I've been running 90# injectors in my L05 for about a year now because they were all I could find. I figured I would be able to tune then down to run fine on my relatively low performance engine. I have been successful for the most part. Everyday driving is great, accelerates great, WOT is great, with one exception, low RPM/low MAP conditions. For example going down hill, or after letting off an out-of-gear rev, the pulse width goes down below .8 at times. It usually doesn't stall, but my wideband often spikes all the way up to 25 before stall saver kicks in and surges the engine back up. Popping off the air cleaner watching the injectors at times of low PW the fuel cone gets horribly sloppy. If I rev it up to 2500 (under the hood at the TB) and let the blades snap shut fuel will stop flowing completely and it will stall.

I'm running fuel pressure at 12psi. My FPR has been made adjustable. Can I bump the fuel pressure LOWER than stock to solve this issue? How low of a FP can TBI operate and will there be any negative effects in the upper RPM ranges? How can I adjust my BPC for the lower fuel pressure?

Or should I start looking for smaller injectors?

 

What ECM are you running?

 

I'm running Rbob's EBL.

Found some stuff out about the stock fuel pressure regulator. I took it off 5 times today, each time taking 1-1/2 turn's worth of pressure off the spring. I eventually bottomed it out, and my gauge was reading barely below 11 PSI. With the little notch halfway up it was reading 12. The first 5 or 6 turns down from the middle didn't really change the fuel pressure at all. Then the last couple of turns brought it down to a bit below 11 at which point it was bottomed out, which leads me to believe that my fuel pump is maxed at 12 PSI. The important thing is that I couldn't lower it enough to solve the problem I'm having, assuming I've even traced the problem correctly. Still sound like injectors too big? Any other ideas?

 

I running the EBL and 80# 454 injectors on a X-ram 82 Cross fire vette... you should be able to get it working with the EBL its just a matter of tweaking. Rbob seems to recommend a VFPR. Are you shure you got 90#'s... Also just seems like you don't 100% from what I have read need to run the calculated BPW you can play with a bit to see what result it gets you... I seem to feel you may be going the wrong way HIGHER pressure may get better results better spray pattern.. did you try increasing and then adjusting the BPW to the new pressure.. I am runnin 16 with 80's and thinking of going higher as more pressure seems to give a smoother faster spray pattern... my wb GOES way past what your saying lean as hell when letting off the go pedal... but comes back and don't stall... I think you need to tweek the TBI, did you follow the idle IAC adjust they talk about and get your IAC less then 5 counts at idle? What size TBI do you have...I think the EBL allows you to fudge just about any setting thats one of its plus's + many more...

 

I'm looking for larger injectors, so if you decide to go smaller, let me know and we can trade if you're interested. I have the stock #68 (orange) injectors running 23psi (which makes them behave like #89's) and they're going static at WOT.

 

I was running 90's at 10.5 psi for a while, no issues. just recalc'd BPC.

don't forget about changing AE, too. I've reduced my TPS and MAP pw's by 50%, reduced AE RPM mult by a lot and it's still too much.
The 90's can squirt some gas

 

You could increase the short BPW bias. That will add extra PW to ensure fuel delivery at short BPWs. Its surpising they dont deliver fuel there. The pintle must be pretty heavy. My smaller delphis run at .6-.8 w/o much issue.

 

I ran 80's at 23 lbs at idle and the ECU flipped to asynch PW to reduce the fuel delivery. that caused a nasty surge at idle as i believe the fuel was delivered at every other DRP. with the fuel being interrupted the stall saver was used. hence a surge. idle commanded to 850 rpms with manual. going synch only at idle the PW allowed a smooth idle and I will guess it was about 1.0 msec(350cid). since i dropped my FP to 20 and it is around 1.2msec and idles smooth as silk. i believe both examples were OL idle at around commanded 13.7/1.

 

Yes, if you still have async enabled, the ECM will skip inejction pulses if teh PW is too short, leaving cylinders lean. This can be changed with teh sync/async thresholds. Lower the entry/exit thresholds and/or setting teh option bit for sync only idle (assuming EBL has this) and itll force it to remain in sync firings.