Does anybody know if these 2 solenoids work in exactly the same way? Note that I'm NOT talking about the way they control the turbos, but the way they open and close the air passage through them when current is applied by the ECU.

The reason for my question is that if they both work in exactly the same way, (for example, both closed when no current is applied and both open when current is applied, or vice versa for both), then accidently reversing the 2 pipes to the precontrol and wastegate actuators will have the same effect as reversing the electrical connectors to the 2 solenoids. However, if the solenoids work the opposite way to each other, (without current - one normally open and one normally closed), then such an accidental reversal of the 2 pipes to the actuators will NOT have the same effect as reversing the electrical connectors, (due to the duty factor control).

You might say,"Why do I ask?" Well, I have a strange overboost problem when the secondary cuts in. (This has only started recently, and, yes, I have been working in this area, changing vacuum and other pipes etc). It only lasts for 1 to 2 seconds but gets way up to 13 - 14 PSI - not good! I checked the pills and the pipes from the primary boost that contain the pills - all are connected OK.

One possible thing is that I may have accidently switched the 2 pipes down near the primary, going to the 2 actuators, as above. However, if this were to give the same effect as reversing the electrical connections to the 2 solenoids, the symptoms would be different, (constant 7 PSI, I think). This is not happening. Hence my question.

I've not quite got my head around whether the observed symptoms would fit the impact of the pipes being reversed IF the solenoids both worked in OPPOSITE ways, (Without current - one normally open, one normally closed, as per my question above), as it becomes complicated due to the duty control of the solonoids by the ECU, but it may be possible that the ECU gets confused in this scenario and causes the observed sympoms.

Today I'm going to trace the pipes from the solenoids to the 2 actuators to make sure they did not get accidently interchanged at the bottom end. However, if anyone knows the answer to my solenoid question, it may all make sense upfront.

Next step is probably to check for a sluggish wastegate control solenoid, if this doesn't pan out.

Thanks

Dave

 

Rather than sort out your engineering theory, I would suggest that you just pull the airbox and determine if your vac lines are properly routed. By the way, both solenoids click open and closed in the same fashion. They just do it at different times as decided by the ECU.

 

If you switch the plugs on the solenoids, you will only get about 7 psi. Switching them will not cause overboosting.

 

jd/adam -

Thanks for your inputs

Already checked it out this PM. All connections are good. So now I need to find out why this overboost suddenly started to happen.

My suspicion is that the cause was already there when I bought the car 4 months ago. Since then I've cured a number of problems, including boost leaks. Therefore I think that, once the boost leaks were eliminated, the overboost appeared, because the cause was really already there - just disguised by the boost leaks.

Anyway, the key thing is that it mainly seems to appear immrdiately after the secondary kicks in, then it settles down to a lower level. If I look at what could cause this it seems that either
1) the wastegate control kicks in too late, causing the full boost of both turbos to come in without regulation by the wastegate, OR
2) the turbo control opens too soon. Difficult to see how this could happen.

I read somewhere on this forum that there have been occurences of a "lazy" wastegate control solenoid that cause slow closing off of the airflow and thus slow actuation, (ie opening), of the wastegate. Any input on how to check this out?

Thanks

Dave

 

They work the same way - normally closed. If you switch the plugs _and_ cross the hoses, they will function like normal.

Page F-93 shows the solenoid test for the wg/pc pair.
You might want to remove the pc actuator rod from the door arm and verfiying proper pre-stretch. There should be only 1-2mm of stretch required.

Dave