Z34 problems

My 1996 Z34 (3.4L) has been running horribly. Just got it back from dealer and said bad O2 sensor, pirometer reading 200 degree temp increase from front of catalytic converter to back - claims cat is clogged, and valvetrain clatter indicating mechanical damage. 1. is my motor junk at 72,000 miles? 2.Can a clogged catalytic converter cause engine clatter? 3. is 3.4L a weak motor? Thanks.

1.The LQ1 motor(3.4 dohc) Engines tend to have alof of problems, and when not maintained properly those problems will double!
2. Not to likly that would cause clatter! But it could! I would try to locate about where the noise is comming from! You can use a paper towel roll to isolate the noise!
3.The LQ1 is a pretty powerful motor! Being the dohc allow a much higher rev that equals to a broader power band! But seeing the aftermarket for these engines is pretty slim , there is not alot of room to grow with this motor for cheap!

Good luck

Problem finally solved! Two knock sensors were interpreting the engine clatter as knocking and were retarding the timing causing it to run badly.
Disconnected the sensors and it runs perfect. One problem though with both sensors disconnected the check engine light comes on. How can I get it to go off? Ive already tried plugging in only one sensor...light goes off but it still doesnt run as it should.

Well I would say figure out what the knock sensor is picking up! Cause more then likly either they both are bad or again you have internal damage that will cause major problems! You might also have a detonation problem, But that would be the least likly of out of the group!

As for turning off the light you can have the codes deleted from the PCM but you would have to find a person that has a hptuner or powertuner(not sure if DHP suports the Z34 yet) Really thought I wouldn;t recommend doing that cause they are there for a purpose!

good luck

You could just swap out the engine

Well I would say figure out what the knock sensor is picking up! Cause more then likly either they both are bad or again you have internal damage that will cause major problems! You might also have a detonation problem, But that would be the least likly of out of the group!

As for turning off the light you can have the codes deleted from the PCM but you would have to find a person that has a hptuner or powertuner(not sure if DHP suports the Z34 yet) Really thought I wouldn;t recommend doing that cause they are there for a purpose!

good luck

You could just swap out the engine
You can also remedy the light by jumping it with a small wire. MIGHT be a little cheaper than swapping motors.