V6 Tech 1967-2002 V6 Engine Related

p0300 from Hell! Please help!

Old 11-14-2013, 10:38 PM
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p0300 from Hell! Please help!

Hey everybody! So I have a few readings on my 2000 camaro V6 3.8L that have been a nightmare for me. They are p0300- (Random misfire), p0174- (system too lean bank 2), and "Evap emissions control system vent circuit malfunction". I have changed all of the spark plugs & wires. Changed the fuel filter, cleaned the MAF, cleaned the fuel injectors, Changed the PCM and still nothing. The car idols smooth, but misfires when ever I try to go uphill. Please help!!!
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Old 11-15-2013, 02:03 PM
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Re: p0300 from Hell! Please help!

This is the LS1 forum, which is the V8 engine in the 98-02 F-Bodys. I'll move this to the V6 forum.

But since you asked, have you checked the fuel pressure? If it's misfiring, and it's running lean on Bank 2, could indicate a connection between those two. P0174 indicates that the Bank 2 long term fuel corrections are attempting to correct for a lean condition, based on O2 sensor feedback. They are adding more than 20% extra fuel, and it still isn't correcting the problem. If the fuel pressure is low, it is going to show up when you are putting the engine under heavy load - e.g. going up a hill. Does it also misfire on a flat road, if you go wide open throttle and try and take it up over 5,000RPM, in 2nd gear?

Have you had the ignition control module tested?

Do you have access to a scanner with "GM Enhanced Parameters"? If so, it can pull up the misfire count by individual cylinder, which may help you home in on the problem, by pointing to specific cylinders.
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Old 11-16-2013, 07:54 PM
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Re: p0300 from Hell! Please help!

Oh yikes... Sorry, new to all of this!

But okay so I checked the ignition coils and found cracks in them... replaced them today, and the car runs a lot better, but the light came back on. went and got another reading and all of the codes have cleared except for the p0300.

So I took your advice and took it up to 5000rpm in 2nd on a flat road and sure enough it misfired! Is that a dead give away for low fuel pressure? My alternator is squealing pretty loudly. I read that a failing alternator can affect the fuel pump which intern, causes a misfire due to low pressure. Is it true that the alternator is a main source of power for a fuel pump?

p.s. seriously, thanks for the help man!
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Old 11-16-2013, 08:10 PM
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Re: p0300 from Hell! Please help!

got the alternator tested... they said it was pushing too many volts... This is really starting to confuse me. Also I should have mentioned that when ever I try to fill it up at the gas station, the pump will always click off like the tank is full unless I apply minimal pressure to the handle of the pump... are any of these problems possibly related to each other?
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Old 12-27-2013, 10:37 AM
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Re: p0300 from Hell! Please help!

High voltage would make the fuel pump put out a little more, not less. You should get a fuel pressure gauge hooked up and tape it to your windshield and make a couple runs to see what is really going on. Random misfires can be a lot of things including ignition system problems and low compression. Don't rule out bad gas, wrong spark plugs, engine too hot, things like that. Do you buy your gas at the same place every time?
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