SP ENGINE MISS AT 4-4,500 RPM

bigdog · Postby **bigdog** » Mon Dec 29, 2008 7:03 pm

this could be a good time for a group buy on Turbosmart Kompact BOVs. I want one, Hammer wants one, Al 'needs' one.... who else needs a new BOV?? I could be wrong, but I suspect Steve Gosbee might be an agent for Turbosmart? They list a 'Steve' at Blaxland as a dealer - once I know how many are required I'll give em a ring and see what we can do pricewise. I have seen them from $259 to $299 plus freight on the web. Let me know asap guys and I'll chase some down.

Marty · Postby **Marty** » Mon Dec 29, 2008 7:28 pm

I'd be interested too Bigdog. Haven't had any problems yet but you never know.

Tezzax5 · Postby **Tezzax5** » Mon Dec 29, 2008 8:09 pm

Adding myself to the list.......

Tezza

Hammer · Postby **Hammer** » Mon Dec 29, 2008 8:31 pm

Too Late Bigdog...I needed one ASAP, so I spent most of this morning calling all the Turbosmart resellers in Sydney and found one that had stock - SAS (Silverwater Automotive Services) @ Silverwater.

Cost was as advertised by Turbosmart - $259 for the Kompact Plumb Back model (Though I think they only have one left of this model. They do also stock the Bosch BOV used by Porsche 993s Turbo (Part #02 80 142 108) that Garry currently uses on his SP).

However, I want to ask assistance from people with experience in this sort of thing. I want to know how to tune the BOV. the instructions does not really say much. It simply says...

"Adjustment to the KOMPACT PB BOV is made by rotating the cap, to increase
spring tension rotate in the direction of hard, marked on the top of the cap."

I'm not really sure what the difference between soft and hard. What should I notice if I go hard or soft?

Plus, as you read below, this is the only instructions on how to tune the Turbosmart Kompact Plumb Back BOV.....

- Rotate the cap in the direction of soft to decrease the spring tension – CAUTION Do not rotate the cap beyond the indicator groove.
- Free rev the engine and back off quickly, the engine should return to normal idle speed – if the engine drops below idle or stalls increase the spring tension by half a turn.
- Repeat this process until the engine free revs and returns to normal idle speed.
- Tests drive the car and ensure that when decelerating or changing gears that the engine does not backfire or stall. If backfiring or stalling is noticed then check all connections made during the installation, otherwise increase the spring tension.

Well, from the moment I connected the BOV at its softest setting (as instructed above) I haven't experienced what they wrote as symptoms, so should I have just kept it at the softest setting? As right now, I did turn it 3 or 4 full turns (I estimate, it's about halfway between fully hard and fully soft) with no noticeable difference. What should I look out for?

Plus to make it more confusing, the diagram on the installation manual had the illustrated Bosch BOV direction of the boost & exhaust going the opposite way to what it really is (See diagram below).

In my model Bosch BOV (part# 02 80 142 103), the boost and exhaust goes the way as how I've marked it in red.

Any help will be appreciated.

bigdog · Postby **bigdog** » Mon Dec 29, 2008 8:52 pm

Never mind the adjustment - did it fix the problem?

I'm guessing you need to go for a run - if you still have the jerky 'pig rooting' problem on partial throttle then tension it up some more and see if it goes away... but I have never fiddled with BOVs so maybe some wiser folk will set us straight?

BTW what is the model number of the correct Kompact BOV? are we on 20mm or 25mm pipes? (I haven't had time to look at mine yet).

Garry · Postby **Garry** » Mon Dec 29, 2008 8:58 pm

Hammer,

The Bosch valve in your SP is fitted back to front. It should have been fitted the same way they have it illustrated in the instructions. Fit the new valve the way it says to in the instructions that came with the valve.

Did SAS give you a price on the Porsche valve Hammer? I called Porsche today to get a new price and they've gone up to $165. :shock:

The one I originally bought was only $60.

Garry · Postby **Garry** » Mon Dec 29, 2008 8:59 pm

You need the 25mm one BD

bigdog · Postby **bigdog** » Mon Dec 29, 2008 9:05 pm

Thanks Garry

Hammer · Postby **Hammer** » Mon Dec 29, 2008 10:24 pm

Garry wrote:The Bosch valve in your SP is fitted back to front. It should have been fitted the same way they have it illustrated in the instructions. Fit the new valve the way it says to in the instructions that came with the valve.

Hi Garry

So on the SP which hose is the boost coming from? The left one or the right (see diagram). The boost should be pushing on the piston of the BOV, right? I'd be keen to know, as I've fitted my Turbosmart BOV with the boost inlet connected to the left hose.

Garry wrote:Did SAS give you a price on the Porsche valve Hammer? I called Porsche today to get a new price and they've gone up to $165. The one I originally bought was only $60.

I actually didn't ask. Tom, at SAS only mentioned they kept them in stock after I've already bought the Turbosmart.

Bigdog wrote:BTW what is the model number of the correct Kompact BOV? are we on 20mm or 25mm pipes? (I haven't had time to look at mine yet).

Hi Bigdog,

As Garry already mentioned, it's 25mm. The 25mm Kompact Plumb Back BOV model number is FG-BOV-KTPB25.

fredbareoz · Postby **fredbareoz** » Mon Dec 29, 2008 10:33 pm

I have put a post in the suspension table.. want to advise on that fellas.

NMX516 · Postby **NMX516** » Mon Dec 29, 2008 10:45 pm

Hammer if you've got the car to idle well, and any backfiring has been reduced, then you're pretty well set. Experiment with it a little and if you find that you can reduce any backfiring by stiffening the BOV more then that's worth doing. Running probs will be closer to being solved by stiffening the BOV adjustment. I would even give it a go at full hard and see how that works, particularly when easing off the throttle from full boost, but not changing gears - that should be nice and smooth. If full hard sees it driving well, and no "chattering" noise when changing gears, then I'd go with that. The SP should still be able to open the BOV on full noise gear changes with it set to full hard...

If I get over to Terry's to try mine on his SP, then will let you know how we go with it.

Edit: Boost is coming from the pipe adjacent to the throttle body. Sounds like you've got it plumbed in correctly Hammer.

Hammer · Postby **Hammer** » Mon Dec 29, 2008 10:54 pm

bigdog wrote:Never mind the adjustment - did it fix the problem? I'm guessing you need to go for a run - if you still have the jerky 'pig rooting' problem on partial throttle then tension it up some more and see if it goes away... but I have never fiddled with BOVs so maybe some wiser folk will set us straight?....

I just came back with more on-road driving testing tonight. there's less cars on the road this time and it's raining.... :mrgreen:

Anyway, after fitting the Turbosmart Kompact Plumb Back BOV, it instantly got rid of the exacerbated jerkiness and fluttering between 3500-5500rpm. So the Bosch OEM BOV must have gone to turbo heaven in the last two days. Now it's back to the ol' SP querkiness of jerkiness when fluttering the throttle on boost.

As you said Bigdog, I might need to do some more testing to see which is the best set up.

But I need to know if I fitted it correctly first. As Garry says, my Bosch OEM BOV was incorrectly fitted the other way around. I did remember a thread about this years ago, I've always thought mine was fitted the right way round.

I just need confirmation on how it should be fitted before I do any more fiddling.

NMX516 wrote:Hammer if you've got the car to idle well, and any backfiring has been reduced, then you're pretty well set. Experiment with it a little and if you find that you can reduce any backfiring by stiffening the BOV more then that's worth doing. Running probs will be closer to being solved by stiffening the BOV adjustment. I would even give it a go at full hard and see how that works, particularly when easing off the throttle from full boost, but not changing gears - that should be nice and smooth. If full hard sees it driving well, and no "chattering" noise when changing gears, then I'd go with that. The SP should still be able to open the BOV on full noise gear changes with it set to full hard...

If I get over to Terry's to try mine on his SP, then will let you know how we go with it.

Edit: Boost is coming from the pipe adjacent to the throttle body. Sounds like you've got it plumbed in correctly Hammer.

Thanks again for the advise NMX516.

Daz · Postby **Daz** » Tue Dec 30, 2008 5:35 am

I have parked next to another SP, totally unmodified and found that our BOV's were installed in the opposite way from the factory ! I thought it was really strange at the time, but I don't suffer from any of the real nasty driveability others have described so I left it the way it was. I might be in on the group buy though, just in case my original BOV gives up !

BTW... I can get em here in the US for $179, but that's not a saving these days with the AUD down....

Garry · Postby **Garry** » Tue Dec 30, 2008 7:13 pm

You are correct Hammer, boost is on the left hose in your pic.

The Bosch valve in the pic is installed incorrectly for the SP application. The boost side should be installed to the tube closest to the vacumm nipple on the valve. For some reason VW/Audi and the SP amongst other have the BOV installed in the reverse direction to the after market BOV's. Maybe because it's a diaphram valve and not a piston type valve like the aftermarket ones.

blackster · Postby **blackster** » Tue Dec 30, 2008 8:56 pm

Garry wrote:You are correct Hammer, boost is on the left hose in your pic.

The Bosch valve in the pic is installed incorrectly for the SP application. The boost side should be installed to the tube closest to the vacumm nipple on the valve. For some reason VW/Audi and the SP amongst other have the BOV installed in the reverse direction to the after market BOV's. Maybe because it's a diaphram valve and not a piston type valve like the aftermarket ones.

The OEM SP BOSCH configuration is actually correct. Putting it the opposite way will not allow diaphram operate during positve/negative pressure.