Engine/Transmission (1998.5 - 2002) Power loss

[FFSchooley]

I've done a search on this topic without any real answers. I am experiencing a progressive loss of power over the last couple months. My truck has over 134,000 miles, and should be just "broken in. " Well it seems like its getting tired, that's the best description for it. I installed the edge comp about 2 years ago, and usually run with it on 3. Over the past few months, the truck acts as if its progressivly lossing power. It dosen't have the get up and go that it used to have. It runs normal, just more slugish. I have changed both the MAP and IAT sensors with no luck. The fuel filter was changed about 5K ago. Air filter is a little dirty, and I did notice that the turbo impeller is dirtier that is usually is... Boost and EGT's read normal. Lift pump was replaced, upgraded, and moved to the tank with 1/2" stainless fuel line a long time ago. Fule pressure reads a little low, and I am going to diagnose that as soon as I can. Other than that, anyone have any idea on what paths to take as far as why my truck dosn't have the power it used to have?

 

[RAJohnson]

Considering you have the comp, and assuming you have tapped the VP, have you ever had to replace the VP yet

 

[FFSchooley]

No, havn't replaced it yet. Havn't read up on the signs and symptoms of one that has failed, so I am not sure how to tell if its bad...

 

[TGibbs]

A VP that is dying will run slower. I just installed a new VP and a RASP and with the comp on 1x3 is equivilant or close to 5x5 before. I just got the wire tapped tonight and took it for a test drive and HOLY SMOKES :--) literally a totally different truck. the EGT gauge was pegged but thats just the next spot of the slippery slope!!

 

[Mike760]

The VP44 could be on the way out but definately make sure that the air filter is clean. A dirty filter can result in a big performance decrease. What about the exhaust? Do you still have the 'cat' in there?

 

[R-N-R]

I had the same symptoms from a comp box going bad.

 

[FFSchooley]

I am pretty sure its not the comp box, since the truck has NO power at all with the comp box off. No cat in the exhaust, 4" RIPS system. I will do a search on this, but how do you diagnose a failing VP?

 

[RAJohnson]

First would be to pull the codes. With yours you need a reader. Second would be wait for it to completely leave you stranded, or a dead pedal. HAve you checked for codes?

 

[Big Bry]

Don't leave out the trans. A trans that is old and going away will definitely rob a truck of power. I am rebuilding mine right now. 150,000 miles on it. DTT torque converter is dead. All new ATS parts going in. I seen that you had 134,000 miles on yours. Did you ever rebuild it yet?

 

[R-N-R]

I recommend completely disconnecting the comp box to eliminate a variable. Mine did not matter if it was on or off when I was losing power. When I disconnected it I had noticably more power than with it connected, on or off. I'm not saying this is your problem, but it is an easy test to eliminate the possibility.

 

[FFSchooley]

I had the trans rebuilt by DDT not too long ago and it has been great, so I am pretty sure I am dealing with an engine problem. Fixed my fuel pressure problem. 14-15 PSI WOT. I still dont think the edge is my problem, since when I turn it off the truck seems to have no power at all. With it on, it runs ok, but not like it used to. I will try dis-connecting it all together. One thing I noticed is that when it is cold, it seems to have the power I am missing. But after a minute or two, I dosn't pull like it should. Feels like I have lost 30-40HP no matter what setting on the comp, on or off. I am going to get the codes read, but I have no check engine light on right now. I am also thinking about checking my cylinder compression? Would that be worth my time or is that something I should be worrying about with 130,000 miles? Any other ideas?

 

[R-N-R]

Member FMcClaren just replaced his ECM and got his missing power back.