Originally Posted by Steve W (Post 6591962)

It varies but it's not significant. Anywhere between 4 to 8 degrees. The ignition timing is kept low to keep NOx as low as possible. Some additional fuel enrichment on throttle transients is what is the true reason for the increase in low rpm throttle response, because the stoichiometric ratio of 14.7:1 is not optimal for power. The O2 sensor controls it to that because that is the ratio the cat is most efficient at processing HC, CO, and NOx. The 84-86 2k programming had a tight control on the mixture loop, locking it at 14.7 no matter what you did. This makes for a lot of sluggishness and delay in response. Unplugging it is what some of the guys did in the old days to release some of this lock and feel more response. The 4k programming from 87 up relaxed this lock and allowed additional fuel enrichment for a few moments when you gus it at part throttle, reducing some of this lag. But stock programming, 84 or 89, still has a lot of sluggishness and delay below 4000 rpm at part throttle. If you want to get rid of it you need to change the programming.

Proper part throttle fuel enrichment and ignition advance is what significantly improves this. You always need more ignition advance at part throttle compared to full throttle, because the fuel molecules at light loads are much farther apart vs at full load, so the speed of combustion is much slower. You need to ignite the burn earlier in order to achieve the peak pressure of the combustion during the stroke at the proper angle after the piston's top dead center in order for the stroke to achieve peak torque. Like packing gunpower tight in dynamite causes a rapid explosion vs loosely fluffed powder tossed in the air which would flash slowly.

As an analogy, compare it to pushing down on a pedal of a bicycle. By pressing down on the pedal at 1:00, you will develop more torque at the rear wheels, vs waiting until 3:00 to press down. Obviously if you press down at 12:00 that is too early and you will only hammer your knees. So timing this right and using a dyno to measure the changes in torque under load is how you want to properly determine the limits.

More ignition advance done properly is what achieves this. The general rule of thumb is that you want roughly 15 degrees more advance at light load part throttle compared to full throttle to accommodate for the slower burn of light throttle. This not only increases the response, but increases the fuel efficiency of the motor. Rarely does ignition advance at low and mid load part throttle cause an issue or damage engines unless done improperly. The combustion pressures are not high enough. If one examines the amount of part throttle ignition advance used by the 964 European Cup cars which their twin plug ignitions which further speeds the burn, you will see the factory used an extreme amount of part throttle ignition advance to improve throttle response, more than I've ever used, because they have no considerations for emissions compliance. So my recommendation is if you need to smog in a stringent state such as California which is reducing the limits each year, swap back to the stock chip temporarily and get it over with.

I will tell you this, there are a lot of championship and podium winning 3.2 and 3.6 race cars out there running my chips pounding their motors out at full throttle two hours a day, 20 to 30 days a year, for years, from 4000 to 7000 rpms with, either on 91 octane pump gas or race fuel, and if the motor ever comes apart, the pistons, rings, heads, and bearings are all flawless. If these cars can survive, don't you think a street car spending 90% of it's life at part throttle at low and mid rpms could do the same?

Originally Posted by ant7 (Post 6592853)

... I cant for the life of me understand why someone would go to all the trouble you have over the years if the gains were as pointless and negative as some would have us believe...

Originally Posted by Smoove1010 (Post 6591442)

Thanks for the photo. Now I know exactly what I'm looking for. I might have counted all the pins on all the chips otherwise.

I'm a newcomer to Porsche-world, but I have lifelong experience in a technology-driven business. I admit that I am swayed in favor of an updated factory unit vs. an older DME with a new aftermarket chip. The beauty of this forum is that all sides of the story are presented, sometimes... uh... "vigorously." Each of us gets to make our own decision and compare notes. It's a beautiful thing!

Originally Posted by Geronimo '74 (Post 6593539)

Full_garage,

Welcome.
Good to see Loren's perpetual BS finally did actually bring something positive to this forum: a new Pelican member.

Stick around, it's a great place to be. After this thread has gone, better ones will come along.

Originally Posted by rick-l (Post 6593467)

Loren
If you reply using this button we could see who you are responding to...

Originally Posted by JJ 911SC (Post 6589319)

...

P.S . Someone on this thread does not know about the "Quote" button :rolleyes:

Originally Posted by dshepp806 (Post 6591409)

mmm...let's see?....

.....(try this, Doyle): Is anyone here familiar with the timing (ignition) maps for the DME in the '88/'89? (As well as the pre-'88 DME?). If so, are you willing to share this knowledge?

How about the fuel maps, while we're at it?

I know they idled it higher.....why?

Thanks, in advance, for any information that can be provided....

Best,

Doyle

Originally Posted by Lorenfb (Post 6593186)

So after about 150 posts, the thread finally has come to the conclusion that the later
28 pin 8K EPROM chip used in the '88/'89 911 3.2 DME ECM did make changes to affect
running improvements over the 24 pin 4K EPROM used in the '87 DME ECM and the
24 pin 2K EPROM used in the '84-'86 DME ECM. That's great!

Then this lastest Porsche update should be considered the ideal stock chip Porsche
produced for the 911 3.2, just as one would consider that Windows XP Service Pack 3
was the final and best version incorporating the lastest updates to Windows XP.

Originally Posted by db_cooper (Post 6593704)

The ignition map for the 3.2 DME is three dimensional. It is not a fixed X number of degrees BTDC @ X RPM, at least at anything less than full throttle. Throw in the processor variables for engine/air temperature, the fuel quality switch and fuel maps..we have a very lively little computer under the seat.

http://www.911chips.com/USignst.gif

This is a stock 3.2..USA..


http://www.911chips.com/EUignst.gif

This is a Euro/ROW 3.2

Originally Posted by rolls 912 (Post 6622069)

Hi
I've installed a sw chip in my euro 3.2 and now it won't start.

I'm running 98ron fuel. Does anyone know what's the correct setting for the fuel adjustment knob on the dme box? Do I turn it clock wise or anti?

Tia

Rolls

Originally Posted by Lorenfb (Post 6593186)

So after about 150 posts, the thread finally has come to the conclusion that the later
28 pin 8K EPROM chip used in the '88/'89 911 3.2 DME ECM did make changes to affect
running improvements over the 24 pin 4K EPROM used in the '87 DME ECM and the
24 pin 2K EPROM used in the '84-'86 DME ECM. That's great!

Then this lastest Porsche update should be considered the ideal stock chip Porsche
produced for the 911 3.2, just as one would consider that Windows XP Service Pack 3
was the final and best version incorporating the lastest updates to Windows XP.