p0300 intermitten problem

**ksstamp09** · 04-22-2010, 10:48 AM

If anyone can help me with this it would be blessing lol. I got this code the other day, have no idea how long its been on. But I had 2 other codes for the O2 heaters so both upstreams are brand new and downs are tuned out (no cats, kooks lt's). This code was present then, but now its back an it is the only code. Car idles seemingly well but has power loss and the misfire becomes very relivent around 2k. It has progressivly gotten worst after the new o2/ air filter change, yet it is an intermitten problem
It is an ls6 swaped crate motor with less than 10k miles, with asa cam. I've cleaned the maf replaced the filter with a fram, checked both the ckp and cmp sensors, both working fine. Tried to do a ckp relearn but never could get it to complete. Smoke tested for vacuum leaks, nothing. I plan to look for an exhaust leak tonight or leaking o2. Would that cause it? I also plan to check computer wiring to the coils. Open for any suggestions and thanks in advance.

**0rion** · 04-22-2010, 11:30 AM

have you checked fuel pressure? How many miles on the fuel filter?

**89RS&98Z28** · 04-22-2010, 11:31 AM

Not to be a smart ass but could you reread what is written and may be edit the post some. Not sure how many times I read???? that post to get to the end.
But I'm sure someone can help you. I for about three months several years ago kept setting the p0300 code and never had a running problem though when I would come to a stop in heavy rain the car would seem to miss badly for several seconds and then quit. As suddenly as this appeared it quit and have not thrown a code in the last couple of years 50,000 miles or so. But the car still does the miss thing in heavy rains but only just after comming to a stop. And every now and then does it if I use a notouch car wash.
Good luck with your problem.....

**ksstamp09** · 04-22-2010, 11:46 AM

Yeah sorry I'm on my phone at work so I was tryin to type and work. But I did check the fuel pressure an its at a steady 58 psi. About 20k on fuel filter. That's what a guy I work with suggested as well. A new one surely wouldn't hurt. It smells real rich when its running too.

-wow ok I see what you were sayin haha. I had copied an pasted that an it screwed it all kinda up. Fixed.

**Damian** · 04-22-2010, 09:19 PM

Few questions:

-Is your car an automatic?

-What size pushrods are you running?

**ksstamp09** · 04-23-2010, 07:08 AM

It is a m6 and has ls6 pushrods that came with the motor. An I very rarely go over 3,000 rpm. But I did test the injectors last night and got 10.6 ohms on each one (beside a 11.2 on one) and had a solid 11.8 v at the connector. They were only drawing like 1 amp apiece as well so I'm thinking they are my problem.

**planemech2** · 04-25-2010, 02:52 PM

P0300 is an intermittent misfire. Mine was a loose #6 plug wire. The O2 could be foreign matter in the fuel. Mine come on sometimes after using Stabil over the winter.

**TerribleTed** · 04-26-2010, 11:41 AM

I got a P0300 initially,,,,due to a very bad mis shift and the result was a bent valve on one cylinder and a bent pushrod on another cylinder.
Both are now replaced correctly and I still get this code,,,but then again,,might be a plug wire or could also be something else I over looked,,time to get out the tools again,,,
and again,,