hunting idle and sluggish performance

[Emil]

Afternoon,

My 2001 V7 2.4T now has close to 260k miles and still going. Admittedly, it has taken a bit of an effort to get her there. The car is now worth few hundred dollars so I am not trying to keep her "like new", but there are two things I would like to resolve. Looking at several forums, the unfortunate part is that based on the symptoms, it could be a array of causes and looks like many people spent a lot of money on labor and parts that didn't fix it.

First is "hunting at idle." It is not "surging" like so many have experienced, as it only hunting between, say, 600-900, and only when warm. I unplugged the MAF and the engine died immediately (why?). I have seen explanations on it possibly being the MAF, but also vacuum leaks, this and that temp sensor, spark-plugs/wires, coil packs, ETM and several others things. So unless I can narrow it down, I may have to live with it. I am hoping "only when warm" should exclude several possibilities.

The other thing "sluggish" off the go, as in when taking off from a standstill. It is as if I am pulling 5000lb trailer behind me. But once up to speed, it is pretty normal, and speeding up to pass is pretty normal. Again, I have seen "bad turbo" and leaks of all sorts as the possible cause, but no common theme of how to narrow that one down either.

I suppose I should mention that I did pull off a code, P0014, which is a first. The timing belt has about 40K on it, and I am not convinced it is off a tooth (nothing to back that up of course). And not sure if this is all related, on something messed up with air/fuel delivery.

So appreciate in advance any feedback you may have.

Thanks,
Emil

[RickHaleParker]

I suggest you go after the stuff in Green first.

284: ECM-644A (P0014) Camshaft reset valve. Slow control. Intermittent fault

Diagnostic trouble code (DTC) information

D2800346 Condition
Diagnostic trouble code (DTC) ECM-644A is stored in the engine control module (ECM) if the camshaft is not in the correct position. The engine control module (ECM) registers this as a fault as soon as the engine is started.

The engine control module (ECM) registers a fault and diagnostic trouble code (DTC) ECM-644A is stored in the engine control module (ECM) if the camshaft position (CMP) sensor flanker is not correct in relation to the engine speed (RPM) sensor.

The engine control module (ECM) registers a fault and diagnostic trouble code (DTC) ECM-644A is stored in the engine control module (ECM) if the camshaft does not rotate quickly enough in response to the control signal.

Substitute value

• The variable camshaft is disabled

Possible source

• Faulty position
  Camshaft belt has jumped out of place on the cogs
  Defective reset valve
  Mechanical fault in the Variable valve timing (VVT) unit

• Faulty control
  Defective camshaft position (CMP) sensor

• Control too slow
  Open-circuit in signal cable
  Open-circuit in power cable
  Contact resistance
  Short-circuit to ground in signal cable
  Short-circuit to supply voltage in the signal cable
  Low oil pressure
  Poor oil quality
  Defective reset valve
  Mechanical fault in the Variable valve timing (VVT) unit

Fault symptoms

• poor performance

[jonesg]

I had that fault last summer.
Oil and filter changed fixed it.
Filter was way overdue.

[DrDan]

Gunked up reset (CVVT) valve(s) acting sluggishly? They're' easy to remove and clean. When I did mine I found it coated with oil varnish which caused high friction. That was at about 90k miles on a full synthetic regular oil change regime...

If you have access to VIDA, you can graph the desired value against actual value before and after cleaning to see if there is a difference. They should follow closely once the engine is warm.

If you are going to try this and need some more information, please post back and I will dig up the pictures I took when cleaning my CVVT valve.

[Emil]

Thank you so much for the feedback. I will start with the "easy" stuff, and go from there. I will be parking the car for three months, so I may not get to it until this spring, but I will put in what I will find out. Again, thanks for all the help.

Emil

[Emil]

Update:

Changed oil and filter today, filter was partially collapsed in the housing, has happened to me one time before. Used Fram filter this time and found out that their O-ring is far better (more meat, stiffer) than the Mann filters I have used for year. Since I had it up, I changed the high pressure line for the power steering. No money would get me to do that again.... Replaced a fuse for the AC/accelerator sensor and took it for a test drive. No more sluggishness out of the hole. No codes appeared, and the "engine service urgent" message gone.

But the hunting remains. I probably shouldn't say hunting, because one can hardly see the rpm needle move (I obviously overstated that initially). One can just hear a steady rhythm of slight up and down engine tone, but not even enough to show up on the meter. So maybe I just don't worry about it.

Thanks,
Emil