Idle abnormal after long trip

[warriorpluto]

I have an 03 envoy and after long trips(100+miles) the idle is stuck at 1000 rpms driving around town whenever i sit at stop lights. i have to press on the brakes with a little bit more pressure for the truck not to move. Is this the pedal sensor acting up?

 

[CaptainXL]

I have an 03 envoy and after long trips(100+miles) the idle is stuck at 1000 rpms driving around town whenever i sit at stop lights. i have to press on the brakes with a little bit more pressure for the truck not to move. Is this the pedal sensor acting up?

It's your thermostat more than likely. It's stuck open. If the coolant stays below a certain temp for long at idle the PCM will command the idle to increase in order to try and heat up the engine to normal operating temp. But obviously it can't if the thermostat is stuck open. This is more noticeable in the winter. Do you have any codes pending?

 

[warriorpluto]

It's your thermostat more than likely. It's stuck open. If the coolant stays below a certain temp for long at idle the PCM will command the idle to increase in order to try and heat up the engine to normal operating temp. But obviously it can't if the thermostat is stuck open. This is more noticeable in the winter. Do you have any codes pending?

No codes whatsoever

 

[CaptainXL]

No codes whatsoever

What is the coolant temp at idle after these trips?

 

[warriorpluto]

It stays in the middle the whole time

 

[CaptainXL]

It stays in the middle the whole time

I don't care what the gauge on the dash shows. You need to use a scan tool to get the temperature from the PCM.

 

[warriorpluto]

I don't care what the gauge on the dash shows. You need to use a scan tool to get the temperature from the PCM.

Oh OK. Ill try to use my scanxl software

 

[fadyasha]

+1 for the Tstat. Had a similar problem til I changed it 4 weeks ago. Though I knew it was bad for over a month the code only came up once

 

[CaptainXL]

IMHO thermostats should be changed every 5 years as preventative maintenance when the coolant is scheduled to be changed. The cost to replace the thermostat is minor when changing the coolant. They also seem to fail around that 5 year mark give or take a couple years. Depends on how many miles are on the truck and if the coolant has ever been changed.

 

[warriorpluto]

IMHO thermostats should be changed every 5 years as preventative maintenance when the coolant is scheduled to be changed. The cost to replace the thermostat is minor when changing the coolant. They also seem to fail around that 5 year mark give or take a couple years. Depends on how many miles are on the truck and if the coolant has ever been changed.

Guess this would be on the list for next month