So last night I took a late night cruise in about 40 degree weather and drove rather gently. After about 15 mins, I pulled up to a stop light and my car had a rough idle out of nowhere and rough/surging acceleration. The car almost felt like it could stall at times (it didn't though).

The rough idle persisted until today and I had the codes read at autozone:

P0171
P0174
P1642
P0301
P1316
P1111- irrelevant

I think P0171 and 0174 are related to an intermittant restricted performance light that comes on when coasting around 50 mph for over 5 seconds, and then goes away after about 15 seconds. That has not triggered a CEL in the past. This has gone on for a bit. I tightened up everything on the intake and cleaned the throttle body connection and MAF sensor. I'm thinking the accordian in the intake pipe must have a small crack somewhere.

What would cause the CAN error code and a misfire code? The car was driving perfectly until all the sudden the roughness occured out of nowhere. The car is drivable, but sounds terrible and I don't feel that its trustworthy to drive around a lot in. Would driving the car damage anything (the cats, exhaust, and etc)? The engine makes a slight pressurized air woosh that changes with the RPM. (I'm guessing the misfire is causing a VERY slight backfire)

Any ideas as to what could be causing all this? I'm guessing a coil, but how would that have crapped out all of the sudden?

 

One issue on these cars can cascade into other codes. The P0171/0174 is the obvious place to start. That issue could be causing the miss fire. Air leaks, as you identify, in the duct from the air filter to throttle body plus the full load breather tube and even a constricted part load breather tube.

Make all that go away and see what is left.

 

A jag with problems? Say it isn't so. Since problems cascade as it was put You may end up spending money and time on crap that has nothing to do with the root cause. I've been telling folks that owning one of these is like having a supermodel for a girlfriend. Except she is dead.

 

I love my car! Only two in the county and the other is a garage queen.

 

HAHA!! That's a new one.

An intake problem with a 2 bank lean situation could lead to a single cylinder misfire? I will take a look at the intake again tommorow.

 

Sure, because while the entire system is lean, there may be one cylinder that is more sensitive to a lean condition. For example, on some engines, specific cylinders are known to be the weak sisters in fuel charge because of intake runner layout.

 

Did they reset the codes at Autozone ? If the P0301 comes back, you could always swap the coils on cylinder 1 and 2 and see if the code changes to P0302. It helps to have a code reader. I got the P0171 and P0174 and restricted performance - it turned out to be a cracked/broken part load breather hose and I actually did this myself when cleaning the part load breather (unbeknownst at the time).