I doubt the GSL-SE ECU have a learning mode but long story short, I had been adjusting the clock spring in the AFM as I have 720 injectors. That was all fine and dandy. Of course the car has hard starts because of the richness. Added a bypass solenoid to add air into the intake like the stock BAC would (but not from atmosphere).

The ECU seems to have taken that reading on the first start and run with it. The car is now acting way leaner on all fronts. I can adjust everything to the extreme to get it to work. It's like it has a vacuum leak. but I have checked all over and can't find one.

Has anyone had experience with this before?

 

Do you still have the air pump? The computer may be trying to run in closed loop, which may be too lean under some conditions if it was expected that the air pump would be adding additional air to the exhaust.

Did you buy actual 720s? Those may be smaller than stock. Stock was 680cc but that is at 2.5 bar, not the 3 bar that most injectors are sized at. 720cc at 3 bar is smaller than stock.

 

Hello! I sent you a Facebook message yesterday and I knew you would be the one to help. No emissions on the car at all. Has been running perfectly the whole time untill I added that solenoid. I even disabled it and it still does the same thing. It just seems like its "base" afr recalibrated somehow. The PSI is the same on the fuel rail. I had it increased to compensate but that's not the answer.

It might be the solenoid unit itself leaking air at all times. I will have to make up another BAC block off to test that.

 

I am 100% certain that you did not send me a Facebook message because I am not on Facebook and never have been.

 

Whoops, that's Pee Kay, my bad!

 

After replacing this with a plate, AFR went back to normal. I guess this plate is leaking! I really need to stick to the idea of fixing what I changed instead of thinking it's something else!

 

By the way, that's not a stock GSL-SE intake (*aka RE-EGI) manifold. You may already know its an S4 intake which has been nodded to fit an SE (*Series 3, i.e., S3), but future referrals to this thread may confuse board members. While the Lower Intake Manifold would be the same, the Upper Intake Manifold is different, along with it's plumbing for Bypass Air Control Valving and how it manages idle bypass air for idle compensation.

The SE (N304) ECU does not have a learning mode. It's a simple map of Fuel Injector firing timing and duration stored within the ECU for cold and hot engine conditions, and is only running in Closed Map mode in 5th gear at steady speed or with Cruise Control enabled. It has no limp mode, no reset timing, and very little complication to what it does. This is what makes it very reliable in these old cars,