New to performance ECU
 

Hi Gang,
I've been reading through all the threads here and understand much more about my car now than I did last week.
I have an AE with upgraded injectors, engine and exhaust. I can't seem to find details, though I'm told by the previous owner that it has "750cc injectors". That doesn't seem exactly right, because most of you have one size for primary and a larger size for secondary.

Can someone here tell me how to find out exactly what's in it? Hopefully it doesn't involve huge disassembly under the hood. And, what else do I need to consider while trying to develop a working ECU map for this setup?

Also, I'd appreciate any assistance getting a good running map for the ECU - LTX12s. I've put in Silverrotor's basic map for stock S4/S5 and it's driveable, but not great. I touched up the Idle settings a bit and improved the idle stability.

So now here's the trouble: It doesn't accelerate smoothly; If I'm gently accelerating, it bucks at different RPM. If I'm standing on it, there is little power until 3200 RPM when you get a kick in the seat and suddenly you're really flying.
Cruising at freeway speed with light throttle foot-pressure, it bucks quite a bit, which I can stop by pressing down and increasing the acceleration.

Lastly, my gas mileage is terrible - 14MPG at last fillup.

Thanks in advance for your input!

- k -

silverrotor's base map is just that, a base map based loosely on the stock Microtech settings. It's enough to get the car running but that's about it.

You probably have 720CC injectors, and the only way to tell where they are is to pull the upper intake manifold. Most people install them into the secondary position but it is conceivable you have 4 of them.

thanks Aaron,
I was hoping that I wouldn't have to disassemble too much, but oh well. I appreciate your input on the map. I expected that the map I used would get it running but not finished.
Would you have suggestion on how to get it optimized? I'm comfortable doing my own work, but this is new territory for me.

- k -

You'll need some way of interpreting the A/F ratio, or the experience do it it by feel.

The car came with the hand unit that I believe displays AFR along with other dynamic data. Do I need something more sophisticated?

Is that from a wideband sensor or the stock narrowband?

Tuning idle is fairly easy and you can get a good low load map without any real monitoring. Tune the idle until it is as smooth as possible and draws the most vacuum.

Light load is fairly easy. Make the timing about 28 degrees to start and then pull fuel until the car is smooth and responsive. Over a period of about a week, examine the plugs. You want them to turn a dark tan colour. Black is too rich, white is too lean.

But really, a wideband is the easiest tuning aid to use for the novice and is almost required to tune in boost. For example, at 10 PSI the car feels the same at 12:1 as it does at 11:1. Except at 12:1 it will blow up.

Thanks a million. I really appreciate the explanation!

On the hand unit, I don't know how to identify the type. It has 4 lines of data in the display and the bottom two continuously change what info is displayed while the engine is running (makes it a challenge to read).

Anyway, I will try your instructions on the idle and low power and see if I can improve things.

Is there comprehensive documentation available easily? I'd like to understand what all these settings mean and how they affect engine operation.

- k -