Unexpained MPG drop

[AH64ID]

I would be very surprised if they ran your truck in 1st gear on the dyno as it won’t load properly. You need to be in 1:1 or OD to get a load on the motor.

 

[User113]

I would be very surprised if they ran your truck in 1st gear on the dyno as it won’t load properly. You need to be in 1:1 or OD to get a load on the motor.

Is that why it says 10% and 0% load in the upper left-hand corner?

 

[TSimonson]

AH-64, totally agree. Like I said earlier, I've been less than impressed with the "new" dyno experience from this shop. Still waiting on the guy that actually runs the dyno to get back from a hunting trip and maybe get some real answers.

User113 - 10% & 0% load are on the dyno rollers.

 

[TSimonson]

So there might be light at the end of the tunnel, but it will probably be very unsatisfying to my TDR friends . The posts by Timd and Darkblood caused my one brain synapse to fire last week and I took another look at the aftermarket CKP I put in back in '05. It's the ROKK with the shoulder milled so you can rotate it to advance the timing maybe 2 degrees. Back in '14 I just checked to make sure it was secure. Last week I pulled it and advanced it as far as it would go. Round trip from Omaha to Minneapolis over the weekend I averaged 17 MPG including the return trip with a bunch of storm doors caddy-corner in the bed. Hadn't seen anything north of 14 MPG since this saga started, and it's consistent with the differences I saw when I first installed it in '05.
So I think the most likely explanation for my overnight performance loss 7 years ago is that the CKP shifted during the drive, retarding the timing. It could be something goofy with the tone ring or ECM, but the movement of the CKP seems like the simplest explanation. It's only been 900 miles, so maybe there's more to the story.
Thanks again for all the advice. I will definitely post one way or the other if this "solution" stands the test of time.

 

[Darkbloodmon]

So there might be light at the end of the tunnel, but it will probably be very unsatisfying to my TDR friends . The posts by Timd and Darkblood caused my one brain synapse to fire last week and I took another look at the aftermarket CKP I put in back in '05. It's the ROKK with the shoulder milled so you can rotate it to advance the timing maybe 2 degrees. Back in '14 I just checked to make sure it was secure. Last week I pulled it and advanced it as far as it would go. Round trip from Omaha to Minneapolis over the weekend I averaged 17 MPG including the return trip with a bunch of storm doors caddy-corner in the bed. Hadn't seen anything north of 14 MPG since this saga started, and it's consistent with the differences I saw when I first installed it in '05.
So I think the most likely explanation for my overnight performance loss 7 years ago is that the CKP shifted during the drive, retarding the timing. It could be something goofy with the tone ring or ECM, but the movement of the CKP seems like the simplest explanation. It's only been 900 miles, so maybe there's more to the story.
Thanks again for all the advice. I will definitely post one way or the other if this "solution" stands the test of time.

Sounds promising and plausible, looking forward too the follow up!

 

[TSimonson]

After another month, I think this case is closed. Another 1,200 miles mixed between mostly empty and a little car hauling, I hesitantly moved the CKP back for the last two tanks of fuel. Poor performance returned immediately. Less low end power, higher EGTs, and lower economy (right back to 13.5 MPG - 20% drop hauling or empty). So in this case it's all about the timing. Looking to reinstall the OE CKP and add timing "for real" with a tuner, but I'll move that to a new thread after I sift through the other posts on the topic. I'm sure there's plenty of great stuff on TDR.
Can't say "thanks" enough for all the contributions. It was a whale of a journey.

 

[AH64ID]

Timing is the most important aspect of custom tuning, so it makes sense.