Fuel cut around 5,000 RPM

[slo03.5msp]

I would have to assume with the way fuel pressure is so high that the rrfpr isasking for more fuel than what your pump can supply. Hence the massive increase in pressure. You need a bigger pump. I wish there were some p5 guys to chime in. Iirc the stock msp pump is 190lph. I don't think the p5 pump is anywhere near that.

 

[KrayzieFox]

You need a bigger pump. I wish there were some p5 guys to chime in. Iirc the stock msp pump is 190lph. I don't think the p5 pump is anywhere near that.

I'm pretty sure they're the same pump.

 

[Wagonbacker9]

I would have to assume with the way fuel pressure is so high that the rrfpr isasking for more fuel than what your pump can supply. Hence the massive increase in pressure. You need a bigger pump. I wish there were some p5 guys to chime in. Iirc the stock msp pump is 190lph. I don't think the p5 pump is anywhere near that.

you've got it backwards, the rrfpr is forcing the fuel pressure up. the fact that it is going up (instead of falling back off sharply at the top) tells me the pump is keeping up.

 

[KrayzieFox]

the fact that it is going up (instead of falling back off sharply at the top) tells me the pump is keeping up.

Well actually, after some more driving around.. I've observed something that might indicate the pump crapping out on me.

1. At WOT my max fuel pressure is 68 psi, but it falls back down to 60-62 psi when I hit the lean spot at 5000 RPM.

2. After some aggressive driving the fuel pressure at idle gets a little bouncy. When just cruising under vacuum the pressure is 36 psi steady, but if I let off the gas it bounces down a little then up to 42 psi, then back down to 36 psi?

I think the pump is at the end of its life. I'm ordering the Walbro from Ken tomorrow.

 

[Alejo_NIN]

allowing the car to flow more (or cooler) air bumps up the voltage reading from the maf. If you were already near the max (Stock MSPs have been know to hit fuel cut in cold weather, I know mine has)... If the voltage goes over max voltage (5V), you'll fuel cut. a maf clamp will stop the ECU from seeing this volatage, and as long as you're not relying on your ECU to match that added air (metered by MAF) with more fuel (if you're using a FMU, you aren't) this will allow your car to run when normally the ECU would shut it down to protect itself...

just for the record, this should ONLY be done when you KNOW you're getting adiquate fuel delivery. if you are getting a lean condition, do this with EXTREME caution. datalog your fuel pressure, wideband, and ideally boost... make sure there aren't any holes or anything.

so, basically this is what a Fuel Cut Defenser does...
hmmm
i have a voltage clamp that works with boost...i might be able to convert it to work at a certain voltage.....but i thought the SS AFC was able to modify this signal and prevent fuel cut....

this is exactly what is happening to me...when the car is cold it fuel cuts like a b****.....i cna't wait for december and see what happens.

 

[tcz]

Have you tried to replace the stock MAF sensor by a high-flow one?

 

[Alejo_NIN]

i don't know how would that help me as i have a stock ecu, wouldn't the ecu go crazy with it?

 

[SeR_Cyclops]

I have a FCD in the for sale section.

 

[u812many73]

Well actually, after some more driving around.. I've observed something that might indicate the pump crapping out on me.

1. At WOT my max fuel pressure is 68 psi, but it falls back down to 60-62 psi when I hit the lean spot at 5000 RPM.

2. After some aggressive driving the fuel pressure at idle gets a little bouncy. When just cruising under vacuum the pressure is 36 psi steady, but if I let off the gas it bounces down a little then up to 42 psi, then back down to 36 psi?

I think the pump is at the end of its life. I'm ordering the Walbro from Ken tomorrow.

So did the pump end up fixing the problem?

 

[squire0311]

What do you use for fuel management JCell?

i dont know how much help it would be but buy a split second air/fuel controller and tune that way. with that u can also put in bigger injectors.(wow)