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Smokey exhaust at an idle

Sent to Car Experts August 20 08:03 PM

I have an 03 Dodge Ram 3500 with a Cummins. 380,000 mi. Fuel consumption is the same as always and power the same as always, however when the engine is at operating temperature and idling (or trying to idle) a continuous cloud of blueish smoke comes from the tailpipe. This smoke smells of unburned diesel fuel and burns your eyes and nose. (When waiting at a traffic light people around me start rolling up their windows) If you bring the engine up to 1600 rpm or more the smoke goes away as well as the smell. When the engine is cold there is no smoke until the engine begins to warm up and the hotter the engine is the worse it smokes. Driveability is as always however when coasting to a stop and the engine is at @ 1200 rpm an unusual pinging starts in like the timing is too far advanced or too much fuel is going through. Also the engine will rarely idle at its normal 700 rpm but would rather idle @ 1000rpm. A Dodge dealer and injection shop checked the injectors by their computers and claimed they were all working and couldn't give me any real answers. I read once that a faulty engine temp sensor can cause the computer to add a lot of extra fuel at an idle (no codes come up and Dodge dealer thinks that only applys to gas motors) or do I have an injector(s) hung up or what????

P.S. I should mention that oil consumption has not changed. Many times I go a complete oil change without adding even one quart. Even though diesel oil is black it doesn't have a thick and heavy look to it which means it would be carrying a lot of soot. Blowby is not a problem.

Edited by Customer (name blocked for privacy) on August 21 2006 at 8:19 AM

 

Optional Information:
2003 Dodge 3500 ram 5.9 Cummins

Customer (name blocked for privacy)
Status:  Closed   Value: $13
Reply
August 21 9:22 PM (1 day and 1 hour later)
         
Relist: No answer yet.
I don't know what else to say other than it is running very rich at an idle and runs normal when at operating speeds. There has got to be a reason for this but the big question is - WHAT? This all started quite suddenly. It started one day last December but wasn't too bad then it went away. Maybe a month or two later it started again and never quit.
Can an injector that's stuck open in a common rail system cause this?

Edited by Customer (name blocked for privacy) on August 22 2006 at 6:31 AM
Customer (name blocked for privacy)
Answer
August 22 7:32 AM (10 hours and 10 minutes and 42 seconds later)
         
REPLIEDCheck Mark
If you had a stuck injector the vehicle wouldn't run as well as it does and fuel consumption would be up.

I do believe your vehicle has a MAF sensor at the air filter housing. Once the problem occurs, unplug the wiring plug from the sensor and see if this clears it up any.

My next port of call would be to get the engine hot, switch it off, unplug the wiring from the coolant temp sensor and either bridge the terminals with a wire or, with a 100 or 200 ohm resistor or thereabouts.

This will cause the ECU to turn down the fuel and if this works then you have a faulty coolant sensor.

Let me know how you get on.

Cheers

Geordie

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Geordie -- Mobile Mechanic & Motor Trader -- 98% Positive Feedback on 216 Car Accepts
22 years of mechanical experience, and I am the mechanic in my own automotive partnership
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August 22 3:15 PM (7 hours and 42 minutes and 3 seconds later)
         
Reply to Geordie's Post: Hey Geordie,
The only thing I could tell from disconnecting the MAF was the check engine light came on. The coolant sensor however seemed to make the engine run quieter to begin with than suddenly started knocking like crazy on one cylinder and the exhaust was blowing smoke rings all over the yard. Could one cylinder be causing all this? Again I go back to a hung up injector or do I have a bad intake valve - pushing unburned gases back into the intake manifold and thus into other cylinders? I can't hear anything that sounds out of the ordinary as far as valves go. I'm also detecting a miss at an idle - not under power. That thing gets up and goes like a scared rabbit!

Will be gone for the rest of the day so will check back tonight.    Thanks, Gary
Customer (name blocked for privacy)
Answer
August 22 4:04 PM (49 minutes and 14 seconds later)
         
REPLIEDCheck Mark
Hi

Before we go any further, disconnect the battery negative wire for a few minutes so that the ECU resets because there will be 1 or 2 fault codes in there now after disconnecting the MAF. There is also a very slim chance that this may make things a little better but we will have to wait and see.

Meanwhile, it is very possible that one cylinder could cause these problems to a degree.

Is your engine turbo charged? I believe Cummins did a turbo charged and a normal aspirated engine.

I also have a gut feeling that your engine may well also be equipped with a MAP sensor as well as the MAF sensor which you tested earlier. Would my gut feeling here be correct?

Geordie

Edited by geordie512 on August 22 2006 at 4:19 PM

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Geordie -- Mobile Mechanic & Motor Trader -- 98% Positive Feedback on 216 Car Accepts
22 years of mechanical experience, and I am the mechanic in my own automotive partnership
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August 23 12:00 AM (7 hours and 56 minutes and 13 seconds later)
         
Reply to Geordie's Post: Geordie;

Just got home and it's 2300 hrs. I wouldn't be doing anything else tonight but yes, it is turbo charged and yes, there is a map sensor. I will do as instructed to reset the ECU in the AM. Thank you.

Goodnight,
Gary
Customer (name blocked for privacy)
Answer
August 23 7:32 AM (7 hours and 31 minutes and 59 seconds later)
         
REPLIEDCheck Mark
No worries.

Sleep well.

Geordie

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Geordie -- Mobile Mechanic & Motor Trader -- 98% Positive Feedback on 216 Car Accepts
22 years of mechanical experience, and I am the mechanic in my own automotive partnership
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August 23 10:45 AM (3 hours and 12 minutes and 34 seconds later)
         
Reply to Geordie's Post: Hi
I disconnected both ground cables for about a half hour - engine light is still on but I think it will also go out after a certain number of times of starting the engine.

I have to leave for on the road now and don't know my return time - however any info you send will be relayed to me and vice versa.

Later

Gary
Customer (name blocked for privacy)
Answer
August 23 11:54 AM (1 hour and 9 minutes and 10 seconds later)
         
REPLIEDCheck Mark
Unfortunately, absolutely everything about your engine apart from the valve timing is electronic.

The injection timing is determined from inputs from the MAP, CKP, CMP, APPS.

If the Check engine lamp is illuminated, have the codes read out, it may well point to one of the above sensors, and my money is on the MAP sensor.

Regards

Geordie

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Geordie -- Mobile Mechanic & Motor Trader -- 98% Positive Feedback on 216 Car Accepts
22 years of mechanical experience, and I am the mechanic in my own automotive partnership
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August 24 9:11 PM (1 day and 9 hours later)
         
Reply to Geordie's Post: Hi,
I talked to Gary and he said that the engine light no longer stays on. However there is a code of 0073 that is still in the system. He wasn't sure if that happened because of following your diagnostic instructions or if it is a true code on its own. He did talk to a Dodge dealer and they said the MAP sensor and a temperature sensor are sold together-they can't be purchased seperately. He is curious as to why that is---
Customer (name blocked for privacy)
Answer
August 25 5:44 AM (8 hours and 33 minutes and 39 seconds later)
         
REPLIEDCheck Mark
Thats a reference to the ambient air temperature sensor having too high a circuit, which probably means that the signal voltage to the sensor is over 5 volts.

Check the input wire to the sensor and tell me what voltage is going into it.

I am looking into the both sold together scenario as we speak.

Geordie

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Geordie -- Mobile Mechanic & Motor Trader -- 98% Positive Feedback on 216 Car Accepts
22 years of mechanical experience, and I am the mechanic in my own automotive partnership
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September 19 11:18 AM (25 days and 5 hours later)
         
Reply to Geordie's Post: Hey Geordie,

It's Gary here with the 03 Dodge Ram. I just got back from an 18,000 mi run. The map sensor is not the problem. I replaced it and within one minute it was noticable that nothing had changed.

Now here's something else I forgot to mention but was reminded of as I went thru the mountains. Pulling the grades was no problem as I mentioned before - full power, however desending on grades of 4 to 5% there is a constant surging - like the engine doesn't know at what speed to be running at - pretty much like at an idle.

Does this give you any more clues?


Let me know,
Gary
Customer (name blocked for privacy)
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September 20 11:03 PM (1 day and 11 hours later)
         
Relist: No answer yet.
Customer (name blocked for privacy)
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September 22 9:59 PM (1 day and 22 hours later)
         
Relist: I still need help.
Customer (name blocked for privacy)
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September 25 8:20 AM (2 days and 10 hours later)
         
Relist: No answer yet.
Customer (name blocked for privacy)
Answer
September 27 3:34 PM (2 days and 7 hours later)
         
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Geordie -- Mobile Mechanic & Motor Trader -- 98% Positive Feedback on 216 Car Accepts
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