Bbk Throtle Body Back Fire

Discussion in 'Fox 5.0 Mustang Tech' started by 306N/A, Jun 24, 2013.

  1. just installed a bbk 65mm tb, just slapped it on with out touching the settings.
    idles rough, and sputters when im going down the road and give it gas... So i followed the bb k instructions on how to set it, and its not idling on its own, when i get it to idle the set screww is all the way forward and it back fires, lots.
    set the possitioning sensor everywhere from .600 to 1300 same thing all the way around.. ??? any suggestions.... ??

    got mad and put the stock one back on to see if its vacume or any other problem.. and works fine... >:/
  2. has anyone had a faulty bbk tb ??
  3. There's nothing about the TB itself that should make it run like that compared to the stock one. IAB installed correctly? TPS installed correctly? Everything connected properly?
  4. Should be... when i set it with the iab disconnected, it will idle ok.. than connect it and all goes to hell?? but works fine on the stock one..
    the tps doesnt help it.. tried from .600 t0 1300..
    im thinking it has to be ajusted EXACTLY PERFECT or computer is not liking it???
  5. unless i have to disconect the battery for ten minutes every time i touch the tps?? if thats the case it should be tunned in a few hundred years!
  6. Despite two decades of online crap to the contrary, the TPS doesn't give a rat's ass where it's adjusted to and the computer doesn't need to be reset when it's changed. The computer reads where it's at when the ignition is turned on and goes from there. Don't burn another single calorie thinking about it.
  7. You need to perform the idle reset procedure to get it to idle correctly.

    Unplug the IAC and open the throttle stop screw and start the engine. Then slowly back the screw down to lower idle until the engine is on the verge of barely running.

    Turn car off, plug IAC back in, unplug battery for 30 mins or so and then restart it and let it relearn idle.

    TPS voltage doesn't matter at all. It can be set from 0.6-1.1 v and will still do the same.
    306N/A and 89stang1 like this.
  8. DO NOT FOLLOW BBK'S IDLE INSTRUCTIONS. They will get you close, but Jrichkers will actually make it work right! Make sure there are no vac leaks and follow the surg. idle checklist. Then do the idle setting procedure he has typed up THAT INCLUDES PULLING THE SPOUT. Mine now almost idles like stock, even with a nasty cam.
  9. You actually shouldn't need to touch the hard idle screw at all. That's probably what's got you buggered up. If you have played with it, you'll have no choice now but to follow the instructions posted by Mike (Mustang5L5) above.
  10. I had to move my BBK hard idle screw in a LONG ways. That is a part of both sets of instructions. Get it to idle without the IAC and spout so the computer can adjust from the new baseline seems to be the concept that works.
  11. make sure where the tps mounts isn't causing a vac leak I had that problem on mine

    Sent from my iPhone using my fingers
  12. Strange. With my last two BBK throttle bodies, the hard idle screw was had blue Loctite on it from the get go, much like the factory and was pre set, much like the stock unit. Playing with the hard idle is generally unnecessary unless you've got a big cam that requires a higher idle speed?
  13. Maybe a vacuum leak or something unplugged accidentally during the install? Ive heard of some throttle bodies whistling. Maybe there is an air leak in the hinge the shaft that holds the throttle plate.
  14. it did run better strait out of the box... was off a little..
    since i set it to bbk specs the idle screw is all the way in and wont idle and backfires like crazy
  15. The idle set screw is there to adjust in variables that are present in any engine setup. One setting might not work with another car. That's why any time i do a throttle body swap, i adjust the idle screw. Beyond this initial setup, you never touch it again though.

    I forgot about removing the spout as well. Pull the iAC and SPOUT and then adjust the idle. I usually set mine as far down as it will go and still run smoothly. My thinking is i want the IAC full closed at idle
  16. Does this car have a chip? I have a cam with a 900 RPM idle so thats what what was programmed into the chip. Then i removed the spout and unplugged the IAC and set it to that idle. The spout shouldn't really cause idle fluctuation though even if its plugged in.
  17. does not have a chip.. when i got it to idle with the IAC disconnected, the set screw was barely pushing on the throtle, turned the car off..
    Plugged the IAC back, then went to start it nothing, would not start just turn over, i would have to throtle it for it to start. and it backfires as well..
  18. The stock one is in there now runs fine.... i will try the bbk again on the weekend..
    So what procedure should i go when installing it back on?? step by step ??
  19. The change here is how much air enters the engine. Popping is usually a sign of improper air/fuel (too much air) that the computer isn't seeing. You could try disconnecting the battery for a lil bit to see if the computer re-learns.

    What kind of MAF? Does your MAF some kind of compensation (programming) to allow for the larger injectors? (Some MAFs are known to peg at a certain CFM)
  20. I have a sneaky suspicion that you've got the TPS sensor on backwards? Which direction are the wires on the sensor facing. They should face towards the firewall.