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Mmmmmmmmm, beer.
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Discussion Starter · #1 ·
I did a search, and found several others who posted this same problem, but none of the posts really came to a conclusion as to what the problem was or what the fix was.

When I start the truck after it has set overnight, it starts right up, and seems to idle fine. But when I start to drive, I almost have to feather the throttle because it runs rough under any amount of acceleration/throttle. This goes on for about 1-3 minutes at the most, then it runs fine. Every once in a while, it will backfire out the TB during that 1-3 minute window, but that only happens if I try to give it full throttle during the time it is running rough. If I feather the throttle though, it doesn't backfire, and starts to run fine after just a few minutes.

I just had my TB off when I installed the 1.7's a month or so ago, and cleaned up the IAC (which is what I thought might be causing this). It does seem to be a little worse since the last round of mods I did, which included Mopar PCM, 1.7's, new plugs, wires, cap rotor, and TB clean.

What I think is that I am just running rich or lean when I first start it up, and the the PCM adjusts. Any thoughts from you all?
 

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******* SPACESTATION
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5,543 Posts
the 02 sensors don't start feeding the PCM information until they warm up, which usually takes about 1-2 minutes.

Any codes?

The IAC would give you a rough idle and could be causing some of the hesitation you are talking about, but not enough to make it backfire.

Did you route the plug wires according to the TSB that's out.
You could be experiencing induction (aka cross firing), when 2 plug wires are in close proximity they can cross fire. This can be remedied by installing convolute (flex conduit) on every other plug wire.
HTH
 

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Mmmmmmmmm, beer.
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Discussion Starter · #3 ·
Ya, I thought about that, so I rerouted the plug wires, but that didn't make any difference (my wires are also not stock diameter, so they have more insolated then stock plug wires anyway, and should not crossfire). I did notice that this all seemed to be worse since the last tune-up I did which, among many other things, included install of Autolite 3923's. I'll try switching back to the stock plug. That will at least rule out the plugs as the problem.
 

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Too Big to Sneak
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If it was the plug wires, it would happen constantly I would imagine - not just at start up. (I'm another one of those who are stumped with this problem)

My list of 'fixes' so far:
New IAC, plugs, wires, cap, rotor, coil, both O2 sensors, Cat, muffler, intake gaskets, Thermostat, temp sensors (PCM and gauge sensors),

Cleaned the throttle body along with the MAP sensor and TPS. Also did the TSB plug wire re-route. Also installed a K&N drop-in FilterCharger that's cleaned and recharged with every oil change.

All of these things done individually had a very minor curing effect - that lasted about 2 days each. Apparently, the PCM re-adapted to the issue that was being compensated for by the new parts or something.

Next up on my list:
- Autolite 3923s
- TPS
- Fuel pump/filter/sending unit (mine has also exhibited rough idle symptoms that seem to be influenced by how much fuel is in the tank as well...)

Beyond that - I'm stumped. I wish the damn thing would throw a code or something... and not just the occasional #7 & #8 misfire BS. Duh - I know it misfired... I was actually listening when it happened.
 
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