Since I got no responses to the last post I will try again with a few more findings. First off we are refering to a early 99 w/5 speed. Truck has exhaust brake and power chip. The truck runs like a mad man after first starting it and runs the same until the truck gets to within about 100 yards of where it acted up the day before. So in short when you get to that spot in road just get ready. Seems like truck goes to de-fuel mode as it has about half power. And as the temp warms up more as the day goes by it gets more frequent. But you can let it drop back to idle and it will come alive for about 6 to 10 miles in relation to outside temp. Mechanic (#9 or10) says that the computer is saying that a air intake sensor is showing to be the cause. He seems to think the aftercooler is stopped up(with what?) or leaking. I know that if I install a boost gauge and egt gauge I could probly narrow it down a little better.<br><br>Now my questions are<br>#1 Where is the IAT sensor located, and can it be cleaned?<br>#2 Between IAT and MAP (or boost sensor) which would be more effected by heat?<br>#3 can the fan clutch not working properly bad cause this but not make the engine temp rise?<br>#4 Can a fram air filter cause this. Going to run just short distance without it tomarrow to see if it's the cause.<br>#5 Can both sensors be cleaned and reinstalled?<br><br>About broke just throwing parts at it. Hard to pay for one that won't pull the load literaly. Please help!!! Thanks!!

 

It sounds like my truck is doing the same thing. Mine is also a '99 with 5 speed. I just purchased it a couple of weeks ago, so I have not had a chance to dig into it. I am hoping it is due to low transfer fuel pressure. I have not tested but plan to do so soon. <br><br>Anyway, I first noticed the situation 20 minutes after signing the check at the used car lot. I was going down the highway at 70 and got on it to pass a car and lost power. It gradually dropped down in speed and would not go faster than 50 with the pedal fully depressed. After shifting into neutral for a few seconds and letting the truck idle it was fine after shifting back into gear. This happened a few more times on the 100 mile trip home. Seemed to be a problem with the fuel so I replaced the fuel filter. It was clean. No change. I noticed it acts up anytime I get on it and let the turbo to spool up. Not really sure engine temperature has anything to do with my situation.<br><br>Well, I wish you luck and hope you will share what corrects the problem.

 

hmm.... sounds like it could be a crank, cam, or iat sensor problem sounds a lot like a cam or cranksensor problem though 35 bcks each from cummins.<br><br>DRecu!

 

Binderman...I am assuming from your post you are experiencing loss of power and performance? The most common symtoms, that cause this is the three things you described. #1. boost leakage, #2. bad map sensor, and #3. dirty IAT sensor. Boost leakage, normally occurs in the hose connections below the turbo (2) of them on the high pressure side of the intercooler. Make sure hose clamps &amp; hoses are securely fasten. Sometimes, the hose slips from under the clamp and will cause leaks! The map sensor controls fueling, in relationship to boost, and is located on the drivers side of the engine block, just behind the fuel filter. There is a two prong wire connector that connects to it. I would save replacing that as the last resort. Next is the IAT sensor, which is located, approx. 6 inches behind the Map sensor. The IAT sensor is a resister type sensor, which also controls fueling as determined by the engine temp. If the engine is cold, the sensor will transmit information to the ECM to add more fuel. If the engine is hot, it will send information to cut back fuel. Since you indicated you have a exhaust brake, the IAT sensor is more prone to &quot;soot-up&quot; and give false readings of temp. to the ECM. Most people will experience a decrease of fuel mileage with a pluged IAT sensor. The IAT sensor, can be removed and cleaned. There is also, a chance there is a leak in your intercooler. As far as blockage in your intercooler, the only possiblity would be, if you blew-up a turbo, and pushed oil and turbo debri in it? A Boost gauge would help to determine any boost loss. I would first check boost leaks in the system, remove and clean the IAT sensor, before going to the Map sensor. I hope this helps, as I'm not there to fully analyis the problem over the inter-net.

Steve

 

Binderman, Two things come to my little mind. From the Turbo to the intake is a long way really, a lot of it is made of plastic...wonder if there could be a crack opening up when things heat up and become plyable(sp?). If one or more of the clamps were over tightened it could crack the plastic pipe.<br><br>The other thing, have you made sure your not pulling vacumm on the fuel tank? Could be that the little cap was left on the breather from the factory.<br><br>It'l be interesting to know what's wrong.<br><br>Good luck,<br>Sned.

 

[quote author=jdeereboy link=board=4;threadid=14231;start=0#133784 date=1051752655]<br>It sounds like my truck is doing the same thing. Mine is also a '99 with 5 speed. I just purchased it a couple of weeks ago, so I have not had a chance to dig into it. I am hoping it is due to low transfer fuel pressure. I have not tested but plan to do so soon. <br><br>Anyway, I first noticed the situation 20 minutes after signing the check at the used car lot. I was going down the highway at 70 and got on it to pass a car and lost power. It gradually dropped down in speed and would not go faster than 50 with the pedal fully depressed. After shifting into neutral for a few seconds and letting the truck idle it was fine after shifting back into gear. This happened a few more times on the 100 mile trip home. Seemed to be a problem with the fuel so I replaced the fuel filter. It was clean. No change. I noticed it acts up anytime I get on it and let the turbo to spool up. Not really sure engine temperature has anything to do with my situation.<br><br>Well, I wish you luck and hope you will share what corrects the problem.<br>[/quote]<br><br>Jdeereboy,<br><br>Your problem sounds like a bad Boost/map sensor. My truck did the same thing when my first map sensor went bad. I would first take the connection loose and spray some contact cleaner in the end of the sensor. That may clear up the problem. If that doesn't work I would try and replace the sensor. If you have a Cummins shop near by they will be able to hook it up to the computer and find the problem in about 20 minutes, but if not I'd sure say it sounds like a Map sensor to me.<br><br>Here is the Cummins part # for a 99 Boost/Map sensor #3348747. One word of advise Cummins will probable call it a Pressure Sensor.<br><br>Hope that helps.<br><br>DB<br><br>

 

Just a little update for all that provided info trying to help me with the problem I was having. I cleaned the IAT sensor and reinstalled and so far the truck has only powered out twice. Think the sensor needs to be replaced? I did'nt have a 32 mm deep socket to remove and claen the MAP, and also wanted to clean one at a time and then test so I could tell what effects each part has on the truck/problem. Thanks to all very much with ALL the help on my problem so far. After spending a chunk of money over about a year, a 1/8 can of ether has done more than the 8 or so mechanics/dealers have done. The internet is the best tool in my box!!! Gettin closer!!! Thanks again guys!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!