Here’s a terrible idea: diy eprom programming

[stubble88]

Anyone know anything about programming 28 pin motronic eprom? Equipment, software etc. just curious. Would like to safely play around.

This the only info I’ve found.
https://www.impactbumpers.com/forum/index.php?/topic/27612-diy-motronic-tuning/

[917_Langheck]

Expect an admonishment from a guy who will say no one could possibly be smarter than the eggheads at Porsche, that the OEM program cannot be improved upon, despite the fact that that is exactly what the OEM did, and does, and that anyone selling such "chips" are just selling snake oil.

I'll start the count, 10, 9, 8, 7.....

[ChrisHamilton]

Originally Posted by 917_Langheck

Expect an admonishment from a guy who will say no one could possibly be smarter than the eggheads at Porsche, that the OEM program cannot be improved upon, despite the fact that that is exactly what the OEM did, and does, and that anyone selling such "chips" are just selling snake oil.

I'll start the count, 10, 9, 8, 7.....

Not really sure if you are saying it's possible or not possible. But I will say that a guy named Steve Wong has sold a lot of reprogrammed chips with a lot of satisfied customers.

[jac1976]

Originally Posted by ChrisHamilton

Not really sure if you are saying it's possible or not possible. But I will say that a guy named Steve Wong has sold a lot of reprogrammed chips with a lot of satisfied customers.

He’s saying that, despite the naysayers, it is possible and to positive effect.

[3rd_gear_Ted]

I'm thinking > a Win 95 machine.
EPROM Programming 101 - How to Program an EPROM and Other IC Chips.

[mysocal911]

Found this on the Pelican Forum;

Performance Tuning - The Myth -

and this;

[stubble88]

Oh yeah! This is great. Thanks. Keeping coming

[targa72e]

You will find more information about this on some of the 944 turbo forums. They have been doing this for a long time. You can use a EEPROM emulator (Ostrich) so you can do tuning on the fly. Once you get what you want you can burn a chip.

john

[917_Langheck]

Originally Posted by ChrisHamilton

Not really sure if you are saying it's possible or not possible. But I will say that a guy named Steve Wong has sold a lot of reprogrammed chips with a lot of satisfied customers.

What I am saying came in three posts after yours....

[pmax]

Originally Posted by ChrisHamilton

Not really sure if you are saying it's possible or not possible. But I will say that a guy named Steve Wong has sold a lot of reprogrammed chips with a lot of satisfied customers.

I hear those who have reported butt dyno improvements but the chart does say 4-8% from 4k to 6k.

Is that what our OP's looking at end of the day best case ?

[ChrisHamilton]

Originally Posted by pmax

I hear those who have reported butt dyno improvements but the chart does say 5%.

Is that what our OP's looking at end of the day best case ?

33+ hp gain at 6400 rpm is nothing to sneeze at. That is a massive improvement from just recalibrating the ECM. Almost too good to believe really.

Whether you can trust the various charts and dyno sheets is another story. Lots of ways to make an engine or chassis dyno read higher or lower. Chassis dynos especially. They are good for tuning and that's about it.

A certain shop in California has about the "happiest" dyno I've ever seen. And the Shop has tons of fanboys in the Datsun Z community. Although they never post the actual dyno sheets, so I wonder if they even do testing. I do know that one engine they built was down almost 100 hp from what they claimed. Saw that test (engine dyno) myself. Most people though don't know what they don't even know when it comes to the workings of an ICE. So it's easy for places to manipulate data and make claims that aren't really true.

[mysocal911]

Originally Posted by ChrisHamilton

33+ hp gain at 6400 rpm is nothing to sneeze at. That is a massive improvement from just recalibrating the ECM. Almost too good to believe really.

Whether you can trust the various charts and dyno sheets is another story. Lots of ways to make an engine or chassis dyno read higher or lower. Chassis dynos especially. They are good for tuning and that's about it.

A certain shop in California has about the "happiest" dyno I've ever seen. And the Shop has tons of fanboys in the Datsun Z community. Although they never post the actual dyno sheets, so I wonder if they even do testing. I do know that one engine they built was down almost 100 hp from what they claimed. Saw that test (engine dyno) myself. Most people though don't know what they don't even know when it comes to the workings of an ICE. So it's easy for places to manipulate data and make claims that aren't really true.

Yep, that's usually the case! It's also called "dream on".

[ChrisHamilton]

Originally Posted by pmax

I hear those who have reported butt dyno improvements but the chart does say 4-8% from 4k to 6k.

Is that what our OP's looking at end of the day best case ?

The real benefit of being able to recalibrate an ECM is when you are making modifications to the motor. Increasing the breathing capability with larger valves, porting of the cylinder head, camshaft, etc.

Stock it's very much dependent on how maxed out the factory tune is. There is always something to be gained because OEM's always leave in a margin of safety in their final tune. Leaning out the air fuel ratio is one place where a recalibrated ECM can pick up a few hp at the expense of risking detonation should the user get a tank of bad gas or other things. Generally the older the car and the ECM the more potential there is for a HP gain but not always. And realize that there are tricks that sellers of ECM's can play with a dyno to make the gains seem larger than they are. Always approach any claims with skepticism.

Like I said above it is much more useful when the vehicle has been modified.

[mysocal911]

Originally Posted by ChrisHamilton

The real benefit of being able to recalibrate an ECM is when you are making modifications to the motor. Increasing the breathing capability with larger valves, porting of the cylinder head, camshaft, etc.

Stock it's very much dependent on how maxed out the factory tune is. There is always something to be gained because OEM's always leave in a margin of safety in their final tune. Leaning out the air fuel ratio is one place where a recalibrated ECM can pick up a few hp at the expense of risking detonation should the user get a tank of bad gas or other things. Generally the older the car and the ECM the more potential there is for a HP gain but not always. And realize that there are tricks that sellers of ECM's can play with a dyno to make the gains seem larger than they are. Always approach any claims with skepticism.

Like I said above it is much more useful when the vehicle has been modified.

It's all about how far you want to "push" the ignition timing advance! It's that simple for anyone with a PC & an EPROM programmer, as exemplified in this thread.

[pmax]

Originally Posted by mysocal911

Found this on the Pelican Forum;

Performance Tuning - The Myth -

and this;

An ultimately informative thread but one has to sift thru the chaff and whatnot, I believe hardy anyone left the room without a wound or two LOL, talk about a fun read ...

however ... if I may summarize that long winded thread ....

there's no free lunch. Stock tune has to accomodate a wide operating range so if one is willing to "push it", there's room for some gains. Bosch says "no to little" improvement around the top of that AFR curve, which isn't inconsistent with the 3-4% ... i.e. small ... difference evident on the dyno runs tweaking one point over and under. The rest comes from ignition timing.

Sound about right ?

[mysocal911]

Originally Posted by pmax

An ultimately informative thread but one has to sift thru the chaff and whatnot, I believe hardy anyone left the room without a wound or two LOL, talk about a fun read ...

however ... if I may summarize that long winded thread ....

there's no free lunch. Stock tune has to accomodate a wide operating range so if one is willing to "push it", there's room for some gains. Bosch says "no to little" improvement around the top of that AFR curve, which isn't inconsistent with the 3-4% ... i.e. small ... difference evident on the dyno runs tweaking one point over and under. The rest comes from ignition timing.

Sound about right ?

Excellent! You got it. Hopefully, others will understand too.

[pmax]

Originally Posted by mysocal911

Excellent! You got it. Hopefully, others will understand too.

Thanks, makes sense to me then the highlighted section in this chart for a mostly stock 3.2 except race exhaust from https://911chips.com/dyno.html is all ignition given the AFR's the same. The stock AFR crosses over the chipped around that interval which is interesting and different from the chart above where the stock stays richer till redline, is that the Euro vs US difference ?

[PeteKz]

pmax: yes, that's the basic takeaway.

A note of warning for those installing chips or making their own tunes: The Carrera Motronic does not have a knock sensor, so it can't retard timing if detonation occurs. You can damage your engine if you got a bad load of gas or other cause of detonation.

You have to use the 964 or 993 engine controls or an aftermarket EFI system to get that feature. With knock sensing, the manufacturers DO advance the timing, and use the knock sensing to retard the timing if the fuel isn't high enough octane. With those systems, it's very hard to improve on the OE maps in a stock engine.