Trac code 26, Misfiring above 40mph
Thread Starter
Driver School Candidate
Joined: Oct 2019
Posts: 17
Likes: 3
From: Illinois
Things done to this car (‘92 ls w/ trac control):: timing belt waterpump, valve cover gaskets, new ignition system (wires, plugs, rotors + distributors) and the capacitors in the ECU have been replaced.
The car idles low in drive (around 400rpm, 900 in park and neutral) and misfires whenever i drive above 45mph. However, this misfiring issue was much better and seemingly went away after getting a full tank of gas today! I also have a trac code of 26, sub throttle valve sticking / not responding.
What should i do? I have a multimeter and could test the sub tps, but I’m not sure what specs it should be at.
Could the misfiring be due to a fuel pump issue? Maybe injectors are dirty? Would more fuel in the tank increase pressure and lead to less misfiring? I threw a thing of injector cleaner along with the full tank of gas, but it certainly has not been driven enough to run it through.
thank you in advance lezus community!!! You fellas are heroes
I've been experiencing a rough idle, misfires, and rough shifting, and have pulled codes from the TRAC system and received the unlucky number of 26--"Even when the sub−throttle motor is con−trolled at wide open, the voltage of the sub−throttle position sensor signal (VSH) does not reach the wide open voltage level."
Are the TRAC sub-TPS and throttle TPS the same part numbers? Is there an easier way to check if the TPS sensor is bad than using feeler gauges? I hear clicking noises from the sub TPS when I turn to ignition--does this signal that the sensor is out of alignment?
Really need this car to start running normally so I can drive to work.
Don't feel necessary to reply to every question I've asked if you know exactly what is causing the issue.
Thank you very much,
Justin
The car idles low in drive (around 400rpm, 900 in park and neutral) and misfires whenever i drive above 45mph. However, this misfiring issue was much better and seemingly went away after getting a full tank of gas today! I also have a trac code of 26, sub throttle valve sticking / not responding.
What should i do? I have a multimeter and could test the sub tps, but I’m not sure what specs it should be at.
Could the misfiring be due to a fuel pump issue? Maybe injectors are dirty? Would more fuel in the tank increase pressure and lead to less misfiring? I threw a thing of injector cleaner along with the full tank of gas, but it certainly has not been driven enough to run it through.
thank you in advance lezus community!!! You fellas are heroes
I've been experiencing a rough idle, misfires, and rough shifting, and have pulled codes from the TRAC system and received the unlucky number of 26--"Even when the sub−throttle motor is con−trolled at wide open, the voltage of the sub−throttle position sensor signal (VSH) does not reach the wide open voltage level."
Are the TRAC sub-TPS and throttle TPS the same part numbers? Is there an easier way to check if the TPS sensor is bad than using feeler gauges? I hear clicking noises from the sub TPS when I turn to ignition--does this signal that the sensor is out of alignment?
Really need this car to start running normally so I can drive to work.
Don't feel necessary to reply to every question I've asked if you know exactly what is causing the issue.
Thank you very much,
Justin
Last edited by RA40; Jun 7, 2020 at 09:49 PM.
Pole Position
Joined: Dec 2009
Posts: 3,278
Likes: 317
From: ct
Sorry Justin, meant to merge the threads but did a post merge. 
I've been experiencing a rough idle, misfires, and rough shifting, and have pulled codes from the TRAC system and received the unlucky number of 26--"Even when the sub−throttle motor is con−trolled at wide open, the voltage of the sub−throttle position sensor signal (VSH) does not reach the wide open voltage level."
Are the TRAC sub-TPS and throttle TPS the same part numbers? Is there an easier way to check if the TPS sensor is bad than using feeler gauges? I hear clicking noises from the sub TPS when I turn to ignition--does this signal that the sensor is out of alignment?
Really need this car to start running normally so I can drive to work.
Don't feel necessary to reply to every question I've asked if you know exactly what is causing the issue.
Thank you very much,
Justin
Are the TRAC sub-TPS and throttle TPS the same part numbers? Is there an easier way to check if the TPS sensor is bad than using feeler gauges? I hear clicking noises from the sub TPS when I turn to ignition--does this signal that the sensor is out of alignment?
Really need this car to start running normally so I can drive to work.
Don't feel necessary to reply to every question I've asked if you know exactly what is causing the issue.
Thank you very much,
Justin
6th Gear
Joined: May 2021
Posts: 6
Likes: 1
From: Washington
Same issue with code 26. Procedure differ with SUB TPS??
I've been over that tech write up many times and my 1990 with Trac control has two throttle positioning sensors on the throttle body... You physically can't rotate the sensors clockwise as they are blocked if I remember correctly? I have an ohm meter and just picked up some thickness gauges at Napa so I'm ready to do this, but I'm guessing I must need a different write up other than that one that only shows having one TPS.
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