2G Maf in a 1G

[Andrew7DG]

First I would like to say that I tried to do a search on these forums for this subject and for some odd reason the search engine doesn't like any abriviations like 2G MAF MAS 1G MAFT
Weird

So time to write a post.

Just info on car
1990 GSX
Non EPROM
So I am trying different ways of tuning around this

I just bought a 2G MAS for my 1G and i got different reports on it. I did some research on it and now just realized (and please correct me if I am wrong) that the closest thing I can do to get it to run properly without tuning is use 550cc injectors. So the stock 450s wouldn't really work out then?
However it doesn't look like an exact compensation like something is still going to be out of callibration

However how bad is it to run just the 2g mas with the 550cc with out AFC. Is there anything else I can turn up turn down to fix this? Fuel pressure?

So heres another question. What would be the best tuning tool to correct this imbalance.
Unfortunatly I have no Eprom so no dsm link (I really want one though!!!)

Also budget is kind of low

Also is having a 2g mas a really big improvement over the 1g? or does it just flow better?

Thanks

 

[ROOKIE1]

http://vfaq.com/mods/2GMAF-1G.html . First paragraph , says very little tuning needed . Yes it is better flowing . I would not adjust anything without a logger first .

 

[steve]

Also is having a 2g mas a really big improvement over the 1g? or does it just flow better?

The only reason to run a 2G MAF over the stock 1G MAF is because your overrunning the stock MAF and need to flow more air. Using it to correct for a 550cc injector upgrade is a cheap hack that gets the car drivable at best.

It wouldn't be my first mod to a car.

Steve

 

[Andrew7DG]

Ok

I am just asking to clarify

Steve you said

"It wouldn't be my first mod to a car."

I should really update my mods. Currently running:

2.5"-3" inch exaust
Evo III exaust manifold on its way
255 fuel pump with fuel pressure regulator

Have a Palm logger

Going to port the 14b soon with O2

After I said my mods list to one of the local shops they sugested switching to a 2G MAS so i could run the 550cc injectors, however now I am reading I am going to have to buy a AFC controler with this mod

So using the 2G MAS, what do people recomend to buy for an AFC using this mod to tune it out correctly?

 

[steve]

So using the 2G MAS, what do people recomend to buy for an AFC using this mod to tune it out correctly?

You really should be asking what do I want to use for tuning my car as I modify it going forward.

You have four main choices.

SAFC
MAFT
Custom EPROM/learn to make your own chips.
DSMlink

Steve

 

[kelvinb]

You really should be asking what do I want to use for tuning my car as I modify it going forward.

You have four main choices.

SAFC
MAFT
Custom EPROM/learn to make your own chips.
DSMlink
megasquirt

Steve

updated

 

[DSM90AWD]

Just to illustrate the "why" w.r.t. the S-AFC ,

The 2G MAS flows 33% more mass air at the same output signal to the ECU as the 1G MAS and 550cc injectors flow 22% more fuel than the stock 450cc.

So without further "calibration" you will be running ~11% leaner on open-loop operation (WOT), whereas under closed-loop (when ECU will use the O2 sensor to maintain a 14.7:1 AFR) will likely be unable sustain 14.7:1 even with maximum LTFT correction.

Although an AFC of some sort is a great tool for fine tuning, it's much more preferable to get the calibrations set without fibbing to the ECU too much

As is the case, as Steve mentioned, the EPROM/DSM Link is the best all-around choice. Though, with the 2G MAS and 550s, turning up the base fuel pressure from the 1G 37psi to the 2Gs 43psi (via aftermarket AFPR), the difference in calibration would be near zero (44psi would be exactly zero)

 

[steve]

The 2G MAS flows 33% more mass air at the same output signal to the ECU as the 1G MAS and 550cc injectors flow 22% more fuel than the stock 450cc.

If the 2G MAS always flowed 33% more than a 1G MAF it would make the problem simple but it doesn't. I can't find the chart for the 2G MAF right now but the difference in flow varies based on the flow.

If a set of 550 injectors delivered 22% more flow all the time than the stock 450cc injectors it would also make the problem simple but again they don't. Pesky little things like injector deadtime get in the way.

Though, with the 2G MAS and 550s, turning up the base fuel pressure from the 1G 37psi to the 2Gs 43psi (via aftermarket AFPR), the difference in calibration would be near zero (44psi would be exactly zero)

This is the urban myth that I was trying to discount. We have two independant variables that don't cancel out even if you raise the fuel pressure. The errors are small enough that the car runs but sigificant from a tuning perspective.

Steve

 

[scottsee]

The problem lies in airflow g/rev. So many things effect this it's imposable to calculate and graph a reliable HZ difference for the 1g guys. Everything from air temp, pressure, elevation, humitty have to be identical to replicate. The best, most efficient way to offset the overly lean mixture is to compensate the MAF signal with a EFI system. like said above your LTFT's will need manipulating. 2g MAF signals can differ in overly lean conditions for the 1g's from 15% upto 25%, the stock ecu can only compensate for up to +/- 12.9% either direction for the fuel tables. You can see why uncorrect MAF signals can be tricky... AFPR can do the job of adjusting fuel pressure to compensate for some of this, but it's just a band aid. You need something to get your LTFT low,mid,high corrected or suffer the consequences of bad gas millage, and unreliable fuel delivery at WOT

 

[Kevin Jewer]

Best bet with no EPROM and low budget is to get an AFC and set up the correction curve manually. You can get the low throttle curve set while parked watching trims, up to 4 or 5k when the ECU goes open loop. Just continue the shape of the curve from that point. For the WOT map tune with a WBO2, either bought, borrowed, or on a dyno. With this done the ECU can handle the adjustments for everything in between.

One advantage I do see to this swap is being able to run 550s with minimal airflow signal ####ery, or 650s with better than usual corrections, probably more like running 550s without the 2g MAS, if that makes any sense.