Adjusting the MAP response - need a good log

[jcrews]

Since installing RC2, the MAP goes up past the top of the sensor's scale. What's annoying is that if the part throttle response looks correct, the full load response overshoots quite a bit. If I get the full load response to calm down, the part load response appears to have a lot of lag. Somewhere between those points should be where I need to be, but a known good plot would save a lot of time.

Something that has group 011 with routine acceleration and a few WOT sequences would be nice to have.

 

[gth]

I don't know what you're up to, but I hope this helps.

If you PM me your email I can send you the original log in csv format. For now, here's the one in xls format. Let me know when you're done with it so I can take it down.

 

[aNUT]

Stock MAP graph for a good running ALH. MAP is reduced by ~200mBar because of altitude correction. Click the picture for a large image. Target for RC2 should be ~1260 mBar over absolute.

How much unregulated vacuum do you get into the VAC port on the N75?

How much vacuum does it take to pull the VNT lever onto the stop screw?

Your actuator doesn't leak right?

 

[jcrews]

I'm getting closer. Those plots were helpful. I fiddled with the vane actuator rod until at WOT the response curve crossed the specified MAP.

I found the response to adjusting the rod isn't exactly what I first thought. Too short, and the response is about what is to be expected. There's a very narrow range where the response is correct and the software finds the control range. Slightly long, the initial position will cause constant high pressure (full load) (overcorrecting slow initial build-up response). Beyond that, the response starts to look familiar, but the overshoot is too great, and the correction is also too severe.

Now I'm having to dial in the QA position sensor voltage. It basically has to be matched to the turbo response map to get the pressure to rise to the correct point. Slowly I'm getting the actual to closely match the requested. It's times like this I wish I had easy access to a dynomometer to evaluate each change more effectively.

 

[jcrews]

Well, I just had a smack in the head moment.

I was able to get the response about as good as it could possibly get with MAP reaching the control point very quickly. The only problem is that it only did that a few times and started acting wacky again.

I finally got smart and hooked up a mityvac only to find the doggone actuator doesn't hold vacuum and it takes just over -60 Kpa to reach full stroke, though it's hard to tell with the thing leaking like a sieve.

Time for a new actuator. Oh well, live and learn. I'll be back once the new one is in place.