Idle Issue

[cleatus12r]

Three things Dave....

Min ICP (IPR) duty cycle at the top of "parameters".

Base PW map in the low ICP/MFD area (WOW, BIG DIFFERENCE)

IPR Duty cycle map in the low ICP ranges.

[907DAVE]

I see what you mean about the Base PW map, but don't quite understand the ICP duty cycle map/ min. parameter issue.

Can you please explain.

[907DAVE]

And why only when coming down off of a fast idle?

[soutthpaw]

did I miss something? where do I get a 200HP DD

[cleatus12r]

Originally Posted by soutthpaw

did I miss something? where do I get a 200HP DD

Once you get injectors and compounds like Dave has.......

[soutthpaw]

Heh, would have to change those lil' thingies in his Avatar pic first... Hoping to do an Adrenaline this summer, Injectors down the road but prob just single shots

[907DAVE]

Originally Posted by soutthpaw

did I miss something? where do I get a 200HP DD

Whoa......new mod in town.

Have fun parting it up hardcore with the other mods.

[cleatus12r]

Ok......

The relationship between the injection pressure regulator and the actual/desired injection control pressure goes a lil' sumpin' like 'dis.

1. The PCM bases an initial injection pressure regulator duty cycle using the IPR map to attain a desired injection control pressure.

2. The PCM looks at the actual injection control pressure data from the ICP sensor.

3. The PCM makes fine adjustments in the IPR duty cycle to get the desired injection control pressure reading from the ICP sensor.

Every varying load/RPM will start with an initial duty cycle commanded by the PCM and constantly tailored adjustments by looking at ICP sensor output.

This entire system is called a "feedback loop". It's very similar in operation to how the oxygen sensors relay to the PCM about how accurate the air/fuel correction is.

When the base IPR duty cycle is off, then the initial duty cycle for a desired injection pressure is off and if it's off too far in a certain operating range, then the PCM cannot correct it and maintain a stable RPM because the actual pressure desired varies too much from the desired and the PCM basically fights itself because the map is no longer valid. I recognize that as a run-on sentence but I'll leave it that way because that's how it came out of my head.


I know what I want to say but I don't think it came out right.

[907DAVE]

Came out fine.

Thanks, it makes more sense now. The duty cycle map is a bit more involved than I originally thought.

How would a guy fine tune this map, besides in the low ICP range with BO is it even necessary?


oops....BO= big oil.

[cleatus12r]

Originally Posted by 907dave

I see what you mean about the Base PW map, but don't quite understand the ICP duty cycle map/ min. parameter issue.

Can you please explain.

Well, I don't know for sure.....

But the IPR map is going to at least cause a couple issues. I can't say for sure WHAT will happen with the values you have there but remember how that map needs to be changed just a little bit even with an Adrenaline pump sometimes....

Heck, if you look at the tune I sent you (the one seems to have had an issue with breaking things ) look at the IPR duty cycle near idle......it causes things like near-stalls when coming back down to an idle and a slow recovery back to the correct idle speed.

I don't remember what pump you're using for your HPO, but having a "hard" (parameter set) MINIMUM duty cycle of >9% and commanding a minimum of <11% in the IPR map is very high (for big oil). You are holding a lot of HPO back (not draining). For comparison, your 400DD uses the stock IPR map which must work very well and is bypassing plenty of oil.

You are also running around TWICE the base commanded pulse width in the 200 vs. the 400 in the "idle range". I don't know what the 200 and 400 denote, but if you're using both of those tunes with the same injectors, there are going to be issues.

These are just the differences I saw and the issues that may come of them.