Engine/Transmission (1998.5 - 2002) Mpg

[MRiley]

So long story short, within about 8 months I lost both the injection pump and the ECM. I replaced the injection pump with a "high output" unit from blue chip. The ECM was a cummins reman'd unit. I put the Smarty tune back in and the truck seems to run smooth and pull just like normal. Here is the strange part. I get 3-4 mpg more empty than i have ever gotten. I'm also getting 4-6 mpg lower when towing than I have ever gotten. Nothing on the truck has changed except the vp44 and the ECM. This truck was a always a smokey one but it seems to black up my fender more now as well. Any ideas? I'm running out of things to check....

 

[phantomusa]

What setting on your smarty
The smarty will blow smoke if not set right
Take the smarty off then you should be back to normal
Pappy

 

[MRiley]

the smarty isn't the issue. I ran it before. Its set on 9 like it has been since I bought it. The issue is the dramatic reduction in towing mpg. I don't understand why i'm seeing an increase in unloaded and a decrease in towing mpg post changing the VP44 and ECM. Towing milage is down 4-6 mpg over what it was before i made the changes.

 

[FCrowder]

If you put in a blue chip special x pump it has added timing advance built into the pump. If you are running level 9 on the smarty it adds timing so now you have more timing then you used to.
level 8 is the same as 9 but without the added timing.

 

[MRiley]

Mine was the 17x the standard replacement for the HO engine. I didn't think the 17x offered any additional timing.

 

[NIsaacs]

Are you doing the math or using the overhead?

Nick

 

[MRiley]

i am doing the math. the over head was always overly generous. I have had this truck since it was new. I'm pretty familiar with the way it runs. I just can't figure out why MPG went up with no load and down with a load. I could see may 1-2 mpg change but its down 4-6 with a load... I don't get it. ECM and VP44 are the only things that have changed.

 

[lpennock]

Transmission slipping under load?

Leonard Pennock (AD7AS)
Sent with Tapatalk

 

[MRiley]

Sorry for the slow response i was out of town. i don't think the trans is slipping. RPM seems to be normal and i don't notice any slipping under load.