Reduced engine power without cel

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

OP
OP
T

travstick

TYF Newbie
Joined
Nov 6, 2022
Posts
14
Reaction score
4
Check ltft against stft and report back. Mine did this when I developed a vacuum leak in my intake manifold.
What should the numbers be? Do this at idle or try to see what they are when it goes into reduced power? I normally work on all my vehicles and I know what long and short fuel trim is, but I don't really know much about using scan tool other than the typical check codes stuff
 
OP
OP
T

travstick

TYF Newbie
Joined
Nov 6, 2022
Posts
14
Reaction score
4
I just had the same problem with my 03 Tahoe. I replaced the TCM and the TPS and neither fixed the problem completely. I had to replace the throttle body. The drive motor for the throttle body was going bad causing the throttle blade to flutter at idle which caused rough idle and reduced engine power. I however got a code.
I've been thinking throttle body but you know how throwing money at a problem is......I can make the "rep" happen sometimes with it still in park by just blipping the throttle and it seems to me like it takes too long to idle down after it's been rev'd up. Like maybe the throttle body is too slow or is this normal?
 

Fless

Staff member
Super Moderator
Joined
Apr 2, 2017
Posts
10,246
Reaction score
20,306
Location
Elev 5,280
I've been thinking throttle body but you know how throwing money at a problem is......I can make the "rep" happen sometimes with it still in park by just blipping the throttle and it seems to me like it takes too long to idle down after it's been rev'd up. Like maybe the throttle body is too slow or is this normal?

The behavior noted in that post leads me to believe the idle air control (IAC) isn't able to manage the airflow at idle. Classic signs of a dirty throttle body butterfly that won't close all the way. Suggest you clean it with throttle body cleaner and see if that does anything for your issue.

As also noted by @wjburken a discrepancy between those two sensors can wreak havoc. If you can graph the movement of the accelerator position sensor and the throttle position sensor on the throttle body, you should be able to see any variations between them, or a dropout in either one. One thing to check while you're poking around the TB are the wires to the sensor; inspect them carefully for broken or compromised wires within about a foot or so of the TB. Sometimes they break underneath the insulation.
 

BG1988

Full Access Member
Joined
Nov 14, 2018
Posts
2,925
Reaction score
1,329
It's drive by wire
No it's not 2012 is electronic throttle body and e-gas pedal , as it has been electronic since 2004 model year...

most likely if you have all ready replaced the throttle body sensor the gas peddle sensor is broken..


try wiggling the pedal around see if it does it still


check with the OBD2 reader with live data the inverse and outverse have to match
No match = REP on the display


GM GENUINE PArt 23362231
 
Last edited:

wjburken

Supporting Member
Joined
Dec 26, 2017
Posts
9,705
Reaction score
26,282
Location
Eastern Iowa
No it's not 2012 is electronic throttle body and e-gas pedal , as it has been electronic since 2004 model year...
That’s the definition of “drive by wire” vs “drive by cable”. The throttle gets its command through a wire that powers its actuator vs a cable that is physically connected to the pedal.
 
OP
OP
T

travstick

TYF Newbie
Joined
Nov 6, 2022
Posts
14
Reaction score
4
The behavior noted in that post leads me to believe the idle air control (IAC) isn't able to manage the airflow at idle. Classic signs of a dirty throttle body butterfly that won't close all the way. Suggest you clean it with throttle body cleaner and see if that does anything for your issue.

As also noted by @wjburken a discrepancy between those two sensors can wreak havoc. If you can graph the movement of the accelerator position sensor and the throttle position sensor on the throttle body, you should be able to see any variations between them, or a dropout in either one. One thing to check while you're poking around the TB are the wires to the sensor; inspect them carefully for broken or compromised wires within about a foot or so of the TB. Sometimes they break underneath the insulation.
I cleaned the throttle body when I replaced the tps, I checked the wires at the plug but will check then further away from the tps.
 

Forum statistics

Threads
128,781
Posts
1,805,302
Members
91,760
Latest member
MyCleftNut

Latest posts

Top