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I’ve been chasing this issue on my 01 5.9L Ram since I bought it early this year. There are 109,000 miles on it. You can easily feel the vehicle vibrating at idle. When maintaining speeds above which the torque converter clutch is locked (~40mph+), it will occasionally vibrate, buck, or kick, but not constantly. It runs fantastically under acceleration, especially at wide open throttle. Fuel economy is much lower than it should be, however.
The cap, rotor, wires, and plugs are all new. IAC is new, was replaced for a separate problem. (nearly stalling when idling cold) The O2 sensor values are within normal limits as are the STFT and LTFT. Failing all else, I suspected the infamous intake plenum gasket had blown, so I replaced the entire manifold with a Hughes/Edelbrock FI Airgap intake. When the old intake was removed, I could easily see the gasket was intact, which was disappointingly surprising. They rarely last this long on a Magnum engine. No codes are present, pending or otherwise.
The problem persists. A new symptom is that I can smell fuel outside the vehicle immediately after turning off the engine. You do not smell anything while it’s running. Outside the vehicle, the exhaust sounds as if it is misfiring or has a mild cam in it. There is a knocking sound when idling in park which I have attached a video of. You have to listen closely because all the phone picked up was the bass from the exhaust, but it’s there. The sound disappears when putting the vehicle in gear, but can still be heard when revving the engine OUT of gear. I’ve never heard the sound while driving.
[video]http://www.youtube.com/watch?v=0nCRG83WCOE&feature=youtu.be[/video]
When accelerating hard or driving with a window open, it makes a ticking sound precisely like that of an exhaust leak, however neither I or a professional have been able to find any leaks upstream of the cat. The catback is fairly well rusted, but that shouldn’t affect performance. The sound seems to be coming from the front of the vehicle. The shop I use when I’m outside my comfort zone did a diagnostic on the truck and could not find ANYTHING wrong. He checked parameters on his Verus and didn’t see anything out of the norm. Neither of us could locate any vacuum leaks, either. I could try to make a video of this, in case any of you want to hear it and verify that it IS in fact an exhaust leak.
Despite not being able to locate this exhaust leak, I can’t come up with any other solution to the way it’s running. As much as I hate to load up the parts gun and shoot it at the vehicle, I’m about ready to replace the entire exhaust with long tube headers, a high flow cat, new O2 sensors and a new stainless catback system.
I’m at my wits end over here, and if I hadn’t sunk so much money into it already, I’d probably replace it. At this point, though, I have to finish what I started.
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When you started the truck the second time what yellow light came on
and went off? The rpm looks steady. Try looking for the exhaust leak
first thing in the morning when the cold smoke would show when you hold
back the exhaust with a rag and someone to look. It will show alot easier
with the smoke if there is one.But the noise seems to go away in gear and an
exhaust leak would be constant.http://www.ericthecarguy.com/faq/diagnosing-noises-in-your-car?start=7#ExhaustNoises
The CEL lit up as I cranked the engine, and after it fired up the ABS light came on momentarily. I believe both of those are bulb checks?
The knock noise goes away, yes, but the rough idle does NOT. If anything, it is more pronounced when in gear. We’re getting a bit of a heat wave tomorrow, so it won’t be cold enough for visible exhaust condensation for a few days. Could shifting of the engine make an exhaust leak come and go if it was leaking at a gasket between the manifolds and the downpipes? You can’t hear the leak at idle, either.
I got an extremely strong fuel smell inside the cab this morning. The plastic fuel line connecting the two fuel rails had cracked and was leaking fuel all over the intake and the driver’s side valve cover. That could’ve been REALLY BAD. That is getting replaced tomorrow with a proper rubber line, and the vehicle isn’t getting driven until then.
The audible exhaust leak has become louder. It’s much easier to hear, and locate. It is most certainly somewhere on the passenger side manifold. Is this leak most likely to blame for the rough running?
The rough running could also be the leaking fuel line.
see what happens when the fuel line gets fixed.Fuel line is fixed. No more potential rolling firebomb! 🙂
However, the problem remains. I noticed tonight that even when idling in open loop, dead cold, that the problem persists and is arguably worse than when the engine is warm. If an exhaust leak confusing the upstream O2 is to blame, wouldn’t it idle smoothly in open loop mode?
Update: I got a flashing CEL today while accelerating from a stop, up a steep grade, at about 3/4 throttle. When I hit 3500 RPM the light flashed four times. No codes.
[quote=”LJ11194″ post=120129]Update: I got a flashing CEL today while accelerating from a stop, up a steep grade, at about 3/4 throttle. When I hit 3500 RPM the light flashed four times. No codes.[/quote]
The flashing means your misfiring and to much raw fuel is going to the cat.
That’s what I believed, but I wasn’t sure. I thought that it would leave a pending misfire code in the computer.
I’m still confused, though. If the exhaust leak is making it run poorly, why do the fuel trims and O2 readings look normal?
I’m considering seafoaming it to make the leak much more apparent. At this time I’ve yet to find it but it sounds like it’s between the manifold and the head. Donut gaskets would be far preferable, though.
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