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Discussion Starter · #1 ·
Ok, first post here. This is a strange one. Ten months now my 2007 Jeep Commander (4.7L) Limited has been acting up when it reaches operating temperature. It NEVER hesitates when cold and now is a guarantee to misfire and sometimes even stalls when it gets hot. It's not too hot. I'm keeping an eye on all of that by using a Bluetooth ODB II adapter and my phone running Torque (love it by the way).

No CEL, the plugs just changed to mopar replacements, changed the MAP sensor, cleaned gas tank, shop checked and cleaned injectors, tested coils, and just today took readings off of fuel rail. When it hesitates, the pressure changes about 3-4 psi. I don't know if that's much to worry about, but it otherwise stays perfectly steady.

I'm only doubting fuel pump because I can't see how it's tied to the engine heat.

I live in Cusco, Peru, so my options are limited, but I really need help from this community. I just got it back today from the Jeep dealership here in Cusco. The Peruvians are just as lost to the issue (although they did update all software).

Any ideas folks? Can anything but a fuel pump and regulator (one piece, right?) affect the fuel rail pressure?

Thanks!

Scott
 

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Discussion Starter · #2 ·
Feeling lonely here. Everyone else stumped too?

At least, can someone answer me this: can anything aside from the fuel pump and regulator cause jumps in fuel pressure? If the coils aren't pushing the voltage, or plugs not firing, can it cause a hiccup in the fuel rail pressure?

Scott
 

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So after running into a similar issue, I wanted to send out some of my repairs I had to do to fix what happened with mine.

There is a service update for the engine management system that is for the O2 sensors. There can be a condition in which the upstream season gets too much 'noise' on the sensor line the computer monitors. This will lead to incorrect Air/Fuel ratio readings and the computer will mess up the fuel delivery with the incorrect data.
Get this update first if you can.

Secondly, over heating headers will cause some heat damage to the wires that are traveling down from the top of the motor. I had a set of wires that had been compromised by heat and cause the impedance of the wires to change and threw the computer off because all the read values had changed because the physical wire was damaged. This directly led to some of my stalling issues I had when at operating temperature.

The area where this occurred is on the side of the vehicle where the Battery/Fuse box side of the motor... Not sure if your car, being south american, is in the standard north american setup with the drivers side being on the left.
Look at the top front of the motor for the water temp sensor just under the throttle body. Follow this wire down the motor and inspect this portion of the wire loom. It is here I found the heat damage. this loom has Water Temp/Knock Sensor/Upstream O2 sensors (Bank 1). All of these could mess things up in relation to running at normal temps.

Dave
 

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Feeling lonely here. Everyone else stumped too?

At least, can someone answer me this: can anything aside from the fuel pump and regulator cause jumps in fuel pressure? If the coils aren't pushing the voltage, or plugs not firing, can it cause a hiccup in the fuel rail pressure?

Scott
I have 06 Commander with the same problem, solution ...Factory recall to update the modules, but the problem was the dealership where They supposed to updated.They say my commander is ready, but in the dashboard the warning lights was ON, and They want me to pay $100 dls to check again. I dont pay nothing I take my commander and I take it to different jeep dealership, I They told me, They other guys mess the modules, and the cost of the new modules $1400 dollars to fix it.
But the only ones can made the updates is the jeep dealerships.
 

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I have 06 Commander with the same problem, solution ...Factory recall to update the modules, but the problem was the dealership where They supposed to updated.They say my commander is ready, but in the dashboard the warning lights was ON, and They want me to pay $100 dls to check again. I dont pay nothing I take my commander and I take it to different jeep dealership, I They told me, They other guys mess the modules, and the cost of the new modules $1400 dollars to fix it.
But the only ones can made the updates is the jeep dealerships.
@Toluco09; Welcome to the forum;

Just out of curiosity, do you have a copy of this factory recall?

I haven't heard of this particular recall before, which is why I'm asking; It would be nice to have the documentation to reference & pass along if anybody else needed it.

If you at least know the recall # (Such as N23, P57 etc.) I could probably look it up.
 
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