Engine/Transmission (1994 - 1998) What happened to my to my fuel mileage

[PA95CTD]

After installing a Rips 4 inch turbo back with a muffler exhaust system three weeks ago, my mileage went from 18. 5 to 14. 5. The truck runs good and sounds good. I use stanadyne every tank. I plan on turning the timing up and adding a plate in the next several weeks. Will these up grades get my mileage back up?Also MY Westach dual boost/egt guage is in the mail.

 

[fox]

Fill out your profile see we can see what you are driving.

Otherwise we will have you changing out good parts like some tech's at the dealers!!!! Change parts till it runs right.

There are some GOOD knowledgable techs too.

 

[bmoeller]

fox, he did fill out his profile, just not the sig. ---



1995,2500,Fwd,Quadcab,Always dirty black,Stock motor,147,000k,stock plate,afc housing slide forward,screw turned in 100%. Star wheel full forward,Full 4''Rip's exhaust.

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Marc, you need to stop standing on the go pedal now. :-laf Sorry, couldn't resist.



Did you make any other changes at the same time? In your profile, what do you mean by "screw turned in" ? When did you move the AFC housing or mess withe star-wheel? When was the last time the air filter was changed?

 

[PA95CTD]

Thanks for the reply,I've been a member for over a year but only replyed twice. I can't figure out how to turn on my signature on, any help?

As for the screw,it's the air/fuel screw behind the inspection plate. I have a bhaf with a outerwears sock that is about 1 1/2 old, it still looks new.

 

[wsmalley]

Clean/replace your air filter and check your fuel filter. Those two areas can cause drops in fuel mileage if they are getting old. Otherwise with all that bottom end pre-boost fuel you are going to lose a little bit of mileage.

 

[HEMI®Dart]

Marc,



You don't live at high altitude , do you?

 

[PA95CTD]

The only change I made in the last year and a half was the exhaust. I change fuel filters every 10k, and buy fuel at high turn over stations. Elevation is only 1500'a/s. I don't run it overly hard,it hasme puzzled because it wassuch a drastic change.

 

[tp0d]

hmm.. same problem here

My dad's 99 2500 is having exactly the same problem. The truck is all stock, except for a 4" exhaust from diesel performance products, with a straight thru muffler. (4" downpipe also). He used to get 17-18mpg fully loaded at 8500gvw (service truck, we carry a lotta tools all the time), but now after the exhaust, the truck only gets 14-14. 5 on the highway. city is worse. Is there any way to turn up boost in a 99? hmm. . I have not investigated this much, he was talkin bout takin it to a cummins shop.



lata

jk

 

[Mike Ellis]

I'm confused boys, shouldn't a higher-flowing exhaust give MORE boost and performance than the restrictive stock setup??



The filters seem like a good place to start. I have noticed on my truck that if I go very long without running it hard, performance seems to drop off. Pulling hard after a couple of months of running unloaded will result in quite a bit of gunk out of the pipe, always assumed it was soot clogging up the cat until higher temps / rpm blew it out. Truck runs noticeably better after a good stout workout.

 

[bmoeller]

Re: hmm.. same problem here

Originally posted by jkomaromi

My dad's 99 2500 is having exactly the same problem. The truck is all stock, except for a 4" exhaust from diesel performance products, with a straight thru muffler. (4" downpipe also). He used to get 17-18mpg fully loaded at 8500gvw (service truck, we carry a lotta tools all the time), but now after the exhaust, the truck only gets 14-14. 5 on the highway. city is worse. Is there any way to turn up boost in a 99? hmm. . I have not investigated this much, he was talkin bout takin it to a cummins shop.



lata

jk

jk, you will want to ask this in the 2nd Gen 24 valve engine /drivetrain forum since the '99 has a 24v. The fuel injection equipment is different than on a 12v engine.



There are some sensors on the 24v engines that need to be cleaned sometimes that have an effect on the mileage. Would also check the air filter on it.

 

[bmoeller]

Mike, the boost won't really change much with a bigger exhaust. I gained 1-2 lbs peak boost than with my stock exhaust. The most it will really do, without more fuel, is reduce turbo lag and slightly reduce the max EGTs. Mine dropped about 50*max (before the #10).



Marc, one other possibility is the timing MIGHT have slipped (retarded) on the fuel injection pump.

 

[PA95CTD]

bmoller, would i notice much of a decrease in performance? I have noticed less smoke at low boost, you could almost say i'm enviro friendly.



As soon as the weather breaks i'll check the timing when i tab my pin.



Marc

 

[bmoeller]

It is one symptom.



I think mine may be a bit retarded (some white smoke cold), but still haven't checked mine out.