PWSC troubleshooting advice?

[TNSVTF]

I could really use some input from other PWSC owners. What level of boost are you currently making with the change to summer temps? I just installed my boost gauge while chasing a couple problems and find out I’m currently making (70-80 deg outside) about 6.5 lbs max. I don’t think it’s my gauge either because the car just doesn’t feel strong. It runs PERFECT, idles PERFECT, no change in gas mileage, no CEL's (34k miles origional owner). It just feels like I’m pushing the pedal down about ¾ when I floor it, like it’s in valet mode, no torque steer, no aggressive power.

I don’t know when this condition really started as I drive like an old man and had been gentle on the car since searching for the answer to my never ending CEL’s. I fixed the CEL by replacing my rear 02 and finding 2 vac leaks. One at the brake booster where it connects to the S/C vac tree, it wasn’t seating securely so I replaced the connector, the other vac leak was the vac hose to the boost bypass valve was pulled out I believe from fat fingering with either the brake booster line or install of PCV oil separator about 2 mos ago. One of my big questions here is I have never seen even a film of oil in the filter.

Here’s what I’ve done over the past 2 months in approx order:
1. PCV filter install (still no oil/residue in filter)
2. Replace PCV valve
3. find/fix brake booster vac leak on vac neck
4. Replace rear O2 (w/bosch, it’s all they had)
5. find/fix boost bypass valve vac leak on vac neck
6. replace fuel filter
7. Oil lever arm at boost bypass valve and test that it opens correctly/not blocked
8. remove/re-seat brass nipple at boost bypass valve
9. checked that accelerator pedal fully opens TB when fully pressed

That’s it. My belt is not oily or cracked, I feel or hear no slipping. I’ve gotten no CEL since fixing vac leak/replacing rear O2. I had my car on a dyno a couple months ago and the guy had some trouble due to ‘interferience’. I believe if my knock sensor was going off due to ‘interferience’ that it would affect my level of boost I’m making.

I just don’t know what to do. It’s driving me crazy, I know this is not in my head. Last summer my car still felt great even with all the little issues I’ve had. I’m thinking maybe my belt tensioner is loose but I’m really at a loss about no oil/residue in PCV filter. I don’t have a predator/SCT and no one around here for 7+hours has experience tuning SVT/focus.

I’ve gotten some really good direction from some folks I’ve PM’ed but I feel bad to keep bothering the same folks. Does anyone else have any input? Is this low boost situation normal in the summer, I can’t believe it is, I used to be super impressed by the power, this is not how it felt last summer, now it runs great but I’m not impressed at all…

Thanks to anyone who’s read through this whole thing…
Any advice? Is there anything else I can check? What’s my next step before buying a Predator/SCT and dataloging?

[TNSVTF]

I just noticed I can hit 5+psi at about 3500RPM without being at full throttle but I can get no higher than about 6.5 psi even under wide open throttle.

I hear or feel no slipping but I can't figure out what else it could be, maybe it is primarily the tensioner, I know a lot of people have had trouble with these.

I still dont understand no oil in the PCV filter...

Any other reasons someone could loose boost and otherwise drive normally?

[hEaT]

I'll be upfront and admin I have no experience with the PWSC, but that aside. Have you checked the bypass valve and made sure it's not leaking? Maybe it's only holding up to 6.5psi and then bleeding off?

[MattMatt1182]

I have the pwsc. What boost gauge do you have? My answer would be maybe heatsoak, an or your gauge is leaking. What are you getting for a vac pressure? I'm 15-17 at idle. If the car is moving with no gas 20-21. As for the power you are probably just use to it, when i am heatsoaked I do see 6lbs of boost. It doesent take long sitting a maybe two lights it gets hot. It goes away after I actually start driving an dont catch a light. When I hit the gas I get 8lbs of boost till 5800rpms(give or take) then I get 11lb till redline. As for the pvc filter font have one yet.

[ZX3TUNING]

chances are the problem is the bypass valve is leaking.
it's not uncommon for the valve to become filled with moisture on the top side (basically like a little cup) and over time the linkage rod rusts at the diaphragm and causes a restriction of travel and thus wont hold boost beyond 4-7psi as the rust/damaged diaphragm wont allow the rod to close the valve completely when the vac is removed leaving the valve slightly open to bleed off boost!

i had this happen to mine, pulled off the valve to find the rod completely rusted and travel limted. tried to manually operate the valve and this thick black/rusty goop squirted out the vac-port on the diaphragm and the valve then operated with full travel but with a crunchy, rough feeling.

iirc, you need to contact Magnacharger to get the replacement part, i had a spair charger sitting around to poach parts from!

[HaveBlue83]

MattMatt1182, i get the same boost levels as you, just like how you say. Mostly 7-8PSI. 10 at redline and on colder days I get 10 earlier in the RPM's.......i was thinking heat soak as well. I haven't checked the Vac pressure yet.....I am away from the car now too.

It sucks when you run the car on a cold day at first, because it feels strong. Then a hot day will come and it feels kinda "bottlenecked" and you start getting worried and all that.


I dunno about TN-SVT's problems though....

I DO have a bad FRONT 02 sensor, which is wierd. Look into all the sensors...if one os off, your car may THINK it's bad with the tuning......when my CEL pops on it runs slugghish, because of that front O2.

[focusownerskid]

TN,

Just a note, you're knock sensor will not cause interferance, because it is not turned on w/ the factory MAHLE tune.

Originally Posted by HaveBlue83

MattMatt1182, i get the same boost levels as you, just like how you say. Mostly 7-8PSI. 10 at redline and on colder days I get 10 earlier in the RPM's.......i was thinking heat soak as well. I haven't checked the Vac pressure yet.....I am away from the car now too.

It's a Roots blower, that's how it works.

That doesn't relate to NOT making the correct amount of boost like TNSVT.

The colder it is, the more boost you will get, heat soak isn't a big issue on the PW w/ the cooler. It could be better, but it's not bad.

- Drew

[TNSVTF]

I just spoke with Magnusen (I wish I would have before I was under it yesterday checking the brass fitting in the bypass valve). Anyhow for future reference this is how they told me to check the function of the diapharam on the bypass valve (~$40 part).

Remove the vac fitting. Pull lever arm to it's full travel (I forget if this is actually open or closed setting but I asked and it's the opposite setting from resting position). With the other hand place one finger over the opening on the plastic nipple (remove brass fitting). Release the lever arm. If the lever arm returns back to resting position or 'leaks' back to resting position with finger firmly on vac opening you have a leaking diaphram.

I wont be able to get to this for a day or two but thank you to everyone who read my whole post and I'm still all ears to any advice. I'll update following my function check of boost bypass valve.

[8YURZX3]

dumb question, but have you re-set the computer, unplug & plug battery???

[HaveBlue83]

yeah, i know boost levels change with ambient temp and air density.....it just sometimes makes you second-guess with a roots blower......

I just need my temps DOWN, and i will be happy with it......

and THANKS for the how-to on that diaphram...and little bit of oinfo helps!!! hopefully that will be the issue man.....

[Uncle Tail]

make sure your intercooler pump is functioning, that combined with your other probs may have got the blower hot and made the veins swollen, could have had some damage....

[TNSVTF]

Finally got around to checking by boost bypass valve...it's shot. I have no idea what happened but I think I probably ran it with the vac line disconnected for maybe 2 months and maybe dried up the diaphram but I have no idea. I fully pushed in lever arm to available travel, placed my finger on the nipple as I explained earlier in this thread released the lever arm and it falls immediately about 1/2 way back then holds pressure. Just got off the phone with Magnusen/Magnacharger and they're shipping one out to me for $35.

Now I've just got to figure out how to replace it.....

I'll take some pics and update when I get around to changing it out here in the next couple weeks for future refrence for others that may run into this.