Hey Guys, So I just finished my Mini-ram & I don't see much improvement in higher end. It still pulls to 6300 or so as it did before in 1st & 2nd, but 3rd it drops off early at 5500. Do you suppose it is my fuel pump? What are you all running for fuel pump, mine is still stock. I plan on changin my filter this weekend & takin it for a run, checking Wide Open Throttle pressure, what is a good target for pressure @ WOT? my idle is set at 48. Thanks in advance!

 

48

If it's 45 at idle, then 45; etc.

 

Definitely nothing lower than your idle fuel pressure!!!

(a little higher than idle is fine, but highly unlikely with the stock pump)

 

Thanks! That makes sense, i'll investigate this weekend!

 

You say idle, but do you mean idle with vacuum reference disconnected? Disconnected-idle should be the same as WOT-connected within a psi or so due to some minor vacuum from intake, filter, and throttle body resistance.

If it's 48 at idle, vacuum connected, then WOT should be about 5 to 7 psi higher, depending on the cam/idle vacuum.

The injectors are a little small (you should probably use 28's or 30's) Have you tuned the PROM at all (you should)? Get a wideband in there before you nuke it.

 

Thats exactly what I was about to say.

Without a scan who knows what the car is doing though. Kinda an open question. A lot of people talk about upping the pressure to 50psi to get better spray pattern, but as pressure goes up volume goes down and on a stock pump who knows what he'll get WOT at 5500

-- Joe

 

Unfortunately I do not have the knowledge or resources on how to "burn my own prom," i have solely relied on TPIS to give me the right chip. They told me to test the Fuel Pressure @ WOT first, then if that measures okay, they can work with my chip. I heard of a place down in Illinois (i'm from Wisconsin) called Speed Inc. that does custom dyno tuning for a minimal cost. Maybe I'll check them out after I replace the fuel pump. When you say "Get a wideband in there before I nuke it," what do you mean by that?

 

I believe he's trying to tell you to get a wideband O2 sensor on it and see what AFR's you're pulling at WOT before you burn a hole in a piston from being too lean at WOT....

 

So, I hooked my fuel pressure gauge today & detected 50psi at idle with no vacuum. I attached the gauge to the windshield, hooked up the vacuum hose again & took it for a ride. Getting onto the freeway, I HAMMERED on it & it read 48psi @ WOT, consistently. While Idle @ intersections, it read 42 on the windshield.

Before doing all of this, I re-routed some vacuum hoses and one of them hoses being the one for the fuel pressure regulator. I noticed that particular hose wasn't very tight on the T-fitting, I accomodated by putting a bigger T connector to make a tighter fit for that size hose. Today, on the street, it pulled hard to 6500 6600 before I shifted, has a rev-limiter of 6700. These are my results, your comments are welcome! Is 48 a good spec for WOT?

 

Fuel pressure isn't a spec in the way you're thinking, I think.

48 sounds fine. As long as it isn't dropping at the highest RPM's it means your pump is able to flow enough (hope it's a good aftermarket pump), but it really doesn't mean anything until your injectors are flowing the right amount too, and that takes a wideband and prom tuning to get right.

Fuel pressure adjustment is used to get smaller injectors to be a little bigger. That's about the only real world benefit. Prom should have the VE table calibrated correctly, and injector constants changed to match your injector, and cylinder displacement set to correct, and spark table optimized to your heads, cam, and compression. TPIS can't do it from afar. There's a slight chance that it'll be "good enough." But for the price of one of their chips, you could be learning to do it yourself, the right way (but enough of the preaching).

 

speeed inc is great but your going to pay real close to my home