I started having this problem in the dead of winter. Started with a miss, smoking bad, warmed up and ran fine. Then, when working the truck HARD in the winter, it went into a limp mode(?) up a mountain. (plow on front, 1 ton in the bed, and a 12,000 lb trailer up a 6% grade for 3 miles). Seems better now, but even at 70 degrees air temp, it still smokes and misses when starting. Let it warm up and it does OK, but not great. Stumbles at speed, seemingly below 1500 or so RPM. Took it to a dealer, he drove and ran the codes, nothing came up but MAP sensor. Sound right?? just want to make sure, and I dont want to hurt this truck<br><br>thanks for the help

 

it's possible that the VP-44 isn't working right. have you checked your fuel pressure? maybe a pcm reflash needs to be done.<br><br>Tom

 

Whacha mean &quot;nothing came up but MAP sensor??&quot;<br>Mebbe your Map sensor is cooked?? :<br>Try one off another truck like yours. If it cures it than you need a MAP, if not keep looking....

 

If your white smoke is being generated when the engine is fully to operating temperature, I suspect either a blown head gasket or a cracked head. Neither are that uncommon on a rig pushed a bit and worked really hard. Get an oil analysis and look for coolant in the oil.<br><br>The general rule of thumb for any diesel that is fully at operating temperature is that white smoke is from low compression. Black smoke is from not enough air.<br><br>If you smoke is more blue than white, then I would suspect your manifold absolute pressure (MAP) sensor, or the the crankshaft position sensor (CKP) need attention/replacement. Sometimes the intake air temperature (IAT) gets a bit of grime and will cause a stumble.

 

No, not any coolant in the oil, cleaned the MAP and the IAT, no difference. It does have power when it's at operating temperature, but the stumble is somewhat common. Kinda feels like something is plugged up, cause when it happens, if I punch the throttle, it snaps right back to normal.<br><br>What I meant by the only thing that came back was a MAP sensor code is that the dealer mechanic (I'm still looking for a decent shop out here) &quot;hooked up the computer and drove it around&quot; and that was the only error code that came up. He told me that I would need to replace the sensor, and if that didn't do it he could check further. Is he snowing me?? I'm not really too wise to diesels, this is my first one.<br><br>thanks again, I'll try the fuel pressure and CKP also.

 

The computers in these are pretty smart, and if a MAP error code is being generated I would look seriously at replacing the thing. The white smoke has me puzzled, because that is clearly a sign of low compression. <br><br>I do not know where you are located, but I never take any of my stuff to the dealers for anything other than a parts swap under warranty. I would pay the genuine Cummins guys to run diagnostics and check on your problem. Go to www.Cummins.com and find a real Cummins Service Center in your area. <br><br>If you are out of warranty, most of the basic sensors and such are readily available from Cummins at significantly less cost than through DC.

 

FYI- When I had white smoke and low power it was diagnosed @ Cummins with a hole in the wastegate vaccume actuator. It could also be the VP-44 is on it's last leg.<br><br>Just my .02 from my experience.

 

Ok, I got 30k on my 01 2500, never cleaned the map or the iat. Experienceing loss of power and a new fuel fuel filter made a world of difference... I've heard that cleaning (or replacing) those sensors can be the culprit. WHere are they, whats the best way to clean them? WIll brake cleaner work, or electronic contact cleaner? Woiuld replacement be a more feasible answer given cost, time and peace of mind? Help me out here guys, sorry I'm off the subject someone else mentioned the sensors and I thought it a good time to bring it up. -Dave

 

MAP sensors have two &quot;sides&quot; to them. One is the mechanical side and the other is the electronic side. If the mechanical side is &quot;dirty&quot; (screen is clogged) it can be cleaned. If a fault lies in the electronic side, only a replacement will work. Many times no code is thrown but the MAP is still cooked. And sometimes one computer code can be hidden behind another one. I think that is why the tech said to try a MAP and then see if any other codes develop. HTH<br>