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Boost control solenoid testing?


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#1 Josh18

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Posted 18 January 2019 - 02:46 PM

Hey, I am just starting to go over all my vac lines and solenoids and realize that on my car when I have it in diagnostic solenoid cycling mode the BCS does not cycle, it just stays closed. Is this normal or is it maybe stuck? My boost has always been on the low side on the primary turbo I think.

Also, my silicone vac hose finally arrived and it is not 3.5mm internal as stated, more like 2.5mm. Should I use it or not?

Cheers

Josh



#2 Josh18

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Posted 18 January 2019 - 03:50 PM

I took it off and tested it with a 12v power supply and it works. I tested the wires at the connector coming from the car and they have 12v, but will not actuate the solenoid. Is it a current issue? I turned my power supply right down and it will still actuate the solenoid. This seems weird.



#3 Josh18

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Posted 18 January 2019 - 09:01 PM

After some research I have found off a WRX forum that at least on that car the solenoid doesn't actuate in test mode and also having 12v there doesn't mean it should actuate, something about the current. So I've just run some UEC through it and reinstalled it. I read a bout someone fitting an LED to it to flash when its active to see what its doing, maybe that's and option for down the track.

As for the vac lines, I think I will leave the some of them as they are, especially the boost control ones as they seem to be sensitive to size and length, they have numbers conveniently printed on them and really, they don't look bad at all. Some of the others on the manifold though have been so hard they break in my hand, so I think I'll do replace them on a case by case basis. I think tomorrow I'll bite the bullet and clean out the BBoD. I have had it off and had a look inside and now have an idea of what to do. The lines in there looked in good nick too so I might just clean those and the solenoids out too. Really if I I had issues in the car's running I would be more keen to replace things but its running really well. The only problem I have relating possibly to BBoD and vac lines is that it seems to swap to twin mode rather early and then if you back out of it before the secondary spools it seems to stay in twin mode and just bog down for a while unless you back off and start again. I think this may be a TT'ism though, but have read about (don't know which) the line witch gets blocked up with blow by gunk and causes similar issues. 

Im keen to try the line one mod with the 0.8mm pill which I think seems to hold merit as from what I can see it just slows the rate that the ECV opens. Makes sense to me anyway.

Cheers

Josh



#4 duncanm

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Posted 18 January 2019 - 09:27 PM

Josh,

all the solenoids are negatively switched.

What that means is that with the keys on, they all have 12V on one terminal all the time.

When the other terminal is grounded through the ECU, then its activated. When not activated, the ECU terminal is floating.

You need to check if there's 12V across the two solenoid terminals. Not a terminal to the chassis (GND).



#5 Josh18

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Posted 18 January 2019 - 10:34 PM

Hey Duncan, thanks for that. I was getting 12v across the two wires to the solenoid, I didn't think to check it from positive to chassis ground. This was the same as the guys on the other forum seemed to be getting too though. I was really confused as the multimeter showed 12v across the two wires to the solenoid, 12v on my bench power supply would actuate it but plugging it to the 12v in the car and no action. Made me think about current.

Do you know if it should actuate in test mode?



#6 Josh18

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Posted 19 January 2019 - 08:10 PM

Hey I got it sorted. For test mode I didn't realize the function seems to be different with the engine on to just ignition. With engine running the big actuators cycle but not the BCS in the LH guard, which is what I was doing yesterday, but with just ignition the BCS pulses, either that or from yesterday to today it has freed up.

I cleaned out the BBoD today with UEC, looking at all the lines they all looked good and were nice and soft still so I didn't see the need to replace them. one thing I noticed is that the boost control solenoid inside the box sputtered to life halfway through and started cycling like the one in the guard! So it must have been stuck. Everything else seemed ok, I took off and left off the little filters on the end of the solenoids as I heard the cleaner can block them. I'll put them back when it's had some time to really dry out.

When I first drove it it went really well but started really bucking when the second turbo boosted- I thought I had stuffed it! I had a look at everything and found the pipe from the maf to the inlet slightly crooked so maybe it was leaking? I also reset the ECU at the same time and upped the fuel pressure a bit. I drove it again and it was much better. I dropped the pressure back to where it was and still went fine if not better so I reckon it was the possible air leak or maybe just the ecu freaking out because the second BCS (for the secondary turbo I think) was working. Another possibility is that now it is boosting higher it is blowing out the spark. It did this when I got it in the same situation and new correct plugs and cleaning the coils cured it but now it boosts a couple of PSI higher. Anyway it only slightly broke up now right up the top end- not where I will be driving it so I'm happy.

Cheers



#7 duncanm

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Posted 19 January 2019 - 08:39 PM

yeh - not sure diagnostic mode cycles all solenoids.

 

There may be a low-current path for the other (grounding) terminal on each solenoid in order for the ECU to diagnose open-circuit solenoids.. so my advice may have been a little misplaced.

 

As your mates have said - its all about the current.



#8 Josh18

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Posted 20 January 2019 - 12:45 PM

Thanks Duncan. I thought the big stuck solenoid was a boost control solenoid for the secondary turbo's wastegate but looking at the drawing in the TT guide it is the duty solenoid for the ECV. I don't 100% get how it all works but reading the notes above about that solenoid and the ECV it looks like it can be either open, closed or held in between by that solenoid. So I reckon that stuck solenoid was possibly the reason my car was switching to twin mode really early, it seems to wait until a much more reasonable time now.

Cheers



#9 duncanm

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Posted 20 January 2019 - 05:26 PM

Josh,

 

that makes sense - the two ECV solenoids control the positive and negative sides of the ECV diaphragm, so if one is non functioning, it'll open too early or too late.



#10 Josh18

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Posted 20 January 2019 - 08:40 PM

Damn it goes well now, so smooth across the whole rev range. I think those that complain of VOD have not driven one that is working right.

Cheers



#11 KONG

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Posted 22 January 2019 - 09:44 AM

So true.
Congrats Josh

#12 Josh18

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Posted 22 January 2019 - 10:16 PM

Thanks mate. I've wanted one of these cars for a long time now and now mine is getting to the stage of being a little like it would have felt when new. I cant get over how smooth and refined it is and how well it does everything. They must have been amazing cars in their day.



#13 podmak

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Posted 23 January 2019 - 10:16 AM

I also reset the ECU at the same time and upped the fuel pressure a bit.

How'd you upped the fuel pressure? 


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#14 Josh18

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Posted 23 January 2019 - 08:50 PM

Hey mate it came with a really cheap and nasty ebay pressure regulator fitted and I haven't replaced it for a stock unit yet so I thought I'd give it a try. The install is rubbish- everything rubs on everything else and the bracket looks like they made it from some roofing tin but I have found a new stock reg is pretty pricey so I have to save up for a bit, seeing this one still works ok. I don't trust it though.

That's what I was after the stock fuel rail pic (cheers for that) because I couldn't see how they had fitted it, now I realize they added an adapter plate. When I got the car it used a tonne of fuel and the guy said his previous fuel pump had died- no wonder, the idle fuel pressure was set at around 70psi!






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