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Discussion Starter · #1 ·
I have a engine problem which I would like to run past you guys..


My 91' 2.3 CD Carlsson 127k miles FSH, recent service, ran fine up till about 2 weeks ago.

It now seems to have lost some boost and is making a "honk" noise in 2nd and 3rd gear under medium-hard acceleration.(It sounds like there is a goose under the bonnet <G>)

Although absent once up to speed, this noise is always about 1/2 second long and constant volume, just noticable in cabin.

Lag has increased and there is a feathering feel before the boost comes in.

At all speeds the off boost reading on APC guage is at half way up white.

Max boost is half way up broken red. (never been right into the red but used to go up to start of red)

In addition it has started to jolt a lot, as though the engine mounts were worn (but they are new)

Have researched loads of forum posts and elswhere on the net and have suspicions of faulty Turbo bypass valve. Can anyone confirm? Where is it located as Haynes doesn't show this. (different name?)

Confused by the names used for this component as I have seen:

Blow off valve , dump vave , hooter valve , APC valve, and Turbo bypass valve. Are these all the same thing?

I want to keep the car as "unmodded" as possible but would consider fitting an uprated valve for cleaner response.

I understand this is a recirc.. not atmospheric valve and that atmospherics are the ones that "woosh" which I dont like anyway and are unsuitable for a '91 B234 FPT engine.

I need to fix this by next Friday as I'm off to Europe for a driving holiday.

What do you guys advise bearing in mind mechanical ineptitude and timescales for ordering stuff?

BTW ACC now ok after pressure test and recharge. The pressure had leaked down to 70 psi through split o ring in low pressure switch. Ahhh cold air

TIA

Dave
 

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Blow off valve, dump valve, hooter valve, APC valve, and Turbo bypass valve. Are these all the same thing?[/b]
They are all the same except for the APC valve which is a completely different beastie. Annoying how Haynes ignores the dump valve by any name

The dump valve can produce the honking noise you mention if it's blown. Easiest check is to take it out (2 jubilee clips to undo & a vacuum hose to pull off). Blow through the vacuum hose nipple: if air comes out the opposite +/- 1" opening then it's gone. The diaphragm wears over time.

Euro Car Parts will sell you the Boche OEM part for about £20 + VAT &c. Trent will sell you a very nice Forge one for just under £120 all in. Either way replacing is a 10 min job with a flat bladed screwdriver

Meant to say, both will normally deliver next day.
 

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 Would Forge know in which years Bosch reversed the internals on the BPV?  [/b]
I've no idea.... but you can ask them!
If they sell it to dealers, they must know... in thoery?
But when I spoke to them, I said I've got a 9-5, you don't list it, they said no problem, you need the 007P, do you want chrome or black?

I'm all for supporting specialists too... but when its half price direct....
 

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Discussion Starter · #8 ·
Yes, thanks for the info guys,

I looked on the Forge page and found the audi V6 valve 007P ok, whats the direct from Forge price supposed to be then?

Nice piece of engineering by the looks of things.
But will it fit straight on, will I need bigger bore hoses etc?

Looking into this further i'm starting to wonder about a few tweaks......


Double piston atmospheric dump valves as these are supposed to result in a slightly richer mixture. Without the idle problems.... what are the idle probs associated with atmospheric valves?

If atmospheric valves reult in overfueling would this reduce detonation risks of a bleed valve?

Does a 91 2.3 CD Carlsson have a MAP sensor?

Does MAP sensor = no idle probs from an atmospheric valve?

So many things to consider

cheers

DD
 

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Have a look at this thread . I can thoroughly recommend the Forge. Well made and fast acting. If you go that route check with them (or whoever )on the version for your car. On the other thread it's a DV006.

AFAIK your '91 Carlsson has AMM not MAP. Atmospheric dump valves should work with MAP (like you say) but not AMM. The AMM can't recalculate for the air spent to atmosphere so gets the fuel mix wrong. I don't think there is an advantage to the atmospheric type anyway unless you race the thing, have very high boost levels and mash your way through the gears.
 

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Then there's always Bailey as well...

http://www.baileymotorsport.co.uk/baileymo...port/frame.html

You want the DV30

Mark

PS AFAIK Most dump valves (well definately Bailey and Forge) come with "standard" 25mm fittings, so you don't need different hoses. You might, however, need to cut down the hose becasue they're bigger and in the case of Forge, you might also need a longer length of vacuum tube from the manifold because it doesn't have an elbow on the actuator input.
 

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Discussion Starter · #11 ·
Update on this..........

Ordered uprated Bosch BPV for the time being, at least to see if anything changes and confirm BPV problem.

Just fitted it now and had a test drive....

Result ....... Much improved driveability and no more "Honk".

Trashed the old BPV to find out if it was leaking and could find no splits or tears whatsoever, the only thing that I did notice was the spring was pretty soft.

Happy as Larry for now, the off throttle feel is a lot less juddery as well for some reason, even when off boost, it also vents more loudly than before, to the point where you can hear it with the window down unlike the old one.

New tyres today and £40 used decor panel from Neo Bros tommorrow, the old girl is looking AND feeling quite tidy at the moment.

We will see how she likes the autobahn next week


Thanks for the guidance.

DD
 

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Dave where did you buy your dump valve from,i sent forge motorsport an email and they tell me that the FM DV 004 is the one to fit with a blanking plug or something can anyone shed some light on this for me.

stuart

91 black carlsson honky tonk
 

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In piston operated models (the best) Forge have either the recirculating DV006:



or the atmospheric DV004:



Bailey do the recirculating DV30:



or the atmospheric DV26



If you use the atmospheric type in any installation, then you need to plug up the hole in the inlet pipe that takes the feed from the recirculating output (the one on the left of the DV006 or right of the DV30 in their respective pics), hence the need for a 25mm plug.
 

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Discussion Starter · #14 ·
I bought the Bosch ...008 retrofit valve, as used on Porkers and Audi TT's, same housing as the OEM, but with slightly strengthened internals. £19.99 + vat from my auto spares, but he had to order it in overnight.

Saw this too....

http://216.78.172.244/turbo_folder/toughhooter.htm

Seems Saab have noted this problem in the past.

Am now seriously debating whether to mod or to maintain what seems to be standard 2.3T Carly spec.
 
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