614Streets

What fuel pressure have you been running on your TBI? Please list your engine modifications. No this does not belong in the nitrous section! Thank you very much.

JR305

I ran the 5153 kit on my 305 TBI. At the time I was running just under 12psi of fuel pressure. This was when I only had headers, catback, open element, and an ignition box. The jet combinations form NOS are run very rich, so plan on running to your local speed shop to pick up some smaller fuel jets.

614Streets

Yeah Ive had some problems tuning mine. Up top its just not happening. I usually run 15psi but I havent nailed the tuning. The jet combination is 47 Nitrous 36 fuel for 100 or so they say . I run r42 plugs. Its just not crisp and powerful as it once was befroe the headers, intake, gears, e fan, etc

PhilM

my pressure is also at 15, but I am running 120 hp jets and it is a little lean in the high gears. i ran 100 hp jets with this pressure and it worked very well, but i had a slightly larger fuel jet than that supplied. don't remember the size off the top of my head. running 43 plugs.

614Streets

Have either of you experianced a lack of power up high? Have either of you had it pop or backfire after 3rd gear? I can get awesome launches through 1st and second no problems but by the time I hit 3rd gear I am down on power. A freind told me to wire a thick power wire with a relay from the battery to my fuel pump. I have a granetelli 190 lph(walbro unit). I do have a autometer f/p gauge on the cowl and I dont think I remember seeing the pressure drop. Ive had only a few solid runs with the good power levels. I should be reunning alot faster than I am but I havent got the ghost cornered yet. Are you guys on base timing , and also what size pills do you currently run? I want to try and nail a good pass before I tear it down for the stroker and blower.

JR305

The only time I would get decreases in power was when my bottle was down to around 3-4Lbs of nitrous. I don't remember what size jets I was running, but it was the NOS 100hp nitrous jet with a fuel jet three steps lower than recommended. I had my base timing stock and I pulled 2* for the 100hp shot. I was running the stock heat range plugs.

The main things that I noticed that would rob me of power were a lower than 900psi bottle pressure. Also when my bottle was below half full, but that is probably because of the way I mounted it (not quite at a 45* angle).

614Streets

I ran a very neat scan tool on my truck tonight and noticed that the 02 sensor indicated lean and the values werent moving around much. My Air/fuel gauge (intellitronix ) says otherwise but I know belive my o2 sensor is bad. It also went into open loop as soon as it hit Idle but I expect that since I run a low T stat. It did go closed loop when I got on it. I also saw that I could adjust my TPS sensor. I will replace the 0 2 sensor and hopefully it will survive.

My first holley TBI had the black injector caps the ones that hold down the injectors. Well a couple times they failed when the nut got loose and the injector pushed its way up and out of the bore. It basically flooded the engine for literally a day befor I really found the problem. I bet that wounded the 02 sensor?

I am unsure that my single wire sensor will be able to stay clean. Would most of you recommend a heated 3 wire type?

And do you guys belive that a bad o2 sensor would definately cause the motor to not work as good on the nitrous? The intellitronix gauge must not be all that great because this scanner I had was from Monroe and it is very very expensive. It really read between lean and rich but to the lean side?? The reading wernt moving around like they do on my elcheepo intellitronix unit. I played with the fuel pressure as well bring it down to 10 and up as high as 17(Its a TBI system) but neither ranges made a change on the scanner although I could smell the gasoline in the exhaust when she was high. My brother said it cost around $2800. It was a big hand held LCD + button unit and you could read everything real time. It could read timing and everything.

I also went from a ADS chip back to stock. I really used the ADS only because two reasons , I recieved it as a gift a long time ago , and I broke the OEM prom so I was stuck with it until a nice guy gave me another OEM. So that might also help the nitrous runs. It felt like it picked up alot of midrange torque with the OEM chip. Easy to tell because I had the ADS in there for ages.

So any opinions?

P.S. The a/c doesnt come on , is that beacause the OEM chip I recieved isnt burned for A/C use? I got it for free but thats something I plan on having even with the mini blower for next summer. By then I want to have a fully programmable ecm , we'll see. Sorry for the book, TIY.

PhilM

My car pops and carries on in 3rd and 4th, definately too lean. i haven't done anything with my fuel except turning up the pressure. the wiring idea seems interesting. might try it out.