For those of you that like to do your own tuning...

[geekinavette]

I know there are some of you C4 junkies...errr I mean enthusiasts...out there that like to do your own engine tweaking/tuning (as opposed to paying someone else for a "chip"). For those that do, this little gizmo may be of interest...

http://www.speedtronics.net/aboutprominator.asp

It basically replaces the EPROM in the ECM with a little board that has Flash ROM on it. The Flash ROM can be reprogrammed via a connection to a laptop computer...and can even be reprogrammed "on the fly". ("Pro version can be reprogrammed "on the fly", "Standard" version needs to have the engine stopped) It will also store up to 8 configurations, with a little rotary switch to select a particular configuration.

This gizmo is an idea a friend of mine had a couple of years ago, sounded really cool so I built it! :L

Now, I've been having a few issues with my webserver, so if the site isn't coming up, either try again later or just shoot me a PM.

Oh and just in case anyone's interested...I AM "authorized" to offer a discount for a while ($50 off a "Pro" version or $25 off a "Standard" version).

There are to date about 85 or so of these "out there" being used by tuning junkies...errr "enthusiasts". (it CAN get quite addictive!).


Bill

 

[JonM]

See folks...all the "Smart People" own 84's...

 

[geekinavette]

So put you down for two eh Jon?

:L

 

[Mad-Mic]

whats the price and can i use this on my 2 tpi cars or is it only for 1 individual?

i know Rich Ruble got one but haven't talked to him about it but i am interested

 

[milehigreg]

PROM or EPROM - That is the question

Hi Bill. My understanding is that the earlier C4s have an unprogrammable PROM while later models have a proagrammable EPROM. Is this correct? If so, your device replaces the PROM with an EPROM?

 

[geekinavette]

If the two TPI cars use the same ECM (more specifically the same EPROM size), then yes you can swap it between them. This is one advantage of the TPI cars, they use a removeable MEMCAL module that contains the EPROM. It does require an extra MEMCAL adapter, but allows you to literally "plug 'n play". Each Prominator is configured for a specific EPROM size, in your case probably a 27C128 I'm guessing (could be 256)...so yeah if the two use the same size EPROM then swapping back and forth is a snap. Of course this means leaving the ECM accessable, which is kinda ugly.

There are the two versions, Pro and Standard. Basically, the Pro version can be reprogrammed with the engine running, even driving down the road for that matter (have a co-pilot! :L) without interrupting the ECM. With the Standard version the ECM is interrupted during the upload, then recovers once the file is done being transferred (about 15-20 seconds or so for a 16KByte file), so it's best if the engine is off during the upload. The Pro version normally retails for $275, Standard for $175. Right now I can offer $50 off a Pro, or $25 off a Standard. The MEMCAL adapter is normally $35, and the optional switches range from $15 (no display) to $25 with a cute little blue 7-segment display in a small plastic enclosure.

Yeah Rich picked one up recently....haven't heard much from him so I'm assuming he's become "addicted"? :L

Greg,

82 and 84 crossfires did indeed use a PROM. The Prominator will NOT replace a PROM, ONLY a EPROM. What the crossfire guys do (myself included) is replace the stock ECM with one from a early 80s TBI truck (1227747) or TBI caprice/F-body (1228746) that uses a 2732 EPROM. The replacement ECMs have a pin/socket type harness connector where the stock crossfire harness is the edge-card type. Not to worry...we have that covered also. http://www.speedtronics.net/aboutham.asp There are probably 40 or so "HAM" converted 7747/8746 ECMs in Crossfire cars all over the place! :L

I've been running the 8746 in mine for a couple years now. Last year on the way out to Cruisefest my 84 was getting terrible gas mileage...about 17 as I recall. With a little tweaking in the Baymont parking lot...I was up to about 22 on the way back.

 

[Toms007]

If the two TPI cars use the same ECM (more specifically the same EPROM size), then yes you can swap it between them. This is one advantage of the TPI cars, they use a removeable MEMCAL module that contains the EPROM. It does require an extra MEMCAL adapter, but allows you to literally "plug 'n play". Each Prominator is configured for a specific EPROM size, in your case probably a 27C128 I'm guessing (could be 256)...so yeah if the two use the same size EPROM then swapping back and forth is a snap. Of course this means leaving the ECM accessable, which is kinda ugly.

There are the two versions, Pro and Standard. Basically, the Pro version can be reprogrammed with the engine running, even driving down the road for that matter (have a co-pilot! :L) without interrupting the ECM. With the Standard version the ECM is interrupted during the upload, then recovers once the file is done being transferred (about 15-20 seconds or so for a 16KByte file), so it's best if the engine is off during the upload. The Pro version normally retails for $275, Standard for $175. Right now I can offer $50 off a Pro, or $25 off a Standard. The MEMCAL adapter is normally $35, and the optional switches range from $15 (no display) to $25 with a cute little blue 7-segment display in a small plastic enclosure.

Yeah Rich picked one up recently....haven't heard much from him so I'm assuming he's become "addicted"? :L

Greg,

82 and 84 crossfires did indeed use a PROM. The Prominator will NOT replace a PROM, ONLY a EPROM. What the crossfire guys do (myself included) is replace the stock ECM with one from a early 80s TBI truck (1227747) or TBI caprice/F-body (1228746) that uses a 2732 EPROM. The replacement ECMs have a pin/socket type harness connector where the stock crossfire harness is the edge-card type. Not to worry...we have that covered also. http://www.speedtronics.net/aboutham.asp There are probably 40 or so "HAM" converted 7747/8746 ECMs in Crossfire cars all over the place! :L

I've been running the 8746 in mine for a couple years now. Last year on the way out to Cruisefest my 84 was getting terrible gas mileage...about 17 as I recall. With a little tweaking in the Baymont parking lot...I was up to about 22 on the way back.

Bill, I was just getting ready to mention this when I started reading this thread. I was impressed with the work you had done. Good luck.....oh and BTW Bill is a really great guy.

 

[milehigreg]

ECMs, PROMS and EEPROMS

Hi Bill. I checked my book, "Corvette Fuel Injection" last night. It said that a PROM was used in Vettes through 1993. Starting in 1994, EEPROMS ( Electronically Erasable ) were used. According to the book, the first EEPROMS were somewhat easy to reprogram with a scanner. Once OBD-II came along in 96 it became much trickier. I'm no electronics GEEK, and I know you know your stuff. Does your device get placed in in the ECM to emulate a programmable EEPROM? Can you clear this up?:confused

 

[geekinavette]

Ok Greg hereyago...

The statement "a PROM was used in Vettes through 1993. Starting in 1994, EEPROMS ( Electronically Erasable ) were used" isn't exactly accurate.

We're talking about three different memory technologies here:

PROM: Programmable Read Only Memory. These are One-Time Programmable (OTP) devices. Once programmed that's it, the data is there forever. They cannot be erased. These are the 25xx series devices...2532 for example is a 32Kbit device.

EPROM: Erasable Programmable Read Only Memory. (27xx series) As the name says, just like a PROM but erasable. These devices have a little glass window in them for exposing the chip die to UV light. Takes about half an hour of UV exposure to fully erase a EPROM. They also require a large voltage to program, usually around 20-25 Volts. "Erasing" a EPROM is really nothing more than setting all bits to a "1" (high) state. Only a "0" (low) state can actually be "written" to a EPROM. (not really relevant, just usless info).

What you run into sometimes is that a EPROM is often referred to as just a PROM...which isn't exactly incorrect, just lacking a full description. A EPROM IS by definition still a Programmable Read Only Memory...it just happens to be erasable. EPROMs are a nightmare to deal with. Not only do they require a UV eraser, but also a device programmer to provide the required high voltage and electrical timing to reprogram them. EPROMs are also not designed to survive endless erase/program cycles. Eventually the UV exposure takes its toll on the die of the chip and it will not reliably store data any longer. They are also quite slow as far as programming. A 27128 (used quite commonly in the early C4s starting with '85) takes probably a good 5 minutes or so to just to program the chip...and don't forget a good 1/2 hour to erase it. It takes about 15 seconds to perform the same program/erase cycle with a Prominator.

Then there's the EEPROM. Electrically Erasable Programmable Read Only Memory. Getting to be a mouthful! :L Just like the EPROM as far as reading data from it, but quite different in programming. These devices are much more suited for frequent reprogramming of the memory contents. They do not require the high voltage like the EPROM does. The EEPROM can be reprogrammed in-circuit, where the EPROM must be removed from the circuit to be erased and reprogrammed. This of course requires that the EPROM be socketed. The EEPROM can also handle a LOT more erase/program cycles than a EPROM can.

Flash ROM is very similar to EEPROM in functionality....pretty much identical in what they do, just a little different technology. The two terms are used interchangeably quite often.

The Prominator uses Flash ROM and is a direct replacement for ANY system that uses a EPROM. Prominator is NOT compatible with a system that uses a PROM. It will ONLY work with a system that uses a EPROM. It basically replaces the EPROM with Flash ROM.

The in-circuit reprogramming feature of Flash or EEPROM presents an interesting challenge though. This comes from the fact that you cannot read from and write data to any type of ROM at the same time. What this means is when the ROM is being reprogrammed, the ECM is not able to read valid data from the ROM and will go into "limp home" mode as well as throw a "BAD ROM" error (code 51 I believe). This is why it is recommended NOT to upload a file to the Standard version while the engine is running. The Pro version solves this problem by providing TWO Flash ROM devices....one that the ECM can read data from while the other is being reprogrammed, thus each upload actually writes the same data to both ROM "banks". This allows the ECM to have uninterruped access to valid ROM data during a erase/program cycle.

So, the statement "a PROM was used in Vettes through 1993. Starting in 1994, EEPROMS ( Electronically Erasable ) were used" should really read "a PROM was used in Vettes with computerized engine control through 1984, then a EPROM was used from 1985 through 1993", then a EEPROM/Flash ROM after that"

I think computers came about maybe in 1980 Corvettes (or somewhere thereabouts) with the CCC system (Computer Controlled Carburetor) and surely used a PROM, then the electronic throttle body fuel injection in 1982 and 1984 (Crossfire) which I know for a fact used a PROM (a 2532 PROM chip), then of course TPI in 1985, and those computers use a EPROM (27128 I do believe in '85).

Clear as mud now? :L

Bill

 

[Robertwav1]

I'm impressed! Nice write up!

 

[milehigreg]

Crystal Clear!

Excellent explanation, and good info for everyone here at the .:BOW I assume you have been able to do a shakedown run with the rebuilt tranny and you are ready for the Caravan to Cruisefest. Have a great trip!

 

[geekinavette]

Excellent explanation, and good info for everyone here at the .:BOW I assume you have been able to do a shakedown run with the rebuilt tranny and you are ready for the Caravan to Cruisefest. Have a great trip!

Cool, glad to hear that occassionally my babbling makes a little sense. :L

Yeah been driving her to work alot (65 miles one way), got a little over 2,000 miles since the rebuild and it's working just perfectly (even chirps the tires in second now and then!) Now to do something about all those rattles... (I guess at 180K miles that's to be expected!)

Bill

 

[geekinavette]

I'm impressed! Nice write up!

Thank you!

Bill

 

[WhalePirot]

See folks...all the "Smart People" own 84's...

I thought that was obvious!

Geek, excellent, as we've come to expect from you. There is no mention, so I assume that the device cannot 'self-learn' to target, say, optimum air-fuel ratio?

Sounds like this will work with my 90 Camaro ECM. The tune was superb before the rebuild, but may need tweeking with the 'new' 409.

mike

 

[geekinavette]

Thanks Mike!

NOOOOO...this device does NO "auto-tuning"! There are those that are attempting to do something like that...but boy that's very dangerous ground to be walking on!

Yeah it will work fine with your 90 Camaro ECM...and ya I'd say the 409 will vary just a taaaaad bit from the stocker! :L

It's not too late if anyone's interested in one of these to have one (or more) ready to bring to Cruisefest!

Bill

 

[Mad-Mic]

Thanks Mike!

NOOOOO...this device does NO "auto-tuning"! There are those that are attempting to do something like that...but boy that's very dangerous ground to be walking on!

Yeah it will work fine with your 90 Camaro ECM...and ya I'd say the 409 will vary just a taaaaad bit from the stocker! :L

It's not too late if anyone's interested in one of these to have one (or more) ready to bring to Cruisefest!

Bill

Bill,

I'm definetly going to pick up atleast 1 here next month. it's for my 87 vette. other will be an 85 tpi ecm.

Mic

 

[geekinavette]

Bill,

I'm definetly going to pick up atleast 1 here next month. it's for my 87 vette. other will be an 85 tpi ecm.

Mic

Are you coming to CF next week?

 

[WhalePirot]

NOOOOO...this device does NO "auto-tuning"! There are those that are attempting to do something like that...but boy that's very dangerous ground to be walking on!

Why's that?

Yeah it will work fine with your 90 Camaro ECM...and ya I'd say the 409 will vary just a taaaaad bit from the stocker!

Umm, not changing from the stocker, but from the 11:1 406 that came apart, to a 409 @ 10.5:1; all else the same.

I still have the enlarged Crossfire intake setup, which we discussed a few eons ago.

 

[Mad-Mic]

Are you coming to CF next week?

no i could only wish my car isn't ready yet