should I be fuel cuttin @ 9psi????????????

[skinnykenny84]

No dude, I understand exactly what your trying to say. But if theres no leak then what am I suppose to do?

I ran it up to 20 psi and it held long enough for me to look over the entire intercooler system and spray soapy water over all couplers and suspicious areas, ie t.b., etc..

 

[skinnykenny84]

The main thing I dont understand is if I turn the boost down from 15 to 13psi it does not fuel cut.

If I run 15 psi on a hot day it does not fuel cut. If the temp drops below 80-85* it will fuel cut. Now I know that when its colder outside the air is more dense there for it boost harder.

 

[skinnykenny84]

Short of a getting a EPROM ECU and a chip or DSMLink the only thing you can do is make 100% sure you don't have any boost leaks at the highest boost pressure you want to run and get bigger injectors so you can lie to the ECU with a SAFC or MAFT about how much air is being metered.
Steve

Isnt this what I said I wanted to do in the first place

 

[boostdog]

could his maf be going bad? i know it's a stretch but i was able to boost 17-18 psi all day long and not get fuel cut with a hacked 1g maf.

 

[TSisleeper]

hmm... no one said anything about timming or fuel press ? maybe I'm way off with this comment?

 

[skinnykenny84]

could his maf be going bad? i know it's a stretch but i was able to boost 17-18 psi all day long and not get fuel cut with a hacked 1g maf.

Now these are the kind of replies Im looking for. Something other than boost leak. The car has no boost leak! I know its the easiest answer but cant be the only answer.


There has to be other factors that can cause fuel cut with out having a boost leak, right?
I mean It could even be an ingnition related problem too correct??

 

[skinnykenny84]

So I changed out my MAF with a friends and my fuel cut problems went away, so I thought. After a day or 2 of driving it has returned like a s.t.d.

So back to the drawing board. I do a boost leak test again today and can only get about 6 psi on my gauge. Now Im using one of those weak a$$ air pumps that you plug into your cars lighter, its all I have at the moment. Well at 6psi the only leak I found is the vent hole on the mbc. But isnt that supposed to leak? Its just funny I never noticed it leaking before. Of course when I put my finger over the hole I cant find any other leak and it stays at 6psi for at least 15-20sec. Now I know 6psi is not enough to do much with.

 

[eclipsegsx1736]

So I changed out my MAF with a friends and my fuel cut problems went away, so I thought. After a day or 2 of driving it has returned like a s.t.d.

So back to the drawing board. I do a boost leak test again today and can only get about 6 psi on my gauge. Now Im using one of those weak a$$ air pumps that you plug into your cars lighter, its all I have at the moment. Well at 6psi the only leak I found is the vent hole on the mbc. But isnt that supposed to leak? Its just funny I never noticed it leaking before. Of course when I put my finger over the hole I cant find any other leak and it stays at 6psi for at least 15-20sec. Now I know 6psi is not enough to do much with.

You have to disable the MBC or turn it up to full before doing a boost leak test or it will leak thru that hole. Two things that have caused me to hit fuel cut were a boost leak, and having the SAFC too rich. I had to compensate for an exhaust leak that i had for a few days by richening the SAFC to like +13 or so on stock injectors, and it would cause it to cut above 15 psi, especially at night, because the SAFC tricks the ECU into thinking there is more airflow than there really is, so it cuts.

 

[scottsee]

Let me try and explain what is happening. the 2g ecu has a built in fuel cut (air cut) when it reaches a certian amount of air seen through the MAF, roughly around 2.1g/rev. When you have a boost leak your turbo has to spin (boost) a lot more air through to keep pressure where you have set it. Kind of like blowing through a straw with a hole in it. When you have a boost leak the air passing through the maf will show the inflated HZ air signal making fuel cut (air cut) happen quicker and at lower SEEN boost levels. In actuallity you will be spinning the turbo into much higher RPM's and much lower effency ranges. Think of it like this

No boost leak. 15psi seen, 15psi actual = 1.9g/rev airflow (not actual, just example)
Boost leak. 15psi seen, 21psi actual = 2.2g/rev airflow. (not actual, just example)

Fix boost leaks, keep seen airflow under 2.1g/rev and you'll be golden.

Like everyone has said. You need a device to intercept the MAF signal and change it to what "you" want the ECU to see, or lower your boost.

 

[joe]

you can also hit fuel cut with too much fuel!

 

[sweet97]

you can also hit fuel cut with too much fuel!

Not true. It's been explained very well in the previous posts. Fuel cut occurs when the ECU "SEES" too much air flow.
If you have a good running DSM ( yes they exist!) and added fuel pressure to increase the fuel level all it will do is misfire badly and pour black smoke out the exhaust but it will not cut. Not trying to knock you but that statement is wrong and did not want someone who did not understand fuel cut to get a wrong description of what causes fuel cut.
You do get more fuel when you adjust a MAFT lets say to what is a "RICHER" setting but what you are really doing is tricking the ECU as to how much air is flowing into the motor so it adds fuel but it is the air flow count that causes the ECU to cut the fuel as a safety measure to save the motor as it (ECU) "perceives" that the engine is taking in a lot of air, above it's set parameters, so it cuts. If you get a KEYDIVER chip in an EPROM ECU Jeff will remove fuel cut. Just have the proper gauges to know what is going on in your motor to keep it running safe as now you are in control of what happens to the motor! mark Again it was explained very well just a post or 2 ago. You can go to www.vfaq.com and find the definition of fuel cut. Thanks, Mark