Fuel cut w/2g mas,650cc's,tdo6 20g

[NJdsmguru]

Every since the colder weather has came I've been hitting fuel cut with my car. I'm running a tdo6 20g@ 20 psi 93 octane, 650cc's,2g mas,walbro 255,afc, base fp set @37 psi. I have my current afc settings at lo 1k+6 2k+6 3k+8 4k+8 5k+8 5.5k+8 6k+8 hi...1k-7k=+5 across. It only happens on pump gas. I've seen as much as 2538hz @ wot in 3rd gear. The car starts to pull like a mofo then fuel cuts. What are my options .........raise my base fp?, get a eprom chip w/fuel cut removed? buy maft and 720cc injectors?

 

[peregrine]

get a keydiver chip and be done with it. fuel cut has been a source of great frustration for alot of us. if you have an eprom get it chipped!!

 

[1fastlaser]

your high settings are too rich.Where it cuts lean it out.Im negative 20-30 on all my high settings

 

[HighPSI TSi Guy]

yeah those are some very strange settings.. that's also a very high Hz value for 20 lbs

 

[CanadianTSi]

With the Fuel Cut and the High Hz values it sounds like a boost leak to me...

 

[psychlow]

With the Fuel Cut and the High Hz values it sounds like a boost leak to me...

Bingo!

 

[NJdsmguru]

i check for boost leaks once a week and i have none. It still fuel cuts when i lean it out. I'm running 9.0:1 ross pistons and the car seems to have more power when the hi throttle are in positive range. It only does it during the evening when it's cold as hell.I have a keydiver chip with all stage 3 mods and dual timing maps on the way hopefully it should help me iron out my problem.

 

[psychlow]

I still don't see how you're getting that much Hz, especially on a 2G MAF @ 20lbs....

 

[NJdsmguru]

i leaned out the car again tonight hi throttle -5. i logged hz count again on afc wot 17 psi 3rd gear 2374hz....no fuel cut

 

[NJdsmguru]

oh yeah my hz count didn't go up this much until I installed 3" intake pipe.

 

[nazthug]

you guys need to learn how the afc works and what it does


by adding fuel with it, its bringing your fuel cut even further down then stock

THE ONLY REASON people's cars dont hit fuel cut is because they use the afc to pull fuel


NOW most people think the afc just pulls fuel, but dont know how

By pulling fuel by the afc, what you are doing is actually giving hte mafs a larger range, and making it take more air/boost before it hits the stock fuel cut, youre just scaling it back, so the more you pull, effectively, the less chance of fuel cut as you are raising the bar for where it will hit

soo....PULL FUEL BACK, when you get bigger injectors, you use the afc to scale it the mafs back down to better control the larger injectors, you dont add fuel when you get bigger injectors

NOW...if youre LEANING out thats a different story, instead of adding fuel with the afc, you should just go to a bigger injector, and keep your afc in the negatives, by keeping hte afc positive, youre gonna hit fuel cut faster then even stock


I ran into thhis problem with my car, i have a small 16g, fmic, 550s, etc..

i started runing over 20psi and when i did, it started finaly runing lean, i was at about -15

i started brining it up, and yes it brought the a/f back into safe range BUT it reintroduced fuel cut, as i wasnt giving the mafs a large enough range....

SOO it was time to go to bigger injectors.

 

[peregrine]

you guys need to learn how the afc works and what it does


by adding fuel with it, its bringing your fuel cut even further down then stock

THE ONLY REASON people's cars dont hit fuel cut is because they use the afc to pull fuel


NOW most people think the afc just pulls fuel, but dont know how

By pulling fuel by the afc, what you are doing is actually giving hte mafs a larger range, and making it take more air/boost before it hits the stock fuel cut, youre just scaling it back, so the more you pull, effectively, the less chance of fuel cut as you are raising the bar for where it will hit

soo....PULL FUEL BACK, when you get bigger injectors, you use the afc to scale it the mafs back down to better control the larger injectors, you dont add fuel when you get bigger injectors

NOW...if youre LEANING out thats a different story, instead of adding fuel with the afc, you should just go to a bigger injector, and keep your afc in the negatives, by keeping hte afc positive, youre gonna hit fuel cut faster then even stock


I ran into thhis problem with my car, i have a small 16g, fmic, 550s, etc..

i started runing over 20psi and when i did, it started finaly runing lean, i was at about -15

i started brining it up, and yes it brought the a/f back into safe range BUT it reintroduced fuel cut, as i wasnt giving the mafs a large enough range....

SOO it was time to go to bigger injectors.

this is by far the most thought out WRONG response ive seen on here. the afc controls fuel by changing the airflow signal to the ecu. it doesnt "pull fuel" it just tells the ecu that there is less air coming into the motor so it adds less fuel. this helps with fuel cut becuase the ecu sees less air coming in. your right on the results but wrong in the explanation.

 

[psychlow]

this is by far the most thought out WRONG response ive seen on here. the afc controls fuel by changing the airflow signal to the ecu. it doesnt "pull fuel" it just tells the ecu that there is less air coming into the motor so it adds less fuel.

Agreed. You were right, nazthug, you just didn't explain it as well as you could have.

NJDSMGuru, when you check for boost leaks, how much pressure do you put into the system? I'd suggest trying 25PSI to make certain you have no leaks at high pressure. You have to remember that air from a turbo will be much hotter than air from an air compressor or a bike pump, and may possibly be more prone to escaping through a hot seal than a cold one.

Just a thought.

 

[nazthug]

thats what i thought i said, i was trying to say that most peole THINK it pulls fuel, where in real life, it just tricks the MAFS and manipulates the signal

I should know, i dealt with it for 3 years on my focus before i went standalone and a map sensor instead of MAFS,

 

[crankbender]

this is by far the most thought out WRONG response ive seen on here. the afc controls fuel by changing the airflow signal to the ecu. it doesnt "pull fuel" it just tells the ecu that there is less air coming into the motor so it adds less fuel. this helps with fuel cut becuase the ecu sees less air coming in. your right on the results but wrong in the explanation.

Absolutely correct. The end result is a manipulated signal to the ECU as the afc does not actually change the mafs at all. The ECU sees less air than is actually flowing when you trim the fuel levels down and more air when you trim them up.

This said you can't give a range on the afc trims that will result in fuel cut. They trims are percentages and therefore are completely dependent on what the actual air count is.

In general what wasn't mentioned was that as you increase injector size you will need to decrease fuel trims.

Peter

 

[psychlow]

In general what wasn't mentioned was that as you increase injector size you will need to decrease fuel trims.

Peter, just clarifying:

The fuel trims on the AFC, not the fuel trims as read with a logger. The logger-read FT's you'll still want at 100% (1G) or 0% (2G).

 

[NDgsx]

Keep in mind that the ECU uses the hz count as it's indicator of load not only for fuel maps, but also timing maps. If you have to make an extremely low HZ count to try to get the correct A/F you'll end up knocking, because the ECU will try to give too much timing advance. On a 1G or 6bolt swapped 2G you can retrard base timing with the CAS to lower the actual timing at the plug and see what the ECU is trying to give out as timing advance (the logger is assuming you have 5 degrees base timing, if you have base timing at 0 and the logger says 25 degrees advacne you're actually running 20 degrees timing advance).
While you can just leave the CAS at 0 and run the car low throtle driveability won't be as good and cold starting can be hard. In this case lower you base fuel pressure and increase the airflow signal with the AFC to maintain the same A/F, the higher HZ count will put in a timing map with less advance and allow you to advance the CAS.

 

[peregrine]

While you can just leave the CAS at 0 and run the car low throtle driveability won't be as good and cold starting can be hard. In this case lower you base fuel pressure and increase the airflow signal with the AFC to maintain the same A/F, the higher HZ count will put in a timing map with less advance and allow you to advance the CAS.

i had to do this with my PTE 680 inj's. i never could find a happy medium to get it to run good on pump. i ended up saying screw it and ran 110 octane all the time.