multiple random cylinder misfire P300

[Smith463]

Well, everything was going good for a while untill i have run into this multiple random cylinder misfire. it started out as a 3 & 6 misfire, so i replaced all the plugs and plug wires, then it went to random multiple cylinder, so i did coils and now it is still doing it. Would a cloged fuel filter or failing fuel pump cause this? the pressure at the rail seems okay but not great it will dribble out but not spray out like i imagine it should when running.

 

[Blown]

Certainly, low fuel pressure is a problem and yes it cold be a clogged fuel filter or failing pump. I would change the fuel filter right away if it's not been done. Fuel pressure should be around 64 psi and come squirting out of the schrader valve on the fuel rail.

I also recently went through the ignition system, replaced all you did, codes came back, and went away when I installed a the extra computer I have. I am going to do some research on these computers to see what goes wrong and who is rebuilding them.

 

[Montana Daze]

Vacuum leaks will do this as well. You may want to do a compression test also just to see if all's well inside. I had similar problems on my 2000 and the results of a comp test on it set me in the right direrction

Regards.
Mark

 

[Smith463]

Well i kind of walked away from this as its not my primary vehicle, but i was poking around yesterday and i think the egr may be bad? When i pull the vaccum line off the egr valve there is no vaccum, present, im thinking to change that solenoid and the valve to see if that may be a vaccum leak through the header if thats even possible?

 

[XploderPhil]

Well i kind of walked away from this as its not my primary vehicle, but i was poking around yesterday and i think the egr may be bad? When i pull the vaccum line off the egr valve there is no vaccum, present, im thinking to change that solenoid and the valve to see if that may be a vaccum leak through the header if thats even possible?

EGR valve will not have vacuum at idle, you will only have vacuum when driving it.
Check the fuel pressure