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David Gieswein
David Gieswein,
Category: Pontiac
Satisfied Customers: 89
Experience:  Automotive technician at Doug Gray Dodge/Chrysler/Jeep
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I have a 2007 grand prix and the reduced engine power

Customer Question

I have a 2007 grand prix and the reduced engine power warning is on. I have replaced the throttle body and the pedal position sensor. It has all new gaskets, new plugs, new wires, and has had a valve job. Its also giving me the code of p0101? It says lost communication with throttle, and I can't remember the rest of it. I don't know if I have some wires crossed somewhere or even where to go from here. It drives pretty well. I can still go 70 on the highway, but it does have a hesitation when you try to take off from a stop and when I'm driving for just a second it kind of bogs down and then catches back up
JA: Is this your first time dealing with this issue? What size is your engine?
Customer: It's just the regular v6 base. No supercharger, nothing fancy. And yes this is the first time I've had this issue
JA: Are you fixing your Grand Prix yourself? What have you tried so far?
Customer: Well, I'm not technically fixing it myself. My husband is. Like I said we've replaced the throttle body, and the throttle pedal and sensor. And the spark plugs, spark plug wires, all the gaskets, and a valve spring.
JA: Anything else you want the mechanic to know before I connect you?
Customer: I don't think so. I think that's everything
Submitted: 5 months ago.
Category: Pontiac
Expert:  David Gieswein replied 5 months ago.

Hello my name is ***** ***** I can help you. Please give me a few minutes to review your case and code you have.

Expert:  David Gieswein replied 5 months ago.

Is this the 3.8l or the 5.3l?

Customer: replied 5 months ago.
It's the 3.8 I'm pretty sure. It's whatever came in the 2007 base model. Like that really helps doesn't it? LOL
Expert:  David Gieswein replied 5 months ago.

LOL. Your code is for the MAF sensor. You need to verify it is plugged in good.

Customer: replied 5 months ago.
What??? Ok, so let me tell you a story, David. So I live out in the county, like so seriously in the middle of a field, 10 miles from the nearest town in any direction. So when it first broke down and it turned out to be a broken valve spring, I didn't have the money to fix it so it sat for a super long time, maybe six or eight months. And well so I had a family of rabbits living under the hood (like I can't even make this stuff up!!) And when I turn my heat or a/c on, it smells like barnyard. So its possible that the guy who worked on it before maybe didn't get all that stuff cleaned out? LIke I'm so not a mechanic but I might have a smidge of common sense. That would affect that sensor, would it not?
Expert:  David Gieswein replied 5 months ago.

Oh ok, it could be very likely the rabbits chewed into some wires somewhere. I have experience dealing with rodent damage under the hood. Since the code is for the MAF sensor, I would inspect all the wiring up to the sensor. Here is a pic of where the sensor is located.

Expert:  David Gieswein replied 5 months ago.

#2 in the pic is the sensor.

Expert:  David Gieswein replied 5 months ago.

Simply find the sensor and check it out for chew marks. Then follow the wiring back as far as you can. Check the wiring for chew marks.

Customer: replied 5 months ago.
Thank you so much for your help David!! I'll check it as soon as I get off work!
Expert:  David Gieswein replied 5 months ago.

Ok good luck and let me know what you find or if you need more help.

Customer: replied 5 months ago.
I will. Thank you again!!
Expert:  David Gieswein replied 5 months ago.

Anytime.

Expert:  David Gieswein replied 5 months ago.

Have you looked at the car yet?

Customer: replied 5 months ago.
Actually it's being done right now. And I was sooo wrong on the codes. It was u0107, p1125, p1516, and maybe the last one was p2328? I'm not for sure on the last one since he took the paper with him.
Expert:  David Gieswein replied 5 months ago.

Do you still need my help?

Customer: replied 5 months ago.
I'm not sure. Since we have already replaced the throttle body and the throttle pedal and sensor we have decided to try and clean the MAF sensor and since there were obvious signs of rodents chewing wires, they are going to resolder all the wires and shrink wrap them. Almost all of the research I did yesterday and last night pointed to a faulty circuit or a bad connection with a wire somewhere. I'm really trying to NOT buy a new wire harness. All the ones I checked out were in the neighborhood of $1000 and that's way way way out of my price range!!
Expert:  David Gieswein replied 5 months ago.

If there were no signs of chewing then why are they soldering and heat shrinking??

Customer: replied 5 months ago.
There were signs of chewing on quite a few wires that I was unaware of. They used the twisty type connectors and just regular black tape to put them back together. My guess is that either one of the connections they made is not good enough or something is touching where it shouldn't. So when I stopped at napa and had the codes read the guy looked under the hood and was all like see this and showed me the black tape and connectors and then I just figured that had to be part of the problem since we had replaced all those other things. He suggested that in an effort to not spend a grand on a new harness that we try to see if we can resolder the wires and shrink wrap them
Expert:  David Gieswein replied 5 months ago.

I don't replace wiring harnesses unless they are burnt. You can always repair them. Lets see if they can resolve the issue by making good connections

Expert:  David Gieswein replied 5 months ago.

Just remember, your MAF sensor is critical to the performance and driveability of your car. It stands for Mass Air Flow. It meters the amount of air coming into the engine and then the computer determines how much fuel to inject.

Customer: replied 5 months ago.
I guess I still need your help. So yesterday my friend worked on the wires and my MAF sensor. There were good things and bad things. Now when I drive the rpms don't fluctuate nearly as bad but when I stop and I'm in gear it dies. Every single time. I also did a little of my own research on throttle body and pedal sensors. It talked about the relearn process. I don't think anyone did that when they replaced mine. I'm not positive that I even had the right instructions but at this point what the hell? The wires going to my MAF are kinda thin so I'm picking up a new MAF sensor and a new plug tomorrow. I went to an actual mechanic today and told him what the problems were and so on and so forth and he informed me that since I have a gm car that my throttle body and pedal sensor cannot come from napa or oreillys but must be from a gm dealer. Is that even true?
Customer: replied 5 months ago.
I guess I still need your help. So yesterday my friend worked on the wires and my MAF sensor. There were good things and bad things. Now when I drive the rpms don't fluctuate nearly as bad but when I stop and I'm in gear it dies. Every single time. I also did a little of my own research on throttle body and pedal sensors. It talked about the relearn process. I don't think anyone did that when they replaced mine. I'm not positive that I even had the right instructions but at this point what the hell? The wires going to my MAF are kinda thin so I'm picking up a new MAF sensor and a new plug tomorrow. I went to an actual mechanic today and told him what the problems were and so on and so forth and he informed me that since I have a gm car that my throttle body and pedal sensor cannot come from napa or oreillys but must be from a gm dealer. Is that even true?
Expert:  David Gieswein replied 5 months ago.

Does your car have an electronic throttle? If you are not sure, do you have a traditional cable that goes from the gas pedal to the throttle body? Do you have a check engine light on? Have they tried clearing the codes and see what comes back? I need more details or I may answers may not be helpful enough. Do you have a scan tool or able to stop by autozone for a quick scan?

Expert:  David Gieswein replied 5 months ago.

According to the wiring diagram on your car, you have an electronic throttle. I highly recommend you have the ETC relearn performed. It requires a good scan tool with the ability to perform this task. I have performed it on a few ETCs that were surging up and down. 50% of the time it will calm things down and the engine will run as desired. What really concerns me is the dying in drive when coming to a stop. This usually indicates a vacuum leak or idle control malfunction like a malfunctioning IAC motor. Also, one cool trick to test for vacuum leaks is spray brake cleaner on/around intake gaskets, EGR, and other intake components. If the idle changes at all, you have a vacuum leak in that area. If it was me, I would try doing both of these tasks before doing anything else.

Customer: replied 5 months ago.
Do I have a check engine light on? Hahaha! Since the day I bought it. Didn't even make it home on the day I bought it before it came on. And of course I called the dealer and was like hey I'm not even home and my check engine light just came on to which he replied it's yours now Blondie, you signed the papers so you deal with it. This is the first car I've ever bought , got a loan for and all and I'll never do that shit again. I still owe around 5k for it and I've put close to that amount in repairs. Hell it hasn't ran for two years until recently. So yeah I have a check engine light on
Customer: replied 5 months ago.
we've cleared the codes. Over and over and over again. It's always the same codes. P1125, P2125, P2138, P0442, P1516, and last is the U0107. Seriously I'd live to fix it but we're just getting no where. No matter how many wires we solder back together or how many sensors and parts and pieces I keep on buying, it's just not going to run. Because seriously I've replaced so much of this car that it should be brand new by now
Expert:  David Gieswein replied 5 months ago.

I feel your pain. I will do my best to help you resolve the issue. Just don't give up. I will try the best I can to respond to you through the day, but please keep in mind I also have a full time job so I can't respond quickly right now. Let me review your codes and get back with you in a few. Thanks

Customer: replied 5 months ago.
Oh my gosh!! I'm so sorry!! I didn't realize this wasn't your job! I do humbly apologize. As for the codes I know what they all are I just can't figure out how to fix them. After the valve job it gave me all the throttle body and pedal sensor codes, so I replaced them. It still throws the exact same codes. Then yesterday when the guy at the shop told me it's because I put after market parts on that it will never run right. Seriously? Because who in their right mind is buying factory made parts for a ten year old car with 132k?
Expert:  David Gieswein replied 5 months ago.

Thank you for being so understanding. Aftermarket parts are still ok to use, you just have to run the recalibration procedure with the scan tool. I have all the codes you gave wrote down and would like to do some tests with you when I get some free time today. There is a lot we need to test. Mainly, I am concerned with the app sensors 1 and 2. The codes suggest a disagreement between the two. It would be really helpful if there was anyway you could have the recalibration done on the throttle valve and app sensors first though. However, I understand you may not be able to achieve this goal.

Customer: replied 5 months ago.
Good evening Dave. I was wondering if you can tell me where the app sensors are located. We changed the plug for the MAF sensor and that helped loads. There is hardly any hesitation when taking off and the shifting seems much smoother. However, if I sit too long stopped it still dies. So if we could figure out where the app sensors are then we could check those out too. I can't seem to find any pictures anywhere of it on the internet
Expert:  David Gieswein replied 5 months ago.

Sorry it is taking so long, been very busy today. Let me check

Expert:  David Gieswein replied 5 months ago.

According to the wiring diagram both app 1 and 2 are located inside one box. It is located under the left side of the dash. Here is a pic.

Expert:  David Gieswein replied 5 months ago.

It is close to the brake pedal position sensor

Expert:  David Gieswein replied 5 months ago.

Basically, it is the sensor on the gas pedal. Ebay has one for sale if you need a picture reference. The item number is *****

Customer: replied 5 months ago.
I actually have already replaced this sensor and the pedal once. After the valve job and the half ass rewire job, that's when it first started doing all the throttle position/throttle body codes. So I've replaced the pedal, the sensor, and the throttle body once already. I went to a mechanic on Tuesday so I could maybe just have him tell me this is exactly what needs to be done or they would just fix it. But he wouldn't even look at it. He told me I had to go to GM and put GM factory parts on it and I need to take off all the aftermarket parts and make napa take them back. Now I could see doing that if this was a newer car, but it's 10 years old and has close to 135k on it. Is there a way to tell if my sensor is still working or not?
Expert:  David Gieswein replied 5 months ago.

Don't take it mechanics who tell you what that guy told you. He is just making up stuff. You have to have the recalibration procedure done. You can take it just about any mechanic that has a good snap on scan tool. Doesn't have to be the dealer.

Customer: replied 4 months ago.
Super. I thought for sure that guy was just funning me. I'm working for the next three days so it'll be at least Monday before I can get to a shop to have that done.
Expert:  David Gieswein replied 4 months ago.

Ok, let me know how it goes. Make sure you tell them you want a throttle valve relearn and a accelerator relearn done. They may be one in the same.