Fuel Cut/Fuel Stutter/Fuel Management

p-dub

Member
Please help! I'm not sure if this is fuel cut or what, but it sux and is very frustrating.

I've done a bunch of things to my msp such as:
manual boost control, front mount intercooler (from a DSM starion), custom stainless intercooler piping, cold air intake (straight to the turbo), blitz SS BOV, fuel pressure regulator, custom stainless exhaust, high flow catty, apex-i n-1 muff),i ain't gloatin, juss for info incase they have any bearing on the problem i'm experiencing.

1. I've heard some peeps say that there is no fuel cut on the msp, but I found that when i had my boost up to 10+ psi, and punched the throttle, the flow was being cut off abruptly. On my A/F guage, it would show rich when the boost was spiking and then instantly go to lean when the boost held steady for about 1 second. is this fuel cut? has anyone had a similar problem? how did you deal with it? if it is a fuel cut, how do i get around this, or does anyone know what senses the boost being too high and cutting off the flow.

2. when my boost is turned up to about 10 psi, and i have the throttle about less than half pressed, my car gets this horrible stutter when it gets around 10 psi. my A/F gauge reads rich and then goes to stoich/lean, than back to rich repeatedly. anyone know what this is?

3. If fuel management is the answer to these problems, what have you done? piggy back (what kind) or stand alone (what kind)? even if fuel management isn't the answer to this problem, i'd like feed back on fuel management alternatives because i'll be replacing it this winter.

Sheeit! i didn't mean for this question to be so long, but this problem has haunted me all summer, any info/tips greatly appreciated.

p.s. i was running my boost at 12-13 psi after i got my new intercooler a month ago and within a week i fried my turbo. still works a little, but tails off badly under high rpm (spikes at 10, leaks down to about 6), plus it sounds like a little girl screaming (jokes) when boosting. the turbine is extremely loose. anyway, learn from my impatience/stupidity: don't go crazy with the t-25.
 
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where to start?
1. how does your cold air intake go straight to the intercooler? that would bypass the whole "turbo" thing if that were the case
2. bov vented or recirc'd?
3. what is your fuel pressure set at?
4. for fuel cut, www.joepmbc.com has a fuel cut defenser
5. air fuel voltages are way more useful than blinking lights when trying to figure out a problem
6. your "stutter" may be the hesitation
7. for fuel management, spool is coming out with a stand alone called Microtech or something, or any of the other stand alones will work, Apex'i s-afc won't, greddy might but i'm not sure
8. your turbo could have fried itself because of lack of oil like a lot of people's have, which is why it "screaches". and this "spiking" you're talking about is a characteristic of manual boost controllers for the most part. if there is a lot of shaft play though, you've got problems, probably from lack of oil on the bearings.
9. get a better intercooler than the starion
in conclusion, it's time to learn about how to tune a car and how to keep things safe as you learn how to push limits.
 
p-dub said:
Please help! I'm not sure if this is fuel cut or what, but it sux and is very frustrating.

cold air intake (straight to the intercooler),

sorry, brain fart, i meant to say to the turbo.

and my BOV vents into atmosphere, not recirculated.
 
venting isn't exactly helping your a/f ratios stay where they're supposed to be. many people run it with no problems, but it is going to make you run more rich since the engine isn't seeing all of the air it metered and thinks is coming and has adjusted the amount of fuel to put in based on this metered air (i don't know if that made total sense, but you know what i'm sayin. it makes sense in my mind). sounds like you have more problems though.
 
jred321 said:
venting isn't exactly helping your a/f ratios stay where they're supposed to be. many people run it with no problems, but it is going to make you run more rich since the engine isn't seeing all of the air it metered and thinks is coming and has adjusted the amount of fuel to put in based on this metered air (i don't know if that made total sense, but you know what i'm sayin. it makes sense in my mind). sounds like you have more problems though.

these problems i'm having were occurring even when my car was for the most part stock and all i had done was boost control, intake, and fuel pressure regulator.
 
Call Perfworks about the piggyback - you could tune your entire fuel map. We added two extra injectors on my car, fuel won't be a problem. After one night of tuning, I was running up to 8 psi without a problem. Granted, I'm using a T3; a bit larger and differint from your T25.
 
Something else that you did I'm wondering about. You say you have a fuel pressure regulator. What type of regulator did you buy? Is it a rising rate regulator? Why did you feel the need to buy a regulator?

How are you monitoring all of your info? You say you are boosting to 10psi...I'm assuming you are using a boost gauge....and also a air/fuel meter....how about a fuel pressure gauge?

Not saying that this is your problem, but it might be somthing to look at.
 
OrangeAppeal said:
Something else that you did I'm wondering about. You say you have a fuel pressure regulator. What type of regulator did you buy? Is it a rising rate regulator? Why did you feel the need to buy a regulator?

How are you monitoring all of your info? You say you are boosting to 10psi...I'm assuming you are using a boost gauge....and also a air/fuel meter....how about a fuel pressure gauge?

Not saying that this is your problem, but it might be somthing to look at.

i'm starting to question the fuel pressure regulator myself. someone who had a better knowledge about cars than myself suggested it (even he's questioning it). yes, it's a rising rate regulator.

i have boost & a/f & egt guages. only have access to a temporary f/p gauge.
 
p-dub said:
i'm starting to question the fuel pressure regulator myself. someone who had a better knowledge about cars than myself suggested it (even he's questioning it). yes, it's a rising rate regulator.

i have boost & a/f & egt guages. only have access to a temporary f/p gauge.

Judging from past posts by others, I would find that the Fuel Pressure Regulator would be unnecessary. A/F mixtures already seem absurdly rich, which would mean too much fuel...even at 10psi without upping the fuel intake there were no lean conditions with the MSP.

If you plan on possibly going into fuel management, I still don't think you would need a fuel pressure regulator...in fact part of your problem you say your experiencing sounds like the common hesitation, and JoeP has put out a Fuel Pressure Reducer which cuts back on the amount of fuel dumped into the system and has helped many with the hesitation problem...going back to a stock fuel pressure regulator might help your problems some. I would start there and sell the aftermarket fuel pressure regulator.

just my $.02 though.
 
$100 says you're running way too rich. Most of us have leaned the car out with the fuel pressure mod from Joe P., and it still runs very rich.
 
OK, questions one and two are both caused by the same thing. This is the so called MAF/airflow overspeed "fuel cut". I bet if u put the stock air box on, problems one and two will go away (up to 10psi of boost). it is that CAI that is allowing the airflow over the MAF to flow to fast for the preset voltage range of the MAF. Get JoeP's FCD to fix this problem, or just put the stock air box back on (again, the stock air box is only good, for sure, up to 10psi with out the FCD). Going to lean this rapidly is NOT the hesitation. If it was the hesitation, then it would be WAY rich, but would not feel like u just hit something on the road. I have the Injen CAI, and I hit the "cut" around 9psi on cold "thick air" mornings, but I can go to 10 when it is hot with no real problems at all.

As far as the boost falling off at high reves, this is that POS internal waste gate being forced open prematurely. this will mostly happen in 1st through 3rd, maybe even 4th gear. But you should be able to hold the set boost level in 5th. There is a couple of ways to fix this, but I would say the BEST way is to disable and bypass the stock waste gate, and use an external waste gate setup like the one spool uses. Some people have just tightend the spring, but this seems like a "jerry rig" fix IMO.

And the BOV... Our cars DO NOT like it when u vent the BOV into the air. If u have any stall problems, try recirculating the BOV. I bet that would fix it right up...
 
e-manage won't work with our cars. not compatible with our computer.....and it seems(from talking to greddy reps and techs) greddy isn't looking for solution


ben
 
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