Tampa 928s

Z
I have chips from Tim that were burnt for Shane's car installed. I have slight shudder and a lean out going into boost. I moved my Maf under the fender and it runs good in this location. I am wondering with chips burned for his area there is a sea level difference will that will make an accuate tune hard to accomplish. Seems like I maybe going blind with out a true shark tuning, any feedback?
Tim your welcome to chime in!

Z

I think that you might have an ignition chip like Shane's, but I don't think that you've got an LH chip like his. The LH chip like Shane has is for use with 42lb injectors the modified MAF, and no FMU, which is the stage-3 supercharger kit configuration. Your's being a stage-1 would normally be using the stock LH chip, stock injectors, stock MAF, and the FMU. Your car would run very badly, if it ran at all, with an LH chip like Shane has, the stock sized injectors, a MAF that hasn't been modified like is done for the stage-3 kits, and an FMU. The stage-3 LH chip, the 42lb injectors, and the modified MAF all have to be used together, and without an FMU, for things to work correctly. It's not going to work right if you've only got one or two of those three things installed.

The elevation change shouldn't be enough to cause any issues. The stage-3 chips like Shane's were tuned in Green Bay. He picked up the car there, drove it to Las Vegas, from there to I think somewhere in the Seattle area, and it ran well through all the temperature and elevation changes along the way. Green Bay is around 600' above sea level, so his car has experienced much greater elevation changes than what the difference is between there and where you are in Tampa.

If you did install the LH chip, 42lb injectors, and modified MAF, like the stage-3 kit uses, the car should run well. Some SharkTuning may still help it some then, but shouldn't really be needed. If you do some additional tuning with the SharkTuner then, starting with that stage-3 LH chip will save you a whole lot of time and trouble compared to if you were going to start from scratch.

Tampa 928s

When you say Modified Maf exactly what is modified?
My Maf has been modified by having two Adjustment trim pots for setting the baseline voltage.

Fabio421

He means modified to read a higher volume of air. Either a superMAF or in Shanes case, a metal "shielding ring " that keeps some of the air off of the wire. Maybe Z Or John S. can explain better.

Tampa 928s

Since 7 Lb's is were I will be for a while is this Super MAF really necessary?

John Speake

You will be able to map OK with a standard MAF upto about 460crank HP IIRC . Higher power than that you need Murf's restricot which fits into the mouth of the sensor assembly in the MAF, and a copy of his chip to suit the injector size you are using.

Or a SMAF conversion of a stock MAF ($100) to suit the maps available wit the ST.

Tampa 928s

I am looking into a 2-Bar map sensor has anyone used these if so what is the hook up?
If I go with a Shark Tune and AFPR with 39 Lb or 42 Lb injectors adding a map sensor would allow for better tuning.
Feedback!

dprantl

42lb injectors work only if you use a sharktuner to tune the maps accordingly.

Dan
'91 928GT S/C 475hp/460lb.ft

Fabio421

You might want to call Shane and let him know that

John Speake

42# work fine with ST. John Kuhn fitted a 2 bar MAP to the EZ-F of a car he was tuning. Also used a SMAF (necessary to get extended load maps) This was for a turbo'd car.

You would nedx to ask him to modify your EZ-F.

dprantl

Tuning the fuel map for 42lb injectors with the sharktuner shouldn't be affected whether there is a standard MAF or SMAF installed. The only reason to add a SMAF is if you plan to make more than 460chp.

Dan
'91 928GT S/C 475hp/460lb.ft

Z

A car that's using a MAF sensor and that's properly tuned initially wouldn't have need to be retuned.

The 2-bar MAP sensor as is being talked about would replace the stock 1-bar MAP sensor that's in the EZF. It wouldn't make any difference in the way that the fuel is tuned. The LH uses the MAF for it's load signal, and that has nothiong to do with the MAP sensor in the EZF. Only the ignition timing tuning would be changed with the change to a 2-bar MAP sensor.

If you're using a custom, one of a kind adjustable MAF, you're going to need a custom, one of a kind tune. You're either going to be on your own, or will need to get some help from someone there locally to tune the car for you, or to help you do it. Expect to spend some time to do it correctly, so that it runs like it should under all conditions. If your car has other problems that you may or may not know about, you'll end up tuning around them. If those other problems then get fixed some time in the future, you'll need to do the tuning all over again.

Z

I guess your definition of "properly tuned" is a little different than mine. To me, properly tuned means that you don't need to retune everytime that you drive up or down a hill.

Tampa 928s

If your car has other problems that you may or may not know about, you'll end up tuning around them. If those other problems then get fixed some time in the future, you'll need to do the tuning all over again.

I have time to fix any problems but I do not believe that any problems now exists. The surging however slight has been there since the super charger has been installed. I went back to NA to test and the car ran fine. I moved the Maf under the fender and 98% of the surging issues went away. The lean out issue I believe is FMU related during the transition point.
So what do you recommend to check, everything is new so very little chance for component related issues.

Z

Things to make sure that are in good shape would include power and ground connections, temp-2 sensor, including that it's grounded well to the engine, a good MAF, no wiring problems at the MAF plug, injector connectors, or ECU, ignition system and associated wiring in good condition, fuel injectors clean, fairly new fuel filter, good fuel pump and wiring for it, good spark plugs, no leaking from the fuel pressure regulator(s) and damper(s), no vacuum or boost leaks, good O2 sensor and associated wiring for it, no exhaust leaks ahead of the O2 sensor, cooling system in good enough condition to keep engine in proper operating temperature range during tuning, a good crankcase breather configuration, and fairly fresh gasoline of the proper octane rating.

A super FMU allows for adjusting the fuel pressure increase rate and the point at which it transitions to above stock fuel pressure in relation to the vacuum/boost transition point. I wouldn't bother messing with it though if you're going to go to bigger injectors and SharkTune anyway.