Engine/Transmission (1998.5 - 2002) Drastic mileage drop

[DSeamans]

I had been getting 20 -21 mpg always when not towing. After the Airdog, injectors, transmission and turbo replacement this spring, it never dropped below 20. Two tanks ago, it dropped to 17. 8. The brakes looked like they could be dragging and were getting close, so I replaced rotors, calipers and pads on all four. I just filled up, and it dropped to 16. Brakes are fine, fuel pressure at the vp44 is 15-18. Turbo pressure ( mechanical and attitude) hasn't changed. I normally run the edge on 3X3 and even tried turning it off. Driving style hasn't changed. When home, I always get fuel from the same shell station as I seem to get the best mileage from them. I don't see any leaks. The CEL hasn't come on, but I will scan for codes when done here. I have to leave Sunday for a work trip and this has me very nervous. Where do I look next? Could my VP44 be dying? It is original with 185,000 on it. It does seem to be dumping more black smoke. Any ideas are greatly appreciated!



Thanks,

Dave



There are no codes(scanner, not key/odometer) and no visible leaks,

 

[Colando]

Doesn't sound good

I've always heard that can be the first sign of the VP-44 dying, I hope that's not the case, but I'd be real cautious of it. Good luck and keep us posted what you find.

 

[DSeamans]

VP going

I talked to Chip (Blue Chip) and Midwest fuel injection and they both said the timing piston was going. MFI is $1045 and Bluechip is $1600. I have heard a lot of good about MFI and even talked to a shop in Chicago that has used them and they had nothing but good to say. Is bluechips that much better that its worth the extra?

 

[AKAMAC]

Not to put doubt in the companies listed, but I also was droping in mileage. 19. 2 to 17. 5 , I replaced my IAT and am back to 18. 3 with only 207 miles at fill up with a mixture of both IAT sensors. I'll know if that was the problem on Sunday when I fill up again.

For 35 dollars it is sure a cheaper way to find out. Mike

 

[Floyd4runner]

What is IAT, sorry new guy sindrome with 99 dodge and the same fuel loss.

 

[JLandry]

What is IAT, sorry new guy sindrome with 99 dodge and the same fuel loss.

Intake Air Temperature sensor. Do a search for a diagram on the location and how to replace.



Definitely replace this $28 part before you spend $1000+ on a VP44.



Good luck,



John L.

 

[blacksheepdiesel]

Because of the electronic nature of the 24v all things affect each other. Could be VP44. Could be IAT. Could be boost sensor. Could be APPS. Or, it could be one or more of the above!!!! Hopefully the IAT will increase your mileage like it did for me one time!

Godspeed,
Trent

 

[FYarcho]

I am having the same problem. Just started a few weeks ago. The only thing I have to add the the list of symptoms other than what you have listed is my EGT's seem to run a little higher about 100-150 degrees. Also sometimes the truck is a little hard to start, but this is only somtimes not always. acts like a fuel leak. I have checked every connection and fuel pressure is alway good 15-18psi. So I will be watching closely to see how this turns out. I too have tried everything you have and have thought of all the possible issues I am just not sure where to start. The thing that stumps me is the truck runs great except for this issue.

 

[DSeamans]

It wasn't just the mileage drop that brought the conclusion of a bad vp. I have serious white clouds at start up and black smoke no matter how easy I was on the go pedal. I tried everything from stock to the 3X3 I normally run and I COULDN'T take off or accelerate without a massive black cloud. The fact that I have 185000 on a pump that has been bombed since day one is impressive. Add to that that I went through a couple of lift pumps that were completely dead because I was too ignorant to put a gauge on and the mileage seems amazing for these things. I'll try the IAT, but I think its my turn for the VP.

 

[cArNiVaLwOrKeR]

Seamans, any update to this story???



JoeLee

 

[Vaughn MacKenzie]

It wasn't just the mileage drop that brought the conclusion of a bad vp. I have serious white clouds at start up and black smoke no matter how easy I was on the go pedal.

White smoke at startup is a very strong indicator of a dying VP44.

 

[cArNiVaLwOrKeR]

Vaughn, do you reccommend DDP stage 2's over Mach2's or 3's or 4's? just wondering...



JoeLee

 

[Vaughn MacKenzie]

I have a very early set of DDP 2s in my '96, but I've never driven/experienced the Machs, so I can't really say, but I think both brands of injectors are top notch. . .

Vaughn

 

[FYarcho]

Well my answer finally came with a P1688-Injector Pump Electroincs Failer. I was on a trip to Vacaville, stopped to let the dogs out to do their business, got ready to go and truck wouldn't start. Pulled the 1688 code. So DSeamans if you havn't already I would start looking for a new VP-44 before your truck leaves you dead on the road.



Also a Great thanks to Vacaville Towing (AAA) They were great did a wonderfull job and got me back home. Made a good ending to a crappy day

 

[DSeamans]

Waiting to change

I've been out of town for a week and haven't had net access. I ordered one from MWFI and plan to put it in today or tomorrow. I didn't take the truck, I didn't want to risk it. Mileage is crap and I did notice the egt's running higher. All signs of bad timing.

 

[FYarcho]

Well not to wish bad luck but I hope the IP is your problem. Sounds like it. But I would sure hate for you to spend a bunch of money on an IP just to find out your still in the same boat. At least for me thats how I felt. Unfortunately mine was the IP. The tow didn't cost me anything because of my AAA mebership. But I will also be looking for another IP to have on hand for any future failer. But either way keep us informed.

 

[DSeamans]

Pump was bad

Just finished replacing the VP. What a difference! More power, less smoke, and 200* cooler egt's. I'll fill it up and check the mileage. I forgot that a couple months ago, I had a white cloud out the tailpipe for about 5 miles. Brought it back home and didn't find anything. It went away except at startup. I bet that was the first symptom of the timing piston hanging up. Before you buy a spare, check into the shelf life. I had read on here before they shouldn't sit for more than a year. I'd hate to carry one around only to find its no good when needed because the insides rusted or something.