BIGBEN

Hi all,
I am new to the forum. I'm new to the CTD but not new to this generation of Ram pick-up. I did a bunch of searching before I decided to post this. First off, the truck is a bone stock 2000 Ram2500 CTD 4x4 auto. a couple of days ago I started getting a stumble around 1300 rpm's in overdrive. Now I get the stumble from 1300-1600 rpm, no matter the gear. If I accelerate thru that rpm range it is fine. But if I try and cruz at that rpm it stumbles. Thanks to these forums I was able to figure out how to check the codes (no CEL ever came on) I had a P0122 (APS) and a P1693 (some kind off ECU code?)
now the truck doesn't have a fuel pressure guage yet but I'm working on that.So I can't tell you the fuel pressure. I can tell you it starts up perfect every time, and doesn't miss a beat at idle. It does seam a little slugish. Would the APS be causing this. Can it be reset? and if so how? I am going to change the fuel filter today as this seems to be an easy perhaps simple fix that could solve the problem? but I'm not confidant it will. should I be taking it to have the fuel pressure tested? instead of waiting a week to get a gauge in the truck.
Thanks in advance Ben
(sorry for the spelling and grammer)

BIGBEN

OK.
I can't seem to find this APS sensor aftermarket. I called the dealer and they called it a Bell Crank sensor is this the correct name? They want $710 canadian for it. Does anybody know if this is availible in aftermarket or were it can be had cheaper?

BIGBEN

I checked my APPS voltage at the PCM and I got .442. So I checked the APPS white tag and it said .471v, not a huge difference. I made the ajustments. but after I had it all tightened up and back together I had a reading at he PCM of .475v. At first every thing seemed fine. but now I get the same stumble just a few 100 RPM higher. I am going to try and get it set perfect today.

Does anybody know if this minor (.003v) over ajustment is OK?

Could the APPS sit be faulty even though I get the correct voltage?

If it is OK, could my problem be the actual PCM?

Mike D

How is your fuel filter? I would check the pressure if possible to eliminate the possibility of a failing lift pump.

I don't think the voltage would cause the problem.

I would try to drive the truck with the overdrive locked out until you reach 50 mph. It could be you're feeling the engine lug in overdrive.

BIGBEN

Mide D,
I did just pick up a fuel filter. I plan on doing this this afternoon. I don't have a gauge to check the fuel preesure. I will have to see about borrowing one.

I don't think it is the lug into OD. as it does it when I am alreading in OD lock up. it is more of a Bucking.

But I do agree with you. I need to check the fuel pressure.

I will post more info when I have it.

RowJ

I agree with Mike!
Locked up doesn't really make a difference! Under 1500 rpm in OD is lugging the motor and can cause bucking with a 7000+ lb truck and a very tall OD gear (.69).

Run with OD locked out till 2000 rpm. Gives you more power, more enjoyable driving, no loss in mileage and no "stumble"!
Just takes a little getting use to the engine sound but much better for the Cummins, IMO.

RJ

Fishin2Deep4U

A P0122 code is indicitive of an APPS failure. You could try to reset, but I am betting the symptoms will return.

If they do, you are going to need a new APPS.

Fuel pressure will not cause a low voltage condition in the APPS. Although it may contribute to driveability issues. Also, as mentioned, you should keep some more rpm in OD.

Raising the voltage per DTT's website in an auto truck will cause lockup at a slower speed or at the same relative throttle position to a lesser voltage.

Try the easy stuff first. Check an clean all battery and ground connections. reset the APPS. And keep an eye on it. My gut says you'll be buying one soon.

Dave

ib516

...and yes, the APPS is a dealer only item, and they are ~$800 CDN.

BIGBEN

Dave,
I think your right. I did all the simple stuff un-hook batts, depresses pedel. reset the APPS voltage. I also did a fuel pressure check (it is perfect) changed the fuel filter. the truck ran like a top for about 300 miles. then it started. man it was a **** off. I may try grounding the APPS to the battery. and I may also try to put a filter on the APPS. If I fail it was all cheap and I will pony up and get a new APPS. It 'f'in sucks though. I could get my 35" tires for that money.

APPS Filter Construction - Bring a dead APPS back to life

Steve Clayton Gemcuttr1@cs.com sent this simple technique for filtering the output of a noisy TPS.

I did some experimenting and found that an electrolytic capacitor (440 microFarads, 35 Vdc) with the negative side connected to the SIG RETURN wire and the positive side hooked to the TPS SIG wire gave me absolutely *troublefree* operation! Even though my TPS is basically trashed, the capacitor filters out almost all of the electrical noise, and my auto tranny once again shifts like factory-new!

I dug into the wire bundle coming out of the PCM and soldered the capacitor as close to the plug as I could manage - thinking some "TPS problems" may actually be wiring/connector problems in disguise.

Results with other values were:

220 mF, 35 Vdc - too little filtering. Tranny a little flaky.
1000 mF, 35 Vdc - far too much filtering, and a 1.5 second delay in transmission shift response crept in.
BTW, I might add that since I added the capacitor, my cruise control hasn't dropped out even once in 15K miles - usually a twice-per-week occurence (I drive 1500 miles a week). What I believe is that the dropout problem is caused by an electrical noise spike from the TPS - which is *exactly* what the capacitor filters out.