[kycol]

Originally Posted by Cinderocka1989

I'll spray some throttle body/carb cleaner down it while I'm doing the cap and rotor, I have to have it open anyway.

Very first thing I would try in a new fuel cap.

[Cinderocka1989]

Originally Posted by kycol

Very first thing I would try in a new fuel cap.

But it's not an evap code....??

[Vikingdad]

Cinder,
What year make and model is it? Possibly a cracked cap or maybe a bit of moisture in the cap? (if it is that old).

[axxe55]

Cinder, check the A/C line. if it runs across the back of the motor near the firewall, it could be condesation from the line dripping on the distributor cap and causing a misfire. easiest way to check for this is to look inside the distributor cap and see if it a green colored looking corrosion inside it.

some Chevy and GM trucks, Surburbans, and Tahoes had this problem. not saying it is, just something to check out.

might also check the O2 sensors. sometimes they can cause a misfire code of P0300 to show up.

[Cinderocka1989]

Originally Posted by Vikingdad

Cinder,
What year make and model is it? Possibly a cracked cap or maybe a bit of moisture in the cap? (if it is that old).

97 Chevy Suburban, 5.7 so it has a distributor.

[Trez]

Originally Posted by Cinderocka1989

Yeah I got tune up stuff and possibly fuel pressure regulator. I don't think it's the fuel pressure regulator, it starts, runs good and doesn't smell like gasoline. He has to get it registered this month and that light has to be off to pass emissions.

Originally Posted by DFlynt

Possible bad injector? My Nissan Quest had a bad injector that was causing a misfire and it would throw different codes.

Originally Posted by kycol

Very first thing I would try in a new fuel cap.

Originally Posted by Cinderocka1989

But it's not an evap code....??

Originally Posted by axxe55

Cinder, check the A/C line. if it runs across the back of the motor near the firewall, it could be condesation from the line dripping on the distributor cap and causing a misfire. easiest way to check for this is to look inside the distributor cap and see if it a green colored looking corrosion inside it.

some Chevy and GM trucks, Surburbans, and Tahoes had this problem. not saying it is, just something to check out.

might also check the O2 sensors. sometimes they can cause a misfire code of P0300 to show up.

Yep, I dont miss newer cars any.....

[Cinderocka1989]

Originally Posted by kycol

Very first thing I would try in a new fuel cap.

Originally Posted by axxe55

Cinder, check the A/C line. if it runs across the back of the motor near the firewall, it could be condesation from the line dripping on the distributor cap and causing a misfire. easiest way to check for this is to look inside the distributor cap and see if it a green colored looking corrosion inside it.

some Chevy and GM trucks, Surburbans, and Tahoes had this problem. not saying it is, just something to check out.

might also check the O2 sensors. sometimes they can cause a misfire code of P0300 to show up.

I'm not saying either of you are wrong, I'm just trying to learn. I've seen fuel caps throw evap codes. How would that cause a misfire code?

Axxe I've seen bank 1 or bank 2 lean or bad cat codes for oxygen sensors.

I just think it's weird that it went from multiple cylinders to just cylinder 1. If it's just the one cylinder it would have to be a plug or a wire right?

[Cinderocka1989]

Originally Posted by Trez

Yep, I dont miss newer cars any.....

Hey, it isn't mine.

[Trez]

Originally Posted by Cinderocka1989

I'm not saying either of you are wrong, I'm just trying to learn. I've seen fuel caps throw evap codes. How would that cause a misfire code?

Axxe I've seen bank 1 or bank 2 lean or bad cat codes for oxygen sensors.

I just think it's weird that it went from multiple cylinders to just cylinder 1. If it's just the one cylinder it would have to be a plug or a wire right?

have you checked the plugs or wires?

[Cinderocka1989]

Originally Posted by Trez

have you checked the plugs or wires?

Plugs and wires? Man, I'm a f***ing diesel mechanic, the hell are you talking about?

But no, I haven't checked anything yet, just throwing some possibilities around. The last thing I want is to be the "mechanic" that just throws parts at a problem....