2g mas mod

[gsxitement]

i can't find it in here but i know i read it somewhere about adjusting the screw in the bottom of the mas to get a leaner or richer mixture.....if you know tell me or just link me to it. thanks

 

[ninjanick]

Try vfaq.com It's just a plastic screw towards the bottom of the MAF. Dig out the RTV and expose the screw. Turn it in to get less air and turn it out to get more air through the lower honeycomb section.

 

[nine5raptor]

http://www.roadraceengineering.com/eclipsetech/2gmasadjustment.htm

there ya go

 

[gsxitement]

alright...thanks guys.....

 

[whitegst97]

I ahd a question about this topic, ok, if you let the screw out you will be letting more air in that the computer is not reading, there for the car will be leaner but the computer wont know it right? Then how would you tell how much fuel to add to compensate at idle, or how owuld you know how rich or lean you're running. If the computer is not reading that air then your 02 readings are going to be the same right, or am i wrong, please someone inform me on this. Thanks

 

[nine5raptor]

02 readings are independent of the metered/unmetered air for measuring purposes.
As you let in more unmetered air though, your 02s will drop and you will have a higher chance of knocking and blowing the engine if you don't monitor everything carefully.

 

[whitegst97]

Ok i have one more thing to add, i just logged a run from school to my house and well the timing at 4k is 5 and the 02 readings are at .96. At around 5105 RPM's the timing is at 8 and the 02's are the same, .96. But what i don't get get is how at higher RPM's such as 6160 pm's which the timing is at 15 Deg, but the 02's are still the same. Home come even though the 02's are not changing the timing is, and also at such low rpms like 3k the timing is at 18 withthe 02's being at .90. Can someone explain to me about this log, and why certain things happen. Thanks a lot I really appreciate your time.

 

[raped]

the faster your engine is running the more timing you will get.

 

[kpt4321]

The oxygen sensor reading and the timing advance have no direct correlation. Timing is effected by airflow and knock.

It is natural for the 2g ECU to start with the timing rather low, and then to increase it as the rpm's climb. As long as the timing advances smoothly, then you will probably be fine.

 

[Blk_99gst]

Originally posted by raped
the faster your engine is running the more timing you will get.

Umm, nooo... It is normally true that timing will advance as you increase through the rpm range. But if you have some serious tuning problems (ie running lean and getting knock) in the higher rpms, timing can get pulled and go down.

 

[Blk_99gst]

Originally posted by whitegst97
Ok i have one more thing to add, i just logged a run from school to my house and well the timing at 4k is 5 and the 02 readings are at .96. At around 5105 RPM's the timing is at 8 and the 02's are the same, .96. But what i don't get get is how at higher RPM's such as 6160 pm's which the timing is at 15 Deg, but the 02's are still the same. Home come even though the 02's are not changing the timing is, and also at such low rpms like 3k the timing is at 18 withthe 02's being at .90. Can someone explain to me about this log, and why certain things happen. Thanks a lot I really appreciate your time.

Why certain things happen..hmm, I'll try. Your log explaination above is pretty normal. Although dropping to 5deg of timing when boost hits is a little low in my opinion. The 8degs at 5100rpm is O.K, could wish that it was a little higher. I'll attach a picture of one of my logs when I had the t25, stock injectors and fuel pump.

Here's how things work. Your car is running along fine, timing is high, o2 values are in closed loop by the ecu (ecu is cycling fuel controls). Then you floor it, and when boost hits, the ecu will pull back timing normally to around 8-10degs and it will go into open loop of fuel control. As you increase throught the rpm range, the ecu will continue to advacne timing as long as there is no knock or severe knock. The o2 values stay the say because the ecu is providing the max fuel delievery at WOT and you will run (safely) rich through the rpm range. Hope this explains things a little bit.

 

[whitegst97]

how come you were running so rich? Thanks for the explanation,i thought it was just me

 

[Blk_99gst]

It's really not that rich. Naturally all of our cars run pretty rich stock from the factory. It's a little rich in 2nd gear (.98 and .96), but in 3rd gear, there's a couple of .96's but most .94's. If it was lower than .94, I would start worry about hitting lean condictions. So it's really not that rich; top of 3rd gear is what really matters.

 

[whitegst97]

What really bugs me is that, why do i have to lean out my stock 450 injectors to get a decent timing advance and 02's. Im somewhere around the -18's to -20's. With a 20g and stock injectors, this doesnt seem norma

 

[Blk_99gst]

No, that's not normal at all; not even close. Did you buy the car with any mods or have you done it all yourself? There is NO WAY you will get any sort of timing advance with a 20g, and stock 450 injectors with those -18 to -20% SAFC correction values. Those correction values would be seen if you were running 550cc injectors. You either a) have 550 injectors, b) are running so lean I can't believe the engine hasn't melted yet.

Can you post up EXACTLY what your SAFC correction settings are for you Low and Hi settings and rpm points. Have you date logged your car? What are you O2 voltages at wide open throttle, what is your timing advance? Post up a log if you can.

 

[whitegst97]

Time RPM timing 02's
0.28 2332.0 29.0 0.16 0.78
0.56 2452.0 22.0 0.1 0.0
0.85 2588.0 20.0 0.94 0.0
1.13 2736.0 19.0 0.96 0.0
1.41 2908.0 18.0 0.96 0.0
1.7 3088.0 17.0 0.96 0.0
1.98 3272.0 17.0 0.94 0.0
2.26 3476.0 16.0 0.94 0.0
2.55 3696.0 14.0 0.94 0.0
2.83 3920.0 7.0 0.96 0.0
3.1 4216.0 7.0 0.96 0.0
3.3899999 4544.0 10.0 0.98 0.0
3.68 4864.0 9.0 0.98 0.0
3.96 5196.0 10.0 0.98 0.0
4.24 5524.0 11.0 0.96 0.0
4.5299997 5844.0 12.0 0.96 0.0
4.8 6172.0 14.0 0.96 0.0
5.09 6420.0 16.0 0.96 0.0
5.37 6712.0 16.0 0.96 0.0
5.65 6980.0 17.0 0.96 0.0
5.93 7188.0 19.0 0.96 0.0

The lo settings are 1k -10, 2k -12, 3k -13 4k -13...
Hi settings 3k -15, 4k -17, 5k -18 5.5k -18 same for 6 and 7

I don't know how in the world this is happening, with stock injectors, i bought the car bone stock from a dealer, the only thing that i've upgraded is the fuel pump, as far as fuel goes, and im boosting 15 psi. the mass isn't hacked, maybe i should.? I was also boosting 21 psi for a certain amount of time(very short) withouth getting fuel cut. I don't even want to get bigger injectors because im afraid i won't be able to lean the car enough to run stable. Weird car, and i really don't think the car is running so lean to melt things, i don't think the timing will get any sort of advancement from knock. My friend is going to lend me his 510cc i think from the JDM cylcone engine to see if things get better, but i don't see how much better. Thanks for all your help i really appreciate it, keep the suggestions coming.