WOT Resets?

[Alan Reagan]

I seem to remember that the MAP was reset at either WOT or turning off the ignition and restarting. I assume that it does the same on the 3rd Generation trucks.



My question is, what else is reset? I was headed home last Saturday night following my wife through a winding, hilly stretch of road. On one of the long hills, I pushed the go pedal and the truck dropped out of OD, then downshifted and the RPM was at the redline. I held it there going up the hill. Of course it didn't take long and it shifted, the RPMs dropped and I was gaining on the wife rather quickly so I got out of it.



I noticed on the next hill that the throttle seemed to be more responsive. Since then, I've noticed that the truck seems a lot quicker from dead starts and throttle response is quick and power seems up.



I'm sure I blew the Cat clean at the redline but what else got a tune up?

 

[drewRoberts]

running that high of a RPM probably knocked alot of carbon of the injectors and your now getting not only a better spray pattern, but more fuel going into the cylinder per injection.



I usualy gun it high RPM in 5th atleast once a tank. . . leaves a nice cloud of smoke behind me

 

[lmills]

used to be on the second gens that if you turned the key and pushed the go pedal to the floor it would calibrate the TPS. I am not sure if it still is the same on the 3rd gens or not

 

[Alan Reagan]

running that high of a RPM probably knocked alot of carbon of the injectors and your now getting not only a better spray pattern, but more fuel going into the cylinder per injection.



I usualy gun it high RPM in 5th atleast once a tank. . . leaves a nice cloud of smoke behind me

You might just have something there. I had noticed that I was getting a lot of black smoke under acceleration. Now, there's faster acceleration and there seems to be less smoke. Whatever it did, I'm going to give it the "redline" treatment a little more often.

 

[nickleinonen]

I'm going to give it the "redline" treatment a little more often.

i do that several times a day when i am raci... er... driving if i get into it hard, i'll pull it past 3k in 2nd-4th and at that point i am usually past the speed limit so i slow down. .



this could why i get such poor fuel economy eh? :-laf

 

[drewRoberts]

this could why i get such poor fuel economy eh? :-laf

your fuel economy might be low. . . but your grin factor is probably high Oo.

 

[Alan Reagan]

I know my grin factor sure went up. :-laf

 

[betterthanstock]

I noticed on the next hill that the throttle seemed to be more responsive. Since then, I've noticed that the truck seems a lot quicker from dead starts and throttle response is quick and power seems up.

I was just going to start a thread on this. I have known this since i bought my 03 new. Yes, it takes about 3-4 seconds at full boost and full throttle before the software learns the sensor voltage from your boost sensor. (read the cummins specs, voltage can be anywhere between 1. 4 to 1. 93 volts, so it has to learn your particular sensor) Once calibrated it stays that way until you shut it off, then its all over again. This is not too bad on my 6-speed, but autos downshift before you can nail the boost gauge, and in 4 seconds of full boost you can run into speeding troubles.

This is very annoying in slow traffic, because it takes so long to get it to provide full fueling. I eamailed bully dog twice about their power pup downloader if it fixes this problem, and they had no clue what i was talking about. One way to fix it is to reduce that delay to maybe 1-2 seconds, and not re-learn it every time, maybe only when the temperature changes too much...

 

[Alan Reagan]

There's another little problem it seems to have fixed. Occassionally, when I put it into gear, there would be a slight miss like a kill switch used in marine applications to momentarily kill ignition when shifting into forward or reverse to take the "jolt" out of the outdrive. The truck would usually do it a couple of times a day.



Since the hard WOT, it has not done it once. This is five days later.

 

[rbattelle]

Yes, it takes about 3-4 seconds at full boost and full throttle before the software learns the sensor voltage from your boost sensor. (read the cummins specs, voltage can be anywhere between 1. 4 to 1. 93 volts, so it has to learn your particular sensor) Once calibrated it stays that way until you shut it off, then its all over again.

This doesn't make sense to me. It implies pre-knowledge of the maximum boost on the part of the ECM. How do you calibrate a sensor when you don't know what maximum boost is (it will necessarily vary slightly on each truck)? Or does the ECM use a nondimensionalized version of boost (and if so, what's the range)? Or is the engine-to-engine variation in boost small enough to be insignificant (in which case the ECM can then assume a value for maximum boost and calibrate from there). Can you point me toward the Cummins spec that indicates this?



I'm not trying to be argumentative, I'm just curious.



-Ryan

 

[betterthanstock]

This doesn't make sense to me. It implies pre-knowledge of the maximum boost on the part of the ECM. How do you calibrate a sensor when you don't know what maximum boost is (it will necessarily vary slightly on each truck)? Or does the ECM use a nondimensionalized version of boost (and if so, what's the range)? Or is the engine-to-engine variation in boost small enough to be insignificant (in which case the ECM can then assume a value for maximum boost and calibrate from there). Can you point me toward the Cummins spec that indicates this?



I'm not trying to be argumentative, I'm just curious.



-Ryan

The voltage for intake manifold pressure/temperature sensor, (i am looking at the cummins wiring diagram for 2003 computers) lists:

pressure (inch Hg) -(mercury)... ... ..... voltage DC



15 (=about 7. 4 psi)... ... ... ... ... ... ... ..... 0. 43 to 0. 60 Volt

30 (=about 14. 7 psi)... ... ... ... ... ... ... ... 0. 90 to 1. 25 Volt

45 (=22. 1 psi)... ... ... ... ... ... ... ... ... ... ... 1. 40 to 1. 93 V

75 (37 psi)... ... ... ... ... ... ... ... ... ... ... ... . 2. 40 to 3. 25

100 (49 psi)... ... ... ... ... ... ... ... ... ... ... ... 3. 10 to 4. 22



so you see on my truck it may be 1. 41 volts, at 22 psi, and in yours 1. 92 volts. that means that in yours it will be 1. 41 volts at only about 17 psi, and if it applied full fueling at 17 psi, yours would smoke and mine would not. So, by holding the turbo at a maximum steady (no longer rising boost) point for 3-4 seconds and the throttle potentiometer steady all the way down, it knows that the wastegate has opened, and now it learns on mine 1. 41 v equals full boost, and on yours 1. 92 v equals full boost. Then it computes the intermediary boost pressures.

This is a chep way for cummins to ensure that no engine smokes under any circumstance as long as your sensor is within the above specs. So some trucks may feel a little spunkier than others until you run it flat out for 3-4 seconds, after which they should all run the same.

 

[rbattelle]

The voltage for intake manifold pressure/temperature sensor, (i am looking at the cummins wiring diagram for 2003 computers) lists:

pressure (inch Hg) -(mercury)... ... ..... voltage DC



15 (=about 7. 4 psi)... ... ... ... ... ... ... ..... 0. 43 to 0. 60 Volt

30 (=about 14. 7 psi)... ... ... ... ... ... ... ... 0. 90 to 1. 25 Volt

45 (=22. 1 psi)... ... ... ... ... ... ... ... ... ... ... 1. 40 to 1. 93 V

75 (37 psi)... ... ... ... ... ... ... ... ... ... ... ... . 2. 40 to 3. 25

100 (49 psi)... ... ... ... ... ... ... ... ... ... ... ... 3. 10 to 4. 22



so you see on my truck it may be 1. 41 volts, at 22 psi, and in yours 1. 92 volts. that means that in yours it will be 1. 41 volts at only about 17 psi, and if it applied full fueling at 17 psi, yours would smoke and mine would not. So, by holding the turbo at a maximum steady (no longer rising boost) point for 3-4 seconds and the throttle potentiometer steady all the way down, it knows that the wastegate has opened, and now it learns on mine 1. 41 v equals full boost, and on yours 1. 92 v equals full boost. Then it computes the intermediary boost pressures.

This is a chep way for cummins to ensure that no engine smokes under any circumstance as long as your sensor is within the above specs. So some trucks may feel a little spunkier than others until you run it flat out for 3-4 seconds, after which they should all run the same.

Good info. Then obviously a nondimensionalized boost value is used within the CM845. What's the document number where you got that data? Sounds like something I could really use.



-Ryan

 

[betterthanstock]

Good info. Then obviously a nondimensionalized boost value is used within the CM845. What's the document number where you got that data? Sounds like something I could really use.



-Ryan

cummins bulletin 3666483-02 for ECM part # 4898112

it's the wiring diagram for the 2003 coomon rail 4 and 6 cylinder cummins. don't know if it's the same for the 2005. It probably has an extra turbo rpm sensor, and extra wastegate electronics, but the boost sensors should be identical.