I'm looking for some advice, guys. My truck is below in the signature. When running, if you push the throttle pedal just off idle it seems to miss and the RPM's will bounce around. This gets annoying when I'm idling around town and through my subdivision. Also, lately I've been experiencing rough idle. I had "dead pedal" here about two weeks ago with a p0121 code. I replaced the apps with a Timbo apps hoping this would cure all my problems. So far I haven't had the "dead pedal" or code, but still have the rough idle and missing. Also, I've been having some funky tranny shifting probs. I've already done the Suncoast apps wire ground years ago and that seemed to fix the tc prob, up until now it seems it may be coming back. I've been researching the forums and have come up with everything from needing a new vp44 for rough idle prob to some elec. issue for the tranny problem. Any ideas? I've been pulling my hair out!!!

 

Also worth mentioning, I've disconnected the power puck to make it stock and still does the same thing. Also, recently installed two new batteries.

 

Anybody????

 

Any other codes present?

 

I too have just started getting a rough idle on cold start up. It's almost like it wants to run 3 cyl warmup right away instead of waiting for 2 minutes. No codes at all except for the standing Smarty code.

I'm begining to think that the injectors need replacing. I'm right at 250k. Otherwise the truck runs great. Mileage is down about 1-2 lower than usual for this time of year.

 

1. Change out the fuel filter(s) and clean/replace the air filter?
2. Whats your fuel psi? Check it w/a manual gauge. I'd upgrade the LP.

 

No other codes show up on the OBD II reader. I am going to replace the fuel filter to see if anything changes. My lift pump is an OEM replacement, but has less than 20k miles on it and my low fuel pressure light doesn't come on. I also just ordered the RF filter that Timbo has on his website for the alt. circuit to see if that cures the tranny problem. The truck has 83k on it.

 

To me it sounds like two independent issues from what your saying....

1. Your describing a miss at idle...

2. A transmission that is not locking up...

If its one and the other... or one or the other, then you need to address it as such. Hopefully your describing a miss as the tranny not wanting to enguage off idle...

If that is the case, I would recommend servicing your transmission...You dont mention a transmission service, I do mine every 25k...at 83k if you havent done one, you would be supprised how much difference it makes...change fluid and filter check fluid for metal, which is signs of the TQ going, which would almost surely give you a slug off the line and a lock up issue at speed...

I dont think it would be an injector issue at only 83k, it could be a fuel filter issue, you addressed the batteries, the apps, and the suncoast thingy....double check the negative connections ALL of them. and check to make sure the positive cables are double super tight.

that would be my start point...

1. battery connections, fuel filter (lowest cost first) then jump to a fluid and filter change in the tranny paying attention to color, smell, and metal presence.

NCA

 

Thanks for the response. I agree, it seems to be seperate issues. The tranny has less than 20k on a filter and fluid change, and the oil doesn't smell burnt or anything. When I change the fuel filter I will check the battery connections away from the battery, as I know those are good due to just changing the batteries. Thanks again for the reply. Will update after I get time to work on the truck.

 

Ok...another thing that just hit me is...actually another question for ya..

Have you recently done any work to the fuel system...from the tank, lines, lift pump, fuel filter, injector pump, to the injectors.

If so...you could have introduced air into the system, causing an airlock. This could cause a "miss" like symptom..has it given you any hard start issues after sitting??

NCA

 

No, haven't done any work to the fuel system. No starting issues. The truck can sit for weeks and will start right up.

 

sounds like your tranny is doing a 4th gear hunt like mine did,thers is a way to by pass the ecm,and get rid of the problem for good,go to ats diesels facebook page ask them to send the diagram to fix the 4th gear hunt,also make sure your batteries are good with clean connections,and good cables i just replaced my cables not to long ago and it made a huge difference in the idle.

 

I've already bypassed the ECM on both the ground circuit for the APPS and the wire from the PCM per the ATS and Suncoast instructions. It had fixed the TC hunt problem for quite some time, but then it has recently returned. As stated in a previous post, I'm waiting for an RF Filter from the source on Timbo's website to put on the Alternator circuit. Hopefully, this will fix the problem.

 

UPDATE. I believe I had a low voltage problem. The diodes were bad in my alternator and it wasn't charging right unless the rpms were above 1300 or so. I installed a new alternator and all the problems have vanished! I also installed the rf filter while there and no more tranny issues.Thanks for the help.

 

10 years and 400k later the and all of the other fixes done, the RF filter coil fixed mine finally I hope for good.
Dead pedal and miss could be Crank shaft position sensor.