Announcement

Collapse
No announcement yet.

Rx7 vaf/fuel-cut

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Rx7 vaf/fuel-cut

    ok, well ive been drivin the car around for a while tryin to get the feel of everything and tryin to let everything settle in before i go pushin it to the limits..lol But, for sum reason, im hittin fuel-cut with less than half throttle and at like 7psi boost. the wideband is showing 10.0 and hittin fuelcut when i try to WOT, normal driving is jumpin around at 13.9-15.8 all the time, and idle is at 14.3-14.7. I've tried tuning the vaf, and everytime i go to WOT, or even half throttle i hit fuel-cut. its like if i hit more than 7psi, its cutting back on me. Its been doing this the whole time ive been driving it with turbo. im just curious as to whats goin on. im goin to check the timing 2mrrw. and i also still need to change my oil and spark plugs. just tryin to get the kinks worked out before i do. If anyone has any idea, plz lemme kno.




    Setup:
    t25/t28 turbo
    460cc injectors
    rx7 vaf
    gtx ecu
    gtx intake mani
    walboro 255 lph FP
    AEM wideband
    4 wire TPS




    Drew
    1993 Ford Escort GT-T
    1992 Mazda Mx3 GS((Parting Out))
    1994 Honda Integra LsVtec-Sold
    1984 Toyota Corolla SR5-Sold
    1983 Ford Ranger-Sold



    My Turbo Escort GT build thread

    My HUGE f/s thread. Go buy!!!

    Myspace yooo


    #2
    Ok a few things first:

    What spark plugs do you have? You need at least 2 steps colder than stock

    What is your ignition timing like??

    And last, how flappy is the rx7 vaf? You should actually have tightened it up a couple of clicks from stock position if you are running it with the gtx ecu and 460cc injectors....

    I haven't vaf tuned for awhile, but this is usually the common problems...


    Mexican: "You wanna race for titles?"
    Mormon: "lol, no, I don't want your car."

    Comment


      #3
      I had this same problem and it turned out that the VAF wasn't sitting level. I have my VAF sitting on a shaving cream can and sometimes it'll shift. Long story short, your VAF won't work right if it's not level.

      Edit-lol, I just saw a pic of your VAF.
      The door and the spring are designed to work on a level plain. It's a wonder yours it works at all.
      Last edited by 1st Gen; 02-11-2010, 01:56 AM.
      1991 Protege LX with GTX swap, DD
      1990 4WD Protege with GTX swap, Project/garage decoration
      2006 Mazda 3 with 2.3, Her car
      1980 Ford F100 Short bed with 300ci 6 cylinder, work truck/home for moss

      Comment


        #4
        If a VAF won't work correctly unless it's level how can we go up steep hills in a factory Protege LX and still maintain proper function? My VAF is not exactly level as it sits after having to be modified but it functions beautifully. I could see if it is sitting vertically,but if its off level a little bit it should be alright.


        Oh and Drewhall I've tunred a vaf so much before that it caused this issue. I was careful inside of the case too with what i was doing. There wasn't a true explination as to why it happened it just did. I put a new vaf in and it was not cutting anymore. I also at one point got bad hiccups from spark plugs that were carboned up and it felt like it was cutting out on me so do try to get a set of NGK BKR7E plugs and keep them at the gap they come out of the box at(0.030").
        Last edited by cis2711; 02-11-2010, 09:39 AM.

        Comment


          #5
          yep, i'd level out your vaf and see if that helps

          if it doesn't, then i'd swap out for some colder plugs with a lower gap .028-.032 ish

          check timing

          tighten VAF spring
          -Jack

          ONTARIO MAZDA CLUB! Join! https://www.facebook.com/groups/500055016671733/

          91 626 LX - basically stock and pretty slow still
          http://www.clubprotege.com/forum/sho...my-GD-626-LX-)

          01 E53 3.0i - FOR SALE! pm if interested

          91 USDM Protege LX - SOLD! turbo/manifold up for sale!
          http://www.clubprotege.com/forum/showthread.php?t=46606

          Comment


            #6
            Well I had alrdy leveld out the vaf since that pic. Lol. But ill check my plugs later, then ill tighten up the vaf and see wat it does. Only thing bout tighten it, is that the wideband says full lean out after like 2-3 clicks. Idk but ill jus try it and do a few runs and see wat happens
            1993 Ford Escort GT-T
            1992 Mazda Mx3 GS((Parting Out))
            1994 Honda Integra LsVtec-Sold
            1984 Toyota Corolla SR5-Sold
            1983 Ford Ranger-Sold



            My Turbo Escort GT build thread

            My HUGE f/s thread. Go buy!!!

            Myspace yooo

            Comment


              #7
              tightening the VAF should make it run more rich afaik
              -Jack

              ONTARIO MAZDA CLUB! Join! https://www.facebook.com/groups/500055016671733/

              91 626 LX - basically stock and pretty slow still
              http://www.clubprotege.com/forum/sho...my-GD-626-LX-)

              01 E53 3.0i - FOR SALE! pm if interested

              91 USDM Protege LX - SOLD! turbo/manifold up for sale!
              http://www.clubprotege.com/forum/showthread.php?t=46606

              Comment


                #8
                Originally posted by cis2711 View Post
                If a VAF won't work correctly unless it's level how can we go up steep hills in a factory Protege LX and still maintain proper function? My VAF is not exactly level as it sits after having to be modified but it functions beautifully. I could see if it is sitting vertically,but if its off level a little bit it should be alright.
                The steepest hill you're probably ever going to go up is a 10% grade. If you were in a lab with strict controls and precise measuring instruments, I'm sure you'd see a variation in engine performance. The engine would still function well within parameters so no need to make adjustments, or if you have the skills to make adjustments then no problem. There comes a point where the weight of the door no longer affects the spring in a linear fashion and the adjustment screw becomes inadequate to affect the added variables. In regular driving conditions it's not so noticeable, but when you are putting heavy demand on the engine and it has to perform at peak efficiency, you notice.

                I'm not saying that this could be the only cause, but it's a good place to start. I like cheap and easy
                Last edited by 1st Gen; 02-11-2010, 03:05 PM.
                1991 Protege LX with GTX swap, DD
                1990 4WD Protege with GTX swap, Project/garage decoration
                2006 Mazda 3 with 2.3, Her car
                1980 Ford F100 Short bed with 300ci 6 cylinder, work truck/home for moss

                Comment


                  #9
                  I've been having the same problem since i've boosted mine.this is what i've been telling you about. but I'm on a stock vaf I'm running the brk7e gapped at .028,330 injectors,gtx ecu..I have a rx7 vaf but was not sure if this would help me I had it on there an took it off never trid adjusting it though.....I got my MBC set for 11psi and when you nail it it cuts out ive changed plugs the gap and screwed with the timing and still can not get rid of this cutting out..so if you find out what it is let me know lol

                  1994 Escort GT Turbo

                  Comment


                    #10
                    zexscort have u tried to take takin the gtx ecu out and putin the stock one back in and seein wat it was because i put my gtx ecu in and everytime i go to wot it goes boost cut but when i put my stock ecu back in it boosted fine.then i talked to cis2711 and he told me bout the 4wire tps on the gtx ecu if yall havent tried it.

                    Comment


                      #11
                      The stock ecu doesnt read boost. The timing maps are super aggressive for turboing. Zex when i figure it out i'll let you know.
                      Cincinnati, ohio Bengals for life
                      "Who Dey"

                      Comment


                        #12
                        Originally posted by escorts united View Post
                        zexscort have u tried to take takin the gtx ecu out and putin the stock one back in and seein wat it was because i put my gtx ecu in and everytime i go to wot it goes boost cut but when i put my stock ecu back in it boosted fine.then i talked to cis2711 and he told me bout the 4wire tps on the gtx ecu if yall havent tried it.
                        I haven't tried the stock ecu but something tells me thats a bad idea without some type of piggyback.....I have a 4 wire tps but it's not on there yet...drew's post says he has the 4 wire tps so I guess that doesn't help either.....

                        bomdoutscort just let me know this is killin me I've tried everything

                        1994 Escort GT Turbo

                        Comment


                          #13
                          but zexscort hookin it up and goin up the road wont hurt anythin itll kill the cat however the say it im runnin my stock ecu rite now and runnin rich only cause i didnt adjust my vaf but im puttin my gtx back in as soon as i wire my 4wire up

                          Comment


                            #14
                            Originally posted by bomdoutscort View Post
                            The stock ecu doesnt read boost. The timing maps are super aggressive for turboing. Zex when i figure it out i'll let you know.
                            i understand wat ur sayin but it wouldnt hurt to try

                            Comment


                              #15
                              Originally posted by escorts united View Post
                              but zexscort hookin it up and goin up the road wont hurt anythin itll kill the cat however the say it im runnin my stock ecu rite now and runnin rich only cause i didnt adjust my vaf but im puttin my gtx back in as soon as i wire my 4wire up
                              It might not hurt to try it but i'm not gonna chance it. no offense or anything its just my luck I'd hook it up take a trip up the road and blow it all to hell...and of course it's not gonna hit boost cut on an ecu that wasn't built for boost. it don't have boost cut (just a note i'm not tryin to be a prick it kinda sounds that way though lol)...maybe you got to have the correct gtx vaf for it to boost right?

                              1994 Escort GT Turbo

                              Comment

                              Working...
                              X