[Xenon Supra]

I have an HKS SSQV installed in place of the stock BOV.

I'm on stock twins with dp/ exhaust.

I am running really rich and getting terrible gas mileage and I'm wondering what you guys would recommend to get better gas mileage.

I would really prefer to keep the HKS BOV installed, if possible.

What can I do to fix this. I don't want to do VPC, Map ECU, or AEM.

I have an SAFC-2 on order, will that fix it after I get it tuned properly?

I need some help, gas is too expensive to only be getting 12 mpg.

Thanks in advance.

(Positive rep points for whoever helps me out)

 

[AlxRSPTT]

Hrmm, thats odd. I dunno if im right to assume, but you dont have it recirculated right? I get nowhere near that bad amount of gas mileage (usually around 19mpg), and my car is untuned also, with an HKS SSQV.

I would say that the AFC would help, but ir doesnt seem like to me that the BOV would give yo that bad of gas mileage by itself.

Alex

 

[LIMITED]

Hmmmm. I don't know if thats right Joey. I have mine vented also and get around 18.

 

[LIMITED]

Although, maybe keeping the stocker will help?

 

[Josh M]

I beat u!!!!

I got 14mpg and I had a 3800rpm stall on mine

 

[Chicago///M3]

I would check your O2 sensor, a vented BOV shouldn't make the car run that poorly.

 

[MaliCali]

too bad i dont even really pay attention to my mpg...

i have a sports car and thus deal with things like mpg:dunno:

its ok though joey, just get a 200 dollar econo car beater like me, it saves lives:lol:

-mike

 

[MadMaxSupra]

I have an HKS SSQV installed in place of the stock BOV.

I'm on stock twins with dp/ exhaust.

=(Positive rep points for whoever helps me out)

You mention dp/exhaust. Does this mean your using a Downpipe to replace your Cats? If yes, then this is likely your rich problem.

I had the same problem at idle. I still got 20mpg around the highway though. It was only around town where the mileage was terrible and my exhaust was blacked up pretty bad for a while. Now I went single and no more problems.

Robert
97 6spd TT

 

[Guest]

I dont see how removing the cats will cause the car to run richer

 

[AlxRSPTT]

Uh me either. Our cars run a little rich anyways, but how can the cats make it run hella rich? I run no cats, and i have never seen any black plumes, except when i went down to texas, and boosted 1.53bar, haha

Alex

 

[PM4E]

Obviously removing the bov would solve two problems here:

1. It'll fix your fuel economy problem
2. You won't have the "unique" ricer sounding bov that does not add any performance to your setup.

 

[Xenon Supra]

My downpipe had cats and I had this problem before I got the downpipe, so thats not it.

Nobody has answered my question yet on what I can do to fix it? Will an SAFC-2 fix my problem????

 

[notlownf]

The afc should fix your problem. You should be able to tune your A/F to what ever you want.

Have you taken the BOV off just to see if it still runs rich without it? what is your A/F ratio? If it was me, I would tune the AFCII without the BOV on the car and test the A/F ratio, then install the BOV and test the A/F ratio again and see what the difference is.

 

[supra400hptt]

I don't think the safc will fix it and I don't think the bov is the problem. My guess is the O2. I get 18 mpg with a T78 and the maf with the bov vented. When was the last time the O2 was replaced and if you are running that rich it's only making things worse for the O2. Another possibility is a vacuum/boost leak. Any leak will be letting air escape but the ecu will inject the extra fuel anyway since the maf has read the amount of air that has passed through at that point. The only thing the safc could help with is wot and you're rich at that point. But I'm sure you are not driving around at wot 100% of the time, so rich at wot shouldn't be causing such bad mpg. Most of your driving is at cruise and closed loop where the O2 sensor is controlling fuel.

 

[Hua]

Well, your MAF is compensating for the metered air going into the motor by injecting more fuel. Now that you let that air out, the same amount of fuel is still going in since the incoming air is metered before the BOV. My guess would be to get a VPC or a MAP ECU.

 

[SpeedR]

Well, your MAF is compensating for the metered air going into the motor by injecting more fuel. Now that you let that air out, the same amount of fuel is still going in since the incoming air is metered before the BOV. My guess would be to get a VPC or a MAP ECU.[/QUOTE

Yes that is definitely part of your problem also, if your new BOV is leaking it will significantly increase the MAF - fuel for metered air problem.

I ran BPU ++ for several years with the stock BOV in place and a aftermarket BOV on the other side of the IC near the TB this gives you the best of both worlds. let the stock BOV handle low boost by tightening the spring on your HKS BOV.

 

[Xenon Supra]

What would happen if I tighten my spring a little bit on my HKS right now? What does the tightening/ loosening actually adjust?

 

[Willjs7]

What would happen if I tighten my spring a little bit on my HKS right now? What does the tightening/ loosening actually adjust?

If you make it tighter it will not let out and cause compressor surge I believe.

 

[SpeedR]

If you make it tighter it will not let out and cause compressor surge I believe.

Only if you tighten it all the way

The spring needs to be adjusted so the BOV will stay closed other wise you have a big boost leek.

It should take several PSI to open and close your BOV. The way I did it is I would boost to 3-4 PS then let off if the BOV opened I would tighten it down so it did not open at 4 PSI or less.
Every BOV is different but you do not want to vent your boost below 3 PSI play around with t and find a setting that you like.
NO this will not cause compressor surge

 

[Supradedupra]

um.... i get 12 mpg... and i have a check engine light... "o2 sensor failure"

Also, the gas mileage depends on how hard you push the car also... but I guess that's implied.

I know... when my car is running nice, I get around 22 mpg on the highway

Try driving with the vacum line disconnected from the SSQ and check your gas mileage then. Good luck man