4A-FE Questions! Need help.

[kpopple]

My 1994 Corolla failed its emissions test today (barely).

It passed everything except for the nitrous oxide test, with a reading of 2.5401 grams/mile with a maximum of 2.0000. It has 152,1xx miles on the odometer. The chart shows that the NOx emissions spike when he let off the gas, sometimes reaching 8.5 grams/mile. The tester mentioned that we might try cleaning the EGR valve... anyone know what type of EGR valve the 4A-FE has, or really anything at all about it? He also suggested that other culprits may be the O2 sensor or a vacuum issue. Any thoughts on these or any other possibilities? Any help is greatly appreciated!

[kpopple]

Forgot to mention... the car has a literally brand new catalytic converter.

[REN69]

I bet it's the EGR valve, I had the same problem 2 weeks ago and it was EGR valve problems.

[wheredoesthisgo]

Shut off the No2 bottle next time. Just kidding, your probably in no mood for jokes.

[diver9000]

I agree with Ren. Get a new EGR valve and try it again. Might want to run a tank of super unleaded through it too.

[REN69]

Ask the mechanic to do a test run with the EGR disconnected, see if this improves the readings.

My car was the other way around though, at Idle it passed with flying colours, as soon as you opened the throttle during load (40km/h) the car failed miserably.

[retiredat44]

Originally Posted by diver9000

I agree with Ren. Get a new EGR valve and try it again. Might want to run a tank of super unleaded through it too.

those EGR valves are about $180 here new ! Not sure where you are...

[mvftw]

Failing NOX is either... 1- Cat, 2- EGR, 3- Timing way off

[kpopple]

Thanks for all of the responses. Yes, I did find that a new EGR valve is $160 here. (Metro-Milwaukee Area) I'll take a look at cleaning the EGR valve maybe this weekend. Or maybe I'll shut off the No2 bottle like wheredoesthisgo suggested. Anyway, I'll let you guys know how it goes when I again decide to get it tested.

[piercingarcher]

Originally Posted by kpopple

My 1994 Corolla failed its emissions test today (barely).

It passed everything except for the nitrous oxide test, with a reading of 2.5401 grams/mile with a maximum of 2.0000. It has 152,1xx miles on the odometer. The chart shows that the NOx emissions spike when he let off the gas, sometimes reaching 8.5 grams/mile. The tester mentioned that we might try cleaning the EGR valve... anyone know what type of EGR valve the 4A-FE has, or really anything at all about it? He also suggested that other culprits may be the O2 sensor or a vacuum issue. Any thoughts on these or any other possibilities? Any help is greatly appreciated!

Have you changed your engine oil? Cuz, I failed one emission test due to forgetting to change oil.

[kpopple]

OK... got the car tested again today, this time with a new O2 sensor... failed again with 2.07 something. The guy that tested said that I could drive it to a county nearby that doesn't reformulate their gas (I filled it in Milwaukee last time, where they do), add octance booster, and injector cleaner, and I should pass. In '94, only California cars had EGR valves... Any thoughts on the gas suggestion?

[broke]

Techron every oil change