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1998 Dodge Ram 2500 4x4 rough idle at operating temp
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dodgeram1998
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Dec 27, 2008, 6:25 AM
Post #1 of 8
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1998 Dodge Ram 2500 4x4 rough idle at operating temp
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I have a 1998 Dodge Ram 2500 4x4 with a 360 engine. It starts fine, idles fine for the first few minutes, you can even drive it down the road for the first few minutes until it gets to operating Temp. and then it spits, sputters, backfires, and the RPM gauge jumps up and down. It only does this for abou 3 or 4 miles and then it runs fine the rest of the day, until it sits and gets cold again after a few hours, then it starts all over again. New tune up has been done along with fuel additives and coolant sensor has been replaced. Computer has been hooked up and no faults or codes found. Please advise.
(This post was edited by dodgeram1998 on Dec 27, 2008, 6:30 AM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 27, 2008, 6:39 AM
Post #2 of 8
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Re: 1998 Dodge Ram 2500 4x4 rough idle at operating temp
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This may be a tough one as it seems it's going to behave with any testing.
Ideas: How far does RPM gauge read? Is the reading credible for what the engine is doing?
Does it ever have a good day - drier days, anything?
Perhaps cam or crank sensor is sending bad info about engine speed and for that time other engine controls are making adjustments based on bad info but credible info as no codes show.
It may need a more comprehensive code reading than what you have to be more accurate with the fix the first time,
T
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dodgeram1998
Novice
Dec 27, 2008, 6:59 AM
Post #3 of 8
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Re: 1998 Dodge Ram 2500 4x4 rough idle at operating temp
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The RPM's only jump to abou 3,000 and that is pretty close to the idle when it happens. Not sure about good days, i live in MI and haven't had it long enough for dry warm weather. I purshased it a few weeks ago from a mechanic who just rebuilt the engine. He is the one who hooked the computer up to it while we drove it, ofcourse this was after it had acted up for the day. The Temp guage was rising to the red before i changed the coolant sensor.
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Tom Greenleaf
Ultimate Carjunky
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Dec 27, 2008, 7:54 AM
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Re: 1998 Dodge Ram 2500 4x4 rough idle at operating temp
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Hmmm? Book gets opened with a recent rebuild or extensive work as so many things get touched. The person who did this work will know best what was new, reused, and all the things that were disconnected - connections can be the issue.
It seems temp related and you already replaced the sender for temp gauge but there should be another that tell the computer what the engine temp is to make adjustments as well. The plug and sender should look like this one for identifcation......
These things can just be the plug and wires NOT the part. With no easy codes showing it suggests you are getting credible but WRONG info for a period of time during warm ups.
Question: IYO - was it really overheating or did it just say so? You said you replaced the sender and it's fine now and that might have been just a connection/wiring fault too.
Seems like the common clue is temp sensitive - otherwise fine - right?
T
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dodgeram1998
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Dec 27, 2008, 6:02 PM
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Re: 1998 Dodge Ram 2500 4x4 rough idle at operating temp
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The plug in the picture is the one i replaced. The truck wasn't actually overheating, it just read that it was. Also, when the temp gage jumped to the red, the overflow tank squirted out a small amount of antifreeze. It just seems to only mis and spit, when it is just reaching operating temp.
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Tom Greenleaf
Ultimate Carjunky
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Dec 27, 2008, 6:33 PM
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Re: 1998 Dodge Ram 2500 4x4 rough idle at operating temp
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Ok - if you took a poll of techs with a temp gauge in the red and the recovery tank is overflowing/spitting - my guess is they'd all say it was in fact overheating!
The sensor shown if I caught the correct one is for Coolant or Engine Coolant Temp Sensing - listed as CTS, or ETS - there to tell the vehicle to enrichen fuel mixture when cold really. The gauge is almost certainly another sender - not this one.
In that this was just purchased and so called "rebuilt" engine from a mechanic who did that work I really suggest you take it back for inspection and the fix. Don't allow it to overheat getting it there either. Make certain proper antifreeze-coolant mix is full at radiator first and at proper level in the recovery tank. A good clue of engine temp is running heater and it should stay blowing warm and not vary much. If/when they go cold it could be boiling which won't throw heat - a real sign of air or boiling at that point,
T
(This post was edited by Tom Greenleaf on Dec 27, 2008, 6:37 PM)
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dodgeram1998
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Dec 29, 2008, 11:30 PM
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Re: 1998 Dodge Ram 2500 4x4 rough idle at operating temp
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Well, since replacing the coolant sensor, it hasn't jumped to the red as far as the overheating situation, normal temp and hot heat. I have also noticed that the rough idle no longer pertains to just when it reaches operating temp. It now does it sometimes when you first start it up and then drive without warming it up. As before, it only does it for a few miles then straightens out. Maybe throttle position sensor?
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Tom Greenleaf
Ultimate Carjunky
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Dec 30, 2008, 7:32 PM
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Re: 1998 Dodge Ram 2500 4x4 rough idle at operating temp
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Just so I/we know - who is taking responsibilty for the engine rebuild? If this is all yours now then so be it and let's figure it out.
I still think you saw an overheat that was real even if for just a moment. Guessing of course but I suspect there was vapor/air of some kind in the engine for reasons yet unknown.
In replacing either sensor it probably burped out any air, and in refilling with coolant was better again but a problem still lurks.
Just how did you replace the sensor? Drain coolant low enough or just unscrew it and put a new one in? How did or are you verifying coolant level if truely full in engine - not just recovery tank. For now - having heat working is highly suggestive of being at least close to properly full on engine side of thermostat.
I'm just speculating on what might be an issue with a recent rebuild that had a full tune up according to you.
Not to worry just yet but I suspect that a gasket isn't seating quite right - but close allowing an issue with coolant - perhaps combustion gasses at a certain temp can get into coolant yet not burn thru but a cylinder or more is struggling with imperfect conditions to run smooth - just a guess for the moment,
T
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