I have a question about this modification. What is the reason for the diode install? Since this car is MAF the additional boost and increased air flow will result in the computer changing the injector pulse width to accomodate and add extra fuel, so why is the diode needed? These cars are new to me, but having built a number of nitrous/supercharged mustangs and other vehicles with MAF, I have never had to do this, including cars making well over 500 RWHP. Does the diode lower the voltage feed back to the ECU to keep the MAP voltage within factory range to prevent the computer from "Freaking out" due to the additional boost pressure and sending the computer into safe mode or something? I appreciate the info, thanks guys.

 

vent gauge is good. just put it where you can see it. mine is on my steering collum easy to see

 

you just answered your own question there buddy

 

So what effect does the diode have on the rest of the fuel curve if the voltage is lower than the ECU is programmed for? Seems like from 0-9 psi, the factory range, this would lean out the A/F ratio. Have you dyno'd this and recorded A/F ratios at all RPM/Boost ranges? I am not questioning your knowlege or that this works, it seems you have done it to enough cars to prove that it does, I am just wondering if some other tweaking would help increase this modification. I just found a link that showed the AFR and boost levels. Does anyone have a baseline run with the same recorded data? I'm not sure what the factory spec would look like, but considering 14.7 is ideal and many tuners err on the side of caution and run in the 15's on higher boost applications, the modified sheet looks like trouble in the making. You said that you don't know anyone that has ever had a problem after doing this? Is this sheet with a stock FPR? I wonder if that is the culprit? Have you ever pulled the head off a car that ran this for some time? Do you run a colder plug in these cars with the additional boost?

 

the increase in the maf g/s or airflow increases fuel and keeps the a/f in check. The ecu can add/subtract fuel within certain limits, thats why you are limited in boost unlike a chip.

 

running 15's for afr is lean. safe would be a lower number btw

 

You edited the post and added like 15 ?'s. You asked so many ?'s that all of your thoughts are now way to scattered.

Fuel is fine. For a turbo car you want ~12-12.5:1 a/f for the most power and lower for extra safty. Colder plug can be used when raising boost but lower the gap to .028 is deffinatly needed.

Those are about all i get in your random posted thoughts/questions

 

i run a steady 14.7 at idle and crusing and under boost 11.5-11.2aft

 

I found the link for the cyno sheets and a lot of questions came up. Sorry about the typo, I meant 13 for the A/F. Regarding the dyno run, is that with the stock FPR? I am wondering because I have seen this on Mustangs with cheap or stock regulators. The FPR will start to flutter under the higher boost pressure which will caused that erratic reading. Once a better aftermarket one is installed, this was fixed. How about the stock fuel pump and lines? What Hp are these good up to? What size are the feed lines?

 

The TT is a stock 3bar of fuel pressure with larger injectors and the a4 is a 4bar with smaller injectors. If you are talking about the dyno in the TT thread, he was using a 4bar instead of his stock 3bar which is a factory bosch replacement. Fuel pump is good until you get in the 300whp range and not sure what the stock fuel lines are, but they can handle 500whp range.