rellis3640

I am helping a friend work on his truck and I used scantool to come up with the following codes, while i can see that there is an issue with the EGR valve I believe that the truck is in limp mode causing some of these. Anyone have any ideas.

This truck at this point is running very poorly.

P0401 Exhaust Gas Recirculation Flow Insufficient Detected
P0304 Cylinder 4 Misfire Detected
P0308 Cylinder 8 Misfire Detected
P0171 System Too Lean (Bank 1)
P0174 System Too Lean (Bank 2)

Bert

I'd start with the coil pack or spark plug boots on Cyl #4 and #8. Then check the EGR system to see if it's plugged. Check this: OBD-II Trouble Code: P0401 Insufficient EGR Flow

__________________
Bert

Bluegrass

None of the codes in singular or total result in a Limp mode.
Look for moisture in the two rear cylinders' plug wells from a posssible gasket leak at the hood to firewall seal or some other source.
The 171/174 codes; look for an air leak into the intake from the rubber parts around the intake.
The 401 code may be a plugged port behind the EGR valve.
This is easy to check before you take anything apart.
Remove the vacuum hose from the EGR valve and use another peice of hose to draw vacuum on the EGR.
If the idle is smooth and then goes rough when you apply vacuum, the port behind it is open.
Then you have the DPFE left to suspect as not sending the 401 test result back to the computer.
You have 3 different issues at the same time.
Good luck.