Ok, I have an A/F gauge, the eManage and the Profec all talking to one another and life is pretty good. However, I've noticed that at about 6.5psi my A/F ratio is rising from about 11.2 at 6000 rpms to about 12.1 at 6600+ rpms.

With eManage I can now view the Injector Duty Cycle (which I believe tells me the percent of the time in which the injectors are squirting fuel). What I don't yet have is a fuel pressure guage (my ideal would be one guage that lets me increase fuel pressure and also output the fuel pressure as a variable voltage signal to the Profec.

Anyway, what's happening is that 100% duty cycle is being reached at about 5800 rpms. Since fuel pressure does not continue to rise (I'm assuming since it's a 1:1 FPR and the boost is theoretically constant from 5800 to 6600+ rpms), I'm assuming that is why I'm seeing the A/F ratio increase. Am I right?

I'm assuming that my options are:

(1) Send the ECU back to Technosquare and have them reprogram the ECU to increase fuel pressure--or something like that. Can the ECU be programmed to do that?

(2) Exchange the 1:1 FPR that comes with the PE kit with something adjustable and then reduce the duty cycle at the RPMs where I'm already running rich enough. I'm assuming that E-Manage can shorten the duty cycle, correct? (i.e. are negative numbers allowed and do they do anything)

(3) Buy larger injectors and use the scaling feature of E-Manage.

Since I don't know my current fuel pressure it's hard to know which route to take, correct?

BTW, I had some problems initially with the fuel return line tubing after having the PE TT kit installed. I'm assuming that my installer used tubing that came with the kit--but that's just an assumption on my part. The tubing actually burst one morning. So, anyway, my installer replaced the tubing with high quality braided fuel line--but after that is when I started noticing this A/F issue. Perhaps the lines they used are larger in diameter or something so the FP is lower??

Thoughts, suggestions, links to a fuel pressure guage, etc are all appreciated.

--Steve

 

Steve, you can call me if you need help with this. I think you still have my number.....or PM me.

It doesnt surprise me that your exceeding the capabilities of the injectors. The 440cc injector with the Greddy kit poop out as well, even with solid fuel pressure.

1) A TS reflash will accomplish nothing. Fuel pressure is not an adjustable feature of the ECU, since there is no fuel pressure sensor...just a fuel temp sensor. The maximum duration for any injector is 20ms...once you reach that point..you are done.

2) 95% of raising rate regs are 1:1....you have the right piece there...don't change it. YOu have the Aerometive or do you have the one that comes with the Greddy kit...I cant recall.

3) Your best and only good solution is to get larger injectors and scale with an eManage.

You could try to pump up fuel pressure with another inline pump, but these are all band-aids, and you want to avoid super-high fuel pressure, you might end up with another leak on your hands...or a sticky injector.

 

I guess I'm surprised that with the larger fuel pump (I think it's a Walbro 255--it comes with the PE TT kit along with a non-adjustable 1:1 FPR) and the 380cc injectors that I'm running out of steam at 6.5psi. That doesn't sound right to me--especially since I don't think this was happening before changing the fuel lines.

--Steve

 

steve, with my walbro 255 and 440cc injectors, sans FPR, I was hitting 100% duty cycle at 4800rpm at my 9psi setting, and 5400 rpm at my 6psi setting.

 

Hmmm. Sorry to be dumb, but you're basically saying that at 6psi you were (pre-crash) starting to lean out as you approached redline even with the Walbro?

If so, why am I reading so many posts from Greddy TT guys at 7-8+ psi? And how are fellow PE TT guys like Cheston and Slay2K running around town at 8.5psi?

--Steve

 

I wasnt leaning out...but I was still at 100% duty cycle. I cant explain it entirely. I do know that changes I made in the eManage beyond 5500rpm were not effective or noticable in my A/F curve. On one of my dyno runs, I did get a little bit leaner...but not much.

It's really hard to effectively tune this car without a new fuel system that bypasses the stock FPR. Becuase with the stock in tank FPR, fuel pressure will begin dropping from idle....all the way to redline as you accelerate.

I dont know how Cheston did his car, but each ECU is different, as we've all figure out..some cars run lean..some rich, some smooth A/F charts, others are kinda wavy. Wish I could explain the discrep....

 

Sharif, thanks as always for your answers to my questions!

Having a fast car is cool, but learning new stuff has been what has kept me interested in this "new hobby" over the last year.

--Steve

 

I really like the APS fuel system that's about to come out with their turbo. Do you think us Greddy guys could utilize this thing?

G

 

Steve,
Try plugging your stock fpr. Your lean situation will disappear. That's what I did. I have some epoxy left over and your welcome to it. Works really well now, almost too rich.
MIKE

 

Interesting idea, Mike. Has anyone else done that?

I'm still weighing my options. 650cc RC injectors are definitely in my immediate future and I might just go for broke with the AAM full fuel return system since I'm planning on doing the "big boost thing" soon enough anyway.

--Steve

 

The AAM system comes with that plug. Even with the AAM fuel system, at some point soon...you'll need bigger injectors. Even with a perfect fuel system....my guess is the 440cc injectors are good for about 400whp, if you want to keep them under the proper 80% duty cycle.

I'm not saying you can't run more power, since many member including myself already have with the 440cc injectors, but it's not an ideal setup.

 

Steve,
Several other members have plugged their stock fpr and had good results. AAM offers a plug that you buy and atleast install to see what happens but using the epoxy works good as well and is about $4.00.
MIKE

 

You really want to get that worked out. We have a customer with the GReddy kit that had a similar lean condition in the upper RPM's that just popped his motor. He was at 9psi so you probably have a greater margin for error but its definately an issue to get worked out.

 

I definitely will get it resolved ASAP by immediately installing larger injectors and also purchasing the AAM fuel system.

I'm assuming your customer wasn't pulling any timing so he had a very, very small margin for error

--Steve

 

Larger Injector GB is coming next...then hopefully...an AAM fuel system GB.

 

Sharif - let me know if you want to do an injector GB...we have a few options for you guys