I have a 95 Tahoe with 158000 miles. In Maryland you have to get your vehicle emmission tested every 2yrs and mine passed the highway speed and lower speed exhaust emmissions but failed at idle test. Is this something with the throttle body or a sensor ? Len

sounds dumb but here in maryland people with older vehicles have problems passing emissions test. sometimes fresh oil change can help also possibly vehicle is in need of a tune up including plugs wire cap rotor pcv valve and fuel filter. one other thing could be the catalyst converter might not be cleaning to its full potential. hope this helps

Check for a vacuum leak by doing a smoke test and see where the smoke is pulled into the vacuum line.

if you are failing emmissions test your evaporator canister is expired replace it and then you and your car will get a green light

Hello, you probably have a trouble code P0506 stored in the system, this will keep from passing test. real simple fix. the throttle body is dirty, this will cause not enough air around the throttle body. simply clean out the inside of the throttle body around the throttle plate and bore. you will need to use throttle body cleaner or carb cleaner

with a hand held diagnostic computer it can be done in about an hour. Drive the car as an owner it could take up to a month. It is the driving condition , not mileage that resets the ECM. You have to drive on the highway at certain speeds for a certain amount of time, then in city driving, stop and go and at certain speeds for so long. The computer guides you threw it. If you only drive city or highway you may never get it to reset.

Putting miles on them wont reset the computer. It is how many times you cycle the key on and off. And they will only reset if the problem was fixed. I don't know how many times yours has to be cycled, but some vehicles are up to 100 times. Hope this helps.

it could be the bearings in your transmissin. or you need an alignment

Some vehicles require very specific drive cycles (called "drive traces" if you perform them on a road simulator or dyno) to activate certain self-checks like the catalyst and EVAP monitors. As a general rule, doing some stop-and-go driving around town at speeds up to about 30 mph followed by five to seven minutes of steady 55 mph highway speed driving will usually set most or all of the monitors. Consequently, if you're checking an OBD II system and discover that one or more of the monitors have not run, it may be necessary to test drive the vehicle to set the remaining monitors.

You should talk to a good emission tec, if this is not throwing a code, it is hard to say if that one of the components could be bad. O2,pump,convert, HeO2, every part of the emission system.

With a 1000 miles, and doing what is says above just before the test, and ending driving at the test
should be plenty. If it is not, you will have to have each emission part checked, or when the computer
is plugged in it might show a code that did not trip dash light.

it possibly is a faulty throttle poisition sensor

the porition of plug that went into cyl may have also damaged the valves.I would be very concerned a valve may break and fall onto top of pistion and destroy everything.A v-10 running on 9 i would not recomend towing anything.find an engine and replace.