vexed about driveline
 

ok, so i was driving back home from the army in central texas. after the first day of driving i got to little rock, arkansas and my transmission started slipping and i heard some popping when the engine was revving between 2k and 2500 rpms.

i went to a tranny shop and they found a burnt up 2nd gear band, and a bad torque convertor. so they did a full overhaul and put me back on the road.

once the truck was back up to normal operating temp, the popping was still there. i also noticed that at a certain position of the pedal it will hang at that spot like in cruise control. i have been trying to troubleshoot the APPS sensor since i have an early 04 truck and not 04.5. what im trying to figure out is...does anyone have the testing procedure for that sensor? i'm hoping that its just a noise filter, or a broken wire or something cheap since that sensor in cheap form is still 250 dollars. any help is greatly appreciated.

Any codes?
You running any type of box or programmer?

no programmers or boxes, the only things for mods is a turbo back exhaust, k&n air filter, and ats intake manifold. no codes are being thrown other than a code for the fan which i believe is the clutch going bad. i've been looking for troubleshooting procedures for it but havent gotten very far.

Sounds like you have 2 seperate problems here.

You are hearing popping, does it sound like its backfiring in the exhaust manifold? Like popping corn? If so thats usually low rail pressure. Checked your lift pump pressures? Rail pressures?

Since you have an 04 auto you have a TV cable and throttle cable that connects to the bell crank and APPS assembly at the front of the engine. Disconnect the cable that runs to the trans and see if you still have a hang in the throttle. You also have a throttle cable that runs down to the APPS from the firewall. Check both cables for binding, worn spots, etc.

I had a similar problem with my early 04. Not the tranny but the poping sound. My fan clutch went out because the fan cought the electric fan wire and ripped out the front of my fan cluch which nicked my serpinteen(sorry bad speller) belt that had a strand of belt whiping around and making a poping sound. Thout I cought a rock or something when it happened dident think to much of it since you really cant see much with the fan shroud in the way and dident see anything out of the ordinary. Any way it cost me a new fan cluch and blade, new serpinteen belt, and a new timeing sensor. Just something to check. Good luck

well i haven't noticed binding in the cables. i have noticed that in park, and push the pedal all the way down and let up..it will hang between 2000-2500 rpms. the popping is out of the exhaust that i can tell, its not something in the fan im sure. i have noticed a somewhat erratic idle. by erratic, i mean maybe one miss every 30-45 seconds. i thought a cable might have been hanging but i don't feel any binding anywhere to be honest. i have heard of the alternator spiking electricity causing a close symptom to what mine is doing. a fellow diesel guy told me to look into what they call a "noise filter" which keeps the spike from interrupting the sensors signal. granted its not too expensive so its not a big deal if i pick it up, and will get back to you all when i install it. i just want to know how to test to make sure that sensor is good/bad so i won't be wasting just under 300 bucks since im fighting for employment at the moment.

also to add in, my cruise works on an off...if it has to downshift or accelerate at all, it drops out, and will not function again until power is cycled, which on another thread i have somewhat figured out that i need to get the ecm flashed in order to fix that issue. just thought it might be a good idea to point that out as well.

If the pedal is hangin its usually in the cables, you described feeling the hang so not sure what you mean by you can't feel it??

If its just the rpms hanging and the pedal is returning correctly, that is possibly an FCA problem. Will also cause your CC to not function correctly, surging, dropping out, etc. With the miss at an idle it sounds like you have something going on there with the electronics.

The popping out the exhaust could also be a bad FCA if your fuel pressure to the CP3 is good.Need to verify fuel pressure to the IP and also rail pressure to know for sure.

There is not place except on the trans that a filter will do any good on the 3rd gen trucks, and then only if you have a built trans that is setup a certain way. You have no symptoms of problems there.

If you can verify fuel pressures you will a lot further along. If I had to guess, I would replace the FCA before digging any further or taking it to the dealer.

ok so im not too up to date on the acronyms. whats FCA stand for? the lift pump is only 2 months old, so i hope to god its still good, fuel filter is even younger, about a month old. however i will be putting an airdog or fass system on sometime when i have a steady income again.

FCA is the fuel control actuator, the silver thing on the back of the CP3 with the wiring harness atached to it. Its job is to meter the amout of fuel delivered to the high pressure side of the CP3 to make rail pressure. If it doesn't work correctly all your symptoms are possible, plus others. Its one of the relatively cheap parts on the fuel system.

Did you replace the LP with another cannister mounted pump (they really are junk) or have the in-tank conversion done (better but still junk)?

i put a factory replacement LP hoping it would last me til i picked up a fass or airdog kit. i figured it would buy me enough time to come up with the money for it but its possible i was wrong in thinking it would last longer than 2 months lol

how would i test the FCA?