check engine lite - P0304

[paseoconv]

I have a 97 paseo with the check engine lite on. A little background - The #4 plug blew out of the cylinder due to stripped threads. Had the hole rethreaded, valves ground, all new lifters, all new plugs, wires, and coils.) Compression check on all cylinders was good. The car idles rough in drive but fine in neutral. Doesn't matter if the engine was just started or completely warm. Car runs fine when not idling. The lite came on about a mile after getting all this work done. When I check the code, it comes up as P0304. (misfire in cylinder 4) The funny thing is that I deleted the code, and the engine lite stayed off the rest of the day. Next morning, I start it up, drive a mile and the lite comes back on. (explains why the garage thought the error was addressed). The only thing I can think of is that maybe the fuel injector isn't 100%. Could it have somehow been damaged the day plug blew out? I did drive it 5 miles an hour for about 10 miles when that happened. Any other reason that #4 is not running right? I have to think that this isn't a sensor malfunction since the car does idle rough. (Kind of like a bad plug wire on a V8 will cause rough idle but the problem becomes masked at higher rpms)

[drehtwnftbl]

if it was a bad injector it wouldnt idle fine, nor would it drive okay, it would be extremely slow seeing as it's only a 4 cylindar, it'd be running on 3, and you would definitely notice

[paseoconv]

The more I drive it the more it seems the engine lite is coming on only until the car warms up. This would mean that it is related to the car when the computer is running in the "open loop" mode. (although the idle in drive is rough even when the engine is warm)

[paseoconv]

After further research I have noted the following: The compression checks out 180 in #1, 2 & 3 170 in #4 (within allowed variance), the timing is good, the resistence on all injectors is within allowed parameters, the voltage at the ECM for all injectors is within allowed parameters. I noticed that when I was checking the timing that the timing light was showing the miss by skipping at irregular intervals. I switched the coils around but the timing lite still skips. I also tried putting the timing lite on the #2 wire and the same skip showed up. I was about to replace the injector(for $100+) but now I'm wondering if this is an ignition problem. I'm running out of things to check.

[DragonSeo96]

i had that same problem on my 96 seo.....all i did was change my spark plug wires and spark plugs and made sure nothing was loose. if u had already changed ur plugs n wires n it still does it, than its def. an internal problem. when u r in neutral, does it start to go under 1000 rpm n shake? or when ur in gear n u push the gas n it dosent move the car until a high rpm range?