legacycentral bbs

I want to install a 50k pot in my 93 impreza to lean or richen the settings by altering the maf signal. Whats the easiest way of doing this, at the MAF signal wire at the ECU?

The only reason I need to do this is to troubleshoot my swap (on stock 1.8 ecu, stock injectors, stock maf). For some reason my swap is causing #1 and #2 to run rich. I checked my plugs and 3 and 4 seem to be burning clean, but 1 and 2 are soot black. The engine feels rich too, like when partial acceleration, it has a hard time moving up the rpm range, which tells me rich.

If you suspect fueling differences between the various cylinders wouldn't you want to troubleshoot the fuel system first? Did you do a split fuel rail mod? Ever flow test the injectors or do you have spares you could try? Did you already try to eliminate all the mechancal potential causes ahead of messing with wiring... my 02cents.

Thanks for the suggestions.

Let's see, the fuel system consists of all the under-intake hard fuel lines of the ej22t, but I just transfered over the injectors, rails, and fpr from the 1.8. I'm pretty sure the hard lines are the pretty much the same 1.8 vs 22t.

I wish I had a spare set of injectors for a 1.8, but the only set I have are stock 22t injectors which would only make matters worse lol. But I do know that they worked fine when in the 1.8 engine.

I'll troubleshoot a bit more as I think I have an extra coil from the ej22t. I'll hold off on the pot mod. Thanks again~

I'm not familiar with your swap in detail but are you saying you are running an EJ22t with 1.8 injectors? That seems bad, what about fuel pump is that from the 1.8 also?

It's besides the point, but yes, I am running a complete ej22t with stock 1.8 ecu, harness, pump, injectors, and maf with 0 boost and no WOT in mind. The reason for this is to daily drive it under partial throttle, closed loop, until I can get either a piggy back system with egt and wideband, or a Link standalone system. Then I'll worry about boost and Wot. By that time I'll have the dohc so it'll be worth it.

Back to the point, since I am using a stock fuel system with stock intake system, there should be no reason why this should be burning rich. I'm currently assuming its due to a leak between the MAF and TB (leaking metered air). We'll see how that goes when I get home.

Thats cool, there is another guy on here with a setup like yours. He is running the perfect power piggyback.

You've got more displacment, so volume of airflow is higher past your MAF at comparable RPM to the 1.8 motor, thus fooling the 1.8ECU into dumping more fuel? Could be a possibility.

You could also try messing with timing, the 1.8 ECU is thinking high compression, not low like your EJ22t is could also be a factor...

Do you have the 02 sensor hooked up? The ECU will "learn" and adjust over time, so you might be rich now, but eventually the 02 sensor will force the mixture back to where the suby engineers wanted it.

I think making sure you have not TB leaks is the definate first thing to eliminate.

my3awds - This is not a good way to do things. But anyway: You can't use a potentiometer to alter the MAF signal to richen the mixture. You might be able to lean the mixture out in a not-quite-useless way by hooking it up in one of the following ways; the first is less wrong than the second:
This will not help you troubleshoot your problem.

I actually wonder if the problem is not rich running in those two cylinders but rather a weak spark. Have you tried replacing the ignitor and/or coil pack?

If you do think it's the air/fuel mixture, though, try swapping the injectors from cylinders 1 and 2 with the injectors from cylinders 3 and 4.

Or try swapping the injector connectors (with the connectors switched the car will run funny at low RPMs but at higher RPMs should run okay).

So you have the wastegate wired completely open?

Kinda sounds like you are getting a pressure drop between the fuel rails. I am not really sure why, but two of them could be running rich because of the MAF being freaked out by the extra flow, as Keith said, and then the other two are running cleaner because of pressure loss!?!

Just a theory...