Car may be possessed

[gwrabbit]

Hi all,
132k miles on the engine, and ever since 97k I've had a P0420 (Inefficient cat). The car always has seemed a little hesitant to get up and go but never had any major issues. Fluids are kept up religiously, maintenance always done when problems arise, etc.

However, when I was leaving work today, I went to start up my car and there was no CEL! It's a completely different vehicle now. When I would go slow in the parking lot (5-15 mph), the car would always want to jump. I would also have a semi-rough idle but nothing major by any means.

It accelerates quicker now and is waaaay more responsive. This situation happened a couple weeks ago as well.

I ended up plugging in my scanner and found a P00420/30 code and a P0016 code, but no check engine light.

Plugs are good, PTU, RDU, and Coolant were all serviced less than 10k miles ago. Transmission right around 15k. I just did an oil change this past weekend too. Motorcraft filter, Castrol Edge 5w-30.

Thoughts? It's going to my mechanic next week so they can diagnose it further and potentially call a priest for an exorcism.

 

[yaycandy]

Give her what she wants. An Italian tune up

And some techron concentrate

 

[gwrabbit]

After further research, I think it may be a timing chain issue. I thought I could be one of those few that wouldn't have to deal with that

 

[jman1200]

I thought you had a plugged cat that for whatever reason, the obstruction disappeared.

 

[gwrabbit]

I thought you had a plugged cat that for whatever reason, the obstruction disappeared.

It may be possible. I'm more worried about this P0016 code that showed up on my scanner...But wouldn't that cause a CEL?

 

[jman1200]

Not all codes trigger a CEL.
This is what I found for that code, nothing related to the cats.
P0016 is the OBD-II generic code indicating that the camshaft position sensor for bank 1 does not correlate to the signal from the crankshaft position sensor.

Clear the codes and see if they come up again. I also heard that some codes must reoccur X number of times before they trigger a CEL (i.e. misfires).

 

[gwrabbit]

Not all codes trigger a CEL.
This is what I found for that code, nothing related to the cats.
P0016 is the OBD-II generic code indicating that the camshaft position sensor for bank 1 does not correlate to the signal from the crankshaft position sensor.

Clear the codes and see if they come up again. I also heard that some codes must reoccur X number of times before they trigger a CEL (i.e. misfires).

Interesting!
I started up the car today and had no issues, but the CEL came back. I'll clear the code and see if it comes back. I haven't had the dreaded cold start rattle/timing chain slap. It still accelerates fine, is responsive, and no rough idle. It's still going in next week just to play it safe.

 

[gwrabbit]

Just got the car back.

Timing chain is off 5 degrees and will need to be replaced. Waiting on quotes for that.

Joy.

 

[SHOrod]

Hmmm, if the timing chain is off 5 degrees, why is this intermittent? I'd think that would cause issues all the time. It seems more like a sensor issue, wiring issue, or issue with the camshaft solenoid for the variable cam timing. Do you know how the dealership determined that the timing chain is off by 5 degrees? Are they maybe going off of a sensor reading or guesstimating a "worst case" scenario?

-Rod

 

[gwrabbit]

Hmmm, if the timing chain is off 5 degrees, why is this intermittent? I'd think that would cause issues all the time. It seems more like a sensor issue, wiring issue, or issue with the camshaft solenoid for the variable cam timing. Do you know how the dealership determined that the timing chain is off by 5 degrees? Are they maybe going off of a sensor reading or guesstimating a "worst case" scenario?

-Rod

I took it to a mechanic that I trust. They ended up running diagnostics and found the P0016 code along with the 5 degree variation. I could always replace the sensor and see if the issue goes away. It's just very strange that this check engine light comes and goes and the car seems to improve when it disappears. I'm not sure if that means the sensor is resetting to default values which clears the CEL? I'm not very informed on the electrical/sensor side of things, so I could be very wrong.

There are some days where the car will hesitate under hard acceleration and then finally go, but I always thought that was due to my bad catalytic converter which is a whole other issue that I'm suspect of. Bank 2 cat is under efficiency with a P0420/P0430 code. The shop wants to replace it entirely, but I don't smell sulfur, exhaust, anything like that as of recent.

I've been on top of maintenance as best I can. Oil changes every 3-5k. Transmission usually every 20-30k along with the PTU.

Just a very strange issue.

 

[Majestic]

I've had the same issue with the P0016 code throwing a check engine light and then it will randomly go away on its own. My car runs fine otherwise, though. No rattle at start-up, so I just live with it.

 

[SHOrod]

With the mileage on your engine it may not be bad to consider replacing the timing chain, but I still don't see how the timing being off would be intermittent if it were related to the timing chain, unless the intermittency is more related to a potential catalytic converter issue than the timing. But if it were my car I'd confirm the oil level and change the oil if close to due, then clear the P0016 code before scheduling to have the timing chain replaced. I might even consider replacing the cam timing solenoid since that should be quite a bit easier to do than the timing chain.

-Rod

 

[gwrabbit]

With the mileage on your engine it may not be bad to consider replacing the timing chain, but I still don't see how the timing being off would be intermittent if it were related to the timing chain, unless the intermittency is more related to a potential catalytic converter issue than the timing. But if it were my car I'd confirm the oil level and change the oil if close to due, then clear the P0016 code before scheduling to have the timing chain replaced. I might even consider replacing the cam timing solenoid since that should be quite a bit easier to do than the timing chain.

-Rod

I'll clear the P0016 code before I leave work today and see if it comes back. I had my mechanic do an oil change just to be certain that wasn't the issue. Initially there is a rough idle when the car first starts up but goes away after like 20-30 seconds.