About chris ehlerman Expertise any check engine, abs, airbag, or climate control systems. also any type of mechanical repair or direction
Experience i have 4 years of college schooling. i have been in the repair business for 15 years specializing in computer control systems and hard to pinpoint problems. i help out many repair shops and dealerships in my area
Education/Credentials automotive engineering, automotive repair, ase certified
Question I have a 1999 Grand Am with a 3400V6. Emissions tests results in consistent high NOX (HC & CO are very low.) I have changed cat, replaced egr, cleaned throttle body (and AIC), replaced rear 02, used GM cleens (combustion chamber cleaner). The only ecm code i have is 442-evap leak. Temp is correct, and readings now are all normal thru a Snap On scan tool. What else is left?
Answer hello jay i know you said you replaced the egr valve but did you check with the scanner the proper operation of the egr system. it could not be opening or many times the passage way gets clogged with build up preventing exhaust flow to the intake. also is the car being emission tested on a dyno. if so make sure you have a high velocity fan installed in front of the car. many cars run to hot on the dyno without the fan an will have increased nox readings. also check your evap system it may be creating a small vacuum leak into the intake. follow the test procedures for the po442 code. if you do not have access to the troubleshooting procedure email me at cardoctorc@aol.com with your fax number and i will send it to you. good luck
