Fuel flow problem

[IPT]

HELP ME!!

OK I am at a loss. Here is my situation. I have just installed an older style mutt turbo. 50trim, TA compressor housing, mitsu center section, clipped TDO5 wheel and 7cm turbine housing.

The rest of the car is setup like this:
255 fuel pump
650 cc injectors (ball-disc)
PMS unit with the upgraded MAF sensor
Joe p boost controller
3” O2 eliminator turbo back exhaust
DSM Performance FMIC
Custom IC piping
Ect…

My problem is that at 20 psi of boost. When I get to 6000 rpms the injector duty cycle hits 80-85% and will not go any higher. The duty cycle before that flows the rpms, as the rpms goes up so does the duty cycle. AT 6K the duty cycle flat lines, the O2 voltage drops and timing starts to get pulled the EGTs stay below 1600 F at the 7K shift.

From what I am seeing, I need more fuel. That is why I am confused. There are lots of these 50 trims out there and they have 650cc injectors and have no problem. Why am I?? Is is because there is no restriction in front of the turbo any more and it is flowing more air?? Or what?? I am looking for any ideas on why this is happening and how to solve it.

I have been looking at AFPR. What ones do you have and where do I get a good inexpensive gauge for it??

Thanks.. LAter

 

[Violater101]

That's and odd problem indeed. Smth doesn't sound right because if you needed more fuel, wouldn't your duty cycle be maxed at 100%. I am at around 86% DC myself and not having any problems with my setup. I guess I'm still a newbie, but it doesn't make sense that timing is being pulled, yet your EGT's arn't rising that fast and stay below 1600F. If you timing is being pulled, I would expect to see HIGH EGT's. You might be on to something though with the actual fuel pressure. I hear alot of people are really happy with the spoolinup fpr. Try www.spoolinup.com. I believe they are like $130. Anyhow, good luck

 

[jdmawd]

I would start with a good in car fpg, so you can see if fuel pressure is dropping at 20 psi and 6k. (I never understood why people run fpg's under the hood) the problem could be as small as the stock regulator or a vac leak from the fuel pressure solenoid. i use the AFPR from www.chargedair.com

 

[rdrkt]

I have a Russell fitting welded on to the end of my fuel rail and I have an AEM regulator with the basic $20 screw in gauge and it works great. Sorry no picture

Are your positive that you aren’t out running your maf? What type of air flow numbers are you getting?

 

[IPT]

I have the Blow through MAF sensor that has to be used on a 1G. It is good to over 500 hp. I am sure that I am not that far. I have the car troe apart installing a set of web cams and underdrive pulleys I think it might still be in the tuning. IF I cannot get the stock ecu to do what I want it to do then I will just put the PMS into stand alone mode and make my own fuel maps.

 

[NosLaser]

The only thing that comes to mind is you may be experiencing a pressure drop. You need to install a fuel pressure gauge that you can monitor from the cockpit, and see what it's doing. That's my first guess, and I could definately be way off base.

Regards,

 

[rdrkt]

Mounting a fp gauge in the cockpit is a PITA. I wouldn’t want an electrical unit but a mechanical unit is a an even bigger pain.

What I ended up doing was run a mechanical autometer gauge under my hood and taped it to my wiper and verified that everything worked then just put in a simple screw type gauge when I was all done. YMMV

 

[NosLaser]

That's exactly why a lot of old hot rodders would mount the gauge on the hood. It is a pain, however it's good to have. With today's engine management technology, the O2 sensor and knock sensor are usually enough to save your butt, but in the old days, you had to watch fuel pressure. It's a small price to pay to save your motor, but what rdrkt said will work. Try that, and see if that's the problem.

Regards,

 

[jdmawd]

The new style autometer fpg's are very accurate, they use a processor to speed up the response from the sender.it is as easy to mount, as a boost gauge or any other gauge. they are kinda pricey, I have one mounted in the mustang, and its awesome here is a PIC.

 

[IPT]

OK.. I have a gauge on order. Even if that is not it it is a good tuning tool to have.

Question. Why would the duty cycle climb with the rpms until 6000 rpms where the duty cycle levels off at 85% the rest off the way until I shift. How would fuel pressure cause this??