Engine/Transmission (1998.5 - 2002) Total loss of boost!!!!!!!!

[bsappington]

This evening I was driving back from the mountains with a trailer at about 5000 lbs. Just before I got to the house I lost all of my boost pressure. There is nothing on the gauge. It jumped to about 20 psi once or twice then nothing. When the pressure spiked the truck came to life, but now it is a dog. Must be what driving a regular truck is like. I thought it might be the boots for the charge air cooler, I checked them and they looked O. K. however it is dark and I will look better tomorrow. I believe I can hear the turbo spinning and will check to see if it is free in the morning.



Any advise would be helpful,



Ben

 

[ToolManTimTaylor]

It jumped to about 20 psi once or twice then nothing. When the pressure spiked the truck came to life, but now it is a dog. Must be what driving a regular truck is like. Ben

Check the plug that goes into the back of the Ottomind. If it comes loost iw is like flicking that fuel on an off like a light switch. Speaking of fuel how's pressure?

 

[SS]

Try this thread loss of boost - one of the bolts that holds the clips for the fuel lines may have come out. It happened to at least 2 of us. Doesn't seem like enough to totally lose boost, but mine sure was a dog with it missing. Good luck finding the problem - make sure you post when you do.

 

[ToolManTimTaylor]

Yeah that could be as well. However the power came back on strong again in spots, and that ottomind is like having a comp on 1X2 all the time 24-7. If the connector is loose the map sensor will see real boost and see that it is higher than 20 lbs and bang the cummins ecm will defuel to keep you down under 20 lbs.



Side note must replace batters in wireless keybrd

 

[bsappington]

Thanks for the reply,



This is what I know now. None of the boots have been damaged or blown off. I checked for loose or missing bolts on the fuel system and around the intake manifold, I could see nothing wrong there. I pulled the Ottomind out and removed the barrel plug to check the connections and nothing appeared to be wrong there. I removed the rubber boot from the air filter and checked to see if the turbo was spinning. I also started the truck and found that at idle the turbo is spinning and sucking air. This leads me to believe that maybe the map sensor is bad. If not the map sensor then maybe the waste gate. I believe that it is the map sensor because I get no movement from the gauge at all.



I almost forgot due to the pusher pump my fuel pressure changes sometimes. It is between 15 and 25 psi.



Thanks,

Ben

 

[bsappington]

I just connected the OBD-II computer to the truck to find any codes, there were none. however upon watching the out put of the map senesor it read 29. 9inhg. upon starting the truck this value did not change. When I throttled up the truck I could hear the turbo spool up but there was no change in the value from the map sensor. I removed the sensor and cleaned it and still there was no change. Upon contacting Napa they tell me they do not have a part number for the map sensor, that it is probably a ******* item. They are probaly real proud of it to. Does this seem like I am on the right track? or am I going in the wrong direction.



Thanks,

Ben

 

[WestTN]

You will probably need to build a little boost to see it. You are basically seeing just atmospheric pressure. The engine won't buld boost just by revving it up a little, it will need a load on it.

 

[bsappington]

Even when having the truck in drive and holding the brakes then putting the pedal to the floor there is no change in the readings from the map sensor. The engine would usually light the back tires up now it does not do anything.

 

[ToolManTimTaylor]

Be careful when doing that. It sounds like you still have a stock input shaft and stock trucks can break them easily when powerbraking. The fact you are seeing 30 lbs is odd. The "Fooling" circuit of the ottomind tell the ecm that there is 20 lbs or less as boost goes over 20 lbs. That IS odd you are seeing the exact opposite. Is the harness O. K for the Otto? For some dang reason your truck could be in Limp (No Check Enging Light which again is odd), Have a stuck open wastegate , or a DOA Vp44. When you do Power brake it does it build any boost at all? And is it 100% in First gear? (Possible 2nd gear start kind of thing)

 

[bsappington]

In the OBD-II I am seeing 29. 9 inches of mercury. Off the top of my mind I can't remember what that is in pounds per square inch. When the engine isn't running. It does not change when I start the engine, throttle up, or apply load to the engine. Since I am doing this myself it is not possible for me to see what the turbo is doing, however I can hear it whinning. If there are no known leaks it has to be the map sensor unless the waste gate could bypass enough of the flow so the turbo could not create power. I will just have to by a new map sensor from the ******* tomorrow.

I will keep you informed.



I try not to power brake it to much my wife hates when I have to buy new tires.



Thanks,

Ben

 

[bsappington]

After consulting my conversion program I found 29. 9 inches of mercury to be the same as 14. 68 psi starting from absolute 0. So atmospheric pressure.

 

[Steve St.Laurent]

You can get a MAP sensor from any cummins shop - it'll be cheaper than at a dealer. 29. 92 is "standard" pressure at sea level - aka 0 psi.

 

[I-6DZL]

it doesn't sound like a dead map sensor to me. If the map is dead it just wont let the factory computer know manifold absolute pressure. You're looking at a manual boost guage right ?? If the guage reads zero, then you have absolutely NO boost. Sounds like you have a hole in your intercooler. I know you checked all of your boots, but you need to double check them. Actually grab the boot itself and try to twist it, if it turns you have a leak at that location, fix it. Feel each boot for holes imperfections, buldges etc. any of the above and the boot is bad, fix it.

Just a thought here, but i don't see why you cant pull the boot off of the tube going into the air horn, plug it off with a rag (not the air horn, but the pipe coming for intercooler) start truck and power brake again. This should give you an idea of where you're losing the boost pressure at.



good luck

Curtis

 

[szumilas]

Check your exhaust manifold for loose bolts. I had a similar problem a few months ago. I lost the 2 rear exhaust manifold bolts and I had no boost. The manifold was whistling real bad as the pressure would vibrate the manifold gasket. There is a TSB for manifold bolt locks to be installed, if your truck did not come with them stock.



just my $. 02

 

[bsappington]

Problem solved!!!!!!!!!!!! Oo. Oo. Oo. Oo.



Thank god it was just that the map sensor was bad. $122. 00 to the ******* and she's back on the road. My wife thought there goes the tax return. I would like to thank everyone for there input. I learned alot this time around.



Ben