Another update.... played with the torque table in the trans pages, to re-cap, it is indicated that the table is used in trans torque calculations based on TPS voltage. Thursday after the mpg test I tweaked that table for the 1st time taking baby steps to see the cause & effect. It is clear that either the ECU or the TCU is throttling back the torque output under part throttle conditions. There are 2 columns, one that is ramping up a value starting from something like 293 up to a final value of 528. The other is floating around 520 in all the cells but the last, 549. I believe the 2 represent closed loop (col 0) and open loop (col 1).

Recall that I mentioned I detuned the ecu last week for the mpg test this week. The goal was to make the bottom end power more tame for the up coming wet season (traction). Well with the tweaks to the torque table, all that power I dropped came back and then some. No idea how the ECU & TCU are controlling the torque output but it clearly is.

After the 3 day commute test this week its been a 100% DGAS tank over 130+ miles, as of now, my guess is its a low 18 mpg tank. Gone for up to 2 weeks for work so no testing going on. Anyways... there it is, latest update, and I thought I was done.

 

Bumped the torque table values & found a point where there was no longer a change that i could tell. Concluding the calculation being done will cap the output. As an example, if the motor had another 50ftlb of torque the bumps on the table would continue. These are my thoughts on what i see from changing the table column 0 values

 

Adding link to a post with cam specs Cam specs from the manual


Dyno numbers on the HO cams vs the 2008+ cams, pulled this from another forum post. this guy did the work, dyno'd both setups and posted the results. He does state that there were additional mods between the HO -> '08 cam swap.

 

Had an idea recently that I am gonna see if I can implement this weekend... the output of the air filter box, I suspect there is an area where the airflow merges that is causing some turbulence. going to make & add a divider between the pleats where it enters the intake tube & eval the performance.

ON the air box, below is a crude drawing I did yesterday to post in another thread, adding it here for the next guy.

Reminder the air box is open 100% on both ends.

 

Steve, I'm trying to understand where air would collide? I don't have the airbox in front of me, but as far as I can remember, there is one intake sucking air in from the passenger wheel well, then one output to the throttle body and small hose or two. All the air is flowing in one direction up into and out of the filter. If anything I'm thinking dividing the output would introduce turbulence? I'm sure you've thought this out, so just trying to understand.


On another topic, I thought of you yesterday as I filled up the tank after the timing set replacement that I completed yesterday. https://dodgeforum.com/forum/2nd-gen...ay-oh-boy.html
Really curious to see if/how much this will improve mpg. Was getting somewhere between 13-14 mpg on the Dak. The guides were either shot to hell or completely missing, so I had all kinds of chain slack. Also went from all three 3 inverted tooth chains to 1 inverted tooth and 2 roller chains. We'll see how it all pans out.

Old chains on right....

 

The box is open on both ends, I cut out both ends so there was no obstruction & the flow from both sides goes up the sheet metel into the filter. I tried the thought I had today and on the test drive, dont see any change so that mod appears to not be a good one. I dont see anything negative, just nothing positive.




pics of the upper air box mod for reference...





Going to leave it in and let the ecu adjust fuel trims if there is anything there. I'd seen in the past where a mod I did on this motor was "eh" when the install was done but "woke up" some after fuel trims at time to adjust. I dont expect anything from it but I have been surprised before.

If I were to make this a permanent mod, I'd switch it over to a piece of sheet metal since this piece is so thick. Time will tell & will update in about a week. I'm actually at work next week and not on business travel so it'll get a weeks worth of commute miles.


Edit... after looking at the pic of the lower air box, I noticed the sheet metal is bent up, need to fix that.

 

An update.... a bit of a head scratcher for me, I noticed the last couple of days that the cruise control does a better job at keeping the set speed over various terrain (rolling hills on the work commute with elevation changes in the 0-350' range)

I'd like to say I am going to pull it and re-test the work commute w/o it but I have too much work travel in the next 60 days to get it done. MPGs look like they may have gone up a tad... been getting mid 18's-19 mpg when I can keep my foot out of it. This tank looks to be exceeding the 19.6 mpg tank (best recently) that I had a few months back. Took pics of the dash & compared it to the pic I took of the 19.6 tank & it is performing better at the same # of miles. If there is anything worth posting on this tank (end of the week), I'll post it up.

 

One issue I see is that you've eliminated the air horn, which bends around into the fender and sucks colder air from the wheel well. So now you're sucking hot air.

 

In the 4 years I have been monitoring the obd system, air box horn or not, the air temps always creep up. I do have a piece of plastic blocking some direct airflow from the engine side of the compartment to the air box and the front deflector by the radiator removed.

Also, when I wrapped the coolant lines & the intake tube, temps did drop. I did not log by how much though, it was in the 7~10* range.

 

Just wanted to report back after driving over 1100 miles last week. It was ATL to Orlando RT on the new timing set. The best I got out of a tank was 17.76 mpg, running Chevron 87 octane, almost all highway. I was NOT driving conservatively, to say the least. I can't offer a comparison to what mileage was before the new timing set, as I hadn't completed a long highway drive in many many years. It's been all stop and go here in ATL averaging between 13-14 mpg.