2g MAF in 1g Fuel Cut Question

[habitatguy187]

So I just finished reading the ECU primer again, and out of it I have a question. I'm about to install a 2g maf with 550s in my 1g.

My question is will I hit fuel cut at a different psi due to the 2g maf? Thanks

 

[jking29]

You won't hit fuel cut with the 2g mas unless you are running a turbo capable of 50+lb/min. You'll be good to go.

 

[habitatguy187]

"50+lb/min"

Do you mean psi? And could you tell me why this is. I sorta understand the concept but can't fully grasp it.

Thanks

 

[My1GLaser]

You won't hit fuel cut with the 2g mas unless you are running a turbo capable of 50+lb/min. You'll be good to go.

I don't think that's true.

You won't overrun the MAS until about 2700hz, which is I think what he meant. Every setup will be slightly different for psi and lb/min that it causes the MAS to read 2700 hz, but a 45-50lb/min turbo seems about right. I am overrunning mine now at 44lb/min, but my airflow is overinflated according to DSMLink.

As far as fuel cut, the 2g MAS nearly compensates directly for 550 inj. So thats about 20% less airflow counts which should equate to the same 20% delay in fuel cut.

I would guess about 3-5 psi.

 

[habitatguy187]

I still don't understand what you guys are talking about when you type something like this, "44lb/min" Could someone explain?

Thanks in advance

 

[My1GLaser]

It is a measure of mass airflow. Literally, 44 pounds per minute of air coming out of the turbo. Whereas "CFM" (cubic feet per minute) is a volumetric airflow measurement. Here is a link to a calculator I use, scroll down the page a bit. Turbo and Supercharger Maps I believe it underestimates, since it is generally accepted that we have about 10 whp per lb/min of airflow.

 

[toofast82]

To correctly use a 2g maf and 550s, there are several changes to be made in the coding of the ecu. Ive heard of the compensation but it doesnt feel safe as only means of tuning imho. I wouldnt feel safe running more than 15lbs like that

 

[habitatguy187]

To correctly use a 2g maf and 550s, there are several changes to be made in the coding of the ecu. Ive heard of the compensation but it doesnt feel safe as only means of tuning imho. I wouldnt feel safe running more than 15lbs like that

Yeah I've been told that you'll run lean up top and start getting knock. I'll log it and see how far I can push it. Just waiting on a new intake pipe from the classifieds..........for 2 1/2 weeks now

 

[theebluecrx]

Yeah I've been told that you'll run lean up top and start getting knock. I'll log it and see how far I can push it. Just waiting on a new intake pipe from the classifieds..........for 2 1/2 weeks now

I did but Br7's and base timing at 0" fixed it.

 

[habitatguy187]

I did but Br7's and base timing at 0" fixed it.

Forgive my newbness to tuning, but I thought that base timing was supposed to be at 0*? If now, how hard is it to change the base timing of a 1g?

 

[xxsupralvrxx]

i think 4-5 degrees

 

[habitatguy187]

Yeah Jeff O. explained a little that setting base timing to 0* is bad overall. I'm not gonna do it.

 

[theebluecrx]

Yeah Jeff O. explained a little that setting base timing to 0* is bad overall. I'm not gonna do it.

Your retarding the timing it will save your engine if your tuning isnt down.You dont want too much timing at full boost= blown parts.

 

[habitatguy187]

Your retarding the timing it will save your engine if your tuning isnt down.You dont want too much timing at full boost= blown parts.

He said, "But, setting the timing to 0* to get rid of knock is a bad thing. The car will be sluggish around town, gas mileage will be worse, and driveability will suck, IMO."

Did you notice any of this? I don't understand timing yet so I'll look into doing that once I get a good grasp on exactly what it is and how it works.

 

[jking29]

Leave your timing @ 5 degrees. It will be sluggish off boost. If you have to retard timing back with a 2g mas and 550's to stay out of knock, you have other problems. I ran that combination on my car for a couple of years with very minimal changes to the afc. It is a great combination that is very easy to tune with an afc. I also did not get fuel cut with this combination. With the small 16g, I would spike to 23-24 and settle to 22 and never got fuel cut with it.

 

[habitatguy187]

It is a great combination that is very easy to tune with an afc. I also did not get fuel cut with this combination. With the small 16g, I would spike to 23-24 and settle to 22 and never got fuel cut with it.

Good to hear. The rest of the stuff is supposed to be here on the 6th, I'll let you guys know how it works out.