Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

1999 Mitsubishi Galant Failed CA Emissions Test

1999 Mitsubishi Galant ? 2.4L Failed California Emissions Test. Mechanic noticed car was ?misfiring? at higher RPM during test. Idle Emission passed. 2531 RPM test failed CO2=12.90Meas; O2 =0 MEAS; HC 130 MAX; GP =280; MEAS=6; CO 1.00 MAX; GB=2.5 MEAS=3.55 Why did car fail emissions test? Station who did failing emission test did diagnostics; could not find cause.(They did not give me any codes). Check engine light is NOT on. Maintenance done regularly (but car has not driven in several months) p.s. Timing belt replaced in May 2010; was not broken; just doing routine maintenance. After timing belt replaced noticed ?hiccupping? at highway speeds; gas mileage decreased. Took back to station who did timing belt replacement. They did not find a problem. The Station who did emissions test also checked and timing belt is ok. And car runs well and no other problems!

Please help - what do I do now?

p.s. Love CAR TALK !

“After timing belt replaced noticed ?hiccupping? at highway speeds; gas mileage decreased. Took back to station who did timing belt replacement. They did not find a problem.”

It is possible when they replaced the belt, they got it “one tooth off”…Happens frequently…Once timing has been verified as correct, the EGR valve function can cause misfiring and should be looked at…How many miles on this car?

Current mileage is 74826. Mileage at the time the timing belt was replaced was about 72,100 in May 2010. How do I check for EGR valve function causing misfiring and perhaps emisssions test failure? Should I take car to dealer? Your help is most appreciated!

Wait…May 2010? You’ve been driving it with a misfire for almost a year?

If this just developed recently, then there’s likely nothing wrong with the timing belt.

You need to check into other causes.

Replaced timing belt in May 2010. After timing belt replacement in May 2010, noticed car “hiccuping” several times from May 2010 through September 2010 driving at highway driving speed. Car was NOT driven from Oct-Dec 2010, but was driven from mid December-January 2011 for a short time.

Car has not been driven since Jan 2011,has been in garage and started weekly. Mileage since timing belt replace = approximately 2000 miles. Could the timing belt replacement cause emissions test failure - or not driving/warming up the car cause emissions failure or ? (p.s. the car has never failed emissions test) Thank you for your help.

Not likely on the starting/warming up, no. If you’re going to park a car, just leave it parked. If you start it, put some miles on it before shutting it down. Let everything heat up thoroughly before shut down so as not to just introduce more moisture in the systems inducing an earlier failure.

As for the belt, yes, that’s quite possible. If it’s off a tooth, the valves won’t open/close at the right time, so your fuel/exhaust mixtures aren’t correct, leading to that emissions failure. Try another mechanic, if you can, to verify it’s correct. Or get a repair manual and check yourself. Changing it may be beyond what you can do, but looking at dots and lining them up isn’t, I’m sure. It’s 13 years old…doing minor things like this can save you lots of money.