dyno run, inconstant numbers, transmission slip?

[robertyoke]

I put my truck on superflow's dyno on saturday and had very inconstant numbers. max power was 526hp 1062 tq at 2600 rpm. other trucks with tst box made more hp with single turbo and would rev to 3150 for max power. Boost never went past 38 psi. on the street, after the dyno 60+psi.



I called laserbob and had him set up dyno for some more testing. had runs from 536hp 1150 tq to 280 hp 500 tq. no run made power over 2800 rev.



I talked to mark chapple, from tst, he said that his box does not defuel at any given rpm, and he suggested that it may be torque management, the cummins ecm may defuel if it sees slippage at the transmission, or before it shifts, but didnt know.



Does any one know if the 48re trucks that have stand alone pcm (early 03) have defueling at 2700 rev?? or does this setup see sllipage and defuel to protect the trans??



-robert

 

[DLeno]

cant answer the de-fueling question but, uh, you're pushing a boat load of torque to that transmission. my guess is that the the TC is not holding. or have you bombed your transmission already to correct that?

 

[robertyoke]

it has an ats tc and vb. dtt input shaft and drum. emjay lock up controller.





what is bd's R. A. D. device for??

-robert

 

[AK RAM]

Does any one know if the 48re trucks that have stand alone pcm (early 03) have defueling at 2700 rev??

I get something similar with my standard output 47RE. Twice now I have had the truck fall on its face under a WOT run at 2700/2800 RPMs. I don't have a dyno to get on to verify exact RPM... just watch the needle best I can. Not something that happens every time.



To go along with that, if I have the TST turned up any higher than 4/4, I can put the TAC at 2000 RPMs and watch it bounce. Power coming in and out, in and out, in and out. Runs fine directly above or below 2000 RPMs. There is just that sweet spot.



This has been an absolute bear to diagnose. Same response out of TST. I have an appointment at Cummins Northwest this afternoon to take the truck out with their diagnostic goodies hooked up. I hope we can pinpoint exactly what the ECM is seeing that is causing this. However unlikely, it could be the trans slipping. This is one of the things I will be looking for.

 

[flattracker]

have a TST on an 03 HO have exact same symtoms above 4x4 thought maybe CP3 was starving for fuel with the stock pusher pump but haven't tried to verify yet , would be most interested in what you find out . THANKS IN ADVANCE

 

[KLockliear]

If the dyno can't give you consistent results from run to run on the same truck, then the results are useless.

 

[robertyoke]

have a TST on an 03 HO have exact same symtoms above 4x4 thought maybe CP3 was starving for fuel with the stock pusher pump but haven't tried to verify yet , would be most interested in what you find out . THANKS IN ADVANCE

if you got smoke, thick and black and then it goes away, and repeats it self, is my guess that it is running out of fuel. I saw this with the stock pump and again with DD's pusher pump kit, truck now has 2 black holley pumps, one for each tank and the carter from DD kit, after the slector valve. fuel pressure after the filter never has gone below 16psi with this set up. it can turn day into night with the smoke before the b2 spools up, and then it is still dark.

-robert

 

[AK RAM]

My problems appear to be the Accelerator Pedal Position Sensor (APPS). The APPS voltage is dropping . 2 of a volt as the RPMs roll through 2000, causing the stumble. It is bouncing all around all the time, but it appears to take at least . 2 to make a big enough difference to feel under power. This is with the pedal in a fixed position, not moving, so the voltage should not be moving at all. It immediately jumps back up to where it is suppose to be, then drops again if I am still in that RPM range. At WOT, I get a slight stumble as I pass through 2000 RPMs, then when I hit about 2700 RPMs, the APPS voltage drops from 3. 4 to 3. 1. My truck is doing it on stock power, but when you only have 200hp to the rear, you really can't feel it taking a measly 20hp away for a split second. However, with the TST cranked up, this voltage drop is enough to rob you of over 100hp in itself when at WOT, causing the truck to nose over when it happens like someone just hit the brakes. The Cummins tech said there is a TSB for irregular APPS voltage, among other things, if your truck was built on or before July 25, 2003, TSB 18-027-03. Auto, stick, SO, or HO, 47RE, 48RE, doesn't matter. He doesn’t have the stuff to flash, so I need to visit a dealer to get it done. If that doesn't take care of it, I may actually have a bad APPS sensor which will need to be replaced. Last resort would be to try a Happi Box, which corrects the irregular APPS signal on the 2nd Gens.



The tech at your local Dodge dealership can take a ride with you and check the APPS voltage in just a few minutes with their hand held DRB. One interesting thing to note is we did several WOT runs with the pedal to the floor. The Apps voltage, which equates to fuel being fed to the injectors, was never the same. If the pedal is on the floor, the voltage should be the same every time. On one run it never topped 2. something volts. This would mean I was only getting about 3/4 of the fuel on this run, and you could definitely feel the difference.



Transmission was fine. Pressures were steady and no slipping.

 

[flattracker]

Thanks to AKRAM and robert for the info gives me a definite direction to start looking.

 

[Tomeygun]

http://webpages.charter.net/tomeygun/Diesel_stuff/18-027-03.pdf



Makes it seem its only for autos...



But it seems to fit my problem (and other that are built before the cutoff)

 

[AK RAM]

Would have to clarify that with a dealer. I took a quick look at several auto specific TSBs, and it appears that if they apply to autos only, they specifically say that. For instance, TSB 18-015-03 is for autos only and it says "applies to vehicles equipped with a 5. 9L standard output Cummins diesel engine (sales codes ETC) and a 47RE automatic transmission. " The TSB that may fix this particular problem, TSB 18-027-03, lists possible codes associated with vehicles that have the auto, but the "Models" block says nothing about being auto specific, just "APPLIES TO ALL RAM TRUCKS EQUIPPED WITH THE 5. 9L CUMMINS 24-VALVE DIESEL ENGINE (SALES CODE ETC OR ETH) BUILT ON OR BEFORE JULY 25, 2003. "



Do a search in the 2nd Gen forum on Happi Box and you will see those guys have had this very problem for years. Seems there are design flaws that allow "noise" in the APPS wiring that causes the voltage to fluctuate. There are several people that sell APPS rewire kits that fix this on the older trucks. I only hope it is just a software thing for us or just an unlucky occasional bad sensor as there are no rewire kits or a Happi Box available just yet for the 03s. It will be Saturday before I can get the flash and see what it does.

 

[Tomeygun]

It will be Saturday before I can get the flash and see what it does.

I will be waiting with big expectations, The earliest I can get mine in is next friday

 

[AK RAM]

The earliest I can get mine in is next friday

Geeeeez... . and you work there. I was hoping you could tell us whether it worked or not by the end of the day.



Got any tech friends with a hand-held DRB? I would be curious to know if your APPS voltage is fluctuating as well.

 

[robertyoke]

post your results after you have the tsb done



the happy box was for the tc locking and un locking, correct?? the emjay controller has a filter built in to it, so I am good there. but I wonder if the power delivery is sometimes 75% then 90% then whatever because of the tsb 18-27-03.



still makes me wonder about max power at 2700 revs, is it the pcm detecting different input vs. output speed when the trans is in lock up, and defueling. max power should be at 2900 when stock, so I doubt the ecm is cutting back at 2700 to allow shifting, protecting the trans.

the power was cutting back fast at around that point, 2650~2750 revs.

we did see a nice smooth dyno run with the power box on level 3 and it peaked at almost 2900 rev and still made 504 hp. I am thinking that maybe the trans with the upgrades I made will only hold just above 500 hp??? made 500+ hp at 2100 rpm and 2700 rpm and in between and the hp was climbing,and the dyno got funky. made just at 500 hp and all was good.

lots of theories so little time... . I need to get back to work.

 

[Tomeygun]

Geeeeez... . and you work there. I was hoping you could tell us whether it worked or not by the end of the day.



Got any tech friends with a hand-held DRB? I would be curious to know if your APPS voltage is fluctuating as well.

hehehehe, Looks like I will stealing one for the ride to lunch :-laf

I will post if i get a chance to test

 

[DLeno]

hehehehe, Looks like I will stealing one for the ride to lunch :-laf

I will post if i get a chance to test

an OBD-II scanner such as obd-2.com should work for us mortals that don't have a DRB-III subscription. if the pic comes through you can see how I've configured my virtual gagues. on the lower left is the TP. you can make one of the larger guages to be TP instead if you want to watch it closely. the guage reads both analog and digital.

 

[AK RAM]

post your results after you have the tsb done



the happy box was for the tc locking and un locking, correct?? the emjay controller has a filter built in to it, so I am good there. but I wonder if the power delivery is sometimes 75% then 90% then whatever because of the tsb 18-27-03.



still makes me wonder about max power at 2700 revs, is it the pcm detecting different input vs. output speed when the trans is in lock up, and defueling. max power should be at 2900 when stock, so I doubt the ecm is cutting back at 2700 to allow shifting, protecting the trans.

the power was cutting back fast at around that point, 2650~2750 revs.

we did see a nice smooth dyno run with the power box on level 3 and it peaked at almost 2900 rev and still made 504 hp. I am thinking that maybe the trans with the upgrades I made will only hold just above 500 hp??? made 500+ hp at 2100 rpm and 2700 rpm and in between and the hp was climbing,and the dyno got funky. made just at 500 hp and all was good.

lots of theories so little time... . I need to get back to work.

Same here... lots of theories. The voltage drop seemed a little much to be just "noise" that a filter would remove, but I guess I'll cross that bridge when I get to it. I was under the impression that the Happi Box rewires the APPS to isolate it from the rest of the truck's wiring harness, allowing it to provide a clean signal from a different power source. The affects of the APPS signal appear to be a little different on our trucks versus the 2nd Gens. The signal drop on a 02 will make the trans go haywire. The Happi Box corrects the signal fluctuations on the 2nd Gens, which in turn corrects the trans problems that are caused by it. They tell me that on the 2nd Gens, the in-line noise filter provided by DTT will correct their problem as well. My trans however was acting fine during all of this. Given that, the Happi Box's claim to fame for stopping the trans shifting would do me no good, but it's rewiring of the APPS sensor for a good clean signal is what I would be interested in. Hopefully it doesn't get to that point.



We know the voltage drop is causing the problem (at least on my truck), just not what is causing the voltage drop. From what the Cummins tech was telling me, the throttle cable movement is translated by the APPS sensor, which in turn sends its signal to the ECM as "voltage" on how much fuel to provide. The higher the voltage, the more fuel. When the APPS voltage signal drops suddenly, the ECM just assumes you eased up on the go pedal. It doesn't know any better. Seems simple enough. He really thought the TSB would fix it.



Cummins didn't tell me anything that would indicate the PCM was part of the problem at all. It was just the way the ECM adjusts to the signal drop. We both have similar setups and my trans checked out OK. He measured pressures, temps, slippage, lock-up... . everything was perfect. No slipping.



My truck was doing the same thing at redline. Occasionally my truck will pull hard to redline and sometimes it won't. When we were testing, we made a few runs at WOT to redline that actually felt pretty strong to me, but the tech said the voltage was still dropping a little at 2700 RPMs, give or take. The one run that made the most difference was when I hit about 2700 and the voltage dropped from 3. 4 to 3. 1. When this happened, it was like putting on the brakes. We saw it happen on the monitor, truck nosed over, and we kind of looked at each other like... . coool, that was interesting. So I would think there is a good chance that you are seeing the same thing. The only way to verify it would be to put it on some kind of scanner and go for a ride. At constant pedal pressure, the voltage should not move. You can floor it and let the truck go to redline while the tech watches the screen. If the voltage drops at all before it gets to redline, there is a problem.

 

[robertyoke]

well maybe thats it. I just don't want to take it to the dealer if I don't have to. they look at any bomb as bad.

 

[AK RAM]

I hear ya. Just hang tight. There are several of us with the same problem, so someone is bound to try the TSB soon enough, then we will know for sure.

 

[AK RAM]

Good news and bad news. The flash didn’t help it at all. The good news…



I had TST send me a used box with the twins program on it to try. Hooked up this box and the surge is gone. RPMs are as smooth as silk. The problem is, this box doesn’t feel very strong. 5/5 is suppose to be about max power with this program, but 5/5 feels weaker and less EGTs than 7/7 on the soft program. Don’t know what is going on there. 6/6 on the twins version doesn’t feel as strong, but EGTs are a little hotter than 7/7 on the soft program. Maybe it is just me.



Took the twins box off and put the soft box back on and RPM surge is back.



Don't quite know what to make of it, but still tinkering with it.