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Discussion Starter · #1 ·
Hi I just got a 1999 323i with 83 500km on it its started misfiring 4 days ago I changed the spark plug and swapped the coil pack around and the missfire was still on cylinder 1 I did a compression test here are the number 1/120 2/150 3/160 4/170 5/180 6/180 the car was running poorly I used sea foam and it was running much better for about a day I'm really curious what you guys think is wrong with it
 

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Discussion Starter · #3 ·
Get the tool and read the engine error codes.
Already did the code is P0301 that is missfire on cylinder 1 I'm trying to figure out what is causing the missfire I already changed the spark plug and I swaped the coil pack around and the missfire is always on the same cylinder
 

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2003 330cic, 2003 325iT
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The compression numbers for cylinders 1-4 are very worrying. Did the engine overheat? I would focus on that.

If perhaps the compression numbers aren't correct, then the next logical step is to look at fuel trims. But I suspect the fact you have low compression in the bank 1 cylinders and you are seeing a code there is related
 

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Discussion Starter · #5 ·
The compression numbers for cylinders 1-4 are very worrying. Did the engine overheat? I would focus on that.

If perhaps the compression numbers aren't correct, then the next logical step is to look at fuel trims. But I suspect the fact you have low compression in the bank 1 cylinders and you are seeing a code there is related
The car didn't over heat but it did over Rev a couple days ago my friend missed fourth gear he when into second gear but he was quick to put it into neutral and the compression number are correct it was tested multiple time while the car was a operating temperature right now I'm waiting for a leak down test it will be done on the 6 of May...
 

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The car didn't over heat but it did over Rev a couple days ago my friend missed fourth gear he when into second gear but he was quick to put it into neutral
This important information should be disclosed at the first post. Was this misfire happened right after the over-rev event? It might have bent valves.

Check if #1 has spark and fuel (smell plug right after first crank) and with the plug removed off engine, then plug it to the coil and check for spark.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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Leak down test. With a heavy emphasis on valve seating.
I would also get a borescope ( they're cheap now) and have a look at the butterfly cuts in the piston tops.
If there was contact, it will leave a mark.
 

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Discussion Starter · #14 ·
This important information should be disclosed at the first post. Was this misfire happened right after the over-rev event? It might have bent valves.

Check if #1 has spark and fuel (smell plug right after first crank) and with the plug removed off engine, then plug it to the coil and check for spark.
Issues started the same day as over Rev events
 

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Discussion Starter · #20 ·
I did a wet test in cylinders numbers 1 and I when from 110 psi to 170 something when horribly wrong in that cylinders will have to take the engine apart
 
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