How do you repair Multiple Random Misfire?

Answer 1

I guess Autozone's free check engine light check wasn't free. But it sure make a great guessing tool for them to sell parts! PO301 is the code your refering to. I would try a professional fuel injector cleaning. even if it doesn't solve you proiblem your at least getting somthing you need. You may have leaking injector orings or plugged injectors that are beyond cleaning. Bad Wires can also set this code.

Actually, SAE code P-0301 is a cylinder #1 misfire. Multiple cylinder misfire is P-0300. Only the lowend scanners make this mistake.

However, leaking fuel injectors may be causing this as well as worn plugs or wires. Also consider fuel age and quality. You can go to the same gas station several times in a row and get different qualitity gas each time.

A DTC 301 set at high (over 4,000) RPM with no other obvious faults (i.e., good: plugs, wires, coils, ignition control module, fuel pressure, etc) may suggest a faulty PCM (powertrain control module). It appears that GM had a problem with PCM's for Bonnevilles that year. Incidentally, GM warrants PCM's for 8 years/80K miles. Does anyone have any insight into DTC 304 alternating with DTC 401 for a 1998 Bonneville VIN K - not supercharged)? All of the usual suspects (coils, module, plugs, wires, etc) check-out fine. The problem is intermittent, occurring without a predicatble pattern. Runs fine for awhile, then check engine light and occasionally flashing check engine light. No obvious harness problems visible. Dealership is totally useless with this one: car has 60K and terrific maintenance history. Help?

This can be a challenging code to troubleshoot. My experience has lead to different conclusions. Like above, I have seen worn plugs, bad wires bad coil packs, bad ignition modules, bad ECMs, bad fuel injectors. Rarley a bad headgasket. The most common ones seem to be on the 3.1 engines. Take it to an independent repair shop and try a fuel injection cleaning. the fuel additives won't resolve it as they remove the waxes, but don't really clean the injectors. A professional cleaning involves disconnecting the fule pump and running the motor on this cleaner. I have seen it resolve PO300 codes, make cars run incredibly better or also do nothing.