96 RAM 3500 Van sputters and smokes at 40mph
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Joined: Jan 2008
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96 RAM 3500 Van sputters and smokes at 40mph
1996 Dodge RAM 3500 Van - 360 motor Auto trans
I have been wrestling with this problem for months now.
I bought this van (used 136,000 miles) and it ran GREAT for a month or so. Then it started to sputter and lose power while driving when this first happens, it smokes a little, and constantly smells like a thick exhaust smell (not a rich-gassy smell). This was a sporadic thing. Never shut off completely, but once it started to have the problem, it wouldn't stop until it was turned off and cooled down.
It was not overheating. When I start it, it runs fine and I can idle it for long periods of time in the driveway with no problems. I can also drive it around the neighborhood at about 20 miles per hour with no problems, but once I hit 40 mph, the sputtering starts again.
The check engine light used to come on and the codes said "multiple misfires". I had it checked out with a diagnostic computer and although the mechanic thought it was fuel-related, he said the fuel system was fine. After driving it around with the diagnostic machine attached to it, all codes were fine while it was running fine, then suddenly when it started to misfire the codes went crazy. He suggested a new computer. We looked around and none were to be found. We finally found one at a rebuilding place and bought the new(rebuilt) computer.
The van drove fine for a day and then WHAM! back to the same problem.
We have replaced, cap, rotor, plugs, wires, ECM and nothing has made a difference.
I've read in a lot of forums where these symptoms are related to either a catalytic convertor or to the fuel pump. Today, I removed the cat and replaced it with straight pipe, just to see if it would make a difference, but, nope, nothing has changed.
Any suggestions?
I have been wrestling with this problem for months now.
I bought this van (used 136,000 miles) and it ran GREAT for a month or so. Then it started to sputter and lose power while driving when this first happens, it smokes a little, and constantly smells like a thick exhaust smell (not a rich-gassy smell). This was a sporadic thing. Never shut off completely, but once it started to have the problem, it wouldn't stop until it was turned off and cooled down.
It was not overheating. When I start it, it runs fine and I can idle it for long periods of time in the driveway with no problems. I can also drive it around the neighborhood at about 20 miles per hour with no problems, but once I hit 40 mph, the sputtering starts again.
The check engine light used to come on and the codes said "multiple misfires". I had it checked out with a diagnostic computer and although the mechanic thought it was fuel-related, he said the fuel system was fine. After driving it around with the diagnostic machine attached to it, all codes were fine while it was running fine, then suddenly when it started to misfire the codes went crazy. He suggested a new computer. We looked around and none were to be found. We finally found one at a rebuilding place and bought the new(rebuilt) computer.
The van drove fine for a day and then WHAM! back to the same problem.
We have replaced, cap, rotor, plugs, wires, ECM and nothing has made a difference.
I've read in a lot of forums where these symptoms are related to either a catalytic convertor or to the fuel pump. Today, I removed the cat and replaced it with straight pipe, just to see if it would make a difference, but, nope, nothing has changed.
Any suggestions?
Van & CUV Section Moderator
Joined: Nov 2006
Posts: 5,379
Likes: 116
RE: 96 RAM 3500 Van sputters and smokes at 40mph
I have three thoughts. One, your fuel pump is weak and not supplying sufficient flow at higher engine loads. Two, your speed sensor is failing at higher speeds. Three, the throttle position sensor has dead spots on it.
Since your problem seems to be tied more to speed than engine RPMs, I'd first look into the speed sensor.
Since your problem seems to be tied more to speed than engine RPMs, I'd first look into the speed sensor.
