in the lower intake gasket allowing unregulated exhaust from the EGR port into the oil gallery and picked up through the PCV system. Only reason we found it was luck.
So, the infamous Magnum plenum gasket issue? Mine was fixed in November, preceding all of these problems.
when I put it in neutral …. I hear a strange humming sound. (doesn’t do it in park, it makes a knocking sound then)
Thinking about this, do you have/can get/borrow a mechanic’s stethoscope? Knocking sounds are never good, we need to isolate to one area of the drivetrain. (It does seem to be trans related. Flexplate perhaps. See attachment.)
I’m not seeing your attachment.
Why would I get a sound in neutral but not in park? Other than the block on the output shaft, how are they different?
[quote=”LJ11194″ post=47514]I’m not seeing your attachment.
Why would I get a sound in neutral but not in park? Other than the block on the output shaft, how are they different?[/quote]
Is knocking sound loud enough to drown humming sound? BTW, which trans model are we talking about?
It’s a Jasper 46RE. The humming WOULD drown out the knocking, but it doesn’t knock and hum at the same time. To clarify:
In park: Knocks
In netural: hums
In drive: Every few seconds it misses and when it does, the RPM drops by 200 with a shake
In reverse: Drive and neutral symptoms combined. Stops if I apply throttle.Thanks for taking the time.
Tomorrow I’ll try to make a video, and see if any of the sounds are loud enough to pick up.
Okay, here’s what I understand so far:
1999 Dodge Ram 1500, 5.2L V8, 46RE auto trans, 4X4, 260K miles
Symptoms:
1. Poor mileage (14 mpg)
2. Knocking at idle in park/neutral, felt in steering wheel especially
3. Knocking/misfire under brake torque
4. Shaking at idle in any gear
5. Almost stalling in drive/reverse, and the RPM falls by 200 accompanied by a shake
6. Noticeable exhaust smell inside and out when idling
7. CEL with misfire codes P0300-307, but not 08. No other codes, and most are pending.
8. Can definitely hear vacuum leak with throttle
9. Trans:
a. In park: Knocks
b. In neutral: hums
c. In drive: Every few seconds it misses when it does, the RPM drops by 200 with a shake
d. In reverse: Drive and neutral symptoms combined. Stops if throttle appliedTroubleshooting:
Plenum gasket, plug wires, cap, coil, plugs and rotor replaced
Reroute plug wires per TSB 18-48-98
Checked for vacuum leaks, couldn’t find one
Checked the timing
Has fuel pressure
Not burning excessive oil
Relative compression test sounds good
If you spray carb cleaner in the TB, it may run perfect for a few minutesI had to check my 46RE books to verify my thoughts. Here’s what I found: In park, park pawl/sprag is engaged to lock output shaft & fluid isn’t sent through cooler. In neutral, park pawl/sprag is disengaged and fluid IS sent through cooler via the l/u switch valve. I also attached the troubleshooting list for ‘buzzing noise’ in trans. As you’ll see, that also is pointing toward the trans cooler.
Symptoms 1-7 & 9c-d are classic ‘misfire’ symptoms. As I said earlier, the ignition system has been fairly well verified, let’s start looking at air/fuel side.
For #8, try this: http://ericthecarguy.com/videos/7-videos/27-fuel-and-emissions?start=15&videoid=9CPqbaSgcok Don’t forget to check/test/cap the little vacuum hoses. Those little SOBs have gotten me more than once!
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