Tuning a Motronic System

[iiibdsiil]

I have a 914 with a 1988 911 3.2 in it. I have the autothority air meter and their chip. It came installed when I bought the car.

I don't have 02 sensors for some reason, not sure if it is needed with the Autothority setup.

But, what I want to do is get this thing on a dyno and tune it right. I doubt that anyone around here will have the equipment to tune the stock motronic unit, so I have been looking into some other options.

A friend recommended this doo hickey and this wideband o2 sensor setup. He said that he would then be able to tune it for me, saving me some money, although I could spend the money on the equipment or on the tuning. I definitely trust his abilities.

Is there a better route here? I know there is some Wang or Wong guy that ya'll 911 boys recommend. But, how accurate can it be if he doesn't see the numbers himself?

I understand very little when it comes to fuel injection, so any help is appreciated. And feel free to talk like you are to a 3 year old, LOL.

Thank you in advance.

[silverc4s]

The motronic engine is not going to ever be in tune without an O2 sensor input to work with; as I understand it.
Sooooooo, I would recommend you get that taken care of first, then see what else needs to be done. You did not say what your current (tuning) problem is, perhaps your butt dyno is just telling you that there is some more power there.
One classic area to check is the butterfly position at WOT. Especially with an engine swap, you should make certain that you are getting it completely open when you floor it.
Read up on Motronic, check the threads here on Steve Wong's chips, and keep asking questions. We'll have that little mid engined boxy guy leaping out from under you in no time at all...;-)

[iiibdsiil]

Depending on the weather, it will run real great, or just eh. Either way it is a rocket ship, but usually 1st gear is as fast as you can put your foot down. Just before the trans out, it definitely wasn't doing this. I could tell it just wasn't all there.

I put an email in to Autothority earlier today, waiting for a reply.

I don't know if it is running rich or what. Although I was told it shoots little blue flames out the exhaust on shifts. My exhaust setup is a header to like a 12" glasspack and that's it on each side.

[ausdilecce]

silverc4s,

If a motronic will never be in tune without a o2 sensor, How is it that my factory 930/20 ( ROW 3.2 ) runs superbly without an o2 sensor or cat ?

To get my engine in tune, I just need someone with a gas analyser to set my mixture setting correctly, then the motronic computer ( and its sensors ) do the rest.. ( control spark advance/ fuel duty cycle etc ). And that is what iiibdsiil would need to do to 'tune' his engine.. Putting different chips/exhaust/throttle bodies on goes into the realm of modding, not really tuning.

iiibdsiil, do you know what engine you have ? (930/XX ) and what motronic computer you have ( 911 618 XXX XX ). those two will tell you if you require an o2 sensor or not..

While we are at it, do you know if there were any other mods made to the engine ( high flow injectors/different fuel components, modified CR ?

Any chip you get ( or have ) will need to be matched to the engine/computer(/exhaust?) you have..

As far as Steve Wong's chips.. it would probably be better to search this forum for his name or go to his site http://www.911chips.com/index2.html

[iiibdsiil]

No, I don't know the motor numbers or ECU numbers. I can go look, but it will have to wait a week and a half until I am back home again. Where do I find the motor number?

I live in Tampa for school, and the car is located just south of West Palm Beach, about 200 miles away

[iiibdsiil]

Oh, and the motor is all stock, except the Autothority stuff.

How do you adjust the mixture on a stock motor that doesn't need 02s?

[ausdilecce]

Have a read of this thread ( 2nd post specifically ) for how to read the engine number

911 engine number?

[ausdilecce]

Originally posted by iiibdsiil
Oh, and the motor is all stock, except the Autothority stuff.

Good to know..

Originally posted by iiibdsiil How do you adjust the mixture on a stock motor that doesn't need 02s?

Actually, both motors are tuned the same.. Ones with o2 sensors can 'self-tune' a bit but major tunes are done with the mixture screw which is located on the bottom corner of the air meter ( the corner closest to the back of the car AND the throttle body ) .. The mixture scre is usually covered by a tamper cover which needs to be removed if adjusting..

You don't have a stock air meter so I don't really know how you would adjust it on you air meter. autothority would be able to tell you tho..

[silverc4s]

Go here & read

RoW Carrera Motronic Part Number

[pmillikin]

I don't have lots of technical knowledge but my mechanic said that without the O2 sensor input the Motronic goes to a fail safe fuel condition of full rich. This prevents burned pistons etc. but over the long term causes valve guide & other problems.

This explanation supports the blue flames you see on shifting. Install the sensor first and then listen to the motronic wonks about tuning.

[iiibdsiil]

Now I just need to find the plug for the O2, any wiring diagrams available online? Knowing the place that did the install, it is probably cut out of the harness.