Rx7 vaf/fuel-cut

[concealer404]

What VAF are you using again? I'm almost wondering if your adjustments to the VAF you're using brought it so far out of spec from what the GTX ecu was "expecting" that everything freaked out.

[drewhall07]

Rx7 vaf

[concealer404]

Rx7 vaf

Forgive me, because i'm maz-tarded, BUT:

1) How close is this VAF to the GTX VAF? (That is the ecu you were using, right?)
2) Did you try the GTX ecu with the RX7 VAF in stock adjustment?

This all seems like it's pointing to the ECU or the VAF, and i bet it's a combination of both. I HATE flappers with a passion for this very reason. Yeah, they're safe, and can do a lot of adjustment for the person that doesn't want to get too into it, but they're such a friggin' pain in the ass.


Also, what does your wideband show during cruising or idle?

[cis2711]

Okay I have a question. I just read something that intrigued me. Someone said that a vaf can max out in hertz and then it tells the ecu to cut fuel. What does that feel like? Does it make the engine BUCK or could that buck be detonation? I guess my question is is there a way to unplug something or cut a wire in the vaf to eliminate fuel cut from happening at 15psi if my vaf is being maxxed out?

Maybe this is why we so many of us with bp26 ecus and u-code or b-code vafs are getting this boost cut/ fuel cut/ bucking at lower rpms under high boost levels? Could we be maxing out the vaf's? I would assume it would be easier to max out the sweep on the vaf door if the spring is tightened but we are loosening the vaf in most cases.

[cis2711]

I just read somthing interesting:

http://www.machv.com/fuelcut.html

http://www.streetrodstuff.com/Articl...ion/Page_5.php



I think I can fool the ecu and vaf with the 460cc injectors if I tighten the vaf spring at idle. I think the ecu is just not capable of supplying the necessary fuel at lower rpms with the 330's and the vaf tuned for the 330's. If the 460's are in there and the vaf is tightened accordingly wouldn't it fool the ecu and keep fuel cut at bay?

[concealer404]

Okay I have a question. I just read something that intrigued me. Someone said that a vaf can max out in hertz and then it tells the ecu to cut fuel. What does that feel like? Does it make the engine BUCK or could that buck be detonation? I guess my question is is there a way to unplug something or cut a wire in the vaf to eliminate fuel cut from happening at 15psi if my vaf is being maxxed out?

Maybe this is why we so many of us with bp26 ecus and u-code or b-code vafs are getting this boost cut/ fuel cut/ bucking at lower rpms under high boost levels? Could we be maxing out the vaf's? I would assume it would be easier to max out the sweep on the vaf door if the spring is tightened but we are loosening the vaf in most cases.

Once the VAF maxes out, it SHOULD just dump ALL available fuel, assuming i'm thinking this through correctly. That is what happens on my car. Well, actually on mine, it dumps all fuel possible at 75% throttle, but that's a different matter.

[concealer404]

I just read somthing interesting:

http://www.machv.com/fuelcut.html

http://www.streetrodstuff.com/Articl...ion/Page_5.php



I think I can fool the ecu and vaf with the 460cc injectors if I tighten the vaf spring at idle. I think the ecu is just not capable of supplying the necessary fuel at lower rpms with the 330's and the vaf tuned for the 330's. If the 460's are in there and the vaf is tightened accordingly wouldn't it fool the ecu and keep fuel cut at bay?

To a point, yes. Someone recently just did this, even running an n/a ECU i believe, and put down like 300hp? I'll try to find the thread.

[bomdoutscort]

the dudes in florida do it all the time. they run the na ecu and a wideband and just make sure its rich under boost. its good for speed but bad for gas mileage

[concealer404]

the dudes in florida do it all the time. they run the na ecu and a wideband and just make sure its rich under boost. its good for speed but bad for gas mileage

Well, in most cars, when you're in boost, it's bad for gas mileage.

Those guys should still be able to see 25mpg combined or so if they dont drive like morons.

My MX6 probably dips into the 9s under boost. I still get 25-26mpg combined.

[escorts united]

Well, in most cars, when you're in boost, it's bad for gas mileage.

Those guys should still be able to see 25mpg combined or so if they dont drive like morons.

My MX6 probably dips into the 9s under boost. I still get 25-26mpg combined.

wat ecu do u have?

[bomdoutscort]

Well, in most cars, when you're in boost, it's bad for gas mileage.

Those guys should still be able to see 25mpg combined or so if they dont drive like morons.

My MX6 probably dips into the 9s under boost. I still get 25-26mpg combined.

Its nothing like that. They had 339whp on a stock bp. Big turbo and lots of boost. Tune it to run rich and it wont detonate i was told from them. This was basically a highway race car. Here are some of their vids.

http://www.streetfire.net/video/339whp-Escort-GT-vs-0203_89303.htm

[Zexcort]

Well it finally quit snowing so I went out to the garage and switched my stock vaf to the code b vaf and took it for a spin it's holdin 11 psi with no cut out wideband reads 14.7 at idle and 12.5 at full boost. I was seeing 10.0 at full boost with the stock vaf and it would cut out at 4 to 4500 rpms so far so good I guess...I need to fix my p/s rack bushings now cause there fallin out and when it spools you can't hold it in the road and I know torque steer can't be that bad on 11psi on a vj20 lol so hopefilly I can put my new bushings in and be good to go.Just wanted to let you guys know so far the code b vaf has fixed mine.Not sure if it's had the spring adjusted cause it has been opened before I got it hope this helps.

[bomdoutscort]

Like i said i'll let you know when i get my new vaf. I'm gonna switch out the vaf to see if it fixes it. then i have a Electriconic boost controller which i wont be receiving till sometime next month i bet but atleast its being shipped. Then i have my exhaust side flange that i'll be getting soon also. Then i'm gonna divorce the wastegate on my turbo and run an external wastegate.

[Zexcort]

hopefully this is the fix for us i've had that vaf forever just didn't really understand how to adjust it so I nver messed with it

[concealer404]

wat ecu do u have?

Stock.