Engine/Transmission (1998.5 - 2002) Engine went to idle only!

[mhenon]

Had a strange thing happen today. After travelling for about an hour the engine instantly went to an idle only mode. No response to the pedel at all. I pulled off the road using idle power and found the following codes;



1. PCM. . 1693 (of course) and 0500 (no vehicle speed sensor signal detected during road load condition?).

2. ECM. . 1693 (first time I've got one in the ECM) and 0121 (APPS voltage below minimum)



I cleared the codes with my ScanGauge II after pulling the battery for a few minutes. The CEL went off and all's well. Don't know if this is related but the engines been cold soaking for a few days and temps are in the single digits. The road was wet with snow & slush. i'm wondering if moisture got in the speed sensor (that's in the differential. . right) connector and sent a bad signal to the APPS. That or one of those two sensors is on the way out.

Any ideas?

Mike

ps: truck ran fine for the next 2 hour trip home

 

[Cummins724]

Same thing happened here, APPS went completely out shortly after.

 

[Wiredawg]

I 2nd that on the APPS. I was pulling my 17K Lb 5er when mine first acted up. Thank goodness the mighty Cummins would move the 5er at idle. Happened at a red ligjht in a small town on a Sunday. Acted up again a couple of hours later. I got mine to reset but it went out shortly thereafter. Go to an Advance Auto parts... they'll read the OBDII code on the ECM for free to confirm. Must be a common problem, 'cause all the small 5-Stars had 'em in stock. $388 plus tax.



Wiredawg

 

[rweis]

Did you try recalibration the APPS with the procedure where you read the APPS voltage at the PCM, compare that voltage to the sticker voltage (manufactured data) on the APPS and adjust (rotate) the APPS sensor until the read voltage at the PCM = the sticker voltage (manufactured data) on the APPS?



The APPS might just need calibration. The exact procedure is documented here on TDR. Sometimes called the DTT APS recalibration because the procedure was first written up by Bill K (I think).



Bob Weis

 

[mhenon]

Did you try recalibration the APPS with the procedure where you read the APPS voltage at the PCM, compare that voltage to the sticker voltage (manufactured data) on the APPS and adjust (rotate) the APPS sensor until the read voltage at the PCM = the sticker voltage (manufactured data) on the APPS?



The APPS might just need calibration. The exact procedure is documented here on TDR. Sometimes called the DTT APS recalibration because the procedure was first written up by Bill K (I think).



Bob Weis

i have read that proceedure but thought thats for proper voltage to automatic transmission's. Anyway, I might give it a try. Just strange that it went from running perfect to nothing in a second. Very typical of an electrical glitch. I would like to figure it out where it is before throwing money at it.

I'll probably just order an APPS from HoesliDiesel:

internet specials



The other code in the PCM came on at the same moment (#0500). . is there a connection? Wouldn't seem possible to get two codes at the same time that weren't related somehow.

I'm going to keep an eye on it for now. When the new APPS shows up i'll get brave and start working on (tearing into) the bad one. Is the speed sensor in the differential? Want to take a look at that too. I'll keep everyone informed if the problem shows up or I figure out what's going on.

thanks..... Mike

 

[mhenon]

I'm not sure the APPS is really dead. Had to drive about 5 hours today to get our daughter. Not a hiccup!

Anyway, there's a new APPS on the way so I'll run this one 'til it dies.

Mike

 

[SAndreasen]

I'm not sure the APPS is really dead. Had to drive about 5 hours today to get our daughter. Not a hiccup!

Anyway, there's a new APPS on the way so I'll run this one 'til it dies.

Mike

my apps has been acting up somtimes once every ten hours somtimes once every ten days #@$%! which reminds me i gota add that to the christmas list i sent to terry at moonlight

 

[SquareDave]

I had the same symptoms about a year ago with absolutely no response from the accelerator, then within seconds power and accelerator response returned. About 3 weeks later it happened again, but this time the engine did not kick back in. A few seconds later I managed to nurse it to the side of I-880 in Hayward, CA, and there it conked out --- totally. It turned out to be a dead lift pump.

Since it was the start of a 3 day weekend, I was privileged to be a guest of the local Comfort Inn for longer than I would have liked. The dealer did a fine job in getting me going once all their help returned, and I've had no trouble since then.

Dave (parked in the snow in CO)

 

[Cummins724]

I'm not sure the APPS is really dead. Had to drive about 5 hours today to get our daughter. Not a hiccup!

Anyway, there's a new APPS on the way so I'll run this one 'til it dies.

Mike

Check out issue 52 of TDR mag, it explains how to clean the contacts inside the APPS. This may save you some bucks.

 

[mhenon]

I had the same symptoms about a year ago with absolutely no response from the accelerator, then within seconds power and accelerator response returned. About 3 weeks later it happened again, but this time the engine did not kick back in. A few seconds later I managed to nurse it to the side of I-880 in Hayward, CA, and there it conked out --- totally. It turned out to be a dead lift pump.



Since it was the start of a 3 day weekend, I was privileged to be a guest of the local Comfort Inn for longer than I would have liked. The dealer did a fine job in getting me going once all their help returned, and I've had no trouble since then.



Dave (parked in the snow in CO)

I know it's not the LP as my pressure has been very steady for some time now. Also, there's the issue of the codes that showed up along with the shutdown.

I did read the TDR article on cleaning out the APPS and may give that a try if it acts up again. For now I'm just waiting on a replacement. Now that a new APPS is on the way this one will probably last another 100K miles.

 

[Wyomingcowboy]

Don't know if this is related but the engines been cold soaking for a few days and temps are in the single digits.

What is cold soaking?

 

[mhenon]

What is cold soaking?

I just meant to say it had been sitting for days in low temps without being run or even started. Since this was obviously an electrical problem I thought it might have been part of the problem. I've been running the truck daily lately with no issues.

Mike

 

[Wiredawg]

I took my old one apart after I installed the new one. There is a conductive disk the wiper contacts travel on, varying the resistance, thus voltage. The resistive film had worn off and wasn't repairable. Mine went out around 75K miles.

 

[rweis]

I know the APPS has a couple of other functions (idle verification, etc) and I think this idea has been iterated a couple of other times,



but what if the moving electrical wiper / throttle position were changed to an industrial rheostat (same range and rate as the APPS / TPS) and that signal fed back to where the current wiper contacts are?



Maybe cheaper and a lot easier to replace the TPS / APPS every 100k or so?



Interesting idea? or not?



Bob Weis

 

[mhenon]

I know the APPS has a couple of other functions (idle verification, etc) and I think this idea has been iterated a couple of other times,



but what if the moving electrical wiper / throttle position were changed to an industrial rheostat (same range and rate as the APPS / TPS) and that signal fed back to where the current wiper contacts are?



Maybe cheaper and a lot easier to replace the TPS / APPS every 100k or so?



Interesting idea? or not?



Bob Weis

VERY INTERESTING! The old APPS could almost be tied off to the side, like a passive interface, and the industrial rheostat fixed in the OEM APPS location. If the rheostat was reasonably priced and lasted longer than the Micky Mouse wiper on the APPS it would be a win-win.

I know other members have looked into this before but gotta believe there's an after-market fix for this.

Mike

 

[rweis]

Well, my point is:



If we have a problem with xxx that is a general nature causing a lot of members a problem repetively, then let's find a MUCH better (I like to refer to it as an industrial / commercial solution) solution for it.



Most 2nd gens have this VP44 problem (PSG, fuel supply, engine heat soak). Solutions include: Heat shield the VP44 from the engine, fuel coolers, better lp like the Walbro 392 (RASP, Fuel Boss), after engine shutdown blowers, better fuel filters, build a sturdier PSG, build a better advance piston bore.



The 2nd gen fuel canister (fuel pickup, fuel return, fuel level sensor). Solutions include: DrawStraw, returns to the tank vent line, totally mechanical fuel level sensor.



The 2nd gen APPS / TPS (poor contact design, fragile contacts, ???, ???). Solutions include: ???, ???, ???



Is it time to research, experiment, problem solve the APPS / TPS?



What body of knowledge do we already have "I know other members have looked into this before" and where do we go from here? Maybe some old Apps to take apart and see what is inside? Who, knows what about APPS / TPS?



"There is a conductive disk the wiper contacts travel on, varying the resistance, thus voltage. The resistive film had worn off and wasn't repairable", could we have new conductive disk made up like a repairable swapout?



You know that industry would not tollerate a fragile rheostat design when it would shutdown the machine. What does industry do?



Bob Weis

 

[mhenon]

Well. . it happened again. I had two incidents of the engine dropping to an idle while driving. Cruise control still worked and would bring me back to speed but the peddle was inop. Looks like the APPS is on the way out. I would still like to know what exactly is failing. Doesn't appear to be the wiper/rheostat as it works normally otherwise. I can also get the engine working properly by simply shutting it off and restarting. It's still very cold here but no snow or slushy roads to blame it on this time.

I don't know if I'll find anything... but when I get the new APPS on the old one will be taken apart. These intermittent electrical problems are tough to troubleshoot however so unless it's something obvious... .....

Mike