[zachiatrist]

I'm looking for some ideas from the community around why I am not getting all of the boost that I should be. I say should because I have friends running the same hardware and software that are getting higher results so I am suspecting that I have a leak, or a bad check valve or something.

So here's the background. I have a 2001 automatic 9-5 Wagon that was originally an LPT. I have since swapped it for a TD04, and fitted an open air intake. This of course requires a reflash of the ECU which was done with a custom tune from friend. This friend runs the exact same tune, has the exact same hardware (former LPT swapped to TD04 with, and open air intake). I also have another friend with the exact same setup, but his 9-5 is a manual.

The end result is that both of their cars are doing about 14psi or 1000mbar of boost pressure, while I top out at about 10 psi or roughly 700mbar.

My first thought was to replace all the vacuum hoses, which I have done. I also have done the modification where you plug the top hose of the boost control valve as described in this thread: http://www.saabcentral.com/forums/showthread.php?t=106554

So what else should I be looking at? Any other reasons I could be losing a little bit of boost? I'll be rechecking my vacuum lines tonight and I am going to make sure I have a tight seal with the plug I put on that boost control valve hose.

Thanks for any ideas and input you guys can provide.

 

[Chris 9-5]

I have friends running the same hardware and software that are getting higher results so I am suspecting that I have a leak, or a bad check valve or something.

Just out of interest how are you measuring this?

 

[zachiatrist]

Hi Chris,

Good point, I did not specify how I am measuring.

The flash included the open SID modification, with that enabled you can use the PDIF statistic to view boost. On that I can hit in the mid 700s. There is of course the unit-less boost gauge on the dash as well on which I am only getting to the end of the yellow (second section), it never enters the third, red section (or orange depending on your dash). I am pretty sure that even a stock Aero will boost into the third section on the dash gauge.

But the main point of comparison is the open SID. The friend I referred to is hitting 1000mbar on his SID display as well as getting higher torque (mENG). He is peaking at 370NM torque while I am getting at most around 330NM. This friend also has a custom gauge pod with a boost gauge fitted that confirms he is getting around 14-15 PSI.

So in summary, 3 cars, all with the same hardware and software doing the reading from the open SID, and on one of the cars confirming that with an aftermarket boost gauge.

 

[ivanwakeup]

Hi Chris,

Good point, I did not specify how I am measuring.

The flash included the open SID modification, with that enabled you can use the PDIF statistic to view boost. On that I can hit in the mid 700s. There is of course the unit-less boost gauge on the dash as well on which I am only getting to the end of the yellow (second section), it never enters the third, red section (or orange depending on your dash). I am pretty sure that even a stock Aero will boost into the third section on the dash gauge.

But the main point of comparison is the open SID. The friend I referred to is hitting 1000mbar on his SID display as well as getting higher torque (mENG). He is peaking at 370NM torque while I am getting at most around 330NM. This friend also has a custom gauge pod with a boost gauge fitted that confirms he is getting around 14-15 PSI.

So in summary, 3 cars, all with the same hardware and software doing the reading from the open SID, and on one of the cars confirming that with an aftermarket boost gauge.

don't worry about the dash display, or so called "boost" gauge because that doesn't measure manifold pressures at all....but rather airmass. sometimes on my aero it would enter the red zone, sometimes not. it's really dependent.

 

[zachiatrist]

Thanks for the info on where the dash gauge read from, I didn't know that. It's definitely the statistic I trusted the least though (doesn't even have numbers!). As I mentioned, I am mainly concerned with the SID readings from the ECU when comparing between similarly configured cars.

 

[zachiatrist]

Problem Solved

The problem is solved. After doing another thorough check of the vacuum hoses, and testing the check valve on the line coming from the back of the throttle body, I went ahead an reconnected top hose to the BCV. That didn't seem to have any affect (didn't expect it to).

I then decided to do something I had been meaning to try for a while. I used Sea Foam. I used about 1/3 a can on the throttle body (sucked it through the top vacuum hose on that double nipple to the right of the throttle body). Smoked like mad of course (do it at night so the neighbors don't call the fire dept!) but after about 15 minutes I was getting 1000mbar of boost and hitting 360NM of torque!

Just thought I would post my end result in case others search the forum in the future for missing boost, lost boost, low boost (getting all my keywords in).

Don't know why this worked but I am not complaining.

 

[av_dumitrascu]

???

the problem is solved. After doing another thorough check of the vacuum hoses, and testing the check valve on the line coming from the back of the throttle body, i went ahead an reconnected top hose to the bcv. That didn't seem to have any affect (didn't expect it to).

I then decided to do something i had been meaning to try for a while. I used sea foam. I used about 1/3 a can on the throttle body (sucked it through the top vacuum hose on that double nipple to the right of the throttle body). Smoked like mad of course (do it at night so the neighbors don't call the fire dept!) but after about 15 minutes i was getting 1000mbar of boost and hitting 360nm of torque!

Just thought i would post my end result in case others search the forum in the future for missing boost, lost boost, low boost (getting all my keywords in).

Don't know why this worked but i am not complaining.

what!!!???

 

[cash2490]

what!!!???

i'll second that!

 

[ivanwakeup]

The problem is solved. After doing another thorough check of the vacuum hoses, and testing the check valve on the line coming from the back of the throttle body, I went ahead an reconnected top hose to the BCV. That didn't seem to have any affect (didn't expect it to).

I then decided to do something I had been meaning to try for a while. I used Sea Foam. I used about 1/3 a can on the throttle body (sucked it through the top vacuum hose on that double nipple to the right of the throttle body). Smoked like mad of course (do it at night so the neighbors don't call the fire dept!) but after about 15 minutes I was getting 1000mbar of boost and hitting 360NM of torque!

Just thought I would post my end result in case others search the forum in the future for missing boost, lost boost, low boost (getting all my keywords in).

Don't know why this worked but I am not complaining.

now youve got me thinking. why don't you try dismantling your whole system from turbo to TB and see what you've got? i'll bet you anything your gonna find some blockages somewhere.