Contemplating Throttle Body Replacement - JeepForum.com

 
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post #1 of 7 Old 02-13-2017, 09:43 PM Thread Starter
jobrien9
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2008 MK Compass 
 
Join Date: Feb 2017
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Contemplating Throttle Body Replacement

Hi, all. I own a 2008 Jeep Compass (automatic transmission) with about 53,000 miles on it. I'm thinking of replacing the throttle body because of some recent issues I've had, but I'd like to get a second opinion on it first before I spend money on something that might not solve my problem.

Symptoms:
The problem I'm experiencing is similar to the one posted in this forum on Feb7 by hihosilver74 (the forums won't let me post links for some reason). A couple weeks ago, I started my engine after work, and the ETC light (red lightning bolt with two half circles) and the traction control light both lit up on my dash. I drove the car to the other side of the parking lot and turned off the engine. I waited a couple minutes, turned it on again, and the lights went away. I was able to drive home fine. Over the next two or three weeks, this same would happen again intermittently. At one point, I tried driving a short distance with the lights on, and my Compass wouldn't exceed 20MPH. Some websites I went to described this as "limp mode". I went to an auto-parts store and pulled the following codes: C121C (torque request signal denied), P2110 (throttle actuator control system forced limited RPM), P2112 (Throttle Actuator Plate stuck closed), P2111 (Throttle Actuator Plate stuck open). Additionally, my engine is idling at over 1000 RPMs when in park, the engine shakes a lot more than it used to, and it occasionally "jumps" a bit when it shifts gears. It's also noisier than it used to be at any speed, but I've noticed it's especially loud when idling or at a red light.

Based on what I read on the internet, I started to troubleshoot the problem by cleaning the throttle body. I removed it from the engine last week and cleaned it with throttle body cleaner even though it didn't seem like it was exceptionally dirty. Since then, I've not seen the two DTCs I mentioned above light up after starting the car, but the other symptoms are still present. Today, when I was driving home from work, the ETC light lit up for about a second, and the engine felt like it jumped a little. My guess is that the throttle was stuck open for a brief second.

At any rate, it seems like cleaning the throttle body didn't fix the problem. I'm leaning towards replacing it, but I'm not sure if there is something else I should check first. Specifically, I've heard that throttle position sensors can sometimes fail. I'm researching how to check those, but I'm not sure if that aligns with my symptoms or not. I've also heard that idle air intake can cause issues similar to my idling problem, but it doesn't match up with the codes I pulled at the auto store.

Does anyone have any advice, suggestions, or past experience related to this?

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post #2 of 7 Old 02-16-2017, 08:50 AM
hihosilver74
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Hello! I can update you on what I have done and what I have found so far. I followed the auto parts store codes for a couple of things. I replaced my throttle body and the MAP sensor. No luck. Then I decided to spend 30 bucks on Chilton DIY yearly subscription. I can tell you that what Chilton says and what the auto parts store say are two different things! Chilton recommends checking the voltage on the wiring harness going into the MAP sensor for high or low voltage. PINS 1 and 3 (if yours is the same) are the pins you check for this. I would recommend getting a live scanner, which I did. I spent 38 dollars and got a decent one online. The next step is to check the wiring harnesses from the MAP to the PCM for chafing or rubbing, etc. I plugged in the scanner and wiggled all the wires to make sure it wasn't a bad connection. Long story short, I'm pretty sure I have narrowed it down to the PCM. If your symptoms are similar, and the ETC light comes on, then only the engine light after next start, then it clears again after that, then the cycle starts over, you might be in the same boat. Personally, I wouldn't change the throttle body if your symptoms are similar. I found a PCM online used for 40 bucks also and I'm pretty sure the scanner I bought will set the VIN on it once I switch them. That's where I am at now. If you have any more questions, feel free to ask! Oh, I also checked the PCV valve and hose by taking off the hose and putting my finger over it to check for suction in the hose. I did the same thing with the brake booster vacuum hose, as all of these symptoms were from the codes I got from the auto store. Does your compass run fine when the ETC lights are not on? Do you have the eng code light on as well?

Last edited by hihosilver74; 02-16-2017 at 09:07 AM.
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post #3 of 7 Old 02-16-2017, 08:24 PM Thread Starter
jobrien9
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Thanks for the advice! I'll start by checking the wiring harness to see if that's the issue. The PCM seems like a likely suspect, too. I had some PCM issues about a year ago. I wonder if it's about to finally give out. I'll let you know if I figure it out.

I'm not seeing the check engine light, at all. My Compass runs alright otherwise. The engine's been making a lot of noise lately, but I suspect this might be a separate issue.
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post #4 of 7 Old 02-16-2017, 09:01 PM Thread Starter
jobrien9
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By the way, where did you get your scanner, and what kind did you use?
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post #5 of 7 Old 02-18-2017, 08:46 AM
hihosilver74
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I bought a Kingtime VS580, I'm pretty sure it was Ebay, and it was about 40 dollars. Have you changed your spark plugs lately?
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post #6 of 7 Old 02-18-2017, 04:03 PM
hihosilver74
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Update:

The scanner I bought, although useful, will not program the PCM.
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post #7 of 7 Old 03-05-2017, 09:55 PM Thread Starter
jobrien9
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2008 MK Compass 
 
Join Date: Feb 2017
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As an update for anyone who has this problem in the future, I ended up taking my Compass into the mechanic after it went into limp mode while driving on a fairly busy road. The engine noise had been gradually getting louder and louder because the alternator was going bad. I ended up having to replace both the alternator and the throttle body. Since the replacement of these parts, the symptoms I described above have gone away, with the exception of the engine idling at 1.5k RPMs when I first start it up in the morning (although this hasn't been as bad as it was in the past few days).
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throttle , throttle body , throttle position , throttle position sensor , throttle stuck

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