GP964

Hi Folks,

Purchased a Autothroity MAF unit for my 90 C2, only thing it did not come with was the software.
An independent porsche mechanic in Los Angeles had a chip software available (labeled: C2 Hotwire Custom). I had him install it on the car. It starts, idles fine but once in awhile jumps from 200 to 1100, but idles out when you help it out with the gas pedal.
Due to California gas stations only having 91 octane available, i've been force to use octane boosters (VP racing octane booster) to avoid pinging under load when the temp gauge reaches the 1st marker. Under the 1st marker everything is fine no pinging, no octane booster needed.

After trying that several months, kinda gets tiring.
Today I visited Tony Callas (Callas Rennspeed in Torrance, CA) regarding the problem. Being it was my first time visit to him I authorize him to do a complete inspection of the car. VERY THOROUGH!!!

He checked the computer for any faults with the BOSCH HAMMER, only fault came up was the DME. Having the Autothority MAF Hotwire sensor in place of the factory unit causes the system to identify the MAF change.

Next he check the distributor belt which was fine, but need replacement of the dist.caps and rotors. A week earlier I installed 2 Nology Pro-Fire ing. coils.

Tony also noticed that the car was running lean, probably due to the MAF and custom chip. He then hooked up a CO2 analyzer and found the it was way too lean!!! Reading only 0.008 (idle mixture CO%) at idle on the analyzer. According to one of mechanics it should be 0.800 CO% at idle, which he pointed out is on the manufacturer ignition spec. located on the engine compartment lid.

So basically the car is not getting enough fuel which may be causing the pinging.
Adjustment to the MAF system was done by adjusting the ohms via screw nut on the wiring harness provided with the Autothority unit.

With the O2 sensor in place the closest idle mixture adjustment came to 0.514 CO%, alot better than 0.08 CO%, but a shy of 0.800 CO%.

On the test drive I noticed that the car had more power (butt dyno). It has reduced its pings to a minimal only from stop to go and only lower rpms (less than 2K rpm)and goes away once your up in the rpm's (approx 2K+ rpms).

Finally my question

Is there any way to make the car run richer? basically getting to the 0.800 idle mixture. And want to get rid of the pinging entirely.

Are there any other adjustments or additions that I can do with out replacing the custom software (chip)?

Thanks

GP

BTW, Thanks to Tony Callas and Team.

Adrian

Dear GP,
The short answer is "NO". You will need to get the correctly programmed chip. Running rich or lean is determined by the O2 sensor and the DME. If you like the DME sets the power and the O2 sensor adjusts the mixture to stay legal. This is all pre-programmed and none adjustable (except the CO2 adjustment which should only be touched with an analyser hooked up).
Of course the other item is the fuel you are using. These systems really require much higher octane fuels. Put simply you are using high performance components and running them on low performance fuels. Fuel additives are let us say, unproven.
Ciao,
Adrian
911C4

PS: The fault code would have been 1141. Whilst this code remains so will your problem.

Michael Delaney

GP, I would be very concerned about a prolonged pinging condition. I assume you realize what this noise means. If bad enough you can end up with a hole in a piston, or a melted piston. I would lose that chip as soon as possible if you cannot reprogram. Possibly the knock sensors are protecting your engine but I would be very afraid. Roy

J richard

GP964,

I am running the autothority MAF package on my 93 RSA. Early on I had some trouble getting the setup to pass emissions (too rich and outside the DME's ability to compensate) and not stall due to a lightweight flywheel. I got a re-mapped chip from autothority, it solved the stalling issue but still had a hard time passing emissions, this time too lean. The solution was to put back in the original chip and adjust the program mapping of the DME with the adjustable pot on the top of the unit to a leaner fuel map. (there was a good thread on this on the page about three months ago)This took care of the problem. You might try it, but I think you may just have to pony up the cash and get a chip from autothority. ( I do have the remapped chip that I am not using but I don't know if it is compatable with your DME. might have to check with Adrian )
Regards

GP964

Hi J. Richard,

If your not using the chip, would you consider selling it. It might just fix my problem. I have a 90 911 C2,
email: KZ1L59@yahoo.com

Adrian- will J. Richards chip work on my DME, Before installing the Autothority MAF, I once borrowed a DME w/ a race chip from a friend (Carlos Granados) 94 911 C2, it worked great and alot of fun, but had to give it back

Thanks to all..
Pls let me know

GP

GP964

Hi J.Richards,

Trying to look for the thread, can't find it. Do you have a link to it?

Thanks again

Adrian

DearGP,
Unfortunately you are entering areas of grey.
Basically you cannot change the chip (which is only one of many in the DME) from a newer DME part number into an older unit. The first thing you have to establish is part number of your DME and then the part number of the DME that this new chip comes from.
Working great and passing emissions are two different things.
I really suggest that there is no reliable cheap way out of this. You need to get a remapped chip to suit your current set up.
This can be done by purchasing a correctly mapped chip, by remapping your existing chip or reinstalling an original chip and having this remapped.
This work needs to be carried out by somebody who knows what they are doing. I believe you are way past DIY now.
I cannot advise you to do this and do that because I am not there. I cannot see what is going on. I advise professional help to get you over this problem before you need personal professional help (just kidding)
Ciao,
Adrian
911C4