Bill Ball

I am surprised but not surprised at the same time!!

SwayBar

That's our boy Tim...

jorj7

Thanks Tim.

I know we've talked about some of this before. Your help and contribution are greatly appreciated,
but it may take more work then just plug and play. There are a few differences that could effect
the tuning. The compression, oil breather system, supercharger and top pulley are different, so
the fuel map will probably have to change. I was planning on getting a wbo2 sensor and some kind
of data logger/monitor so I can see what's going on. I figure there will be a lot of trial and error
to get the fuel map right. If your chips and MAF device work as you think and save me all the hassle,
that would be great.

John Speake

Excellent ! You're in good hands.....

Tim Murphy

I assume you now have a T-Trim sc?

What compression are you running?

The crank breather system should not have any affect unless you are pulling in un-metered air, which I doubt you do.

I have tuned this chip from 7 psi all the way to 14 psi so I think it will still work.

For what you are doing, installing the wb02 is a must thing to do. There are a few options for wb02 sensors but I am most familiar with the Innovate units. The output can be configured to plug right into the Sharktunner, should you get the opportunity to get one in your hands.

Even if the LH chip I send to you is a little off, I can make adjustments to the file based on data logs from the Innovate and send you a new chip.

The chip file I have is always going to be a work in progress but I feel it is pretty darn close to covering most all configurations. It will be interesting to see what your results are.

Z

The car primarily used for the chip tuning has been Tim's wife's '87 S4 A/T. Last weekend the same exact configuration that Tim is talking about was put into a supercharged GTS engined car. Even with that engine having higher compression, larger displacement, a different model of supercharger, different cams, and lower boost, with absolutely no additional tuning on it the air/fuel ratio was considerably better than the one in the dyno screen shot posted earlier in this thread.

If you're sending the stock MAF signal to the stock LH, your fuel injectors are absolutely hitting 100% duty cycle. Based on the posted air/fuel ratio chart, it looks like that's probably occurring at about 4,500 RPM. From that point on, any increase in MAF signal isn't having any effect on fuel delivery, and the LH is no longer in control of it. It's wide open. Additional fuel delivery can only come from increasing fuel pressure. The system then basically works like CIS in that fuel pressure is used to control fuel delivery through constantly flowing injectors of a fixed orifice size.

The chart shows that with the current configuration the rate of fuel pressure increase is inadequate in this case. Changing to 42lb injectors alone will shift the fuel curve down. As John mentioned, you'd have to lower the fuel pressure for the car to idle, and it more than likely really won't idle that well then either. You'd also have to experiment with changing the rate of fuel pressure increase that the FMU provides. The fuel requirements of the engine depend on the air mass entering it. The FMU regulates fuel delivery based on air pressure. The LH working with a usable MAF signal regulates it based on air mass, so MAF based LH control is always preferable. The FMU can be made to work reasonably well, but as boost and power levels increase it gets harder and harder to do it accurately.

If you do get a wide band air/fuel setup, I would not get one of the Autometer ones. They may work just fine as an air/fuel meter, but the analog voltage output that they have can't be programmed to work directly with the SharkTuner, like the Innovate and some other brands can.

Bill Ball

George:

I have an Innovate LC-1 and WBO2 sensor we can use for tuning.

IcemanG17

George
With Tims help you should have it running perfect in no time! Might as well start with the Murf Stage III kit and tune from there!

jorj7

Sorry to drag this out, but here's the latest news.

Bill and I installed the 42 lb injectors, a bleed off valve for the SFMU, along with new distributor caps
and rotors, changed the oil (Amsoil 20-50), oil filter, the steering pump reservoir and intake hose. I
have a LM-1 and LMA-3 that we'll be installing and hope to get some better info on the a/f ratio. The
car is running again, but we'll need to spend some time getting it tuned correctly.

On another note, Dave at 928 Specialist has been so kind as to send out a set of rear axles (just
for the price of shipping) to help get the car ready for next season. Thanks Dave, I appreciate your
support.

AO

George,
With the 42lb injectors, you shouldn't need the FMU. I'm only hitting 60-70% injector duty cycle with 42lb injectors with STOCK fuel pressure. Furthermore, you're probably knocking like crazy upstairs, and need to adjust your ignition timimng. So I highly recommend you get hold of a SharkTuner and build you a set of custom chips.

DR

George,
You are very welcome! I hope those work out for you. I am happy to contribute in some small way for all the effort you are putting in to "carry the flag" for the rest of us.

Keep up the good work and effort, it is appreciated by many.