I have a 95 truck 350 tbi stock. The only mods done are open element air cleaner, headers w/ dual exhaust, - cat & running 15.5 psi.
I had my injectors cleaned and flow tested. I input the correct info into the bin constants. (0d mask)
I am running 99.6 in places and blm's showing me 140 - 144. How can I correct this without fudging numbers? I have been working on this for way to long now. I have read and read with no luck. Any suggestions would be greatly appreciated.

Thanks in advance,

R.S.

 

what areas are you running 140+ blms.. 15.5 psi? sounds like the fuel pump is dead headed or maxed out. What was the flow rate on your cleaned injectors?

Have you tried going back to the old injector flow rate? stock injector setting is 61

 

I'm hitting 140's in map 60 & 70, in the rpms 1600 - 3600.

I bumped up my fuel pressure for the mods I have done. My newly cleaned and flow tested injectors were 71.2 & 72.4 lbs/hr. I adjusted my Injector Flow Rate to 71.8 lb/hr. So that is correct for the pressure I'm running. The fuel pump is not maxed out, I had it at 18+ and had to back it back down because that was too much, or so I think. I have not gone back to the factory settings because they would not be correct.

 

Raise the pressure, peak torque area is going to need the longest pulsewidth.

 

Any suggestions to how much I should raise it?

Also, I raised my Inj. BPW vs. Voltage by 10% just below to just above 12vdc.

 

An exhaust/header leak will do just that....

 

Man I just tightened everything down. I guess I'll double check it and make sure their all good. I'll post back either way.

Thanks Ronny.

 

O.k. made sure everything was tight on the headers, a couple 1/4 twist bolts but that's it.

I upped the pressure to 18psi from what I could tell with my 15 psi gauge. I adjusted my injector offset vs. battery voltage by 15% to mirror the 15% increase in pressure. I also went in and adjusted my TBI Injector Flow rate to newly adjusted rate.

Now I'm running RICH, in the 9's but idled fine. I adjusted the VE table accordingly and at idle my BLM's are 97 and still in the 9's. When I give it a bit of gas the AFR get's back around the 12-13. So the bump in pressure did help the VE ceiling I was hitting. Now I don't know why the bottom's falling out when it should be getting dialed in.

Any suggestions?

 

First of all you should determine where your injector duty cycle stands.
Second, when you bumped FP, did you adjust the BPW constant for the higher flow?
I would drop pressure back to 15, then leave the Inj. offset where it currently is to see if that makes a diff. When I have had regions of the VE table go higher than 99%, I first would increase the INJ Bias, then increase FP if necessary to get the Inj DC in line. But make certain the BPW is also correct for the new flow rate when increasing pressure.
I also would increase pressure by 1psi increments
MAYBE 2 at any one time.

 

Did you check the collector to exhaust pipe connections? (that is where my leak was).

 

Nope, it's welded!

 

You welded the headed collector flange to exhaust pipe flange? How to disassemble for service?

 

I dropped my pressure gauge & it's not working right. I had to order a new one that goes to 30 psi this time. I was trying to adjust some fields after I dropped the pressure down a bit. Seems that whatever I did made it run like crap. So I got it to where it would run o.k. for now, until I get my new gauge. I will get it next week, and then I will start at 15 psi, adjust the injector offset vs. battery voltage and the TBI Injector Flow rate. Data log at that point and see if I hit the ceiling. If I do, then I guess I have to "look" for an exhaust leak somewhere.

(side note/question): What kind of pressure might be expected to support my setup? 350 w/ 150k miles, full headers w/ true dual exhaust 2 1/2", no cats, open air filter setup. A bit of insight would help me determine where the line is that I shouldn't cross with the pressure.

Anyone have a link or knowledge of how to install a external fuel pressure regulator to the factory system? I tried one from O'Reily's & it was terrible. Don't know if I had to drop pressure on the stock regulator when installing another one before it or what....
I would very much like to be able to adjust the pressure without having to take the injector pod off every stinking time to make an adjustment.

Thanks,

Rick

 

No service required on my vehicles Ronny.

Nah, if whatever I'm doing requires moving them out of the way and unbolting them can't fix it then I guess I'll be using the saws-all and getting them re-welded or at that point getting them re-flanged. Not my best decision, also not my worst either though.

 

I found a place to get pretty close to what pressure I will need for my setup.
With the factory H.P. rated at 210 (pathetic) with the mods I've done and the tuning to be done I figure 240 + -10 hp would be a good guess. The formula that is given gets me to 15.5 psi with my injectors. So once I set my pressure to 15.5 psi I can then leave that alone and just concentrate on the other fields.

Formula: http://www.dynamicefi.com/TBI_Fueling.php

Also, I did some searching for the external fuel pressure regulator and got that figured out too. But with knowing where I need to set it at I don't think that I will be needing to install one now. Maybe later down the road when I rebuild the engine.

 

Rallye Smith,

Please allow me to introduce you to Robert Rauscher alias RBob.

As for an external VAFPR, you need one if you use // plumbing to install the same size injectors in both TB units found on a Corvette Xfire motor.

 

Yeah, I've conversed with Rob several times. GREAT guy with lots of knowledge. As for the VAFPR, not following you with the plumbing deal though...

 

not applicable to your tbi system(crossfire is parallel with use of same injector size). Stock CF uses differing inj size and runs in series.

I have the same type TB you have and I use external Aeromotive VAFPR unit. 2 springs 0-20 lbs and 20-60 lbs. offers four sources/ports and one return. I have one to TB unit one for FP gauge and one for fuel to nitrous.

 

Concerning the mounting of an external fuel pressure gauge...


BE careful!

A few years ago I mounted a new ACCEL external pressure gauge to my TPI powered Caprice wagon. I was having issues anf wanted to see where I was with fuel pressure after just converting from TBI
To make the story short, the ACCEL gauge leaked from the back of the gauge, not at the rail connection causing a fire. Open headers torched the fuel that was spraying everywhere. Luckily, I was able to confine it to just some fired harness tubing and a few wires.

 

O.k. I read a post by Rbob and he says to find correct offset vs. battery voltage to disconnect alternator. What am I disconnecting? The plug or the alternator from the battery altogether?

Side note: I have my pressure at 15 psi & injector flow lbs./hr adjusted correctly. I was thinking that getting the BPW adjusted will help the cause as well from what I've read. Any other thoughts?

Also, for some reason my display WBO2 is not reading correctly again. I checked it against my LC-1 and it is showing fine O2 readings. I didn't make any changes to my Tuner Pro WBO2 code. What a pain in the butt.

 

I disconnected the alternator from the battery and data logged. Now what fields do I need to be looking at and how do I determine what needs to be done?

Thanks,