No, you just need to jack it up and get under the car and you'll see it.

 

I've been busy for the past few days so I took the car in to get it scanned today.

Now it has two codes: Cylinder 4 misfire and the MAF sensor air flow is low.

Vacuum leak seems to be gone though apparently.

The spark plug wires are new so there's no reason to replace them (bought them 2 or 3 weeks ago). So I went ahead and replaced the spark plugs for cylinder 3 & 4.

I also cleaned out the MAF and the throttle body (had a bit of oil residue).

Check engine light is still on though (no idea for what though as I don't have a scanner) and it still has a rough idle.

 

You have to have a scanner to turn the engine light off. What did you use to clean the MAF?

 

What would be the point in using the scanner to turn the engine light off? Or is that generally the rule?

If there's no longer a problem shouldn't the light just turn off?

I had a check engine light before when I had the old spark plug wires. When I replaced the wires it turned off by itself. I didn't use a scanner. The computer itself detected that the problem was "gone".

Turning it off with the scanner is one solution, but it doesn't really tell me if the code has gone away. I'd have to wait for a couple of days and drive a couple of miles to see if it comes back. Based on what I can tell the car still has a problem if it still idling rough and hesitating....reason enough to keep the check engine light on.

 

You almost always have to clear the codes off. If you don't want to get a scanner you can rent one for free at the parts store (you have to pay for the value of the scanner and when you return it you get a full refund) and that would tell you any new codes you may have. Or you can reset the ecu by disconnecting the battery cables and holding them together for about 2 min. What did you use to clean the MAF? You can only use electronic cleaner on them. I think the MAF is probably the problem.

 

Yes I know. CRC.

Disconnecting the battery cables doesn't help. I've tried it number of times while owning the Jetta and it's never worked once. I know people who've attempted it as well without much luck either.

The MAF could cause the car to idle rough, but not necessarily a cylinder 4 misfire. Until I get the car scanned though the MAF is just an assumption and not as important as a misfire.

 

You think that disconnecting the battery cables and holding them together for a couple of minutes doesn't reset the ecu? I'm not making an assumption, did you know that the MAF is a big contributor in determining the air/fuel mixture? If the MAF is bad it certainly can cause a misfire.

 

Sure it resets the ecu, but that's not what I was referring to. It doesn't remove the check engine light. There's no point in resetting the ecu if the light isn't going to go away. I've tried it before many times as I mentioned before. I tried it yesterday and even I tried it today again.

Yes I do know what the MAF does which is why I went and cleaned out the MAF, the intake, and the throttle body, but a bad MAF isn't the ONLY cause of misfire.

There are plenty of other reasons why I could be getting a misfire and simply buying a new MAF sensor isn't exactly the best solution or even the most affordable one. Sure it's easy solution, but I've known others who have made the mistake of replacing the MAF sensor only to later realize that it didn't truly fix the issue in the first place.

Also as of right now I'm only getting a cylinder 4 misfire. A bad MAF can cause one cylinder to misfire, but generally it'll be the culprit to multiple misfires.

 

I didn't suggest you go out and buy an MAF. So, the MAF code is gone? If the MAF is good then I would suggest checking the pulse of that fuel injector. In my experience, resetting the ecu does erase the engine codes. They come back if you still have a problem. That's just me talking though.

 

I went to autozone again to see if they would clear the light, but apparently by law they're not allowed to because of state inspections (according to one employee).

Out of curiosity I went to an Advanced Auto parts store out of town and asked if they could see what codes were coming up. Several codes apart of from the misfire came up though it took a while for the obd scanner to work and from the looks of it the scanner wasn't in great shape.

I may let a friend take a look at it this weekend or next week.