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Cold Idle Problems


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This issue has been showing itself since early fall when temps were only in the 40's & 50's Farenheit overnight. What happens is this: I start the truck (early 04 5.9, stickshift QCLB) and it will bring itself up to idle. Then there's a slight stumble that you can hear chug like once. The RPM drops below 500 for a second and then it recovers itself back up to about 750 or 800 rpm. A minute or so later, there's a larger & more noticeable skip and it'll almost choke itself out and then it'll recover back up to 900rpm and there's a huge puff of black out the exhaust.If it stumbles bad enough, it won't recover & then stalls. It'll start right back up no problem, but it goes right back into that same cycle. If you try to drive away (because once the truck is warmed up, this problem goes away), it'll act like it's not getting any fuel at all and stumbles & chugs. Then all of a sudden it gets enough fuel & there's a huge black cloud and a puff of white in the middle of it... after it takes off accelerating etc. Now that the overnight low temps are in the 20's this has become a real problem where I can't even leave the end of the driveway for fear of it stalling in front of a school bus etc. When I come up to a stop sign, it tries to die, etc. Like I mentioned, however, once you get on the highway & get it fully warmed up, the problem goes away & it idles just fine.I am trying to correlate this to the grid heater cycling on & off, but it's independent of that...So, what's going on? Please don't let it be more injector BS.....:pray:

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It's been a few tanks of fuel, probably at least 4 or 5 tanks and it's been pretty rare up until this past week when the temps finally dipped down low. No codes lit up, and it starts right up (which it wasn't doing when I dropped injector #5 a year or so ago). I don't have any pressure monitoring gauges just yet....I've just been reading that sticky about the wire loom near the oil filter over on CumminsForum... think it's a possibility? Mine seems a little different than those symptoms that they listed over there.

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It could also be as simple as a sensor, MAP or IAT, that tells the ECM the temp isn't what it is and the timing is off. Do you have any gauges? Access to a scanner, Scan Gauge, or Ultra Gauge?It does seem different, but certainly worth checking that wire loom.

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No access to a scanner or anything similar other than the "key-on" "key off" trick. No gauges outside of factory dash stuff.So, I got under it and there's a set of wires that terminate in a ring-terminal that is on a threaded stud. This stud is above the A/C compressor & under the oil filter. There is no nut holding that ring on the stud. I was able to slip it off & back on by hand. Duh. Have to get a nut to hold that back on, but no wiring seemed to look bad at all.The MAP is located in the intake tube, correct? Where is the IAT?

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This wiring ring terminal was slid onto the oil cooler hardware. Lower right corner of the oil cooler has a nut that holds on the cover, but the nut has a stud sticking out of it. Bolted the ring to the stud & tightened it up. Fired it up and it immediately started the problem again. This time, I could see the smoke in the full sunlight. It's misty grey smoke with a puff of blue-ish white in it. After the truck almost chokes itself down, it recovers back up to about 1000rpm. On the way back from 1000rpm to its normal idle, the injectors rattle and that's when the white/blue smoke happens.I think it's an injector overfueling again. But I don't think it's leaking down when it's parked. The motor starts too easily actually idles just fine in between these weird episodes.Anyhow, heading to Southern Truck Parts on Wednesday morning with my fingers crossed that it's not another (or even the same) injector again. More results to follow...

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Here is a thought, and nothing more. Remove that wire terminal and don't ground it.. maybe it's not supposed to be grounded???But based on the rattle I would think rail pressure, which would make me think the FCA is sticking.

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Here is a thought, and nothing more. Remove that wire terminal and don't ground it.. maybe it's not supposed to be grounded??? But based on the rattle I would think rail pressure, which would make me think the FCA is sticking.

x2. While reading this, I was thinking IAT sensor or FCA..........especially with the injector rattle. Try plugging your truck in overnight to see if that has any effect also.
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Let me support the FCA theory a little more... as I mentioned, it seems to go away when the truck is warmed up. Recently I've been taking a lot of short trips (not really helping things, I know) so the truck doesn't get warmed up unless I take the long route to get somewhere. The other day, in an attempt to get the truck warmed up, I got on the expressway for about a 20 mile loop. On the way to the expressway on city streets, the truck was shuddering and the pedal seemed dead at the very initial tip-in point.

In other words, at the very touch of the pedal, the truck didn't do anything. Once you put your foot in it and moved the pedal quite a bit and the motor cleared up, it would move on out and haze a little bit (leftovers from the chugging down low?). Even after reaching the 10-mile mark on the freeway, where I exited & waited to go across the bridge & head the other way, the pedal still seemed dead at that tip-in point. Eventually, it cleared up & the problem went away...

That makes me think FCA a little bit, too. I don't have the big APPS mounted on the engine. Is the FCA under the battery tray in that case?

I found a parts place that's open tomorrow, so I might replace the IAT & see what happens... just for grins.

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x2. While reading this, I was thinking IAT sensor or FCA..........especially with the injector rattle.

Try plugging your truck in overnight to see if that has any effect also.

Dumb Dumb newb question.... how do I plug this thing in? Where's the heater plug?

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Okay, after reading some FSM pages, I take back my question about the APPS & FCA. They are 2 different things. Steep learning curve some times...:doh:

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If you're getting the "dead pedal", then it could very likely be the APPS. The APPS on my truck is under the battery tray on the drivers side also. Not difficult to change out at all.The FCA (fuel control accuator) is on the CP3. It meters the fuel entering the CP3 and is mounted on the CP3 itself. The easiest way to access it is to remove the drivers side tire, the inner plastic wheel well liner, and then you're looking right at the CP3. That's how to get at the APPS also!!!

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So, having read a few CF threads on how to replace the FCA, it's interesting to me that in the "FCA Removal" section, the FSM says "The FCA is a non-serviceable part." LOL...

So, is this available at... say... NAPA or other general auto parts joints? Or is this a special order dealie?

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Just realized that Geno's garage is about a 45 minute drive from me here in Atlanta. FCA replacement coming right up...

Results to follow. Hope ya'll have a safe & warm New Year's!

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Did you ever find your heater plug? Im not positive that all trucks are sold with the cords, especially trucks that are sold in warmer climates, but it will at least have the heater element in the block. The cords can be purchased at Genos among other places, one end will plug into the element and the other end is for the electrical outlet. If I remember correctly, it should be about mid way up the block, passenger side. It does make a very noticeable difference plugging them in in colder weather.

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I have not looked for the plug. i know there is not a cord anywhere under the hood. There is this one plug on the side of the block that looks like it has a yellow plastic cap on it from the hardware store like you would put on the end of a garden hose... LOL.:thumb1: I think it's screwed on to cover up the heater element. This truck was originally purchased in TX, so I bet it never had a cord.Anyhow I replaced the stock canister fuel filter (only about 2000 miles old) and the FCA a day later. Today it was low 20's at dawn. It fired up & while I scraped frost off the windshield for 5 minutes it never hiccuped or burped once. I'm thinkin' it was the FCA.Thanks for all the suggestions guys. I always read up on CF when I need a general concept of what is wrong. But coming over here is like pulling the old World Book Encylopedia off the shelf & getting the REAL dirt.PS- When I went to Geno's to pick up my FCA, I accidentally bought boost & pyro gauges & a pod and a few other parts. Hope to get all that installed over a long weekend... and then it's on to the Smarty Jr. :woot:

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