2001 V70 T5 - Wastegate / Actuator

[princepugh]

Hiya

I've cleaned up my wastegate/ actuator rod joint this morning. The joint moves nice and smooth now and I've set the calibration boost to 0.3 bar (it needed adjusting several turns in).

The car runs much smoother now but is overboosting so something isn't right :-(

I'm wondering if I now need to reset the system to allow the CPU and TCV to re-learn the new setup, or if in-fact by winding in to the supposed correct calibration setting, it is now no longer capable of venting sufficient boost?

The wastegate itself seems to move through nearly 180 degrees (with the actuator arm removed) but has no spring resistance.

Grateful of any advice before I wind the rod back out for safety.

TIA

[princepugh]

Wound the adjuster back by one turn for todays drive but it's still overboosting - guess it will be one turn back every day until it starts behaving. Interesting that it was set to mate up directly with the wastegate rod in the closed position with no pressure applied to the actuator. Work that one out.

[princepugh]

For anyone interested, I've wound it back out another full turn and it's starting to come back to me now, still overboosting but much more manageable so it's heading in the right direction. Still don't understand how the calibration could be so far off.....

[princepugh]

Well, following a further turn out on the actuator rod today it’s now boosting to just over a bar with no drama – so within 1 turn of a nut (effectively) we’ve gone from out of control to good control. I did try a half turn out instead of 1 full but it was peaking at an indicated 1.4 bar so thought best to avoid, although it wasn’t pulling any ignition or anything and was pulling smooth all the way up the range. I’d read some posts on an American forum that the P2 rod was sensitive to change but man do I know it now!

The reason I’ve been ‘tinkering’ in this area is that I was getting spikes at full chat and I’d exhausted all other avenues of investigation. My plan was simply to check the actuator and wastegate rod assembly for corrosion/ play and calibrate it to manufacturer spec. When I inspected the assembly I found:-

1) The actuator was holding pressure (tested up to an indicated 0.8 bar)
2) There was light corrosion and a slight ‘stiction’ on the arm/pin/rod joint
3) There was a small amount of play in the assembly (meaning a small amount of play on a supposedly closed wastegate). In other words, the rod had no pre-tension to keep the gate firmly shut - I can’t explain how this has come about, perhaps the spring in the actuator has weakened over the years
4) The wastegate itself was moving freely, which was a relief as I was suspecting it might have become ‘sticky’ with deposits.

Dousing with penetrating fluid and scrubbing the assembly up with a wire brush removed the stiction; and using a fuel pressure gauge and plumbing with a hand pump on the actuator nozzle set the manufacturer base boost to 0.3 bar. That this proved to be so badly wrong I can only put down to the quality of the gauge, which at such low pressure readings was never going to be highly accurate.

Irrespective, it’s my belief that the light corrosion and slight ‘stiction’ on the wastegate arm/pin/actuator rod assembly was reducing the ‘feel’ at the pedal and introducing a lag factor, which could also explain the spiking, working on the basis that the ‘response’ from the wastegate was not sufficiently quick enough to relieve the build up of pressure. Moreover, it’s a given that such a spike could then induce ignition retardation and give rise to that horrible feeling that the car is holding back – though thankfully I never hit the fuel cut!

The overall improvement in throttle response came as a welcome surprise as I thought it was fine at anything but WOT after fitting the IPD HD TCV. Just goes to show what you get used to.

Whether my apparent results will last, I don’t know but at least I do know the rod is where it should be and the wastegate arm connection is free to move (high temp copper grease has thus far left a nice lube residue).

Anyways, it’s been an interesting exercise and perhaps it may come in useful to someone at some point, particularly I feel, for those of us with the older Phase 2 units which are starting to need some TLC.

And now I need to find where that knock is coming from at the front end! *sigh*