GP GXP Surging...DoD issues?
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Teching In
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GP GXP Surging...DoD issues? All,
Owned the 08 GP GXP for a year now, has given me zero issues until now. Noticed a little surge around 40 mph...about 300 rpm, just a jolt. Also when cruising down the interstate, around 70mph, its cant decide to stay at 2k rpm or 2100/2200 rpm, which makes me think its not tranny related. Could it be displacement on demand trying to work between 4 cycl and 8 cyl?
Which leads me to this point. My Check Engine Light came on, code reader says P0121, which is Throttle Position sensor. From a little research the TPS is built into the throttle body on this model and would need to replace the whole throttle body. I bought some cleaner and was going to clean it this weekend since it will be above freezing. Is that the right way to go?
I also have the K&N intake installed, havent had any issues with Mass Airflow Sensor, but maybe its needs cleaned as well its just not throwing any codes?
All help is appreciated,
Dan
Owned the 08 GP GXP for a year now, has given me zero issues until now. Noticed a little surge around 40 mph...about 300 rpm, just a jolt. Also when cruising down the interstate, around 70mph, its cant decide to stay at 2k rpm or 2100/2200 rpm, which makes me think its not tranny related. Could it be displacement on demand trying to work between 4 cycl and 8 cyl?
Which leads me to this point. My Check Engine Light came on, code reader says P0121, which is Throttle Position sensor. From a little research the TPS is built into the throttle body on this model and would need to replace the whole throttle body. I bought some cleaner and was going to clean it this weekend since it will be above freezing. Is that the right way to go?
I also have the K&N intake installed, havent had any issues with Mass Airflow Sensor, but maybe its needs cleaned as well its just not throwing any codes?
All help is appreciated,
Dan
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Joined: Nov 2008
Posts: 622
Likes: 1
All,
Owned the 08 GP GXP for a year now, has given me zero issues until now. Noticed a little surge around 40 mph...about 300 rpm, just a jolt. Also when cruising down the interstate, around 70mph, its cant decide to stay at 2k rpm or 2100/2200 rpm, which makes me think its not tranny related. Could it be displacement on demand trying to work between 4 cycl and 8 cyl?
Your torque converter lock up can be between 250 - 500 rpm... so how is the fluid level and how old is the filter?
Which leads me to this point. My Check Engine Light came on, code reader says P0121, which is Throttle Position sensor. From a little research the TPS is built into the throttle body on this model and would need to replace the whole throttle body. I bought some cleaner and was going to clean it this weekend since it will be above freezing. Is that the right way to go?
Yes remove it and clean it well, caution do not open the butterfly more than 80% and do not let it slam shut... be gentle!
I also have the K&N intake installed, havent had any issues with Mass Airflow Sensor, but maybe its needs cleaned as well its just not throwing any codes?
Yes again use MAF sensor cleaner liberally and try to dry it out before applying power again and do not touch the sensors with anything other than the cleaner. If you decide to wash the filter be sure not to over oil it.
All help is appreciated,
Dan
Owned the 08 GP GXP for a year now, has given me zero issues until now. Noticed a little surge around 40 mph...about 300 rpm, just a jolt. Also when cruising down the interstate, around 70mph, its cant decide to stay at 2k rpm or 2100/2200 rpm, which makes me think its not tranny related. Could it be displacement on demand trying to work between 4 cycl and 8 cyl?
Your torque converter lock up can be between 250 - 500 rpm... so how is the fluid level and how old is the filter?
Which leads me to this point. My Check Engine Light came on, code reader says P0121, which is Throttle Position sensor. From a little research the TPS is built into the throttle body on this model and would need to replace the whole throttle body. I bought some cleaner and was going to clean it this weekend since it will be above freezing. Is that the right way to go?
Yes remove it and clean it well, caution do not open the butterfly more than 80% and do not let it slam shut... be gentle!
I also have the K&N intake installed, havent had any issues with Mass Airflow Sensor, but maybe its needs cleaned as well its just not throwing any codes?
Yes again use MAF sensor cleaner liberally and try to dry it out before applying power again and do not touch the sensors with anything other than the cleaner. If you decide to wash the filter be sure not to over oil it.
All help is appreciated,
Dan
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Joined: Jun 2007
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From: Dolla$ , TX
All,
Owned the 08 GP GXP for a year now, has given me zero issues until now. Noticed a little surge around 40 mph...about 300 rpm, just a jolt. Also when cruising down the interstate, around 70mph, its cant decide to stay at 2k rpm or 2100/2200 rpm, which makes me think its not tranny related. Could it be displacement on demand trying to work between 4 cycl and 8 cyl?
Which leads me to this point. My Check Engine Light came on, code reader says P0121, which is Throttle Position sensor. From a little research the TPS is built into the throttle body on this model and would need to replace the whole throttle body. I bought some cleaner and was going to clean it this weekend since it will be above freezing. Is that the right way to go?
I also have the K&N intake installed, havent had any issues with Mass Airflow Sensor, but maybe its needs cleaned as well its just not throwing any codes?
Cleaning the Throttle Body will be useless for this code since they are reading angle and cleaning it wont adjust that at all. However it may of just been a fluke , unplug your battery or reset the code using a scan tool. If it immediately comes back then i would do some more diagnosing/replacing of the throttle body. Some other diagnostics you can do is test the outputs of each sensor and see if they fall into the correct values , or look for dead zones with a multimeter hooked up to confirm that its not a wiring issue to your ECM "unlikley" but not impossible. I usually dont like throwing parts until ive absolutley confirmed its the issue so diagnosing it with a multimeter would be my next step after reseting it and seeing if it returns.
All help is appreciated,
Dan
Owned the 08 GP GXP for a year now, has given me zero issues until now. Noticed a little surge around 40 mph...about 300 rpm, just a jolt. Also when cruising down the interstate, around 70mph, its cant decide to stay at 2k rpm or 2100/2200 rpm, which makes me think its not tranny related. Could it be displacement on demand trying to work between 4 cycl and 8 cyl?
Which leads me to this point. My Check Engine Light came on, code reader says P0121, which is Throttle Position sensor. From a little research the TPS is built into the throttle body on this model and would need to replace the whole throttle body. I bought some cleaner and was going to clean it this weekend since it will be above freezing. Is that the right way to go?
I also have the K&N intake installed, havent had any issues with Mass Airflow Sensor, but maybe its needs cleaned as well its just not throwing any codes?
Cleaning the Throttle Body will be useless for this code since they are reading angle and cleaning it wont adjust that at all. However it may of just been a fluke , unplug your battery or reset the code using a scan tool. If it immediately comes back then i would do some more diagnosing/replacing of the throttle body. Some other diagnostics you can do is test the outputs of each sensor and see if they fall into the correct values , or look for dead zones with a multimeter hooked up to confirm that its not a wiring issue to your ECM "unlikley" but not impossible. I usually dont like throwing parts until ive absolutley confirmed its the issue so diagnosing it with a multimeter would be my next step after reseting it and seeing if it returns.
All help is appreciated,
Dan
The TP sensor 1 disagrees more than 9 percent from TP sensor 2.
The TP sensor 1 disagrees more than 9 percent from the predicted value.
The above conditions are met for less than 1 second .
This means the sensors do not match together like they used to. Sensor 1 is reading "9% variance" from its brother/sister sensor." I would start with reseting it via a scan tool or disconnecting the battery , if it immediately returns then its a very high chance its an issue with one of the sensors not matching the other. Cleaning it will be a waste of time for this issue. If the code returns immediatly , you can triple check it by using a scan tool to see the posistion sensors output and check for deadzones , or use a multimeter to check for deadzones and or strange readings to confirm
Last edited by Sint3k; Jan 18, 2015 at 12:29 AM.
Thread Starter
Teching In
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Ill born SS....thanks for the input..now might sound a little misinformed here, but as far as torque converter goes, how do I check the fluid and filter (are you talking about the tranny fluid level and filter?) I changed that when I bought the car at 70,000 miles. I dropped the pan and changed fluid and filter.
Also, cleaned the throttle body yesterday, kept it on the car, disconnected the intake, and has the wife hold the throttle open in the car while I cleaned with rag. I didn't spray directly into TB only on the rag directly. I cleared the code via odb 2 tool and hasn't come back yet after a 70 mile trip.
It does feel like my throttle/idle is higher and takes longer to relax back down....ie pulling a little harder at stop signs..since throttle acts like it's a little engaged.
I haven't changed plugs and wires (not sure if it ever has been changed). Should this be a do it now thing or give it time?
Just changed oil yesterday and will monitor how much it uses. Was 6,000 miles on old oil and was at the bottom of the dipstick.
Sint3k- I'm assuming if it comes back after my cleaning and checking those reads I'll be buying a new throttle body? Is the ls2 throttle body the upgrade?
Thanks all,
Dan
Also, cleaned the throttle body yesterday, kept it on the car, disconnected the intake, and has the wife hold the throttle open in the car while I cleaned with rag. I didn't spray directly into TB only on the rag directly. I cleared the code via odb 2 tool and hasn't come back yet after a 70 mile trip.
It does feel like my throttle/idle is higher and takes longer to relax back down....ie pulling a little harder at stop signs..since throttle acts like it's a little engaged.
I haven't changed plugs and wires (not sure if it ever has been changed). Should this be a do it now thing or give it time?
Just changed oil yesterday and will monitor how much it uses. Was 6,000 miles on old oil and was at the bottom of the dipstick.
Sint3k- I'm assuming if it comes back after my cleaning and checking those reads I'll be buying a new throttle body? Is the ls2 throttle body the upgrade?
Thanks all,
Dan
TECH Enthusiast
Joined: Nov 2008
Posts: 622
Likes: 1
Ill born SS....thanks for the input..now might sound a little misinformed here, but as far as torque converter goes, how do I check the fluid and filter (are you talking about the tranny fluid level and filter?) I changed that when I bought the car at 70,000 miles. I dropped the pan and changed fluid and filter. Yes the tranny fluid, check it in neutral and hot/ operating temp. It is good you had it serviced already.
Also, cleaned the throttle body yesterday, kept it on the car, disconnected the intake, and has the wife hold the throttle open in the car while I cleaned with rag. I didn't spray directly into TB only on the rag directly. I cleared the code via odb 2 tool and hasn't come back yet after a 70 mile trip. A good start but you should really remove it to get it really clean and while you are at it clean your MAF sensor with MAF sensor cleaner
It does feel like my throttle/idle is higher and takes longer to relax back down....ie pulling a little harder at stop signs..since throttle acts like it's a little engaged.It was pretty dirty especially around the edges of the butterfly and the build-up would not allow it to return to 0 and also allow it to stick to the wall of the throttle-body... thus giving the code
I haven't changed plugs and wires (not sure if it ever has been changed). Should this be a do it now thing or give it time? I would plan for this soon as the factory plugs do not really last as advertised when you are using the DOD/AFM. I would recommend using the NGK brand plug number TR6IX and set the gap at .035"
Just changed oil yesterday and will monitor how much it uses. Was 6,000 miles on old oil and was at the bottom of the dipstick.SO basically short by 2 quarts this loss is caused by the DOD... there are options if you would like to pursue, let me know
Sint3k- I'm assuming if it comes back after my cleaning and checking those reads I'll be buying a new throttle body? Is the ls2 throttle body the upgrade?As for replacing parts I would wait for now.
Thanks all,
Dan
Also, cleaned the throttle body yesterday, kept it on the car, disconnected the intake, and has the wife hold the throttle open in the car while I cleaned with rag. I didn't spray directly into TB only on the rag directly. I cleared the code via odb 2 tool and hasn't come back yet after a 70 mile trip. A good start but you should really remove it to get it really clean and while you are at it clean your MAF sensor with MAF sensor cleaner
It does feel like my throttle/idle is higher and takes longer to relax back down....ie pulling a little harder at stop signs..since throttle acts like it's a little engaged.It was pretty dirty especially around the edges of the butterfly and the build-up would not allow it to return to 0 and also allow it to stick to the wall of the throttle-body... thus giving the code
I haven't changed plugs and wires (not sure if it ever has been changed). Should this be a do it now thing or give it time? I would plan for this soon as the factory plugs do not really last as advertised when you are using the DOD/AFM. I would recommend using the NGK brand plug number TR6IX and set the gap at .035"
Just changed oil yesterday and will monitor how much it uses. Was 6,000 miles on old oil and was at the bottom of the dipstick.SO basically short by 2 quarts this loss is caused by the DOD... there are options if you would like to pursue, let me know
Sint3k- I'm assuming if it comes back after my cleaning and checking those reads I'll be buying a new throttle body? Is the ls2 throttle body the upgrade?As for replacing parts I would wait for now.
Thanks all,
Dan
