I stopped in at Autozone and they pulled codes P0138 & P1456. The dealer is replacing the O2 sensors, and diagnosed the P1456 as a cracked evap canister. While there, they also pulled P0300, but no definition as to which bank. The car also has a mild knock at about 2250-2750 rpm when under load. The dealer can't determine which coils, if any, are bad (or so they claim).

So... given all of the chatter about these lovely coils, I'm looking for opinions. Are the coils in fact in concern here? I've also seen reference to a possible air leak. I removed the short ram and modified the stock air box. maybe something at the manifold end? Is this possibly all related to the O2 sensors?

After the O2 sensors are replaced, I may just dive in and inspect each plug to try to narrow the issue.

Comments please.

 

How does the engine usually run? The p0300 code is for a misfire. The p0138 is saying the sensor is out of range. If you have a misfire that will change your burned A/F ratio which will in turn set an 02 code. Get the misfire fixed FIRST, then if the 02 code comes back then replace it, otherwise you're potentially wasting your money.

Also usually when a coil goes bad it USUALLY gives a primary igntion system code. P1320 IIRC. How many miles? Are the plugs still original?

 

The O2 sensor is being covered by the dealer, so I'm not wasting anything there, but I do figure the codes are related in some way, though they dealer says otherwise. They're trying to diagnose the misfire with no luck.

The car seems to run smooth, less this mild knock at the rpm range stated. Fuel mileage is good, the engine is strong. It does seem to idle very low when its up to temp though, I'd say under 500rpm (not sure what the norm is). With the PR motor mounts, it shakes the hell out of the car. Get the rpms up a bit and it's fine.

The car has 70k miles, w/ original plugs.

 

It's probably time to change the plugs. I'd do it anyways since they are original weather or not that is the problem.

The idling @ 500 rpm is below spec and PROBABLY isn't plug related, but could be. Does it loop @ idle?? I.E. go from 500 to 1000 back down to 500?

 

Negative, it'll just idle really low. Typically when sitting at a light for a few moments. I agree - probably unreleated, so we'll stay on topic.

 

bump
I've seen others discuss the engine knock/ping. Have we narrowed the cause of this?