Yes I am also curious on performance. Since swapping the fuel pump I have had just 1 17.x+ mpg tank. However the grin factor has gone up significantly with the '03 manifold and 12 hole injectors. the last tank was a 15.9 last week for the work commute. Really hard to keep the foot out of it and CC is the best way.

On the injectors... the LTFT indicates it runs really rich at idle & off throttle but otherwise it eventually becomes as expected. First plan of attach when I start tuning will be to shorten/dial in the duration tables. Minimally fuel has to be cut back some to compensate for the 12 hole injectors and stronger pump.

Not sure if I am going to dive into it just yet, still planning on swapping the y-pipe. I am expecting that to be in Feb/Mar time frame.

 

Going to start tuning the Dak, any interest in knowing what I do and the results? This truck is already far from stock in the sense that all of the intake track is modified to reduce a lot of turbulence in the airflow into the 70mm TB. Additionally it has the '03 intake manifold with shorter runners and newly installed JBA headers with the 12 hole injectors. Exhaust behind the headers is still stock and originally planned to do the y-pipe before tuning but... well seems like I cant wait and have already lowered the fan on temp and raised the idle.

Right off the bat I need to fix the fuel gauge as it is way off from the pump change. From day one of the new pump, mpg's have dropped approx 1~1.5 mpg. Previously was getting upper 17's into the 18's pretty easy. After the pump swap mpg's took a 1.5+ mpg hit and have been seeing 15.7~9 to low 16's. When the injectors went in there is some over fueling at idle and lower load conditions which is where some of that mpg's have been lost, from what I can tell from the LTFT.

Performance wise as it sits power is way up on the stock tune and again, if I never had tuning capabilities would be more than happy with it. But I need to fix the over fueling. To start the low rpm/load pulse width needs to be fixed, then timing. After that, not sure what if anything needs to be tweeked until the y-pipe goes in.

Anyways, again if there is interest, will document it here on DF.

 

I'd say go for it

 

Hi Steve, i'm very interested, but i don't know if i will follow with the tune yet.

I found a damaged Grand Cherokee overhere, it was in an accident and got hit on the left rear, broke the axle as they told me.
It just came up, heard it from a friend of mine, who knows the owner, i wan't to check it out and maybe buy it and change over the HO motor, i dont know how many miles it has, and need to find a place to store the jeep before i can make the swap.

I will follow you're post and i hope you can get it to run right, just mind the A/F ratio's with tuning.

Good luck with it and keep up the good work Steve

 

Hey Ludo...! The HO motor would be an awesome swap, just make sure it is indeed an HO motor. I also have thought of doing the same on the Dak. What would be better is an HO motor in a manual trans awd standard cab shortbed :-) that would be fun to drive with all the added power. As is, in 2wd I am having traction issues on wet roads :-) lol.

I will keep this thread updated. Planning to do the 1st tune change today with the injector pulse change. Yesterday I worked on the datalogger setup but for some reason some of the data is not actually getting logged. Once that is corrected then the tune will go in.

 

first tune is in, reduced high vacuum injector pulse width by 5% in an effort to get the amount of fuel being pulled normalized, it appeared on the gauges that the ecu was pulling the max amount of fuel it could. Elsewhere the pulse width reduced by 2% to start. Timing bumped in the 1400+ rmp range by 1.0*, 0.5* in the 1200 rpm column. Planning to run this tune next week to check mpg's on the commute. Performance wise I cant really tell the difference in the test drive I did but, in a steady state on the hiway going up the steepest hill I call the home depot hill, there was no downshift climbing this hill. This was a first for this truck, it would previously always downshift on this hill. There is another hill on the way to work that is also requiring a downshift, have not hit this hill yet and will see how it does tomorrow.

I pulled the mechanical fan and have set the fan on temps as needed to keep the motor in my target temp of <190*. If temps are not controlled well enough during hot temps, will yank a fan off a durango and see how that does as it is 1" larger in diameter.

The goal in tuning is to get it to run its best on the worst fuel without pinging.

I also checked for the cyl 7 misfire I expected to see after yanking the fan and it showed up in the freeze frame data but no CEL. Past experience showed me the fan removal tripped this misfire and once the ECU adapts fuel trims it goes away. Will be monitoring this as tuning progresses.

I only have 1 tank to & from work to compare against after the header install last month and it came in at 15.9 mpg. I had been seeing 18-19 mpg before the fuel pump swap and upper 16's after. I suspect the old pump was weak and not delivering the same amount of fuel per squirt (2 hole injectors) and once I did the 12 hole injectors, mpg's went down further. Knowing this, I plan to drop the injector PW more to see the cause & effect on performance and mpg's. As it sits with the current tune, performance is awesome. I also plan to re-install the potato launcher mod and tune with that to see what can be squeezed out of it. That will be down the road a bit.

stay tuned... will probably be a week or more before the next tune goes in.


Mods: (all of this is documented in this forum with pics)
2.5" vacuum controlled exhaust cutout on the air box
Air filter divider under filter to reduce turbulence as air flows into the filter
Airaid intake tube with turning vane installed int he 90* bend
Insulated intake tube with exhaust wrap
70mm throttle body
Insulated plate mounted under the intake manifold in an effort to reduce IM temps (did not work)
Insulated bottom of intake manifold in an effort to reduce IM temps (did not work)
2003 Intake manifold with shorter runners
Insulated fuel rail with exhaust wrap
12 hole fuel injectors harvested from wrecking yard chevy's
Insulated coolant lines over the intake manifold with exhaust wrap
JBA headers (exhaust is stock otherwise)

and now tuning.

Future mods:
Custom y-pipe
Custom exhaust from y-pipe collector back, considering a 3" setup with a spot to install a reducer to control flow as needed (to suit my driving tastes)

 

Driving feedback update... this tune drives better than the stock tune + mods. Bottom end will cruise easier without downshifts, hard to explain but wanted it posted here.

Next download, going to add another 0.5* to that bottom end area.... Probably will happen by the end of the week.

 

Are you keeping a spreadsheet of what you change, and how much?

 

No, each change gets a new file name so I can compare against another file. There is not a lot to adjust compared to the Ram, it is pretty basic. I'd like to know how the DFCO works, as it sits there does not look to be anything in there that would help (no tables of any kind, just switches and single value parameters). Will need to go ask the experts on the HP forums for guidance on it.

Have 115 miles on this tank... I wanna go fill it up :eyeroll Seeing the miles driven vs the fuel gauge would be encouraging however I rescaled the fuel gauge so it is an unknown as to how the tank is performing. The ultimate goal on the fuel gauge is to get it accurate, 1/4 tank = 6 gal of fuel left (24 gal tank) & 3/4 tank = 18 gal. I can adjust the set points in a table in the tune so it should be do-able.

Pretty excited to be able to dial in the tune with the mods! should be able to get the most out of it now. (still have the y-pipe & rest of exhaust to work on)

And... since I am in here, checked for freeze frame data on the cyl 7 misfire and have none.

 

1st tank in, 224.0 miles, 17.815 mpg. Have not seen a 17mpg tank in a long time let alone one close to 18. 2nd tune will go in tonight.

Plan is to further reduce the high vacuum fuel pulse width and bump the previous timing changes 0.5*.
Fuel gauge measured just half past 1/2 a tank and the gallons used was 12.57x gallons so that looks good so far.