Throttle Hesitation After Replacing VVT Oil Control Valve

After replacing my bank 1 VVT oil control valve due to an occasional P0012 code, in the driveway the truck started and ran fine. Next morning I went out to head to work and it was behaving very badly, stumbling and hesitating a LOT whenever I pressed down on the accelerator. This mostly cleared up in a couple of miles driving and I thought the ECU just needed to relearn something after the component replacement. I had not disconnected the battery when doing the replacement.

Taking the truck out today, I noticed there's still a bit of hesitation off of idle. It acts just like a failing accelerator pump in a carbureted engine, bogs a bit at the initial press of the pedal then acts fine after that. I went ahead and disconnected the battery and then let the ECU do a relearn after reconnecting the battery; the problem persists. I re-verified that I didn't leave the vacuum line on the back of the air filter housing off, and cleaned the MAF for good measure (had only been 5K miles since the last cleaning, so didn't figure it would change anything). Still there.

I'm fairly certain this was not happening before the oil control valve replacement. In fact, there were no symptoms other than the once per year P0012 code that I could clear and move on. Just about everything you can name as far as normal maintenance items goes has been done in the last 8K miles. Truck is v6 auto, 4x4, DCLB with 118K miles.

No cam timing CEL currently present. Found a C1241 and C1290 via OBD Fusion tho, cleared those and went to a parking lot to do the VSC calibration. Seems clearly unrelated.

I'm considering doing the bank 2 oil valve but don't want to muddy up the waters just yet. Any suggestions as to possible causes?

 

So you currently have no codes showing?
Correct?

 

I replaced both of my oil control valves and it fixed the off-idle stumble I had. I do recall there being filters for those valves too. Maybe they're clogged?

 

Correct. Engine runs strong, just has the slight hesitation.

I checked the one for bank 1 (passenger side) before replacing the valve and it was clean as a whistle.

 

Good post, nice example of a clear & detailed description of problem & relevant maintenance history & recent actions taken to correct.

At ~120K miles it's at least possible (if not likely) that your fuel pump is having issues, possibly due to gradual accumulation of crud in the filter sock. The symptoms sound a bit like fuel starvation.

Less likely, and just throwing darts here, I wonder if replacing one OCV (oil control valve) without replacing the other could cause "off" timing in the engine, because the new OCV responds quickly to commands while the older one might hesitate due to wear, varnishing, etc. If they don't act synchronously I would think that would lead to the combustion timing being slightly off & thus pistons fighting one another at least a bit until the older OCV "catches up" with the new one whenever changes are commanded by the ECU. (Which is basically every time the engine spools from low RPM up to higher.)

 

I don’t think this is the fuel filter/pump; having it act up right at the time I replace the oil control valve would just be a little too coincidental. And the engine runs fine other than the slight hesitation.

You may be on to something with regard to the other oil control valve. I usually do things like this all at the same time, but I figured this was likely a case of one slightly sticky valve, so I opted not to replace the other one. I’ll go ahead and get that one on order and see what happens once it is replaced.

 

Agreed that the odds are highly against the fuel pump starting to choke at just the same time as the OCV was replaced, but I find it's always good to keep the constant possibility of simultaneous-but-unrelated failures in mind, to avoid getting total tunnel vision with respect to some particularly line of diagnosis / fault analysis / troubleshooting.