Hey guys, so my gf 07 S is having some throttle related problems. Her car is extremely jerky and very sensitive on throttle when you left off the gas. If you are giving is gas it acts ok but once you left off throttle is burps and is very unpleasant. It really feels like an air issue, idk how shes been driving it like this for this long. Her CEL came on a little while ago pulling 2 codes (U0107) Lost communication with throttle control mod. (P2138) Throttle/pedal position sensor/sw d/e volt correlation. She has pulled code (P2138) about 6 months prior and we checked it and cleared it and it was ok for a little while. We believe this is her throttle position sensor going bad. We tried cleaning the sensors with compressed air, from looking on here we saw that fixed some problems. It only made the car feel better for the day and then the next day after it sits over night it's just as bad or worse than before. She bought her car from carmax and bought the warranty, and a new throttle body is running about $500 so we were going to get her $250 deductible to cover the rest. The only problem is they wont fix anything on it bc we reset the codes after trying to fix to it. Being a throttle code they only pull if it continues to happen and this one isn't likely to pull for another couple of months and I prefer her not to have to drive it being as bad as it is to try and get the code to pop.

Sorry for the long story but my questions is does this sound like the sensor is going bad?
If so, is it safe to turn the car on and unplug the the throttle position sensor to pull the code again and then take it back up to carmax to fix it?

Thanks, any help would be appreciated!

Craig

 

Do what is called battery reset procedure. Disconnect both positive and negative battery cables and with them disconnected jump with jumper wire positive to negative. Then turn key to 2 position. This erases all memory in ecu and restarts from factory. Leave like this for 10 min. Then turn ignition off. Now reconnect battery cables. After procedure need to do "idle learn" let car fully warm up till fans come on, then let idle for 10 minutes no loads. Do not touch throttle. Thats it!

This is a normal dealer/manufacturer procedure.

This procedure is done for weird/intermittent or strange issues.

 

If it runs fine after i wouldnt worry about it. If code resets. Then go from there.

 

Ok thanks I'll try that, and see if that fixes it.

 

I'm curious if you left some pertinent information out of this procedure. (Disconnect both positive and negative battery cables and with them disconnected jump with jumper wire positive to negative) Almost sounds like you're saying to jump the positive and the negative terminals on the battery which is like a big no no. I'm assuming you're saying to jump the two cables that go to the battery. Is this correct?

 

Right, jump the black wire to the red wire. DO NOT TOUCH the battery terminals at all in this procedure.

Here is the deal, in any complex electrical system there is some inherent 'capacitence'. A capacitor is an electrical component that stores a charge, almost like a battery. So with this built in capacitence, even with battery terminals both disconnected, there can be a charge left in the whole system, enough to run the ECU and retain any learned programming. To make sure a battery disconnect really does clear the ECU memory, you have to drain off all this charge.

Think of it like draining all the water from your pipes in your house. You shut off the water main, but you still got water stuck in the system. How to drain it all? You gotta open up all the taps and let gravity do its work.

With yours cars electrical system, turning on key is like opening the taps, and connecting the wires together is your gravity, giving the juice someplace to flow to.

 

Well after looking this up I was as well a little confused and did some more research which brought me to the unplugging the backup fuse which does the same trick with less work. Unfortunately this didn't work and its still not right. I have an 05 and she has an 07 and the throttle is different. Should they be close to the same, or different, since her's is electric throttle control and mine is wire throttle control?
I tried unplugging it and different codes came up so that didn't help either.

 

Unplugging the fuse is the equivalent to disconnecting one of the battery terminals. So its not the equivalent of the procedure described where you drain off any residual charge by jumping the battery cables to each other.

In the water pipe analogy, pulling the fuse is like turning off the water main. You still got a whole set of pipes filled with water.

You want that water gone you gotta give it someplace else to go and a way to get there.

This is wbat you do:

- use a 10 mm wrench to remove the negative battery cable from the battery

- use the same process to remove the positive battery cable

- connect the negative cable to the positive cable (nothing is touching the battery!)

- with the terminals connected like this, turn on the ignition key switch

- there ain't enough juice stored in the capacitence to turn on a y dash lights or anything so it doesn't seem like you did anything. But rest assured any juice that was bottled up is being drained. The spec a couple replies up says to leave ignition on for like minutes or something. I can't see how more than seconds could be required, but I won't argue the point. There could be a valid reason.

This process is so easy to do. I get maybe you are intimidated by touching battery cables together, but its not to be feared. If nothing is touching the battery terminals, you are safe.

Just be sure whatever means you use to hold negative cable to positive cable stays connected during the procedure so tbe juice can flow.