DASC Tune-up

[xxxJohnBoyxxx]

Did you know you can adjust the bypass valve?

There is a adjustment screw on there and mine was off a few turns not letting the valve close completely so boost was leaking back and looping through the SC. Also I found if you put the vacuum line from the bypass valve to the boost port nipple instead of the TB vaccum port the boost pressure helps to press the flap close tighter.

Just a few FYI's if your a little light on boost. It doesn't cost anything to check that adjustment.

[Danny318]

nice

[performanceisland]

Originally Posted by xxxJohnBoyxxx

Did you know you can adjust the bypass valve?

There is a adjustment screw on there and mine was off a few turns not letting the valve close completely so boost was leaking back and looping through the SC. Also I found if you put the vacuum line from the bypass valve to the boost port nipple instead of the TB vaccum port the boost pressure helps to press the flap close tighter.

Just a few FYI's if your a little light on boost. It doesn't cost anything to check that adjustment.

ok so my boost guage works, the vac is at about 18 at idle, then when i drive and floor it the boost guage shows 6psi, then it jumps/spikes to about 8psi when i hit the rev limiter at which point the transmission light goes on, and i have to turn the car of and restart it to get rid of the light, although the light doesnt limit my trans to 3rd and 4th gears as it tipically does when it goes on.

why only 6 psi? im in illinois where it is no more then 30 degrees F outside. could this be the same problem you had, should i check my bypass valve, how can i tell if thats it?
why trans light?

[xxxJohnBoyxxx]

Originally Posted by performanceisland

ok so my boost guage works, the vac is at about 18 at idle, then when i drive and floor it the boost guage shows 6psi, then it jumps/spikes to about 8psi when i hit the rev limiter at which point the transmission light goes on, and i have to turn the car of and restart it to get rid of the light, although the light doesnt limit my trans to 3rd and 4th gears as it tipically does when it goes on.

why only 6 psi? im in illinois where it is no more then 30 degrees F outside. could this be the same problem you had, should i check my bypass valve, how can i tell if thats it?
why trans light?

Can't help you with the trans light, I run a Manual. Try putting the bypass valve vacuum line on the second boost port nipple on the DASC manifold or put a tee connector on one of your line off of the DASC. This will ensure the valve is slammed close and held there with boost pressure.

Are you running a digital gauge or dial mechanical?

Need some information. What engine M42 or M44? What size SC pulley? What size crank pulley?

The proper way to measure a pulley is to remove the belt and wrap a string around the pulley in the belt grooves. Then measure the string and divide by 3.14 for pulley diameter. If you give me you crank pulley and SC pulley sizes I can tell you what boost you should be seeing.

It is normal to see a mechanical dial gauge jump around when hitting the limiter. When you hit the limiter the car will gain vacuum and the bypass will open on the SC then close quickly. Even though the SC is only putting out 6psi the sudden on off of 6psi will make the machincal gauge jump past 6psi. That's why I asked about digital or machanical.

Long story short you most likely have the 4" pulley and will only see 6psi unless you go with a smaller pulley. pulleyboys(dot)com

[performanceisland]

Originally Posted by xxxJohnBoyxxx

Can't help you with the trans light, I run a Manual. Try putting the bypass valve vacuum line on the second boost port nipple on the DASC manifold or put a tee connector on one of your line off of the DASC. This will ensure the valve is slammed close and held there with boost pressure.

Are you running a digital gauge or dial mechanical?

Need some information. What engine M42 or M44? What size SC pulley? What size crank pulley?

The proper way to measure a pulley is to remove the belt and wrap a string around the pulley in the belt grooves. Then measure the string and divide by 3.14 for pulley diameter. If you give me you crank pulley and SC pulley sizes I can tell you what boost you should be seeing.

It is normal to see a mechanical dial gauge jump around when hitting the limiter. When you hit the limiter the car will gain vacuum and the bypass will open on the SC then close quickly. Even though the SC is only putting out 6psi the sudden on off of 6psi will make the machincal gauge jump past 6psi. That's why I asked about digital or machanical.

Long story short you most likely have the 4" pulley and will only see 6psi unless you go with a smaller pulley. pulleyboys(dot)com

the pulley is definately not 4", i varified with downing atlanta and its a 3.6 they say, when i measure it around the belt area it comes out to be 3.4 to me. my crank pulley is stock. my guage is a mechanical one, i am going to try antoher guage to check to see if its a piece of crap guage. as for the bypass valve i have not tried that yet, it just snowed here so its har to take the car out for a spin, will be trying that and a different guage as soon as the snow is gone on wednsday, thanks.

[xxxJohnBoyxxx]

Originally Posted by performanceisland

the pulley is definately not 4", i varified with downing atlanta and its a 3.6 they say, when i measure it around the belt area it comes out to be 3.4 to me. my crank pulley is stock. my guage is a mechanical one, i am going to try antoher guage to check to see if its a piece of crap guage. as for the bypass valve i have not tried that yet, it just snowed here so its har to take the car out for a spin, will be trying that and a different guage as soon as the snow is gone on wednsday, thanks.

What motor M44 or M42? doubt you have a 3.4" from Downing...Measure with a string around the pulley and divide by 3.14, no belt on pulley and do the crank at the same time. Can't help you much if I don't know what size pulley you have or what motor you have

[lpcapital]

I used your method when I insalled my SC and here's what I got:

- Crank (main pulley) 5.6"
- Supercharger 3.7"
- Alternator 2.1"
- Water pump 4.9"
- Power steering 5.4"
- Crank (A/C) 5.4"
- A/C compressor 4.6"

Believe it or not I haven't put on a boost gauge yet so I dunno what I'm pushing...

[performanceisland]

Originally Posted by xxxJohnBoyxxx

What motor M44 or M42? doubt you have a 3.4" from Downing...Measure with a string around the pulley and divide by 3.14, no belt on pulley and do the crank at the same time. Can't help you much if I don't know what size pulley you have or what motor you have

m44 crank is stock and supercharger pulley is the 3.6inch, just confirmned it. also just installed new autometer guage, more expensive then my original and different brand and am getting 7.25psi on this guage, however i am also getting less vaccum at idle about 15.5. now the last three days (all after the DASC install) the car does not want to start from cold, it turns over, and battery is full, i have to hit the gas pedal and rev it a little to get it to idle before it will stay running.

[Danny318]

sounds like you are leaking somewhere. check everything everything, all the hoses, intake boot, etc.

[performanceisland]

Originally Posted by Danny318

sounds like you are leaking somewhere. check everything everything, all the hoses, intake boot, etc.

well i went out there to my garage to look for leaks and found antoher problem, coolant leak at back of motor, any ideas ?

[marko]

this is it... between the motor & the fire wall.
cheap - like 30 bucks.




you can find details here...

http://www.realoem.com/bmw/partgrp.d...3&mospid=47506

Originally Posted by performanceisland

well i went out there to my garage to look for leaks and found antoher problem, coolant leak at back of motor, any ideas ?

[lpcapital]

If you followed the DASC instruction and installed the bypass hose from the rear of the block to the side, it's probably likely that hose put too much tension on that plastic thing and it broke. They are already fragile as it is.

If you take a look at my install here you'll see I removed that hose and made two plugs.

PS: I would suggest you not to post unrelated questions in a thread or do multiple posts. It just creates a lot of confusion on the forum. It's best to start a new thread as you'll get the attention of more people...

[marko]

sorry man, didnt realize I was answering an off topic Q.

Originally Posted by lpcapital

PS: I would suggest you not to post unrelated questions in a thread or do multiple posts. It just creates a lot of confusion on the forum. It's best to start a new thread as you'll get the attention of more people...

[performanceisland]

ok, im justs antsy, want to get this thing running perfect, anyway thanks for the help, i think its probobly that piece that i broke, i wonder if i have to take the supercharger off to get at it. And i saw your plug method, i wanted to install evrything according to the manual but i see now that the plug method woudl work better, that hose laying there under the supercharger does have a lot of strees put on it.

[Danny318]

Originally Posted by lpcapital

If you followed the DASC instruction and installed the bypass hose from the rear of the block to the side, it's probably likely that hose put too much tension on that plastic thing and it broke. They are already fragile as it is.

If you take a look at my install here you'll see I removed that hose and made two plugs.

PS: I would suggest you not to post unrelated questions in a thread or do multiple posts. It just creates a lot of confusion on the forum. It's best to start a new thread as you'll get the attention of more people...

this forum is so slow I dont get how anything could be confused. THere are like 6 people that post here