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Jeep Compass throttle gap

Maintenance/Repairs
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#1

2007 Jeep Compass 2.4L

The car has recently started developing a lurch when I back off the gas after accelerating. It usually happens at medium throttle or higher, like when accelerating up an on-ramp or something. It accelerates fine, but then has a single, brief lurch like the throttle gets fully closed for a moment as I slowly back off the throttle when getting to the speed I want, or get over the crest of the hill, or whatever. After the lurch the revs return to normal. It’s the same effect as if I quickly took my foot right off the gas pedal, then immediately pushed the pedal back to where it was.

It’s drive-by-wire. I’m thinking that a bad spot has developed in the gas pedal sensor. I probably won’t be able to figure out very much about it before I give up and take it to the shop.

  1. Before I start playing around with the pedal, are there any other obvious places I should be looking?
  2. If it goes to the shop, would this be a dealer-only option because of _____?
#2

I think the throttle pedal sensor is a pretty good bet. As far as the “playing around”, that depends on the tools you have to play with. Do you have a scanner that can data-log the sensor signal? That would show any signal noise to verify sensor problems. Do you own a digital voltmeter that you can probe the output signal from the sensor to look for noise in the signal? If you don’t own this stuff you could take a chance and just change the pedal and sensor assembly.

No, it is not a dealer-only thing. Aftermarket parts are available (see link below from RockAuto) and you could just change it yourself ($65 part) as a pretty simple DIY job. Not much of a gamble at $65 and 3-4 bolts and an electrical connector.

http://www.rockauto.com/en/moreinfo.php?pk=2064234&cc=1433554&jsn=434

#3

No, no scanner. For the pedal I was mostly thinking about a multi-meter on the bench. Beyond that I’d have to pay somebody for diagnostics.

New complication: it did it once yesterday with the cruise control on. I’m starting to think there’s some programming glitch that closes the throttle too fast - some self-learn thing gone awry?

#4

It could be an occasional misfire.
I once saw this symptom due to a cracked spark plug.

#5

Thanks, but would that always happen only when just backing off the throttle after accelerating?

#6

Not much cost or effort to inspect the plugs.
If it were the pedal sensor wouldn’t the engine “hiccup” every/most times the pedal moves past the bad spot, not just coming off acceleration?
Does this have a hot wire MAF sensor? That could just be dirty.
You’re not using an oiled air filter, are you?

#7

Another idea if you haven’t solved it yet, sometimes the injectors get a little clogged and it causes problems in metering out small volume flows of gas. No effect on medium to high fuel flow rates, but when you just need a small amount of gas to keep the engine running during deceleration, instead of a little, at first you get too much, then none at all, as you back off the gas pedal, which causes a jerk sensation. Try running a can of fuel injector cleaner through the tank, see if that has any effect.