[LNF SS/TC] - Stock Internal & BW S252 Turbo

pisco

Well-Known Member
I've made some progress finalizing the intake piping on my goblin. Per peoples advice, I increased the pipe diameter of my MAF sensor area from 2.5" to 3" for about 18 inches or so. I got a MAP bracket from Adam and welded it onto the 3" pipe as well as a new MAF bracket, so everything is sealed and in place in my new 3" pipe.
  • The donor was stock with a draw-through ~3" K&N Typhoon intake
    • ECM was stock, car ran fine I'm assuming (I never drove it)
  • The goblin runs/idles fine with the 2.5" pipe in blow-through configuration
    • Once in 'higher' boost the MAF throws an out of range code occasionally
  • The car does not idle or run with the 3" pipe on with the MAF plugged in in a blow-through configuration
    • It idles if the MAF is unplugged, as expected
I've done some research on MAF scaling on YouTube but I don't fully understand how to manipulate it to get it idling so I can start scanning to dial the MAF back in for the 3" blow through.

Anyone have some thoughts on what direction I can go to get a base MAF scale to idle and begin scanning?

Add/Subtract? What %? Trial and error until I get a decent idle and then go from there?

Thanks for any thoughts!
double check the maf is in the right way
 

Ross

Goblin Guru
I've made some progress finalizing the intake piping on my goblin. Per peoples advice, I increased the pipe diameter of my MAF sensor area from 2.5" to 3" for about 18 inches or so. I got a MAP bracket from Adam and welded it onto the 3" pipe as well as a new MAF bracket, so everything is sealed and in place in my new 3" pipe.
  • The donor was stock with a draw-through ~3" K&N Typhoon intake
    • ECM was stock, car ran fine I'm assuming (I never drove it)
  • The goblin runs/idles fine with the 2.5" pipe in blow-through configuration
    • Once in 'higher' boost the MAF throws an out of range code occasionally
  • The car does not idle or run with the 3" pipe on with the MAF plugged in in a blow-through configuration
    • It idles if the MAF is unplugged, as expected
I've done some research on MAF scaling on YouTube but I don't fully understand how to manipulate it to get it idling so I can start scanning to dial the MAF back in for the 3" blow through.

Anyone have some thoughts on what direction I can go to get a base MAF scale to idle and begin scanning?

Add/Subtract? What %? Trial and error until I get a decent idle and then go from there?

Thanks for any thoughts!
So increasing your intake from 2.5" to 3", but using the stock MAF sensor, right?
Well, I would do the math to make a best guess, and tune from there.

2.5PI = 7.85 sq. inches
3PI = 9.42
9.42/7.85 = 1.2 so you have increased the intake cross section area by 20%

Go to MAF Calibration table, (Airflow vs Frequency) and multiply the whole table by 1.2


Update: I should have used PI R^2 to calculate the area, not PI*Diameter.

PI(1.25^2) = 4.91 square inches
PI(1.5^2) = 7.07
7.07/4.91 = 1.44 So you have increased the intake cross section area by 44%

Multiply the MAF table by 1.44

Then do standard MAF tuning from there.

HP Tuners defines the MAF table as:
[ECM] 12160 - MAF Airflow vs. Output Frequency: This table is used to calibrate the MAF sensor. The MAF sensor works by outputting a frequency signal that is proportional to the airflow through the meter. This table is used to lookup the Airflow (g/sec) value for a given frequency and ultimately calculate the Airmass (g/cyl) used for fueling calculations. If you modify your MAF meter you will likely have to modify this table.
 
Last edited:

Mayor West

Goblin Guru
double check the maf is in the right way
This is more of a tuning question than an assembly question, the MAF is pointed correctly.

So increasing your intake from 2.5" to 3", but using the stock MAF sensor, right?
Well, I would do the math to make a best guess, and tune from there.

2.5PI = 7.85 sq. inches
3PI = 9.42
9.42/7.85 = 1.2 so you have increased the intake cross section area by 20%

Go to MAF Calibration table, (Airflow vs Frequency) and multiply the whole table by 1.2

Then do standard MAF tuning from there.

HP Tuners defines the MAF table as:
[ECM] 12160 - MAF Airflow vs. Output Frequency: This table is used to calibrate the MAF sensor. The MAF sensor works by outputting a frequency signal that is proportional to the airflow through the meter. This table is used to lookup the Airflow (g/sec) value for a given frequency and ultimately calculate the Airmass (g/cyl) used for fueling calculations. If you modify your MAF meter you will likely have to modify this table.
In response to Rauq's suggestion to multiply the whole table, I said that I read that it's not as simple as that... so I was just wanting to make sure from others experiences... because of the whole "blow-through/draw-through" changes as well especially since the car originally came with a 3" intake. There's a lot of variables.

I'll try the 1.2x multiplier and see where it gets me.
 

Ross

Goblin Guru
There are only a few tuners in this forum...
Do you have a reference to what you read, or where you read it? HP Tuners forum?
Since all Goblins have changed their intake, then anyone who has MAF tuned a Goblin has some experience, maybe not the specific experience of changing the intake pipe diameter and tuning it themselves.
 

pisco

Well-Known Member
This is more of a tuning question than an assembly question, the MAF is pointed correctly.



In response to Rauq's suggestion to multiply the whole table, I said that I read that it's not as simple as that... so I was just wanting to make sure from others experiences... because of the whole "blow-through/draw-through" changes as well especially since the car originally came with a 3" intake. There's a lot of variables.

I'll try the 1.2x multiplier and see where it gets me.
Sorry I didn’t read the whole thread, just a quick thought as to why it revs and no idle.
 
Last edited:

Gtstorey

Goblin Guru
Not weighing in on the tuning problem, but the first suggestion of 1.4x is the correct increase in cross sectional area for a 2.5 inch to 3 inch pipe increase. Ross used the formula for circumference not area.
 

Ross

Goblin Guru
This is more of a tuning question than an assembly question, the MAF is pointed correctly.



In response to Rauq's suggestion to multiply the whole table, I said that I read that it's not as simple as that... so I was just wanting to make sure from others experiences... because of the whole "blow-through/draw-through" changes as well especially since the car originally came with a 3" intake. There's a lot of variables.

I'll try the 1.2x multiplier and see where it gets me.
If you are really worried that you are a long way off in air/fuel ratio, then I can think of 2 things to do to keep the engine safe:
1. Increase the fuel 10% above where the math calculates we need to be. (Always tune from rich starting point)
2. When you first start your engine, put it in closed loop, so that the ECU can change the short term fuel trims.
 

Ross

Goblin Guru
Not weighing in on the tuning problem, but the first suggestion of 1.4x is the correct increase in cross sectional area for a 2.5 inch to 3 inch pipe increase. Ross used the formula for circumference not area.
Thank you for checking my math! Oops... wrong formula.
 

Rauq

Goblin Guru
Ross's general take aligns with mine. If it runs without the MAF but won't even idle with it plugged in, you're either hella rich, hella lean, or have other (hardware-ish) issues. If the only change was increasing the diameter of the MAF pipe, then it makes sense that the MAF would underestimate airmass (because it's seeing less of the cross-sectional area of the pipe). Increasing that table by 44% across the board isn't going to get it perfect, but should at least get you into the neighborhood and idling so your scans can start telling you where your future corrections need to go. And like Ross said, another 10% should get you into the rich side of stoich so you can work towards ideal from the safe side.

I hope this isn't too far off topic, but doesn't the LNF have a factory wideband? Do you have an aftermarket wideband just for the gauge?
 

Mayor West

Goblin Guru
I hope this isn't too far off topic, but doesn't the LNF have a factory wideband? Do you have an aftermarket wideband just for the gauge?
Yeah, I didn't know that the LNF had a factory wideband until after I spend 300 bucks getting a stand alone gauge. I may try to sell it but I haven't thought about it too much.
 

ctuinstra

Goblin Guru
Use the multiplier that Ross mentioned. Then data log without putting it under heavy load or high RPM and adjust from there. The closed loop system will compensate up to a point, so keep an eye on the fuel trims to see what they are doing. Ultimately doing a MAF tune will dial it in better than any suggestions or guesses. Many of the builders get away without tuning and the closed loop takes care of it, but doing the tuning helps a heck of a lot and did wonders for our car. The MAF tuning is easy and there are a couple of us that can help you with it.
 

pisco

Well-Known Member
Use the multiplier that Ross mentioned. Then data log without putting it under heavy load or high RPM and adjust from there. The closed loop system will compensate up to a point, so keep an eye on the fuel trims to see what they are doing. Ultimately doing a MAF tune will dial it in better than any suggestions or guesses. Many of the builders get away without tuning and the closed loop takes care of it, but doing the tuning helps a heck of a lot and did wonders for our car. The MAF tuning is easy and there are a couple of us that can help you with it.
I’m excited for this stage of my project but a long way off. I’ve been wanting to learn about tuning for a long time.
 

Mayor West

Goblin Guru
Goat Rope Garage is a decent resource but I think his videos are way too specific to his particular build, and I find it difficult to take his advice and apply it to my situation.
 

Mayor West

Goblin Guru
Your S2000 has heat, so did my M3 when I took it out in the winter with the top down. #ConvertibleLife

To answer your question, I haven't worked on it lately.
 
Top