For all you DME hackers.
 

I took some pics of my DME box and chip. I think it was verified here to be a Euro DME box. So what can you tell me about the chip? The engine is a US spec 3.2

http://forums.pelicanparts.com/uploa...1088686772.jpg
http://forums.pelicanparts.com/uploa...1088686830.jpg

It's a DME for a Euro high compression motor. If you aren't running it with a Euro motor you might want to change the chip.
-Chris

Chris,
The car runs great. What could happen if I drive it with the Euro chip? I have done a DE and several auto-Xs and some long road trips. Always runs good....no pinging or anything. Is it time for a Steve W chip?

If it's a setup for a HC motor then wouldn't the mapping retart ignition and add more fuel to prevent detonation?

Then again, I was under the impression that the Euro DME/Chip combo were a desirable upgrade for US cars.

No guarantees on this since porsche were definitely concerned about the quality of US gas, whereas euro gas was more of a known quantity for them.

So is the only difference the chip? Could I put a US spec 24 pin chip in and have basically a US spec DME? Or is it deeper than that? I looked on your website Chris and thru the links discovered the chip is a Euro chip for "inferior gasoline". (M240)

Shawn,

I have a stock 24 pin chip from an '85 if ya wanna try. :D

The "Euro" chip and the "inferior gasoline" DME's do have the same chip. However, the fuel quality switch is turned to position 4 (~ 3deg less advance) on the "inferior gas" version. See the excellent explanation of the fuel quality switch on SteveW's web site.

Please get one of Steve's chips - one more referral and I get a set of steak knives. :D
-Chris

Yes Chris, I've got cases of Ginsu steak knives here waiting for all the referrals, and I set one aside just for you. And if Shawn acts now, I'll even throw in the special tear-free onion dicer, a $19.95 value, yours absolutely free, as the only tears you will shed are tears of joy! :D :D

But back to the original question, the Euro chip and Euro box is not set up to recognize any O2 sensor input, so it runs open loop. The Euro boxes can be modified to accept a O2 sensor, by the addition of a network of resistors and capacitors in the upper right corner of the lower analog board where it looks like a bunch of parts are missing, and the installation of a U.S chip. The stock Euro chips, besides running open loop, are programmed with a partially fatter part throttle mixture, and a little more ignition advance right off idle between 1000-2500 rpm, giving the Euro cars apparently better throttle response and low end torque. WOT though is not much different than a stock U.S. chip of similar vintage. Full throttle power output will be about the same as a stock U.S. car. Ignition timing curves are basically the same, with the Euro chips being fatter in certain rpm ranges, and leaner in others. If this chip was used on a stock U.S. car with a cat, it is possible that total acceleration time could decrease because of the fatness of the WOT fuel curve.

Thanks Steve. That makes sense. The car has a US spec 1986 3.2, no cat, the O2 sensor is disconnected anyway and runs thru Bursch headers and bursch dual in/ dual out muffler. So I got no worries?

You'll be fine Shawn. The timing is so conservative that your air fuel ratios could be all over the place and not do any damage to your motor. Currently you're probably putting out about 230 hp. On the other hand if you want to step up to the next level you can go with a chip for headers, and pull another 10-15 hp out of the car. James Achard is apparently pulling 219 rwhp (258 flywheel) on his stock 87 3.2 with only headers and a chip.

Steve,
thanks. One of your chips is on my list. The headers are the shorty style with street adapters. My plan is to remove the adapters and run two glasspacks straight ou the back and spring for a set of Webers or PMO's!

You make a chip for Motronic used with carbs right?

Cool, that setup should rock.

Steve - Do you know anyone that re-maps chips and labels them with colors?

I have a DME with a "Brown Chip 24 Pin Label" on the case of the DME

the chip it self has a white label on it with no markings.

What's your insight on this mistery?

Can't say that I do. The only chips that I've seen with colors are chips guys got off of Ebay, and those were usually copies of someone else's old obscure chips. If yours is a chip with a white label with no markings, it most likely is a counterfeited copy of someone elses chip. The sticker is just there to protect the eprom window from accidental erasure. No legit chip tuner I know of would label their chip with a blank sticker.

I figured as much. I swaped DME's for a week and didnt really notcie much difference, if any(on the street) unfortunetly I didnt have a Dyno or track time to really test it.

My wrench was nice enough to let me borrow the extra DME, I am taking it back to him tomorrow.

Since you will be using the carbs to control the fuel delivery, you can leave the DME to control the ignition spark and timing, but you will only have partial mapping control because Motronic uses the input from the AFM to sense load and deliver about 15 degrees more advance under light loads compared to the full throttle ignition timing map. You can leave the wot switch locked closed with carbs to keep the ignition maps referenced to full throttle, but you'll probably won't get as good a gas mileage. However with carbs. you're probably looking at only getting less than 10 miles per gallon. so it's probably all the same. I know someone who gets 100 miles per tankful on his tuned 2.7 with Webers, no matter how he drives. He has to stop for gas pretty often. It might be better if some kind of throttle position or map sensor could emulate the AFM engine load and send that signal to the dme for the light throttle advance.