mpg keeps getting worse after fuel efficiency mods??HELP!!

[sms8921]

Ok I put a banks dowpipe and free flowing flowmaster muffler on my truck. Also just installed a hypermax cowl intake and k and n air filter. Slightly adjusted the timing cause it had to much clatter still when the timing advance went off, sounds way better now. I am getting worse mpg with all these mods than when I had the cushed downpipe and stock air intake assembly. I went from a sold 14-15 to 10-11, and the 14-15 was through the winter last year. Truck seems to run better just cost more to run. I run injector cleaners and additives alot. I cant figure it out, still wet behind the ears with this diesel. Any input is greatly appreciated!! Thanks!

 

['94IDITurbo7.3]

how many miles on IP and injectors? rear end gear, tire pressure?

 

[sms8921]

Injection pump and injectors look like factory paint still on them. 4.10 gears and air pressure all checked out ok. It was as soon as I did the mods that mpg went down noticably fast within a tank or two of fuel...

 

[riotwarrior]

Did you EAR time it or with proper timing meter? Maybe it's quieter but wasting the burn....perhaps timing is a key component.

Whats your IP like turned up? How's your EGT's

Any changes in tyres? New ones or more aggresive tread?

Loaded differently?

Need more info!

 

[sms8921]

I timed it by ear I couldnt find any local shop that even knew there were IDI's still around. I have no idea if the pump is turned up or not and I dont have a pyrometer to tell the egt's yet. Tires are the same. I tow a 3000lb trailer 3 days of the week, But my calcuations are accurate when empty and not towing or towing. I didnt think that retarding the timing would effect it that much. Maybe I will advance it a hair and see if that helps. The truck used to make some black smoke when in the throttle but the hypermax intake seemed to clear alot of that up. It starts great and smokes very little on a cold start for about 2 mins then clears up...

 

['94IDITurbo7.3]

either way it is time for new IP and injectors if they are original.

 

[sms8921]

Well buying new ip and injectors doesnt justify why the mpg went down when I put the mods on to gain more mpg. I dont think both my ip and injectors would go bad in one tank full of fuel would they?

 

[Mulochico]

Could it be that you are enjoying the right foot more with the mods?

Maybe idling more (drive-thrus, etc.)?

 

[kc0stp]

Just IMHO but excluding playing with the timing none of those really seems like a MPG mod... those are all performance mods and in the case of the K&N anti performance (or at least anti longevity) now it is possible for an injector to start leaking or the timing to be way off but with you doing all of that at once its kinda hard to narrow down what 1 item caused the change (and it could just be the go fast pedal)

 

[redneckaggie]

timing is critical for mileage, the rest of that will not really increase mpg maybe a tiny little bit but not much

 

[ah1988ford]

If your pump and inj. are going bad you will get really bad mpg's, just before my pump went out I was getting less than 10 mpg around town.

 

[fuzzy1626]

I'd put the timimg back and see what the mileage does. Get yourself a tube of K&N sealing grease and put a thin layer between the filter box top and the filter. Don't overtighten the nuts and push the edge of the filter out to far.

 

[sms8921]

I am going to put the timing back this morning. It wont hurt anything to have that light clatter still after the timing advance goes off?

 

[icanfixall]

Its your changing the timing that killed the mileage. Too bad you didn't ask here before messing with the timing. I would have told you not to but if you did anyway I probably have told you to make a center punch mark in the injection pump to gear housing joint. Then matching it up later would have been easy...

 

[sms8921]

I did scribe the pump and housing so I will take it back to where I had it before.