Diagnostic Codes Po 300 and PO 441

[skit0321]

I ran the diagnostics and got these codes Po 300 and PO 441 for Po 300 it says to check or replace the following sensors: TPS, MAP, ECT, CKP, MAS, CMP, and VSS. For PO 441 it says to replace: TPS, EGR, MAP, and MAS. I have already replaced the TPS, and am doing the MAP today. So far however there is no change and am still experiencing missfire. Any hel;p woulf be greatly appreciated.
Thanks,
Scott

[dsatt12]

Weeell, P0300 is a multiple/random misfire, and P0441 is this:

P0441 Evaporative Emission Control System Incorrect Purge Flow
(according to obdii.com)

I'd say instead of replacing the sensors that are reporting the misfire, I'd look into the spark side of things to stop the misfire. How old are your plugs and/or wires? You can very easily pull the front 4 out and check the gap and check for deposits, oil, or discoloration. Also open your hood at night and have someone rev the engine with the plastic engine cover off. You may be able to see the wires arcing to the engine block. If you're at all in doubt, I'd recommend replacing both the plugs and wires with AC Delco parts- you've already likely spent more on sensors than this would cost you anyway. For that matter, if you've got newer aftermarket stuff on of a different brand- Auroras have been known to be really touchy about using other ignition components.

I don't really know what that purge flow code means. It COULD be an EGR valve problem. The thing is, they're so damn expensive I wouldn't replace it just to TRY and fix a problem. I think I'd address the misfire first, clear the codes, and see if they come back. If you're not burning off your fuel in the cylinder, maybe an 02 sensor is saying something emissions related isn't getting purged right is the best I can think of.

Where'd you get that list of things to check? That's a heck of a lot of stuff- throttle position, manifold pressure, coolant temp, crankshaft position, mass airflow, camshaft position, and vehicle speed sensors just for a misfire? The thing is I can't think how any one of these alone would produce *just* a misfire.

Let us know if you figure anything out.

[skit0321]

I already replaced the plugs with none other than acdelcom platniums, checked gap before install to assure it was correct. As of where i got all those things to check it was from the obd . I think I shall replace the wires and perhaps coil packs, mabey the timing chain?

[dsatt12]

Just start with the wires only. Your coils shouldn't really go bad unless the wires have been shot for a long time, but then you'd notice a misfire...

Don't worry about the timing chain. The northstar is a postive interference engine- which means if you have a problem there you're already missing your valves. It's not meant to have to be replaced.

[skit0321]

checked the plug wires and the coil packs and neither were arcing so what should i do now, start with the long list of sensors that could be bad?

[dsatt12]

I still say just replace the spark plug wires if they have more than a few tens of thousands of miles on them. They don't necessarily arc through the insulation- it's just a telltale sign if they are. That's just a routine maintenance item that should come up anyway.

If that doesn't work, it seems to me paying a mechanic $60 to figure out what is the matter would be far cheaper than replacing *all* of those sensors. He has the specs and the tools to tell if they are working correctly without just throwing new parts in. Those things really shouldn't just go bad. With the exception of my EGR valve, every sensor you've listed is likely still the original (I bought my 95 used) at 185,000 miles. You can point the finger of blame squarely on me for the dirty EGR for trying to scrimp and save on cheap gas too. Have them check the coils too just in case the bad wires killed one off.

Another suggestion I've seen is to buy one new one (coil pack that is) and rotate it through the 4 possibilities and hopefully find a dead one if that is the issue.

Good luck!

[skit0321]

Have mechanic working on it now he is not quite sure as to what is the problem. So who knows