Tech Tip - Max Load Timing Offset

[Mopar1973Man]

I really have a good grasp of how this works and how to get the best use from it. Max Load Timing Offset is used in conjunction with vehicle weight and/or weight towing. In a nutshell, your cruising along in your cruise timing and then you just exceed the limits of that now you flop over to the Max Load Timing Offset. This will retard the number of degrees you have set at this point. 

 

For example my economy tune... 

 Timing: 17°, 20°, 23°, 26°, Max 27°

Max Load Timing Offset: 1°

Then my Cruise timing is 6°

 

Normally cruise down the road empty my truck loves the 24° @ 60 MPH timing in cruise state. When I exceed my cruise load then it flips to the Max Load Timing Offset which now retards back to 18 @ 60 MPH. Now I hauled the RV back home tonight. Figured I would hold to my typical driving standards. I found that the Economy Tune works awesome but has a small tweak needed. I need to bump the Max Load Timing Offset to 2°. This is because when I'm cruising and roll into to the throttle and giving more power I started to buck a bit. The timing curve is just a bit to steep so the change to 2° on the Max Load Timing Offset made it quit bucking. 

 

My tow tune should be...

Timing: 17°, 20°, 23°, 26°, Max 27°

Max Load Timing Offset: 1°

Cruise timing is 6°

 

A guideline is more weight or towing weight you need to add more to the Max Load Timing Offset to pull bit more retard across the map. Empty trucks with no cargo can use 1° Max Load Timing Offset or less. More weight more you need to head towards 3° of Max Load Timing Offset.

 

If you only experiencing the bucking at WOT then that RPM range that it starts at is the one that is too advanced. Might consider redoing you spread if you are uneven between RPM bands. 

 

Another thing I figured out that any Economy Tune that you truck likes the timing on can be used in just about all normal driving condition. Meaning that like my Economy Tune works great timing wise for Towing but need to tweak the Max Load Timing Offset and possibly the fuel map. So if I was to build a Performance Tune I would clone out the timing setting again most likely tweak it for less Max Load Timing Offset keeping the timing more advanced. Then just build a fuel map to fit the purpose.

 

My suggestion is that if you build your economy tune and can reach good high mark like 20 MPG or better that timing set up is what you'll use for all your tune from here on in. The only time you'll possibly change that timing setting is with wear of the injectors and losing pop pressure or changing injectors outright then you have to find your optimal timing all over again. 

 

As for finding optimal timing you have to experiment to find the values that produce the lowest EGT and Engine Load values at a set speed. Like all my testing was based 65 MPH and built the values to give me the lowest of both. Now I will warn that you can crank up some serious timing advancement on cruise state but you need to listen to the engine there is a change of the rattle and the MPG will fall with too much (negative torque). My testing of the +7° was too much and lost some MPG from it. I will say 18° to 19° in performance timing (non-cruise state) at 2,000 RPM works pretty good. 

 

I will release a new version for my tow tune soon. 

Edited May 1, 2019 by Mopar1973Man