Compressor surge bad BOV?

[horizontalkev]

I have compressor surge and I think its because of my BOV (tail Q) not opening after letting off the throttle. Also my car dies if I let off the gas I have to keep pressing gas to keep it running. Are these problems related and can I clean the BOV? The vacuum line from the BOV runs to the TB and seems to be holding up

 

[Bud92gsx]

I'm having the same issue with the car wanting to die when you let off the gas..I did go out and buy like 10 feet of vac lines..Which I will be replacing in the spring.

As far as the compressor surge.Your bov may be too lose or tight, causing this.

I had comp surge when I had no bov hooked up when I moved my car 20 feet..I pit the bov back on and it took care of that..But the dying problem is most likely vaccume related.

If not,I would really like to know why letting off causes the car to want to die..

 

[horizontalkev]

What exactly is to be tightened? The clamp holding it onto the intake?

A vacuum leak can cause compressor surge aswell right? I've heard of some sensor or valve in the TB could cause compressor surge and idle problems as well.

 

[WES_393]

Are you still running the stock MAF? If so, the Tial Q is the reason your car dies when you let off. You need a BOV that can be recirculated.

As for the compressor surge, you may just need to adjust the spring tension (or swap springs, I'm not familiar with Tial BOV's).

 

[miguelmcv]

I have compressor surge and I think its because of my BOV (tail Q) not opening after letting off the throttle. Also my car dies if I let off the gas I have to keep pressing gas to keep it running. Are these problems related and can I clean the BOV? The vacuum line from the BOV runs to the TB and seems to be holding up

I don't know where exactly on the throttle body is your line (BOV) hooked up, But the BOV needs to be hooked up to the Intake Manifold, If you have it hooked up to a tiny nipple at the throttle body, then that's your problem with the surge.

 

[horizontalkev]

Are you still running the stock MAF? If so, the Tial Q is the reason your car dies when you let off. You need a BOV that can be recirculated.

As for the compressor surge, you may just need to adjust the spring tension (or swap springs, I'm not familiar with Tial BOV's).

It isn't the stock maf its after the BOV and its the red "hp in a box" maf translator. I've owned turbo cars but they were all stock and never had any problems, I bought this car already modded and still learning all of the mods done to it

I don't know where exactly on the throttle body is your line (BOV) hooked up, But the BOV needs to be hooked up to the Intake Manifold, If you have it hooked up to a tiny nipple at the throttle body, then that's your problem with the surge.

And yes its connected to the throttle body to a little nipple, where on the intake manifold?

 

[Wildside22]

Are you still running the stock MAF? If so, the Tial Q is the reason your car dies when you let off. You need a BOV that can be recirculated.

This would only be true if the bov is NOT closing efficiently.

I am not trying to start an arguement, but just saying that his vented BOV is the issue is kind of a blanket statement and just saying that that is the issue in a whole is kind of misleading.

The real issue needs to be addressed.

A tight running car with no vac leaks and a properly funtioning/hooked up BOV vented with a stock maf or upgraded one will work fine with minimal side effects.

There are thousands and thousands of cars running vented BOV with no issues ONCE the car is set up correctly on stock maf systems.

The issue with getting it "set up correctly" is that there are those who cannot get "their" car to run properly while venting a bov and then they jump on the band wagon of venting is bad.

I ran my turbo XS bov vented for over 6 years without the isses he described ONCE I got the vac system set up correctly and the spring pressure set up right.

I had to figure out how to do it myself, because when I looked for help on the issue I ran into the wall "venting a bov on a stack maf is bad".

I figured out that it was easier for most people to just tell me that venting was bad then it was to figure out how to solve the problem, but I loved the sound and was determined to keep it.

Both of his issues can be atributed to the BOV being vented, but both isses are easy to fix.

As a previous person stated "The vac line need to be hooked up after the throttle body".

"If" its on a throttle body nipple the BOV would not open or close correctly and that has to be addressed "BEFORE" the spring pressure can be accuratly set.

Once the vac source is corrected or if its correct you need to adjust the spring pressure.

You can change springs or pull the spring and add a few washers underneath it. (yes, your car will run rich on decel and during a shift on a 5-speed but thats a whole different arguement thats been beaten to death).

 

[WES_393]

This would only be true if the bov is NOT closing efficiently.

So your saying that venting to atmosphere won't have any serious negative effects?

yes, your car will run rich on decel and during a shift on a 5-speed but thats a whole different arguement thats been beaten to death

So running rich, which can cause sputtering and stalling issues, isn't a serious negative effect? Especially when the OP is suffering from sputtering and stalling issue?

Sure, now that the OP has mentioned he is using a blow-through MAF, venting the valve isn't a big deal and there is obviously other factors at play. But venting with the stock MAF causing issues is far from a theory. If anything here is misleading, it's the notion that venting doesn't throw off the factory tune. I mean, unless you can post a datalog showing that the AFR's while venting aren't considerably richer than when recirculating...

 

[horizontalkev]

How do I properly setup the vac system for the BOV then?

This is where my vac is connected to from the BOV.. Post number 22, first attachment. Is that the correct nipple?
LINK: http://www.dsmtuners.com/forums/newbie-forum/454838-bought-gsx-few-questions.html#post153176994

Update: hheard the bov then it turned into compressor surge again and since then its still only compressor surge

 

[miguelmcv]

I have being running my BOV vented, and for what I remember, It has stop only twice, However, Vented BOV with stock MAF is not recommendable, You really need to play a lot to make it work properly.

How do I properly setup the vac system for the BOV then?

This is where my vac is connected to from the BOV.. Post number 22, first attachment. Is that the correct nipple?
LINK: http://www.dsmtuners.com/forums/newbie-forum/454838-bought-gsx-few-questions.html#post153176994

Update: hheard the bov then it turned into compressor surge again and since then its still only compressor surge

You are using your P nipple, that's for Smog only, BOV is not getting enough air to perform well, There is another Bigger nipple right next to it, that's your BOV Nipple.

Your car is a little different from most 2gb cars, Here is a diagram for your specific car, Fallow the diagram and reroute what ever you have wrong.

(post #17).
http://www.dsmtuners.com/forums/newbie-forum/395822-99-gst-vacuum-help.html

 

[horizontalkev]

I have being running my BOV vented, and for what I remember, It has stop only twice, However, Vented BOV with stock MAF is not recommendable, You really need to play a lot to make it work properly.




You are using your P nipple, that's for Smog only, BOV is not getting enough air to perform well, There is another Bigger nipple right next to it, that's your BOV Nipple.

Your car is a little different from most 2gb cars, Here is a diagram for your specific car, Fallow the diagram and reroute what ever you have wrong.

(post #17).
http://www.dsmtuners.com/forums/newbie-forum/395822-99-gst-vacuum-help.html

What is the "b" in 2gb? And what's different about it? I know it has a 6 bolt motor if that's the difference. Anyways thanks for your answer ill look at it tonight and let you know what I see

 

[miguelmcv]

2ga.---- 1995/1996.5
2gb,---- 1996.5/1999

There is a difference on the look (body) of both (2ga, 2gb).
There are differences on the wiring from 2ga (1995/1996.5) to 2gb (1996.5/1999), But there are several differences as well on the wiring and some other stuffs between 2gb (1996.5/1999), wiring changes,,,,,,, 1995/1996.5 has almost the same wiring, 1996.5/1998 has the same wiring and 1999 has a different wiring, However, most of the parts and wiring on 1995/1999 can be swapped with some minor modifications.

6 bolt engines came only on 1992.5 and olders, 7 bolt engines came on 1992.5 to 1999.

But from 1989 to 1999, most of the parts are interchangable as well, and again, with some light modifications.

 

[horizontalkev]

Im giving you rep points thanks a lot!

Could my BOV line being connected wrong be whats killing the motor after letting off the gas?

 

[miguelmcv]

NO it's not.

Your problem is the BOV it self.
You need to recirculate it, that's the only thing it can prevent the car from stalling,
If you want to keep it vented to the atmosphere, I will suggest to recirculate it first, once you have it recirculated, bring your car to specs, I mean to have the car running perfectly (no boost leaks, TPS calibrated, ICS working perfectly, good O2 sensor, etc, etc, etc), and making sure you have your car in very good working conditions, once you get all that sore it out, then you can vent the BOV and you might be able to get it to work.

 

[gusu]

We should really consider using "more correct" terms.

I researched A LOT on compressor surge to see about it's effects. True compressor surge happens on throttle only, the term surge comes from going past it's surge line. At that point the air becomes unstable and choppy.

Even though the term does not directly convert from where it came from (Jet turbines) a better term would be compressor stall. I only say this because it makes slightly more sense. Since the turbo is spinning, the throttle plate is closed and you aren't venting/recirculating properly but still trying to compress air. Since it can't it kind of stalls the flow resulting in the flutter sound. The fluttering is thought by many to be bad for the turbo, however extensive research (Millions of dollars) done by many high end racing teams have show nothing to support bearing damage. However, I don't know that I'd risk not running one. We have a solution to avoid the possibility of damage, who not use it?



But back to your problem, it sounds like your blow off valve is not set properly which is causing it to not vent the air. However because you are venting to atmosphere your car isn't actually seeing the metered air as it is being vented away AFTER the sensor (MAF).

 

[tkelly27]

Miguel, he already said he has a MAFT and the MAF is after the BOV, so it doesn't matter if it is vented or recirculated, or even if the IC piping is hooked up. So that's not what is making the car stall.

Did you check to see if the valve is now seeing vacuum? It should be easy push the valve open when there is vacuum on the top port and difficult to open when there is no vacuum. If it is a Tial Q it is probably too new to be having any kind of binding issues. If it is not easy to push open when you have engine vacuum going to the port you may need to take it apart, clean it, and lubricate it.

You may also need a spring that is less stiff. The previous owner may have thought they were going to be racing the car and put a spring that is too stiff in it. Honestly you shouldn't need a spring that is very stiff at all for most any reasonable boost levels.

Do you have a narrow or wide band? Can you take datalogs? That will help a lot with the stalling on decel.

 

[Marc91GSX]

For all of the people saying that he needs to recirc, please stop. His problem is not vented MAF because he is using a translator and has the MAF behind the BOV. The stalling is probably not a vacuum leak either as they tend to cause a higher than normal idle meaning the car won't stall off throttle but instead will tend rev up. More than likely the compressor stalling(surge as he called it) is due to having his BOV vacuum hooked to the wrong nipple and/or not having the spring tension set properly. The most effective place I've found to hook up the BOV is to add a T to the vacuum line running from the intake manifold to the FPR.

As for the stalling issue, my bet is that the translator is not tuned properly/faulty, or that your TPS has gone bad.

 

[boost97gst]

Venting to atmosphere will NOT have serious effects. Its way overhyped. Your car runs rich between shifts for a split second..... Damaging? I think not. The only time i noticed vent to atmosphere effecting my car was with a tiny ass t25 that boosted instantly. I had to recirculate or else it would try to die letting off throttle. I have a 8lb flywheel and vent w no problems. I can hit 30+psi in a pull, let off throttle and throw it in neutral and it will idle just fine.

Sounds like, as gusu said, your BOV jsut isnt adjusted properly. Too stiff would be my guess. Not familiar with tial bovs. Surge is under boost, bov flutter is not surge.

 

[horizontalkev]

We should really consider using "more correct" terms.

I researched A LOT on compressor surge to see about it's effects. True compressor surge happens on throttle only, the term surge comes from going past it's surge line. At that point the air becomes unstable and choppy.

Even though the term does not directly convert from where it came from (Jet turbines) a better term would be compressor stall. I only say this because it makes slightly more sense. Since the turbo is spinning, the throttle plate is closed and you aren't venting/recirculating properly but still trying to compress air. Since it can't it kind of stalls the flow resulting in the flutter sound. The fluttering is thought by many to be bad for the turbo, however extensive research (Millions of dollars) done by many high end racing teams have show nothing to support bearing damage. However, I don't know that I'd risk not running one. We have a solution to avoid the possibility of damage, who not use it?



But back to your problem, it sounds like your blow off valve is not set properly which is causing it to not vent the air. However because you are venting to atmosphere your car isn't actually seeing the metered air as it is being vented away AFTER the sensor (MAF).

I've heard from many that its bad, and from some that it can't hurt the turbo. But just in case I don't want to take the chance . And yeah MAF (maf translator) is after bov.

Miguel, he already said he has a MAFT and the MAF is after the BOV, so it doesn't matter if it is vented or recirculated, or even if the IC piping is hooked up. So that's not what is making the car stall.

Did you check to see if the valve is now seeing vacuum? It should be easy push the valve open when there is vacuum on the top port and difficult to open when there is no vacuum. If it is a Tial Q it is probably too new to be having any kind of binding issues. If it is not easy to push open when you have engine vacuum going to the port you may need to take it apart, clean it, and lubricate it.

You may also need a spring that is less stiff. The previous owner may have thought they were going to be racing the car and put a spring that is too stiff in it. Honestly you shouldn't need a spring that is very stiff at all for most any reasonable boost levels.

Do you have a narrow or wide band? Can you take datalogs? That will help a lot with the stalling on decel.

Im going to Try and check as soon as I find my keys, third time losing them already

And I believe I have wideband..? And Im sure I can do logging, found a PDA M505 under the seat that hooks up to a cord that I think runs to the port underneath the dash

 

[tkelly27]

I've heard from many that its bad, and from some that it can't hurt the turbo. But just in case I don't want to take the chance . And yeah MAF (maf translator) is after bov.

Im going to Try and check as soon as I find my keys, third time losing them already

And I believe I have wideband..? And Im sure I can do logging, found a PDA M505 under the seat that hooks up to a cord that I think runs to the port underneath the dash

Cool man, let us know what you find. You'll learn a whole lot from a data log. It is probably running MMCD. If it is, you can find a ton of data on MMCD by searching google. I put in the term "mmcd mitsubishi" when I want to learn about it.

One of the smartest things I've ever done is to put a spare key in my wallet. If I loose my keys I'm fine, if I loose my wallet I'm a little worse off but I still have keys. I've never lost both at the same time and if I ever do that means I've done something really stupid and deserve to walk

 

[miguelmcv]

I've heard from many that its bad, and from some that it can't hurt the turbo. But just in case I don't want to take the chance . And yeah MAF (maf translator) is after bov.

Sorry, I didn't pay attention in that (MAF)

Discard my post back there.

You will not hurt anything with that, it will with the MAFT but not with the MAF,
The only problem you might have is if you get a boost leak with out knowing and running it like that, your turbo will be overworking causing to die if you don't pay attention, That's the only down side it has, but rather then that, It is safe.

Miguel, he already said he has a MAFT and the MAF is after the BOV, so it doesn't matter if it is vented or recirculated, or even if the IC piping is hooked up. So that's not what is making the car stall.

Thank you to address that out.

To the OP, Just change your BOV hose line and see what it does, if you are lucky, it will solve your problem with the stalling, otherwise you will need a good tuning.

 

[horizontalkev]

Cool man, let us know what you find. You'll learn a whole lot from a data log. It is probably running MMCD. If it is, you can find a ton of data on MMCD by searching google. I put in the term "mmcd mitsubishi" when I want to learn about it.

One of the smartest things I've ever done is to put a spare key in my wallet. If I loose my keys I'm fine, if I loose my wallet I'm a little worse off but I still have keys. I've never lost both at the same time and if I ever do that means I've done something really stupid and deserve to walk

Okay awesome the pda I found under the seat is compatible. I've ordered a charger for it and should be here early next week. I can't alter the tune this way though right? Just monitor it?

And I have thought about making spares....but I keep forgetting

Sorry, I didn't pay attention in that (MAF)

Discard my post back there.

You will not hurt anything with that, it will with the MAFT but not with the MAF,
The only problem you might have is if you get a boost leak with out knowing and running it like that, your turbo will be overworking causing to die if you don't pay attention, That's the only down side it has, but rather then that, It shouldn't

No you're fine, and I would be able to determine a boost leak if boost gauge stopped reading as high?

I looked under the hood and there are 2 nipples unused sticking from the side of intake. One is small and the one to the right of it is bigger. Is it the one on the right that's for the bov? And when I take the hose off the nipple its incorrectly on now, will I need to cap it off or leave it?

 

[Marc91GSX]

Okay awesome the pda I found under the seat is compatible. I've ordered a charger for it and should be here early next week. I can't alter the tune this way though right? Just monitor it?1

And I have thought about making spares....but I keep forgetting


No you're fine, and I would be able to determine a boost leak if boost gauge stopped reading as high?2

I looked under the hood and there are 2 nipples unused sticking from the side of intake. One is small and the one to the right of it is bigger. Is it the one on the right that's for the bov? And when I take the hose off the nipple its incorrectly on now, will I need to cap it off or leave it?3

1) Correct, that will only give you the ability to log whats going with the engine. To tune it you will need some type of SAFC, Programmable Eprom, Standalone, etc... AEM has a new device out (well it's been out for a few years but it's still new when compared to most of the other options) called the FIC, that is a fuel and ignition controller. It was designed to give you an easy way to turbocharge a N/A car or truck. I've looked into and I am positive you can make them work on our cars. It's cheaper than ECMlink and gives you more tuning options than an SAFC will.

2) Not necessarily, only if the leak is extremely bad and exceeds your turbo's ability to push that amount air will you notice a difference on your boost gauge. I am trying to think of a technical way to say this but I'll just give you a analogy instead. Picture trying to fill a leaky bucket with water from a hose. You have a small hole in the bucket and it takes you 5 minutes to fill the bucket but you still fill the bucket. The next day you notice another hole in the bucket and it takes you 10 minutes to fill the bucket, but you are still able to fill the bucket. On the third day there is a third hole in the bucket and this time, despite trying for an hour, you are unable to fill the bucket because the leak is so bad the hose cannot compensate for it. Your turbo is the same way, it can push enough air for you to see the same boost level on your gauge unless the leak is so bad that it cannot compensate for it.

3) Any nipple after the TB will work for your BOV to see vacuum when the throttle blade is closed. Yes, unless you hook another source into the nipples you will need to block them off or you will have a vacuum and/or boost leak from that point.

 

[horizontalkev]

1) Correct, that will only give you the ability to log whats going with the engine. To tune it you will need some type of SAFC, Programmable Eprom, Standalone, etc... AEM has a new device out (well it's been out for a few years but it's still new when compared to most of the other options) called the FIC, that is a fuel and ignition controller. It was designed to give you an easy way to turbocharge a N/A car or truck. I've looked into and I am positive you can make them work on our cars. It's cheaper than ECMlink and gives you more tuning options than an SAFC will.

2) Not necessarily, only if the leak is extremely bad and exceeds your turbo's ability to push that amount air will you notice a difference on your boost gauge. I am trying to think of a technical way to say this but I'll just give you a analogy instead. Picture trying to fill a leaky bucket with water from a hose. You have a small hole in the bucket and it takes you 5 minutes to fill the bucket but you still fill the bucket. The next day you notice another hole in the bucket and it takes you 10 minutes to fill the bucket, but you are still able to fill the bucket. On the third day there is a third hole in the bucket and this time, despite trying for an hour, you are unable to fill the bucket because the leak is so bad the hose cannot compensate for it. Your turbo is the same way, it can push enough air for you to see the same boost level on your gauge unless the leak is so bad that it cannot compensate for it.

3) Any nipple after the TB will work for your BOV to see vacuum when the throttle blade is closed. Yes, unless you hook another source into the nipples you will need to block them off or you will have a vacuum and/or boost leak from that point.

1. Awesome thanks! Hopefully the pda still works and we can see what's going to more in detail.

2. I understand what you're saying that makes perfect sense.

3. And the nipple the the bov hose is on now I was told is for smog only and isn't enough vacuum for the bov. The other 2 nipples below it aren't capped or anything no vacuum hoses, is that bad?

 

[tkelly27]

1. Awesome thanks! Hopefully the pda still works and we can see what's going to more in detail.

2. I understand what you're saying that makes perfect sense.

3. And the nipple the the bov hose is on now I was told is for smog only and isn't enough vacuum for the bov. The other 2 nipples below it aren't capped or anything no vacuum hoses, is that bad?

3 ya, those are metered air leaks. Google "boost leak test" and do one. Those need to be capped, and you may have more. At the very least hook the bov up to one of those that has vacuum and use a piece of hose to route one nipple into the other. That will effectively cap the two and make your bov work properly. You'll know ot has vacuum on the port when you cap it off with your finger, or you can use a boost/vac gauge and hook it up to the port and take a rwading. Any port with manifold vacuum is OK for the BOV.

If you like loud BOV sounds you're going to like when that thing goes off properly. I love mine!