I just got a p304 and p171 code pop up. Running rough but is drivable. I know the p304 code is a misfire and p171 running too lean just wondering if its ok for me to drive it to my mechanic about 15miles away. Could it be something like a head gasket problem? Thanks

 

A misfire caused by being lean is bad. That said the ECM should pull timing if it detects knock. Though I haven't heard of one being destroyed by knock yet. If it's truly lean you don't want to push the engine much and definitely stay out of boost. My guess is it would survive a 15 mile trip on city streets if you keep your foot light.

To see if it's really bad just run it at night and look at the exhaust manifold. If it glows cherry red then it's very lean. Lean engines run very hot. Like melting pistons hot.

 

Wow, I never heard that before.

If you have a 4 cylinder and have a misfire, running on 3 is rough. The code indicates that #4 is missing so, it would be good to unplug #4 injector. How long has your CEL been on?

If you have AAA or towing on your insurance, you can always drive 1/2 mile from home and call a tow truck from there for the rest of the trip and it won't cost you anything.

How long has the CEL been on?

 

I wouldn't focus on cylinder 4. That ECM does not have the ability to determine which cylinder is misfiring. That generic code (as well as the generic codes for misfires in the other cylinders) all correlate to the same Volvo code. It is also very sensitive to misfire and does not provide frozen values for when the misfire occurred, which makes diagnosis very difficult.

Most of the time, the car is not even noticeably misfiring. It may misfire once or twice when cold and set the light but the driver never notices anything.

 

Is that the standard Volvo code set when computer is not able to distinguish cylinder missfire ES6T? Each manufacturer is different in that way and am not familiar with the Volvo protocall.
P0304 would be indicating a missfire detected at cylinder 4 as oppossed to P0300 Random missfire or no codes stored.
Original Post indicated that engine was running rough but "driveable". "Driveable does not always mean "should be driven".
I think the biggest danger here might not be destroying engine further so much as causing even further damage to the catalyst converters. The computer controls in todays fuel injection systems will compensate only so much untill they just stop and throw on a CEL with 171 or 174 codes.
rspi note about unplugging the injector is a fabulous idea to get to the repair shop. You are at least then removing the fuel from the blast furnace being created in the CAT system when a missfire like that is occuring.
Normally a CAT converter operates in the 1000-1500'F range to function correctly and turn the bad emissions into harmless water and CO2. This is achieved by a carefull balance by engine computer to cycle mixture rich-lean-rich-lean-etc. providing just enough residual oxygen into the exhuast to allow the Converters to clean up the exhaust emissions. When you have a fullblown missfire, the engine is not only blowing a full unburned fuel charge into the CAT system but also a huge charge of oxygen. It effectively creates a Blast Furnace condition and raise temps into the 10,000'F + range that can burn up those incredibly expensive converters in a very short time.
Flashing CEL should tell you that the missfire is that severe. It is the only reason CEL should ever flash and not just come on and stay on.
Price a set of warm up cat converters and a Main cat converter then call tow company and see how much money you will save.

 

The generic OBDII codes correspond to ECM-44, which is for a misfire. It does not determine which cylinder had the misfire or the engine conditions.

 

I ended up driving it to mechanic and its the coil, hopefully just that, as he cant get any parts til monday. Thx for all the replies

 

Changed coil, running okay now.

 

Good deal.