Issues about Emission and U-Joint

[dahell]

1. I failed state inspection due to emission test failure. The machanic couldn't tell what it is because I recently changed my battery. However, I have had check engine light on for a while and once a mechanic said their diagnosis system stuff indicated that it was about the fuel system. I have been having some problems about the rough idling(frequently) and stalling(just two times). I researched and found that it was a common symptom of bad fuel filter. But could it be the cause of failure of emission test?

2. After searching through the internet I think that the cause of noise from under the body was a u-joint problem that the car makes squealing noise at low speed and a deep low booming noise with vibration(not from the steering wheel) at high speed (above 60 mph), no sign of hard shifting with clunks from park to reverse or drive. I lifted up the rear only and tried to hear if there is any noise in drive and reverse. I couldn't hear any. With all four wheels on the ground, the rear DS didn't move at all while the front DS moves(rotational) about 1.5 inches that I could hear a slight clunking noise rotating the shaft by hands. Is it normal or possibly the front u-joint gone bad?

Please help me.

[gavin]

Originally Posted by dahell

1. I failed state inspection due to emission test failure. The machanic couldn't tell what it is because I recently changed my battery. However, I have had check engine light on for a while and once a mechanic said their diagnosis system stuff indicated that it was about the fuel system. I have been having some problems about the rough idling(frequently) and stalling(just two times). I researched and found that it was a common symptom of bad fuel filter. But could it be the cause of failure of emission test?

if the CEL is on, regardless of the code, it will cause you to fail emissions. Even if the light isn't on and you have a P1000, which is the code for, basically, "systems check incomplete," the vehicle will fail.
This is most likely the reason you failed. As for the mechanic saying something about the fuel system, it's possible that was a pending code and would not have caused a CEL.
You need to get it scanned when the CEL is on to see what the codes are, which will help pin-point the issue you've been having.

Originally Posted by dahell

2. After searching through the internet I think that the cause of noise from under the body was a u-joint problem that the car makes squealing noise at low speed and a deep low booming noise with vibration(not from the steering wheel) at high speed (above 60 mph), no sign of hard shifting with clunks from park to reverse or drive. I lifted up the rear only and tried to hear if there is any noise in drive and reverse. I couldn't hear any. With all four wheels on the ground, the rear DS didn't move at all while the front DS moves(rotational) about 1.5 inches that I could hear a slight clunking noise rotating the shaft by hands. Is it normal or possibly the front u-joint gone bad?

Please help me.

when checking u-joints, make sure to have the transmission in neutral. Otherwise the pressure on the drivetrain will prevent you from being able to find any play.
It's also possible it could be the cv-joint at the t-case end of the front driveshaft. But a bad u-joint can cause a constant vibration.

[G-96XLT]

Originally Posted by dahell

1. I failed state inspection due to emission test failure. The machanic couldn't tell what it is because I recently changed my battery. However, I have had check engine light on for a while and once a mechanic said their diagnosis system stuff indicated that it was about the fuel system. I have been having some problems about the rough idling(frequently) and stalling(just two times). I researched and found that it was a common symptom of bad fuel filter. But could it be the cause of failure of emission test?

2. After searching through the internet I think that the cause of noise from under the body was a u-joint problem that the car makes squealing noise at low speed and a deep low booming noise with vibration(not from the steering wheel) at high speed (above 60 mph), no sign of hard shifting with clunks from park to reverse or drive. I lifted up the rear only and tried to hear if there is any noise in drive and reverse. I couldn't hear any. With all four wheels on the ground, the rear DS didn't move at all while the front DS moves(rotational) about 1.5 inches that I could hear a slight clunking noise rotating the shaft by hands. Is it normal or possibly the front u-joint gone bad?

Please help me.

Just one thing I have to comment on, lose that mechanic. What mech gives a generic fuel system error and doesn't tell you what's wrong. When I failed the etest in canada we got a piece of paper with the NOX , CO and HC readings .. My fail was the NOX and changing the DPFE fixed that problem by over 1000 points. CO can be reduced with an additive and a plug change. HC I think is the CAT/

I don't know what system you guys have there but we can have a check engine and still pass. I was driving my 96 at the end of its life with a bunch of tranny codes and a half broken tranny and it still passed.