'92 Park Avenue Ultra with SES Code 57

I've started getting a SES code 57, which is entitled, Boost Control Problem. It started to happen two days ago while driving to work. I accelerated to go up the ramp onto the Interstate and the SES lamp goes on and then off a couple of seconds later.
That same day I had an alternator problem and in the process of repair cleared the code. But, the next morning while zooming up the road, the SES does its thing again.

A week or two ago while looking into other acceleration problems I took the boost control solenoid off to test. I hooked it up across the battery and tried blowing through the outlets. The thing seemed to be OK. I'm pretty sure my vacuum is OK and the little hoses in that boost control area look OK.

But I haven't done too much work on it yet and I was wondering if anyone had any thoughts on the best way to go about testing and or repairs. I just got over some issues with the ignition coil packs and I'm running on three scavenged coils for now until I can get new replacements. I hope these issues may be related, but I can't see how.

Thanks for any info you have to offer!

P057 Shorted Transaxle Temp Sensor Circuit

P057 Shorted Transaxle Temp Sensor Circuit This is a 92 model, no "PO" codes on this one. Code 57, is for the boost control solenoid. Rare code, however fairly cheap to replace the solenoid.

This is a 92 model, no "PO" codes on this one. Code 57, is for the boost control solenoid. Rare code, however fairly cheap to replace the solenoid.

Sorry about that....Got the year/code wrong.

Well, I got a new Boost Control Solenoid today and installed it. I hoped it would make a difference, but unfortunately on the way home from work, I got another Code 57 while going up the on-ramp to the Interstate.

I haven't had any time to do much testing other to have pulled the vacuum line off the Boost Control Actuator and have the "wastegate" drop down. I'm thinking I should try bypassing the control solenoid's vacuum lines to see if it will pull the BCA down. Or try measuring the vacuum from the manifold pressure port and then duplicate that on the lower port of the BCA with a small vacuum pump. The point is to see if the BCA will release the bypass flap...or what ever it's called.

From that point I guess I need to verify I have voltage on the BCS. There is a troubleshooting tree in the workshop manual, but I don't have a Tech1 to trigger the ECM to open and close the bypass valve.

Thanks for your comments!!

A little follow-up from yesterday's post.....

This morning driving to work the PAU feels like it's got boost, almost certainly starting off from a dead stop. I even got the tires to squeal a little!

Is it possible that I get Code 57 when the car wants to kill boost but it can't? Maybe I have a sticky actuator that won't release?

Why didn't they install a boost gauge in this "old guy's car" in the first place? I should probably read the shop manual a little closer.

Mea culpa! I think I tracked it down. About 2 weeks ago I stuck a salveged MAF in my car to test another problem I was having. It seemed to be fine so I left it in. But now I see I made a boo-boo and assumed that if it fits it's OK. I didn't make the connection when the code 57 started to show up.

My original MAF is type AFH50M-02C and my replacement is AFH50M-02E. I didn't realize a SC MAF could be different from a non-MAF; air flow is air flow, right?

I really futzed around with the supercharger checking vacuum and pcm control and connectors. Putting the original MAF back in and going for a little test drive makes me feel sure this is the problem I created for myself.

Oh, yes, I have a spare BCS and I figured out a way to replace it's little foam filter. Oh boy, the things you learn from your mistakes!!