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Ongoing mystery lurching, check engine


LuxMirabileVisu
06-02-2008, 04:23 PM
Sorry this is so long. First, I know nothing about cars. Forgive my ignorance. Second, my problems have been ongoing since October, and I'm at the end of my rope. Any help would be greatly appreciated.

Back then, my car lurched horribly when I slowed or stopped, then was extremely difficult to get going again, being unresponsive to pressure on the accelerator. Ultimately it stalled and had to be towed. At that point the timing belt and components, along with spark plugs, were replaced. The lurching stopped, but since then, the check engine light comes on, and each time the RPM's drop and it becomes unresponsive to pressure on the accelerator. I back off the gas then slowly reapply pressure and it works. Usually these instances come closer and closer together until it stalls. They consistently found codes 304 and 340.

Since then, here is what's been done: a loose fuel injector was reconnected, the fuel filter was replaced, the PCV hose was replaced the the power control valve was cleaned, transmission was checked and found to be fine, the pickup coils and CAM sensor were replaced, and the crank sensor and crank misfire sensor were replaced.

At this point the car is lurching again and is not drivable. In addition, the whole check engine light/loss of power thing is still going on. I've been to a dealer and a reliable mechanic. The dealer sucked, and the mechanic is at his wit's end and doesn't know what else to try. Any suggestions?

LuxMirabileVisu
06-02-2008, 05:04 PM
Nevermind, apparently it was the crank misfire sensor, and this new problem was caused by a loose wire.

Memo to Sonata owners: if you have a mystery problem involving engine misfires, look to the crank misfire sensor.

BeatnikTermite
06-03-2008, 08:29 AM
Nevermind, apparently it was the crank misfire sensor, and this new problem was caused by a loose wire.

Memo to Sonata owners: if you have a mystery problem involving engine misfires, look to the crank misfire sensor.

So, the Crank Misfire Sensor was the culprit (in the other thread it seemed like you said it was not) and this time a wire was just loose?

Which wire was loose? Do you know where the sensor is off hand?

I've been chasing the same problem on a 2001 V6 GLS for over a year. I replaced, or discounted, a lot of the same things you did. My next step was going to be the transmission sensors. I've heard that a difference in the input and output speed sensors can "trick" the onboard computer into thinking the car is in a different gear, and thereby adjusting the gas and transmission accordingly.

Thanks.

LuxMirabileVisu
06-03-2008, 02:16 PM
I also have a 2001, forgot to mention that. Well, my car is apparently fixed after replacing the crank misfire sensor (although the crank sensor was replaced at the same time, so I suppose it could've been that, but the mechanic thought crank misfire was the problem). I'd thought it wasn't fixed because the loose plug was causing some of the same symptoms, but when they plugged it back in it immediately stopped. So it's only been a couple days, and my confidence has been sufficiently shattered that I can't say positively it's fixed, but it seems like this time it really might be.

The loose plug was really obvious; you could hear it hitting things and the whole engine was shaking. I don't know what it was called or what it does exactly, but without it there really was a misfire due to a lack of sufficient power.

As for location of the crank misfire sensor, it's difficult for me to describe since, as I mentioned, I know nothing about cars, so I took a picture.
http://www.flickr.com/photos/jillouci/2549014800/
Umm, I can't figure out how to display that picture here, but the link is http://www.flickr.com/photos/jillouci/2549014800/.

1 is the crank sensor (you probably knew that).
2 is the wire that leads to the crank misfire sensor. I don't know where the actual sensor is, but the mechanic said he had to take everything apart to get to it and it was a major pain.
3 is where the loose plug was, under the cover there.

Hopefully this helps a little.

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