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Old 04-18-2012, 12:38 PM   #1
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kalle28 is on a distinguished road
Join Date: Apr 2012
Posts: 1

1999 SL2
Default can't shake the P0304 code

So, I am new to the forum as a member, but have definitely used it as a reference tool which has helped me out tremendously with some issues, but I can't seem to shake this code, even after all the troubleshooting I have done by reading posts on here.

I have a 99 SL2 and I am getting the P0304 Cylinder 4 misfire code reading and it is obvious when I drive.

It doesn't necessarily idle roughly, but when I start her up, the rpms rev up for a few seconds and come back down to normal idle speed. However, when I put the car in gear (any of them, it makes no difference) I can tell that the engine is running roughly and out of sync. Also when I drive here are the symptoms:

-poor acceleration
-slightly rough gear shifts
-somewhere between 2nd and 4th gear the engine will start to knock pretty hard if I don't give it a lot of gas
-mpgs have gone down from an average of about 32 to 26

Here is what I have tried so far from my troubleshooting:

-replaced wires, plugs and coil packs (although the coil packs I got from a junk yard and I don't know if the other car was the same model or year, but the parts looked exactly identical. They appeared to have less corrosion than mine as well. Let me know if that could still be the issue. I can add pictures of them, or go into more detail about what parts I picked if anyone thinks that might be the issue)
-replaced ECTS
-I tried the carb cleaner test on the intake manifold at cylinder 4 (although I did this test with brake cleaner because I had no carb cleaner on hand)

If anyone has any ideas I would greatly appreciate any help. The car just rolled over to 207K miles and I would like to keep it alive as long as possible to try to save some money. Thanks.
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