96 silverado 5.0

Po300 random/multiple cylinder misfire.i have this code and i read up on it and basically i got the cause of this to be a vacuum leak which i sprayed around the intake and hoses and the idle didnt change. could it be internal? also the fuel pressure but my question is has this happened to anyone or what do u guys think is the more common one. i had code for an o2 sensor and i unplugged it and the code po301 which is for cylinder 1. could that be my trouble cylinder?

 

This could be fuel or spark related. I would check plugs, wires, cap and rotor. If they are in good shape then I would bet it is the spider injection.

 

yeh i changed the plugs wires cap rotor all that and still misfiring so ill check that out thanks

 

Im with Shamrock on this, the Spider Injections are well known for random misfires.

 

I recently had the same code PO300 & PO332 trigger the Engine Service Light. They recommended: R & R intake manifold plenum & replace both knock sensors. Also, a fuel injection service. As follows: 2 sensors, 1 gasket kit, 1 sealant = $296.00 parts -- labor $325.43 Grand Total $602.03 Guess what? As I was driving it this very afternoon 1/8/11 the Engine Service Light starts flashing like a strobe light for about 20 miles and then went solid. Checked the code after I got off the highway... PO300 is back. I am very frustrated with GM vehicles and you can understand why if you read my most recent post on "Broken Brake Cable" Good Luck with your repair.

 

I have to agree with u on this as far as GM service, it really has fallen off from what it should be. Too many horror stories of unnecessary repairs and the real problem not being fixed. Sorry for ur bad news. I feel thats y alot of people come on these forums to troubleshoot they're own symptoms. We promote this and love to talk about it to help save money and headache for others. Although we wont always have the rights answers, posted solutions take place. Appreciate ur input skoot61, lets keep this goin!

 

you guys think a 02 sensor could be making it misfire? i have the po300 code, an 02 sensor and p1351. i got a new ignition coil and 02 sensor today and im ganna put them on after work. Any chance one of these or both could be causing po300?

 

i have a 96 gmc 4.3 vortex with a multiple random misfire code, ive changed the cap and rotor and pulled and cleaned the plugs. the plugs were very fuel soaked... its running really rough...if anyone has any ideas what would cause this i would really appreciate the input... thanks!

 

Im pretty sure yours is gonna be the spider injection set up from factory gone bad.

 

Probably will not be ignition module usually when they go bad you won,t get any spark.
If it is not spider , check dist shaft maybe worn down .