• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

I F*cked Up. Help Me Find the Damage...

maxitoman007

maxitoman007

Member
Joined
Feb 15, 2017
Location
Calgary, Alberta, Canada
1987 740 turbo with lots of mods.

Decided to try do a cold boost leak test and ended up getting frustrated with air leaking past the turbo seals (apparently they need oil to seal up). Forgot I still had the end cap in and tried to start the car. The car struggled to start up and I thought nothing of it (stupid stupid me) but it did end up starting and running before i realized what I had done and turned the car back off.

Now Since the car started with an end cap in, that means that a lot of air could get in from somewhere else... And I doubt its from that tiny nipple going to the pcv...

Car still has about 18mmHg vacuum warm at idle but I can't help but wonder where all that air was getting in. I have pressure tested from the turbo outlet to the throttle body and it checks out fine holding 20 psi. Haven't checked post throttle body yet, but I was hoping you guys could give me some insight on where I may have caused damage.
 
maxitoman007 said:
1987 740 turbo with lots of mods.

Decided to try do a cold boost leak test and ended up getting frustrated with air leaking past the turbo seals (apparently they need oil to seal up). Forgot I still had the end cap in and tried to start the car. The car struggled to start up and I thought nothing of it (stupid stupid me) but it did end up starting and running before i realized what I had done and turned the car back off.

Now Since the car started with an end cap in, that means that a lot of air could get in from somewhere else... And I doubt its from that tiny nipple going to the pcv...

Car still has about 18mmHg vacuum warm at idle but I can't help but wonder where all that air was getting in. I have pressure tested from the turbo outlet to the throttle body and it checks out fine holding 20 psi. Haven't checked post throttle body yet, but I was hoping you guys could give me some insight on where I may have caused damage.
Click to expand...

Does it run any different? The only components I can think of that would fail in such conditions are intake hoses. Try pressurizing your intake again. It won't hold pressure, but you should be able to hear leaks or see them with soapy water.
 
alright I'll try with the engine warmed up, to hopefully reduce blow-by. I fixed a bunch of other things before I did the test so there is really no way of comparing before and after. AFRs are good but my mpg is still quite low from what I can estimate (haven't actually calculated it). Also have heard some people say I should be seeing like 20mmHg at idle vs my 18
 
maxitoman007 said:
alright I'll try with the engine warmed up, to hopefully reduce blow-by. I fixed a bunch of other things before I did the test so there is really no way of comparing before and after. AFRs are good but my mpg is still quite low from what I can estimate (haven't actually calculated it). Also have heard some people say I should be seeing like 20mmHg at idle vs my 18
Click to expand...

Vacuum is dependent on the elevation above sea level.
 
Interesting, looked it up and I'm around 3400 ft above sea level. does this account for the lack of vacuum?

As for a mods list:

Ebay "60 trim" turbo
Ebay header (flange flipped)
big front mount intercooler (the bigger of the 2 common ebay sizes)
cold air intake
browntop injectors
AC delete
Hoodpipe exhaust
boost cut off bypassed
running 21 psi of boost
 
maxitoman007 said:
Interesting, looked it up and I'm around 3400 ft above sea level. does this account for the lack of vacuum?

As for a mods list:

Ebay "60 trim" turbo
Ebay header (flange flipped)
big front mount intercooler (the bigger of the 2 common ebay sizes)
cold air intake
browntop injectors
AC delete
Hoodpipe exhaust
boost cut off bypassed
running 21 psi of boost
Click to expand...

You would lose about 12% vacuum at that level. Or max vacuum would be about 88%.
 
maxitoman007 said:
So that means my vacuum is actually pretty good then?
Click to expand...

17-19 compared to 19-21.

At sea level: Atmospheric pressure: 14.70 psi, Maximum vacuum level attainable: 29.92 in/hg
at 3000 ft: Atmospheric pressure: 13.60 psi, Maximum vacuum level attainable: 26.80 in/hg
at 4000 ft: Atmospheric pressure: 12.68 psi, Maximum vacuum level attainable: 25.80 in/hg

This elevation also effects boost level.
 
Last edited:
You must log in or register to reply here.
Back
Top