Hey everyone. Well just my luck, I got the check engine light flashing. My ultragauge gave me the codes and it reads PO300, PO301, PO302, PO304, and PO305. Thought changing the spark plugs would fix it but well, it didn't work out as much. It helped a little but the misfiring is still going on. Would it be dumb of me to drive it 3 miles to my school and 3 miles back?

 

Most definitely would be a dumb idea to drive with that many misfires. It will not only cause damage to your catalytic converter, but depending on the actual cause of the misfire itself, possibly cause engine damage.

Due to the fact you're engine is misfiring on so many cylinders, I would say that you either have a primary side fuel or ignition related issue occurring. But first, being these motors have SO many issues with clogged EGR ports that cause this same issue, I'd start there. Simply remove the upper intake plate that sits right on top of the motor. You will see multiple passages that will more than likely be filled with a crusty black carbon buildup...and if you do clean that out.

Otherwise, I'd suspect the following:
Bad fuel pump and/or pressure regulator
MFI relay sending reduced power to injectors/coils/fuel pump
Extremely dirty air filter or something obstructing the intake tube
Bad/improper grade fuel

Of course there's many more things that it could be but I've listed the 'most likely'.

 

If the buildup is the issue, would cleaning it fix the misfiring? Whats weird to me is that I moved my car and it had no issues at about 6:30 in the morning. At 4:20 this afternoon, the misfiring happened. It came out of nowhere.

 

Yes, cleaning it would fix the issue immediately correct the misfire. Buy a few cans of carb/brake parts cleaner as well as a can of SeaFoam and go to work. There will be a large diameter hole beneath that plate that sits to your right, fill that hole up completely with SeaFoam while using the spray cleaners to clean the passages. Be sure that when you initially start the engine up NOT to rev the engine up too high because it will be sucking a lot of the chemicals into the intake/EGR valve and don't want to do any internal damage.

 

if it all happend at the same time then you are only looking for one problem.

 

The most likely cause my dad and I think is the Ultragauge. I picked this up 3 days ago from a friend with a Dodge Ram. I changed the settings up but it or I could have (and probably I did) do something to mess with the computer. If its not that, it is something else but the Ultragauge is the main suspect right now.

 

i just looked that up online.. I think that could be the culprit.

to find out simply remove the unit and reset the ecu with the 7.5 amp fuse under the hood passenger side firewall. also disconnect the battery too.. just to make sure everything is lost in its memory. i also leave the lights on to make 100% sure everything is drained. wait 5-10mins. then put everything back to how it was and u should be golden.

that thing is just a toy thats going to distract you and get u in an accident. so don't be upset when it's gone LOL

 

Agreed. Signal 'interceptors' are very notorious for eventually scrambling sensor data rather than modifying it. Most are lucky if PCM remains unharmed after removing these types of units.

 

Check your coil packs..

 

So I did what CL-S progression said and thoug it helped, one or two cylinders are still misfiring. The car is being checked out at a mechanic while I'm driving my dad's chevelle in the school's homecoming parade. So I think I'll be okay Thanks so much for the help you guys. I'm getting my money back too from the ultragauge.

 

Right on man, keep us posted on what the issue was.

 

if ur mechanic can prove the ultragauge screwed up ur car make them pay for it. for sure!!

 

Hey everyone, car is fixed. Took it to a shop and they weren't sure it was the Ultragauge but I had two blown coils. Got those replaced and I gave the guy his ultragauge back so he'll give me my money tomorrow. Car runs great now, even though its only a CL-P haha Thanks everyone for the help! I really appreciate it.

-Stefan