I've always felt as if something was just "kind of " holding me back a bit when pressing on the peddle but being a new diesel owner I was to dumb to know different. Yesterday after work I took some time and removed the vacuum hose from the Map Sensor. The hose connection to the manifold end was as hard as a rock, probably original hose. Finally got it off and blew in the Map Sensor end of the hose and out dislogged a bunch of hard gunk. Replaced the vacuum hose with a new one I had on hand.

I always thought my truck ran pretty good ... wrong. What a difference now, much more push in the seat. First time I've been able to hear my turbo spool and cruzing freeway speeds I need to back off on the peddle considerably or it just keeps going faster.

Oh, I tried the 10K mod a while back but took it out for poor performance so think I'll put it back in again now that the Map Sensor is functioning.

 

Good info, I may have to try that on mine as well.

 

the crud build up is oil that entered the intake via the ccv, the ccv mod will elmiinate that problem as well

 

Thanks "cOOn", that is on my list for this weekend of to do things. In April I hope to do the down pipe and cat delete as one job .. think it would be easier. With diesel prices and everything going up it's hard anymore to get everything done I want to. Family has to come first !!

I'm trying to avoid PMS on the credit cards .. so far so good.

 

Did you have problems with the MPG before fixing that?

 

Yea, I was only getting 12-13 MPG city and I'm running 3.55's. Just filled up yesterday so won't know what the improvement is for another week or so although I do expect an increase. Don't have to keep the foot on the peddle as much to keep it going.

 

Well, yesterday I unplugged the MAP sensor and the engine doesnt change anything at IDLE, does that means that the sensor is bad?, because my truck seems to run fine, other than get 11-12 MPG. I suppose that the hose is clear because I can get 14-18 psi of boost at WOT or loaded.

What do you think?

 

No nothing changes at Idle because there is little or no boost, so the map doesn't have any pressure to see. If you disconnect it and drive around, it should be more of a dog w/o sensor connected. Try that out.

-Robb

 

There are three ways to check the map sensor.

First is to unplug the electrical connector and drive it around a bit. You will get a cel and the PCM will attempt to run a pre-programed routine to emulate the map sensor. If your truck runs a bit better in this mode then the map sensor is probably not working.

Second is to leave the electrical connection plugged in and disconnect the hose at the sensor. Plug the hose end with duct tape or something and take it for a drive. If it drives really dogie then the sensor is probably OK.

The best way to test the sensor is to use a Digital-Volt-Ohm meter with a frequency option (Hz) scale, some do and some don't have that option. Get a really tiny sewing needle and stick it through the middle wire on the map sensor, that is map signal out. Connect the DVM to it and other lead to ground. Here are the results I got ...

KOEO 108.6 Hz Key On - Not started
600 RPM 108.4 Hz
1000 RPM 108.6 Hz
1500 RPM 109.2 Hz
2000 RPM 111.1 Hz
2500 RPM 111.8 Hz

This was in park sitting in my driveway. Your results may vary somewhat due to altitude. I'm about 2000 ft. It was interesting to see that with KOEO atmospheric pressure caused the map to run at 108.6 Hz and at idle (600) rpm I dropped a bit below atmospheric. Above 1000 rpm I began picking up boost above atmospheric.

Oh, and don't forget to check that tini-tiny little hole where the hose plugs into the engine. Also a good place for clogs.

Jim

 

Ok, amigos, Robbgt and Hussler for your input, Im going a try that. Thanks a lot.

 

Where is the MAP sensor located?

 

here two picts:

 

The one with the oblong plug attached to the firewall?

 

yeap, with tree wires and in the center of the pics.

 

Finally did the fill up and it worked out to be 17.25 MPG. Was hoping for more but not bad considering I was having trouble keeping my foot out of it, PMS turbo sound thing. Most driving were city streets and couple miles freeway and some rural roads with lots of stop signs, just back and forth to work. Next is the down pipe and cat delete as funds permit.

Just filled up here in southern Oregon and was at $4.09 ....