Overboosting after refitting wastegate actuator?

[mikeloadsasaabs]

I posted a few weeks ago about loss of power on my 1994 CSE 2.3lpt, which turned out to be the wategate actuator rod dropping off. Having refitted it, all seemed well, except that I have noticed a few times (nearly always) that when I floor the throttle for a quick blast, there is a sudden jerk and I lose power for an instant. Now, this seems like an overboost cutout that I persistently suffered on a previous 2.3fpt, but didn't happen before I refitted the actuator rod. A couple of thoughts spring to mind here.

Firstly, I bought the kit from Saab which contains the R-clip to stop the rod dropping off the wastegate arm, and also a circlip. I fitted the R-clip but not the circlip, I was vaguely wondering if the rod was moving on the actuator arm to a slightly odd angle & jamming because the circlip wasn't limiting the movement on the arm.

Secondly, I was wondering whether the base boost could have altered itself whikle the actuator rod was hanging in fresh air waiting to be refitted.

Neither sounds particularly likely, does anyone have any other thoughts?

[john]

Mike, not sure if base boost could have changed, but if you are experiencing overboost cut out, then my first port of call would be to verify that base boost it correct. IIRC base boost should be 0.40bar on the 9000. I'd confirm base boost is correct before checking other things.

[mikeloadsasaabs]

Mike, not sure if base boost could have changed, but if you are experiencing overboost cut out, then my first port of call would be to verify that base boost it correct. IIRC base boost should be 0.40bar on the 9000. I'd confirm base boost is correct before checking other things.[/b]

True, but it didn't do it at all in the 4 years I've owned the car until I put the actuator rod back on the wastegate arm - it's literally all I've done. Could it really have changed that much so easily?

[john]

True, but it didn't do it at all in the 4 years I've owned the car until I put the actuator rod back on the wastegate arm - it's literally all I've done. Could it really have changed that much so easily?[/b]

I don't know. That's why I recommend that you check rather than speculate.

[mikeloadsasaabs]

I don't know. That's why I recommend that you check rather than speculate.[/b]

Good point. Silly question, but I've never had to do it before - how do I do it and what kit do I need?

[john]

BillJ's website has the check base boost procedure, here

[SteveN]

BillJ's website has the check base boost procedure, here[/b]

Do check the base boost as /john suggests: it takes next to no time. FWIW I don't think the boost can alter just with the wastegate disconnected. As to needing the circlip and R clip, when I did mine I just used a split pin and it held fine.

[KenManiac]

it sounds like the actuator is binding on the pin.

some hi temp grease or graphite may help. if it was off for a long time rust may be an issue, and indeed some may have gotten wedged in there.

i would take it off again and make sure you can move it by hand (it's a strong spring, but you can move it)

unless the locknut backed off and it unscrewed itself, rather than falling off, i doubt the adjustment changed. unledd the diaphragm has a hole or a split in it.

put a hose on it and suck on it. if it doesn't hold, it's NG.

[mark e]

True, but it didn't do it at all in the 4 years I've owned the car until I put the actuator rod back on the wastegate arm - it's literally all I've done.[/b]

As Ken says, this points to a mechanical problem. If you take the actuator arm off the wastegate, does the wastegate move freely? If so it's probably an actuator problem.

[mikeloadsasaabs]

As Ken says, this points to a mechanical problem. If you take the actuator arm off the wastegate, does the wastegate move freely? If so it's probably an actuator problem.[/b]

Well, certainly the wastegate arm was moving freely when I reconnected them, and the actuator rod needed a good tug but seemed to slide on well enough. They were only disconnected for a matter of a week, and about 40 miles, so I'd be surprised if there were any issues relating to rust etc - the arm seemed nicely smooth. When it's dry enough I'll crawl underneath again and see what I can see. Not the easiest thing on the car to see!

Thanks for everyone's help so far, I'll report back, although tbh it's not top priority at the moment (SWMBO seems to tho think that finishing the half-decorated dining room is more important - strange woman!).

[ant9000turbo]

Well, certainly the wastegate arm was moving freely when I reconnected them, and the actuator rod needed a good tug but seemed to slide on well enough.[/b]

Just thinking back to when I changed my turbo on my B234R (TD04) and set the base boost on my standard actuator rod. I didnt really need to tug it on the arm, it seemed to be just enough to hold the wastegate firmly shut..
If your actuator was wound up a bit too tight causing base to be too high, that would certainly make it overboost I would have thought.. I guess as has been said, check base to know for sure..

When checking base, it may be worth connecting the 'C' hose direct from the compressor to the wastegate, that rules out any other problem and will limit you to base boost without having to mess around with the brake pedal etc

Just a thought....