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[dieckman001]

Just created a profile as i am running into some issues with our 2008 Yukon XL. I'm a fairly good mechanic, i think in where if i can get some direction i will tackle most any repair. Going to the dealership is typically my last resort. I am current working through some CEL issues for our emissions test before registering the vehicle in our newest state. Need so direction on how to reinstall a throttle position sensor as i have the P0121 code. Any guidance? BTW, I have already bought the parts and started the repair but the throttle response is not correct. It starts off fine with the key turn, but once you hit the accelerator it wants to stick around 2500 rpm and won't come back down.......
Nick

 

[NathanJax]

I posted your question in the proper section so hopefully someone will help out soon.

http://www.tahoeyukonforum.com/forum/showthread.php?t=65066

 

[fiatdale]

Almost sounds like it needs to relearn the idle.

 

[sbubbaklein]

make sure all of the hoses are hooked up and that the linkage at the throttle body is not binding. Spray some brake clean around the throttle body area while running and look for any increase in rpm that would indicate an air leak, pinched gasket or o-ring.

 

[dieckman001]

Throttle Position sensor cont.

Fiat Dale, how does the computer relearn the idle settings? Does the dealer have to reprogram in the shop? That is the information i got from a service department, that the ECM needs to be reprogrammed for the new settings. Makes it tons of fun when i can't drive the vehicle there at the moment. I told the service advisor, "if there are parts that require specific dealer only programming, then it should be marked with something on the packaging." Nothing like replacing something to find out your can't do it on your own. Good thing i still have the old unit. I might just reinstall it since the computer should still have those settings. I have unplugged the negative battery cable this morning thinking maybe the computer once plugged back in would do a self test and realize the new sensor and "relearn" the new part. Sound plausible?
sbubbaklein, I'll put it back together with the new part and see if the vacuum leak thought is plausible. There is only 1 electrical connection, and 1 tube, besides the intake pipe from the MAF to the throttle body, so hopefully i didn't miss something simple.

Nick

 

[fiatdale]

No parts will say that it needs programming. Its no different than replacing a window switch that may or may not need to be programmed.

Whenever you clean your throttle body, replace those parts, etc, it usually has a very high idle for some time. It CAN relearn on its own, but it takes a little bit of CAREFUL driving with it. Otherwise, the dealer can relearn it with the Tech II.

Does the Idle come down after sitting there for a while running?

 

[dieckman001]

Didn't leave it running too long to know if the idle would drop back down. Running at 2500 rpm is not something i feel comfortable letting it do sitting in the driveway. I'm going to try this one more time once i get home and if it doesn't work will put the old one in.

As for the part labelling, comparing it to an electrical part that is critical to engine operation and some accessory is not fair. Any sensor connected or related to basic drivability that requires some detailed equipment for installation should be highlighted is all i'm saying. Just my venting session because i hate having to spend extra money to have a dealership service the vehicle especially when the work is simple, just don't have the specialized computer tools.

 

[fiatdale]

Replacing a BCM is extremely simple. One part, unplug it and plug it back in. So is changing out an ignition switch, or an ECM. They all need programming at the dealer, its how they make their money. Saying its not fair, is whats not fair. This isn't a 1980 Silverado. All components talk to one another and need to be recognized. Been this way for quite some time with ALL vehicles, not just GM.

I would let it run for a bit at idle, then drive it around somewhere safe, and have your left foot ready on the brake. It will re-learn in time, or you can drop it at the dealer and have them do it in 30 minutes.

 

[dieckman001]

Reconnected everything with the negative cable also. Now the new CEL shows a p0507 vice the p0121. Is this now the idle air control circuit? Does this mean I need to pull off the throttle body and clean it fully? I cleaned around the butterfly valve with carb cleaner during the TPS check. I reverted back to the old TPS now and it still idles high once you hit the accelerator pedal. So now both new and old parts are giving the same symptoms. Any quick suggestions?