1998 Dodge Truck Problems

Old 05-18-10, 08:19 PM
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1998 Dodge Truck Problems

1998 Dodge Ram 1500 4x4
318 V-8, Auto Trans
Bought this truck last week. It had sat un-used for a few months. Ran excellent. Plenty of power, no problems. Second day we had this the check engine light came on. Took it in for a scan and the mechanic said the downstream O2 sensor (after the converter) was bad. He said that it could be showing bad from sitting. The next day the light went out, so we figured we would wait for a bit before changing the sensor.

A couple of days later we went on a trip. After driving for about 1/2 hour or so, the engine would occasionally ping as we went up hills. Then the check engine light came on again and would occasionally flash. Then it started pinging and dieseling more. We arrived at our destination 2 hours later and by that time the truck was starting to run kind of rough. As we started on our way home, the truck ran worse and worse, even to the point that we were worried about getting home. It had little power and was using a lot of fuel. We stopped at the next town we came to and checked with the local Dodge dealer. The diagnosis was a clogged catalytic converter. Of course this was a Saturday afternoon and there was none to be found, so we continued on our way home. I did punch a hole in the converter to release some back pressure.

The dealer said that when there is a major problem that the computer goes into a "limp" mode, that will allow you to continue driving until you can get some help.

Today I put a new converter on it, and both new O2 sensors. The truck ran much better but still not as smooth as before. So, that's the story. Now the questions.

1. Does the computer have to be reset? We unhooked the battery while we put the new converter on, and the check engine light has not come on since we put the new converter on. Will it stay in this limp mode until it is reset, or until it is started a number of times?

2) Could a clogged converter damage the spark plugs? I checked one and it was nice and tan the way they are supposed to be.

Any info will be appreciated. I think I am going to put new plugs in tomorrow, but is there anything else that I should check?
Old 05-19-10, 03:27 AM
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Driving in such a poor condition certainly carbonized up the cylinders, valves and plugs. As you indicated it was using more gas, so it was not detonating properly and had to deposit itself somewhere. You may opt to just run it for a while to see if the normal aspiration will help clear it up, or you could go in for an injection cleaning which will also help clean carbon from the internal parts. Even though the CEL is not on, the computer could have stored some codes. Have the codes checked again and have them clear the codes. It couldn't hurt and may help.
Old 05-23-10, 12:56 PM
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Go a parts store and have them reset the computer with the scanner. I had the lights go on for the CO2 sensors on my 99'. I only have 48,000 miles so...might not be the exact situation.

I would look into doing a tune up. I would pull the plugs and see what they look like. If there a carbon mess replace them and the wires.
Old 05-23-10, 05:30 PM
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The computer should take itself out of limp mode based on readings from the sensors. The computer is constantly learning. It adjusts settings based on recent driving activity.

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