Quantcast




All times are UTC - 6 hours [ DST ]




Ask A Question Reply    Go to page 1, 2  Next
Author Message
 

contributions: 5
ok so i have a 2001 silver ado with the 4.8 150k i bought it used a year ago. i have a p0121 code throttle position sensor out of range. i replaced the tps. code came back. found my throttle body was all gunked up. so i cleaned it all up. reset codes. and it came back. checked and tightened all the electrical connections and grounds on truck and checked wiring harness.. looks good reset. came back. checked voltages at tps. battery ground to output on fps 5volts. battery positive to tps ground 12v. looks rite per book.. reset came back. read up on how it works. ended up replacing maf sensor. reset codes. drove and it returned. had truck scanned found map sensor off by 1 point. replaced and code returned. replaced all spark plugs. i did find they were gapped at 36, book calls for 60. set all to 60 and installed. they are the iridium type. reset codes and they returned. checked for air leaks checked all hoses and connections, all looks good. reset. returned. replace tps again just in case. reset and returned. replaced computer with reprogramed one with current gm program. code returns. pulled and checked air idle valve. broke it. replaced it. reset and code returned. the idle seems a little erratic after replacing air idle valve. runs fine. this whole time the truck has run fine. seems to shift fine, a little ruff some times but no real problems. i will reset codes. it will drive fine for 10-20 miles and it seem every once in a wile i will be at a stop light and when i pull off the line i will have no throttle response. it will pick up speed slowly and runs fine and after that is when the code returns. the truck had the code when i got it so i can't jude it for normal operation, i would seem to no be very powerful. but it is a 4.8 my last one was a5.7. . I'm a industrial mechanic by trade so I'm well accustomed to trouble shooting and repairs, but this thing has got me beat..
any input would be helpful. thanks


Share on FacebookShare on DiggShare on DeliciousShare on TechnoratiShare on TumblrShare on Google+
   
Reply with quote  
* Search   
 
User avatar

contributions: 1992
Images: 37
Location: Oregon
you're going to need to look at the freeze frame data for your code. once you see where it is acting up, you will need to drive with a scanner hooked up and graphing your dtat stream. See it there is a glitch in your TPS circuit. Make sure to watch toy TPS voltage when you let off the throttle. See if you can notice if the TPS voltage stays too high. Should drop below 1.0 volt when you let off the gas pedal. If there are any drop outs check you wiring to the TPS.


   
Reply with quote  
 

contributions: 5
So a up date. So I hooked it up and drove it around. Looked at the freeze frame data. Found it trips out at idle. According to info the projected vacuum is at 61 pascals. Says max should be 60. Not sure what that means. Pulled map and found the boot on it was ripped. Also found the vent solenoid valve was leaking air. When and replaced both. Also have replaced all of the connectors for the sensors. Rechecked everything for air leaks. Found my idle was about 500. Looked up and found a service bulletin for the pcv. Replaced it with the new gm fixed oriface type. Plugged the hole in The throttle body blade and adjust the idle .08 as per instructions. Been through all the wiring and connections front to back but I no problems found. Idle is much better and seems to run better. But if I put in in drive I can hear the motor pinging. Pretty sure it's not normal. Still getting the code Pop up after about 25-50 miles. I can drive a 1000 miles on the highway without a problem but stop light driving gets me the code. I also noticed all winter long when it was cold here in Texas conifer popped up the matter how I drove it. But as soon as it got hot keeps popping up. I suppose it could be a fuel issue. Any input would be helpful other than an exorcism


   
Reply with quote  
 
User avatar

contributions: 1992
Images: 37
Location: Oregon
if you are still getting the TPS code I would look at the scanner while driving again and graph the TPS voltage. Pause the graph when the check engine light comes on as see what the tps did to set the code.

what does the freeze frame show the TPS stat when it set the code? was it withing spec?


   
Reply with quote  
 

contributions: 5
When we looked at the freeze frame. Everything appears normal. When I hook up my meter I got 5 volts input.67 closed 4.2 wide open. I can oped and close it. Snap it open and close never skips a beat. When I turn on the air is the rpms supposed to change. Mine gos down. About 100.


   
Reply with quote  
 
User avatar

contributions: 1992
Images: 37
Location: Oregon
when you turn on the ac the idle air control should go higher and raise the idle up. the tps should stay the same. the IAC should open up and let more air through to make the idle go up higher for the additional load the ac puts on the system. While this does affect your idle rpm it shouldn't change the tps


   
Reply with quote  
 

contributions: 5
Ok so this morning I was looking up how to test the Air idle valve. it said after replacing it to reset the computer By disconnecting the battery. now I replace the valve last year because I broke the other one. I don't remember if I did that or not. So this morning I disconnected it for about a half an hour then reconnected it and went for a drive. I got to say the truck is never ran better much crisper throttle better pick up. It was much smoother. when I put it in gear the RPMs drop and come back up and when I put it in park the RPMs go up and come back Down. It's never done that before. So it's possible the problem was just that simple that I never reset the computer. I will see. Thanks


   
Reply with quote  
 
User avatar

contributions: 1992
Images: 37
Location: Oregon
congrats, sounds like you fixed it. Hope all goes well


   
Reply with quote  
Ask A Question Reply    Go to page 1, 2  Next

   Similar Topics   Author   Replies   Views   Most Recent 
New Articles View the first GMC 2001 Sierra does not always start!

in GMC Trucks

rkcrump

1

399

Wed Oct 19, 2016 10:54 pm

carriedi View the latest

New Articles View the first Attachment(s) Chevy 2001 4.3 blazer hose melt

in Chevy Blazer

roy33

2

346

Wed Dec 28, 2016 3:36 pm

Guest View the latest

New Articles View the first 2001 Chevy 4.3 Blazer Trany stays in 2nd & speedo @ zero

in Chevy Blazer

roy33

1

231

Sat Jan 07, 2017 1:11 pm

carriedi View the latest

New Articles View the first 2001 GMC sierra 1500 4x4 vibration in floor when acceleratin

in GMC Trucks

shackleferd33

1

967

Wed Nov 25, 2015 1:51 am

carriedi View the latest

New Articles View the first 89 silverado

in Chevy Silverado

chuyluna

1

1060

Sat Nov 14, 2015 9:20 pm

carriedi View the latest

New Articles View the first New or Used Chevy Silverado

in Chevy Silverado

bradstuart2303

1

1503

Tue Aug 05, 2014 11:34 pm

carriedi View the latest

New Articles View the first 2003 silverado

in Chevy Silverado

timcogan

5

1666

Wed Jun 22, 2016 5:34 am

carriedi View the latest


All times are UTC - 6 hours [ DST ]



Search for:
Jump to:  
Contact Us