For a couple months now my truck has had a slight surge. If it's 50 deg. or more, it doesn't do it, if its in the 40's it does it but is hardly noticeable, and if it's in the 30's or less it is very noticeable. Engine temperature has no affect, warm or cold. Also, it will only do it under slow acceleration. It's almost like the Smarty is kicking on and off, but the truck still does it when I set the Smarty back to stock, it's just not as aggressive. I'm not getting any codes, i've reset the apps and since the problem seems dependent on outside temperature I tried cleaning the IAT sensor, and nothing has changed. Any ideas?

 

Yuup its the 24v timing shutter, happens on some 98.5s-02s with lots of fuel, I have dealt with this sense I did my Machs last winter, to get rid of it you need to put a warmer (190) t-stat in, and you need to fool the IAT sensor to think its warmer than it is, this can be done with a potentiometer, that way it can be set at stock voltage for cold weather starts, and then switched for hard driving, here is some more info

http://dodgeram.org/tech/dsl/sensors/IAT/clean.htm

For those considering the IAT mod, here's some info from a previous thread describing what I did:
Quote:
First I verified timbo's suggestion by purchasing a 1k ohm resistor (1/2 watt for the thicker leads so it plugs into the connector) for less than a dollar and
bypassing the IAT sensor. The miss was gone, but cold starts were an embarrassing challenge. Recently I purchased an IAT extension harness and modified it to place a potentiometer & switch in parallel. The purpose of the extension harness was solely to avoid modifying the factory wiring harness. I placed the potentiometer and switch in series with each other, and the pair is wired in parallel with the stock IAT sensor. With the switch ON/closed the pot reduces the IAT resistance (tells the ECU the intake air is very hot so it pulls timing) and alleviates the miss. With the switch OFF/open it's the same as stock for cold starts. I didn't want to bypass the IAT altogether so the ECU will be able to verify that the intake grid heater is working. I also went with a pot over the 1k resistor this time so I can dial in the maximum timing without causing a miss.

I purchased the pot, switch, and a small project box at a local electronics shop for ~$5 total, but it looks very similar to this over the counter version.
Since this is a topic of interest again hopefully that info will save some search time. The topic of relocating the IAT sensor has come up as well, and the IAT extension harness mentioned above would work for that as well.

Edit: While I'm at it, here's a table of IAT resistance vs. temperature
Code:

Deg F Ohms
32 34400
76 12800
96 6600
112 4800
122 3800
128 3000
140 2400
150 2100
160 1900
165 1700
190 870
212 625

Circuit diagram
I was asked to clarify the circuit layout, so here's a quickie diagram showing the switch and potentiometer in parallel with the IAT sensor:


Again, with the switch open it's the stock configuration. Close the switch and the potentiometer is placed in parallel with the IAT sensor. The equation for determining the combined resistance of the potentiometer and the IAT sensor (ie. what the ECM sees) is:


Refer to the IAT calibration info in my previous post to convert resistance to temperature.

Once again, if you purchase an IAT extension harness you can tap into that to place the switch/potentiometer in parallel with the IAT sensor while leaving your stock harness unharmed. That's up to you.
Attached Images

This info was posted by EHrul on TDR, here is the full 8 pages if you wanna read it

http://www.turbodieselregister.com/f...dge-fixed.html
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Well today I swapped out the APPS's on my truck and my brother's 02. After the swap my truck drove fine, but so did my brothers. I then re-swapped them and my truck is still driving normal. Could it have just been a bad connection to the APPS? I still don't understand how the colder temperatures could have affected the APPS???? Any thoughts?