Faulty knock sensor

[Fat Charlie]

Too many people see codes as actual diagnoses, and unfortunately some repair shops as well. Unless you've got time (and a backup vehicle), equipment and work space, you're a prisoner to the shop that says they have diagnosed your problem and have a solution for you.

[Xist]

Lordherald, an automotive class would be great. I have been wondering if I should find some "Easy A" classes to boost my GPA and self-esteem.

It certainly would be nice to have more independence of those with expensive whims.

Fat Charlie, I do not know if the first shop, which charged $100, did more than read my codes, but it ended up being as simple as replacing the sensor. The part was $115 and even if an hour of labor was the same, that would be less than half of the quote.

The guy in the Forester forums said that his faulty knock sensor made his engine run poorly. How likely is that? He said that his car ran fine as soon as he replaced it.

Had they said it would be $230 I would have had it done immediately, saving me countless frustrations.

Regarding the timing belt, the knock sensor was a confounding variable, as well as the fact that the car ran fine for a week and a half.

Honestly, I keep wondering if I would do better as a mechanic. I am not doing well in school and while Speech-Language Pathologists provide a vital service, everybody needs mechanics, and I would hate to have my family go through drama just because dealers and shops are dishonest and\or inept.

[Fat Charlie]

Don't do it.

[lordherald]

This is where a basic repair class should come in handy. The knock sensor is looking at the exhaust to see if the mixture is correct (at least on my car). The computer uses this to adjust the fuel mixture and in some cars retard or advance the ignition. If your timing belt was getting to the end of its life it will have both stretched and may have worn.

The belt has cogs that interact with the cam or cams and the crank.
In some cars it also drives the water pump.
This site has a number of good pictures Auto Timing Belt Repair | Last Chance Auto Repairs

Once the belt has worn it can throw off the timing enough to foul plugs and sensors. If it had been a while since you changed the plugs and wires then this can happen even faster.

As to why it ran good on and off it can be as simple as the weather, the temp, and the operating temp of the car.

My car currently needs a cam sensor installed its a $20 part and a 8 hour job.
Because the computer is not entirely certain of the cam position is stumbles a tiny bit until it is warm.

Your chosen position is a good one and if it is something you want to do just keep plugging away at it.

Auto mechanics can make good money but in most markets the properly trained ones have to compete with a vast number that are often in over their heads. These shade tree mechanics are often good at many things but when a proper diagnosis is needed turn into part swappers.

[Xist]

Okay guys, I will keep trying with my current major.

Except for the CEL, my car seemed fine, but it was time to replace the timing belt, so I paid the shop to do so, and they said the tension adjuster (or something) went out afterward).

[vskid3]

Originally Posted by lordherald

This is where a basic repair class should come in handy. The knock sensor is looking at the exhaust to see if the mixture is correct (at least on my car). The computer uses this to adjust the fuel mixture and in some cars retard or advance the ignition.

I think you're thinking of the O2 sensor. The knock sensor detects knocking and adjusts the timing as needed.

You don't need to be a certified mechanic to be able to work on your car or to help friends and family. With the internet, most problems can be diagnosed with basic tools and a general understanding of how cars work. You can even find walkthrough videos for some repairs on youtube. Even if you can't do the actual repair, a couple hours on Google can save you from getting screwed when you take it to a mechanic. Sometimes they like to throw parts at the problem instead of doing a good diagnosis, but you can prevent that if you already have an idea what could be wrong (either by letting them know where to look or to know when to refuse an unnecessary repair).

[Xist]

Originally Posted by vskid3

I think you're thinking of the O2 sensor. The knock sensor detects knocking and adjusts the timing as needed.

You don't need to be a certified mechanic to be able to work on your car or to help friends and family. With the internet, most problems can be diagnosed with basic tools and a general understanding of how cars work. You can even find walkthrough videos for some repairs on youtube. Even if you can't do the actual repair, a couple hours on Google can save you from getting screwed when you take it to a mechanic. Sometimes they like to throw parts at the problem instead of doing a good diagnosis, but you can prevent that if you already have an idea what could be wrong (either by letting them know where to look or to know when to refuse an unnecessary repair).

Well, aside from two CEL diagnoses totaling $150, I think that I was able to prevent myself from wasting money, and it could have cost me far more than that amount, but the time involved was very unreasonable.

I was able to do some help for the friend that I mentioned before with the Sable, but fortunately, the friend and her car are not my concern anymore.

[Fat Charlie]

This isn't about Xist's car, this is just an update on my "customer" who bought the short running valve actuator that I told him wouldn't fix his car. He just called back (he didn't tell me it was him, but I'm not that stupid). He had me chack a part number that teh interwebs gave him; it was the original part number for the actuator. I cheerfully told him that the part number ending in AA superceded to an AB, which is not available separately, but was serviced as the manifold. I didn't get into the side note that offered a separate actuator because that was the piece I sold him in the first place, telling him it wouldn't fix his problem. He was upset that something that can be taken apart can't be bought that way and is now going off to the junkyard in search of a used short running valve actuator. Which won't fix his problem.

It's funny- yes, the PCM says the actuator isn't doing its job. But in this case the factory has found that it's more likely that something in the manifold is broken and the actuator is working perfectly. So they stop making actuators available separately. But since the code says actuator, trying to sell anything else is just being evil.