Question about 2000 Mitsubishi Galant
Took my mitsubishi through CT emissions 4 times and failed everytime on nox only, my numbers dropped a little everytime with repairs until i put the new egr valve on then my numbers shot up higher then they were in the first place and now i'm not sure what to do. new plugs new wires distributor and cap and router tryed the gas additives air filter evap canister cant afford a new cat so any help would be greatly appreciated.
NOx emissions are the result of high combustion chamber temps pure and simple. NOx readings go up whenever there are hot spots that exceed about 2400 degrees. Things like lean mixtures contribute to high chamber temps, as does over-advanced ignition timing.Lean mixtures are usually caused by some failed components or by air (vacuum) leaks in the intake.
Poor fuel quality contributes to detonation, another cause of high chamber temps.
Posted on May 20, 2009
I would closely examine what you did when you changed the egr valve, you want to make sure you're going forward, not backward in this repair. Make sure you have all connections back in place, electrical and vacuum. There are a few basic things that cause high nox. Generally speaking; the heat of combustion, but more specifically; a lean mixture, over advanced timing, or excessive compression. The lean mixture can be caused by a contaminated airflow sensor, I believe your car has an odd style of afm called a karman vortex meter, they have known problems. I wouldn't recommend playing around with this thing just yet, but something to keep in mind in case you have no choice. Make sure the air intake hose is well connected and no splits. I suspect it's your problem because you said all the other gases passed, it would be helpful to know their values. A lean mixture prevents the cat from lighting up completely. The cat must be fed exhaust with a minimum of .45 % CO content. Good emission repair shops will drill a hole ahead of the cat to insert their gas analyser tip in there just to measure pre-cat CO so they don't end up replacing cats for no reason. A brand new cat will do nothing to reduce nox without at least .45% CO. Has anybody measured pre-cat CO?
High compresson can be caused by combustion chamber deposits. If you do a lot of around town driving, it's possible there are deposits that have built up enough to cause a problem. A combustion chamber cleaning process may be beneficial, how many miles on this car?
Ignition timing is the single biggest factor in nox production, you must check it now! If it is correct, then your problem will be a bad cat if you know for sure pre-cat CO is .5% during the drive cycle. That said, some people that have engines with distributors can very easily cheat their way through the test by dropping their ignition advance about 10 degrees. This has a drastic effect on the production of nox and enables the car to pass the test. Dropping the advance has the detrimental effect of reducing power and gas mileage so these people usually put the advance back where it was meant to be after they get through the test.
Posted on May 20, 2009
a 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of.(from cars to computers, handyman, and even drones)
click here to download the app (for users in the US for now) and get all the help you need.
Posted on Jan 02, 2017
Tips for a great answer:
on Jun 18, 2010 | Chevrolet 1500 Cars & Trucks
Dec 06, 2012 | Cars & Trucks
Sep 13, 2012 | 1988 Toyota MR2
May 31, 2011 | 1999 Isuzu Rodeo
Apr 12, 2017 | 1999 Isuzu Rodeo
Nov 19, 2010 | Saturn SC2 Cars & Trucks
Oct 06, 2008 | 1992 Dodge Colt
1,003 people viewed this question
Usually answered in minutes!
Step 2: Please assign your manual to a product: