Is there a safe way to check your rev limiter?

[R22tech]

I've been worried about this for awhile. The other day I took out the DME and tried to check and see if it had been "chipped". I had no idea what I was looking for-just looked like a couple of circuit boards so I put it back and said, " oh well". On my way home just now I had the music up a bit and couldn't hear the engine. Trying to fulfill my need for performance, I put the pedal to the metal and just went! I look down as I'm shifting into 3rd and my tach is at like 7000 rpm!!! The car never lost power, so I'm wondering do I even have a rev limiter? The car is fine, no unusual sounds, idles the same, ect. What's the deal? How do figure this out short of reving it up until the engine blows!

[marcesq]

R22:

The rev limiter is contained in the DME unless it has been chipped. Typically, one of the changes incorporated by the aftermarket chip is a higher rpm limit. The problem with the higher rev limit on 3.2 is the overstressing of the rod bolts, which, of course is not a good idea.

It is my understanding that the OEM rod bolts should be changed if OEM rev specs are increased by a chip, and higher revs are utilized on a regular basis.

FWIW

[R22tech]

Anyone? Can you tell me specifically, step by step, how to tell if it has been chipped? All I did was remove DME from car and remove cover/case to inspect. I didn't know what I was looking at but I could probably fix it if something was wrong with it!

[marcesq]

When you open up the box, look for a 24 pin chip.

Will look like this:





It might be soldered in for your year. If it is after market it will probably have the name stamped all over the top.

Hope this gets you started.

[911pcars]

Not sure about the configuration of a DME rotor, but couldn't you install a mechanical rev-limiting rotor to act as a backup to the unknown chip software?

Sherwood Lee
http:././members.rennlist.org/911pcars

[APKhaos]

Marc's pic is what you want.

Once you have opened the DME case, take o look at the black plastic spacers that are holding the two boards together - carefully pop then apart [they telescope together] and open the two boards like a book. The chip is on the lower board.

The stock chip has a number [1267355102 or 1267355180]. The Autothoriy and Weltmeister chips both have logos as well as numbers - can't miss 'em.

FWIW, the Weltmeister rev limit is set to 6800 & change, but the Autothority limiter is at 7000. There is no mistaking when you hit the limiter - the car will buck a little as the fuel is shut off and on to keep the revs at the limit number. Everyone is different, but you might not want to rev too high unless you know its fresh adn strong through the valvetrain. Racewear rod bolts are great insurance!

[Steve W]

The rev limiter is programmed in the chip at location 103h. The factory rev limiter is set at 6520, with some chip companies setting their rev limits higher. Weltmeister sets theirs at 6840 and Autothority sets theirs at 7040 which I think is a bit too high. The club sport model had its limit raised to 6840 but I heard it had lighter valves. This may mean the stock rod bolts are ok to this limit.

If you have a relatively unknown chip, the only way to truly know is to dump and read the chip's contents. If the limit is too high, the only option is to correct the value at 130h, and reprogram the chip or replace it with another for which it is known.

[Early_S_Man]

Per Paul Frere, the Club Sport chip only raised the rev limit by 200 rpm. He has contacts with the factory engineers most writers can only dream about!