Full ignition tune up
#1
05-30-2017, 01:41 PM
Full ignition tune up
Hi All,
New user here. I recently got a P0420 code and my new mechanic replaced the cat converter. After installing the new cat converter he strongly suggested a "full ignition tune up" ASAP to avoid damage to the new part. when I asked about the tune up details (which costs $247) he said it includes replacing the spark plugs, cleaning the oxygen sensors, and reseting the computer history so the new cat converter can yield a better fuel efficiency. I honestly am not sure if I can trust this guy, I have recently moved inter-state and this shop happen to be close to my new apartment. My question is whether the suggested tune up is really necessary. Also, is there a way that I can evaluate the spark plugs myself to see whether they are in poor condition as he claims? Thanks!
New user here. I recently got a P0420 code and my new mechanic replaced the cat converter. After installing the new cat converter he strongly suggested a "full ignition tune up" ASAP to avoid damage to the new part. when I asked about the tune up details (which costs $247) he said it includes replacing the spark plugs, cleaning the oxygen sensors, and reseting the computer history so the new cat converter can yield a better fuel efficiency. I honestly am not sure if I can trust this guy, I have recently moved inter-state and this shop happen to be close to my new apartment. My question is whether the suggested tune up is really necessary. Also, is there a way that I can evaluate the spark plugs myself to see whether they are in poor condition as he claims? Thanks!
#3
05-30-2017, 04:10 PM
Really, the spark plugs are about the only thing that make up an "ignition tune-up" for that car. IIRC your car should get new plugs every 105k, so hopefully yours have been replaced once.
You can remove the plugs & look at them. NGK's website has photos of plugs that are normal vs. not-normal for various reasons. Probably every other manufacturer has something similar. Those photos are better then me trying to explain in words.
There may be issues with the coils (one coil for each plug), but that should result in misfire error-codes.
Cleaning the O2 sensors sounds a little bogus to me. In fact, at 165k my first thought for a P0420 would have been to check or replace the secondary O2 sensor (in the cat) rather than replacing the more expensive cat-converter itself.
One aspect of "cleaning" the sensors that does make some sense is about external crud and/or exhaust leaks. The O2 sensors really measure the oxygen DIFFERENCE inside vs. outside of the sensor. That can throw off the measurement under circumstances like these:
- exhaust leak blowing onto the outside of the sensor (1st or 2nd sensor or both)
- grease, oil, dirt building up on the outside of the sensors
You can crawl underneath & have a good look around to see whether this kind of thing is happening. Make sure you support the car properly so it doesn't fall down on you.
Other "tune-up" things you can check for yourself.
- air filter full of leaves & insects
- PCV valve - this can result in oil blowing through the line into the airfilter box which you'll see when you check the airfilter. Also check the large rubber connection from the airfilter to the throttlebody for oily residue.
You can remove the plugs & look at them. NGK's website has photos of plugs that are normal vs. not-normal for various reasons. Probably every other manufacturer has something similar. Those photos are better then me trying to explain in words.
There may be issues with the coils (one coil for each plug), but that should result in misfire error-codes.
Cleaning the O2 sensors sounds a little bogus to me. In fact, at 165k my first thought for a P0420 would have been to check or replace the secondary O2 sensor (in the cat) rather than replacing the more expensive cat-converter itself.
One aspect of "cleaning" the sensors that does make some sense is about external crud and/or exhaust leaks. The O2 sensors really measure the oxygen DIFFERENCE inside vs. outside of the sensor. That can throw off the measurement under circumstances like these:
- exhaust leak blowing onto the outside of the sensor (1st or 2nd sensor or both)
- grease, oil, dirt building up on the outside of the sensors
You can crawl underneath & have a good look around to see whether this kind of thing is happening. Make sure you support the car properly so it doesn't fall down on you.
Other "tune-up" things you can check for yourself.
- air filter full of leaves & insects
- PCV valve - this can result in oil blowing through the line into the airfilter box which you'll see when you check the airfilter. Also check the large rubber connection from the airfilter to the throttlebody for oily residue.
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