BPT misses at about 13psi constant boost

[brianho]

Has anyone had this problem? My BPT has some sort of miss/hesitation when I keep the boost at around 12-13psi (full throttle). After the miss, the car runs normally for a few seconds then misses again, and continues doing this for as long as I hold the throttle down. I have new plugs gapped at .028, new wires, upgraded ignition, 255 RX-7 fuel pump, upgraded engine grounds, greddy boost controller, etc. It seems like there is a fuel shortage, and that's why it's missing but with that upgraded fuel pump I don't see how that is possible, unless the stock fuel pressure regulator for the BPT doesn't maintain enough pressure. Can you get an after market FPR for the BPT?<p>Normally I'd just set the boost down to about 11psi and everything is fine, no miss, nothing. However, I just got a new high flow cat put in, and my normal boost now is now around 13-14psi with the boost controller turned off!!! (note: when I got my BPT, the turbo was already boosting at 10~11psi right out of Corksport's garage no mods or boost controller) My whole exhaust is custom 2.5 inch all the way, but my last cat had some serious problems which is probably why I never got the full effect from the better exhuast system until now.<p>Does anyone have any ideas on how to fix the miss, and/or the overboosting problem? Derrek suggested boring out the waste gate on the turbo.

[natural born honda killer]

what are you using for a ecu. just wondering cause ive never heard of anyone being able to run right without a full standalone. i would maybe say check you ecu and make sure its not shot.

[OsoSlo z28]

how advanced is your timing? i'm also interested in what type of engine management you're using. i'm not sure how you have so much boost creep? the stock boost is 8.5psi. i also have 2.5" exhaust from the turbo back, straight pipe, and my boost doesn't creep but to maybe 9.5psi and that's rare. i did a datalog and it hit 10lbs at wot one time for about 2sec. the stock fpr is good up to and maybe beyond 15lbs. what size injectors are you using? this could be your problem as well.

[maldo]

I would say it is your injectors, BPT runs the same 330cc injectors as the B6T (correct?). I know that when I maxed out my previous set of injectors it felt like severe misfiring. Check your timing, 10* is normal but you should be pulling 1-3* when you start to see boost. The BP loves 14* but even then you should start pulling 2* for every pound of boost or you go boom. <p>What's your EGT gauge telling you? (you do have one right? ) It may be time for an upgraded rail, anything over 12psi and it is something to consider. Shiv gained 30whp by doing this simple and effective upgrade.<p>Sounds like you have an excuse to upgrade the ecu to the Haltech or something similar. Are you using a fuel computer or ignition computer of any sort?<p>Do you still have your Cat? Get rid of it. You may want to put the downpipe off and inspect the wastegate flapper door to ensure that it is sealing properly.

[OsoSlo z28]

yeah, the bpt injectors are 330cc. so yeah, at 13lbs, you're going beyond the limits of the stock injectors. i have eclipse gs-t 440cc injectors and they work fine. if you upgrade to a bigger turbo, i suggest some 550cc injectors.<p>as for the timing, that's the benefit of a stand-alone. i haven't taken any timing away. actually at 8.5lbs(stock boost) i'm running around 26* advance.<p>[ December 30, 2002: Message edited by: cre8v mx3 ]</p>

[brianho]

- ECU is from the BPT's
- timing is at 12 degress (advanced 2 deg over stock) I don't have anything that will retard my timing, but so far no pings at all
- injectors are BPT's 330cc
- no fuel computer, but I have a Jacobs ignition (thinking of getting Greddy E-manage)<p>Thanks for all the replys. Where can I get an upgraded fuel rail?

[maldo]

Fuel rail is basically a custom affair. Electromotive sells fuel rail stocks that would need machining. Vishnu sells a dual feed rail for the Miata, not sure of the compatibility with the BPT manifold (Ashley??). Search the net, there are some links out there on how to modify your stock rail to dual feed.

[boostedmx]

if you contact force efi they will make you one. 1/2 inch inside diameter(overkill but good). youll have to convert your existing lines from tube to hose which isnt hard, just a compression fitting and a union. while your at it get an adjustable fpr. aeromotive makes a boost sensitive one that is very nice and right up your alley. i have pics of both on my site... check it out<p>http://boostedmx.freeservers.com/photo.html<p>[ December 30, 2002: Message edited by: boostedmx ]</p>

[brianho]

Hey Boostedmx how much was your fuel rail, and that adjustable fpr from Force EFI? Is your fuel rail dual feed? Also, what is a compression fitting and a union? I'm looking for the simplest solution possible, just get the part and bolt it on type thing. <p>I've got a lot to learn when it comes to forced induction, but every litle bit helps. Thanks for the relpies.

[boostedmx]

everything all together( rail, fittings,adjustable fpr) was under $300 and thats on the high side. im guesing that your pump is good. the fittings i was speaking of is what you will need to convert your standard tube style fuel lines to the AN hose style. there is a kit for this.
when you are running higher pressures through a bigger rail there is no need for a dual feed rail anymore. the rail itself is from force efi and is custom made to your request. you give them the injector boss size and the spacing and they make you a rail!! make sure you explain the mounting too.
the fpr is from jegs or summitt racing. i go through jegs because they are faster and usually have everything in stock, plus there 2 day shipping is very cheap.

[brianho]

Thanks BoostedMX, $300 is pretty good, I was expecting more. I just sent Force EFE an email. I think this should solve my problem.<p>Thanks again everyone.

[atila]

The vishnu fuel rail should work that's what adam use in his escort bpt. Check at www.escortracing.com for the spec of his motor

[94mx3rsr]

How did you fit the BPT ecu on the car??? Did you use the wiring of the bpt or the wiring from the mx3....Is the 92 mx3 wiring much different from the 94...OBD1 or OBD2? can the 92mx3 wiring be fitted on a 94 + B6ZE mx3 without any changes? <p>thanks in advance!