I have a 944s ventiler and have seen some re chips on ebay which say it will improve torque and bhp and drivability, didn't realise you could chip such an old car, has anyone re chipped there s or any model apart from turbo which of course responds very well to re chips, is it money wasted or any good? I do like my s as its a revy engine and pulls well from 4500 rpm
944s re chip any good?
- Thread starter Lance
- Start date
924nutter
PCGB Member
The 16v engine is not a particularly torquey engine, and my understanding of the 16 v concept was that it enabled Porsche to offer 160 bhp in the States in both configuartions of emission cotrol. I don't remember where I read it, but it was either Michael Cottons book or in the blurb that came with the owners manual from my own 944s. I thought the lower torque on the S was more to do with the peaky cams and the fixed valve overlap, and they can't be changed by rechipping, but obviously if the map is tweaked to advance the ignition lower down and increase the fuelling the there must be benefits to be had. The limiting factor is the 10.7 to one compression ratio, and how it will affect pinking. All theory and conjecture of course. There is a saying that goes you pays your money you takes your choice. When I had mine, knowing it was sluggish "of the cam" I used to try to anticipate and get it on the cam before hand. When I has my S it was only 4 1/2 years old and I really didn't feel the need to modify the performance envelope, I just used to love putting it in 3rd and "releasing the catapult, and winding it round the rev counter to 6800. When you do that it flies, as you well know. I think that the most annoying aspect was that at 70 in 5th you were always well below that sweet spot, but its good practise for when you upgrade to a 944 turbo.
pauljmcnulty
Active member
Does the 2.7 have the same "economy" throttle cam as the 2.5 Lux? If so, the fast throttle cam is a cheap and safe way to give a sharper response. People who had them fitted at the Porscheshop open day were all impressed by it, £25 well spent.
I understand what your saying about the 16v engine, I don't want to strain any ignition and fueling parameters for the ske of a few extra ponies and maybe in the process change the characteristics of the engine, I bought it knowing that below about 4.5k rpm a mobility scooter is quicker but above this and around 6 it does fly, maybe I will just lighten it....free power eh
Indi9xx
New member
There are a few ways that a chip can improve on what the factory did.
When the factory tested the cars with the support of Bosch developing the maps, they had to assume really poor fuel quality in some markets, as well as numerous local emissions regulations, as well as various altitudes and vastly different climates.
All of these considerations were implemented into one ecu.. On some models this means multiple maps which can be locally tweaked, but never are, taking up precious ROM space, as well as there being big baggy margins in the maps for extremes of fuel and climate.
The margins for altitude, for a airflow meter car are important to keep in there, as not many models were fitted with the altitude sensors in the passenger footwell, but for MAF or MAP sensor maps, you can take up that slack as well.
The main gains for most chips are through narrowing the margins for fuel quality, which means the chip tuner has advanced the ignition further and sometimes, sloppily, globally..
Further gains though are found is using some of the unnecessary maps and the space they contained by increasing the resolution of the maps, as well as in some cases turning 2d maps into 3d maps, which can be especially useful on turbocharged models.. This is an example of modernising the tuning strategy of the ecu.
Another improvement is through other strategies.. as Porsche wanted the cars to be smooth and quite soft in some respects, so for example on turbo models the mapping was designed to make boost smoothly, however through running a little leaner as the turbo first spools, you can build up thermal energy which brings the turbo on sooner, which massively improves torque and mid range boost, which is just one reason why cars I tune often have monster amounts of torque, some tuners don't put the effort into that part of the map.
By specifying with a chip that the fuel has to be of a minimum quality level, a chiptuner can also remove the Porsche assumption that it could be getting fuel from plastic bottles on the side of the road in new deli... I tend to tune with 94/95 RON fuel, which means you can use just about anything in the UK.. However I can also tune a car with a minimum of 97 or 98 or higher fuel knock thresholds to improve performance further.
Then there are the assumptions of varied wear and manufacturing tolerances on the engine and support components which Porsche had to dial into the DME/ECU.. which is why a custom map, which is tuned on the road and the dyno always make more power, as some safety margins can be reduced further as well as the maps tuned for that specific car.
The 16v 2.5 cars are a bit of an oddity in some respects of the DME, as it was the first time that Porsche had used that revision of Motronic, so some gains can be had from using the software side of the later code used in the same Motronic version but with customised maps for the 2.5 16v
Its a bit of a minefield really.
When the factory tested the cars with the support of Bosch developing the maps, they had to assume really poor fuel quality in some markets, as well as numerous local emissions regulations, as well as various altitudes and vastly different climates.
All of these considerations were implemented into one ecu.. On some models this means multiple maps which can be locally tweaked, but never are, taking up precious ROM space, as well as there being big baggy margins in the maps for extremes of fuel and climate.
The margins for altitude, for a airflow meter car are important to keep in there, as not many models were fitted with the altitude sensors in the passenger footwell, but for MAF or MAP sensor maps, you can take up that slack as well.
The main gains for most chips are through narrowing the margins for fuel quality, which means the chip tuner has advanced the ignition further and sometimes, sloppily, globally..
Further gains though are found is using some of the unnecessary maps and the space they contained by increasing the resolution of the maps, as well as in some cases turning 2d maps into 3d maps, which can be especially useful on turbocharged models.. This is an example of modernising the tuning strategy of the ecu.
Another improvement is through other strategies.. as Porsche wanted the cars to be smooth and quite soft in some respects, so for example on turbo models the mapping was designed to make boost smoothly, however through running a little leaner as the turbo first spools, you can build up thermal energy which brings the turbo on sooner, which massively improves torque and mid range boost, which is just one reason why cars I tune often have monster amounts of torque, some tuners don't put the effort into that part of the map.
By specifying with a chip that the fuel has to be of a minimum quality level, a chiptuner can also remove the Porsche assumption that it could be getting fuel from plastic bottles on the side of the road in new deli... I tend to tune with 94/95 RON fuel, which means you can use just about anything in the UK.. However I can also tune a car with a minimum of 97 or 98 or higher fuel knock thresholds to improve performance further.
Then there are the assumptions of varied wear and manufacturing tolerances on the engine and support components which Porsche had to dial into the DME/ECU.. which is why a custom map, which is tuned on the road and the dyno always make more power, as some safety margins can be reduced further as well as the maps tuned for that specific car.
The 16v 2.5 cars are a bit of an oddity in some respects of the DME, as it was the first time that Porsche had used that revision of Motronic, so some gains can be had from using the software side of the later code used in the same Motronic version but with customised maps for the 2.5 16v
Its a bit of a minefield really.
Thank you for your input, it was rather interesting, so in summery would you recommend live mapping as opposed to just fitting a generic chip?, in your experience how would you proceed in tuning the 16v? I'm not after fire breathing performance but just a little extra eagerness! Making the most of what's there, thanks
andy watson
Moderator
Lol [
]That did make me laugh!
No chips needed, just push the load pedal more, rev it hard that's what was intended
Mine has a Promax chip, the previous owner said it made it a little smoother, but I don't have anything to compare it with. I have been a passenger in Andy's original map car, but I imagine the difference is so marginal you wouldn't tell as a passenger. Only thing I will say, is mine isn't too bad to cruise at low revs (around 2000rpm) as long as you don't expect any snap acceleration, but I've heard a few S owners saying that the standard car is not happy in say 4th gear in a 30.
If I get really serious about my S I think in the long run I would go to standalone management to see what modern systems can eek out of it. It's a shame that the cam timing is fixed as it would be interesting to see what you could gain playing around with that. Will be interesting to see how that 2.5 16V supercharger project goes that Barks (was it Barks?) started.
If I get really serious about my S I think in the long run I would go to standalone management to see what modern systems can eek out of it. It's a shame that the cam timing is fixed as it would be interesting to see what you could gain playing around with that. Will be interesting to see how that 2.5 16V supercharger project goes that Barks (was it Barks?) started.
Martin Sage
New member
Good advice Andy and I have just started using Shell Nitro which makes a noticeable improvement IMHO []
]Ex Skyline
New member
I've got a JMG 9xx chip in my '89 Turbo [8D]! WOW!! Say no more [8D]!
Ex Skyline
New member
Forgot to say, has your car been mapped for "Gucci" fuel Martin? If not, you're just wasting your money [].
].
924nutter
PCGB Member
I am of the notion that e-prom stood for erasable program read only memory, which to me means than the program in the memory is erasable. i.e. changeable. I know that some of our packing machinery had e proms in them and we were able to fine tune various timers within it to optimise the machinery's performamce.
You can write data to an EPROM using an EPROM blower, so it would have to be removed from the ECU to be written, likewise they are erased using UV, so would have to be removed to clear them.
An EEPROM can be written electrically on the fly so I would guess a more modern ECU uses EEPROM or flash memory.
An EEPROM can be written electrically on the fly so I would guess a more modern ECU uses EEPROM or flash memory.
Indi9xx
New member
The kit we use for dyno and road tuning is an eprom emulator.. A ribbon cable plugs in where the eprom goes and connects at the other end to our eprom emulator, which connects to a laptop with a USB lead.
The laptop uploads the eprom image to the emulator, which then serves the data to the DME.. Basicly, as the DME requests data from what it thinks is the eprom, the emulator then sets the correct bits on the ribbon cable, for that data address in the image on the emulator...
Using software on the laptop, which iscolates the maps we have identified on the eprom image, as well as visualising them, we are then able to change the fueling in any data location of any of the maps.
Likewise, we have all the original C and machine code source code for the software and maps in the Bosch Motronic Porsche ECU's, so we can tailor software to do what we want it to and recompile it.. Or in our case, re-assemble it as machine code/assembler is much more efficient than languages such as C.
Once finished on the dyno and we are happy with the editied image on the dyno, we than save the data as a .hex file on the laptop and burn a new image to a fresh eprom and install that in the car.
Not as easy as flash coding a Boxster etc, but we have full control over a Motronic eprommed ECU, where as some areas are always protected on flash progamming the later 98 onwards DME/ECU.
The other good thing about the software is that we can see exactly as a highlighted item in the data, where the ECU is polling data at any one point, so, if for example we know nothing about the map locations in a 1991 BMW 535i, we can plug in the emulator with an image from the original eprom, and see where it is taking data, as well as running code, as the engine is running.. However, finding things such as rev limiters, often either means having the source code, or knowing how Bosch formats their maps to find them all.
As you can imagine, had this kit for donkeys years, so were quite annoyed when flash reprogramming the later cars became essential, as it meant the first learning curve on reverse engineering something in about 20 years, and our man at Bosch stopped being involved in about 1997
We used to keep how we did it under our hat, but now most of our customers know how we do it anyway, so sod it.. you all know now!
I have just finished writing a book for the 944 which is available in April (just a buyers guide for a publisher) but am thinking of writing a 101 projects for your 944 book, which will let lots of secrets and cats out of bags, seeing as the market is small enough to not support itself properly in a commercial sense.
The laptop uploads the eprom image to the emulator, which then serves the data to the DME.. Basicly, as the DME requests data from what it thinks is the eprom, the emulator then sets the correct bits on the ribbon cable, for that data address in the image on the emulator...
Using software on the laptop, which iscolates the maps we have identified on the eprom image, as well as visualising them, we are then able to change the fueling in any data location of any of the maps.
Likewise, we have all the original C and machine code source code for the software and maps in the Bosch Motronic Porsche ECU's, so we can tailor software to do what we want it to and recompile it.. Or in our case, re-assemble it as machine code/assembler is much more efficient than languages such as C.
Once finished on the dyno and we are happy with the editied image on the dyno, we than save the data as a .hex file on the laptop and burn a new image to a fresh eprom and install that in the car.
Not as easy as flash coding a Boxster etc, but we have full control over a Motronic eprommed ECU, where as some areas are always protected on flash progamming the later 98 onwards DME/ECU.
The other good thing about the software is that we can see exactly as a highlighted item in the data, where the ECU is polling data at any one point, so, if for example we know nothing about the map locations in a 1991 BMW 535i, we can plug in the emulator with an image from the original eprom, and see where it is taking data, as well as running code, as the engine is running.. However, finding things such as rev limiters, often either means having the source code, or knowing how Bosch formats their maps to find them all.
As you can imagine, had this kit for donkeys years, so were quite annoyed when flash reprogramming the later cars became essential, as it meant the first learning curve on reverse engineering something in about 20 years, and our man at Bosch stopped being involved in about 1997
We used to keep how we did it under our hat, but now most of our customers know how we do it anyway, so sod it.. you all know now!
I have just finished writing a book for the 944 which is available in April (just a buyers guide for a publisher) but am thinking of writing a 101 projects for your 944 book, which will let lots of secrets and cats out of bags, seeing as the market is small enough to not support itself properly in a commercial sense.
Indi9xx
New member
Oh, and a combination of a road tune, followed by a dyno tune to polish up the map is the only way to get the best out of a car.
Some places just dyno tune them, but in that situation you are tuning the car to be the greatest car in the world at towing a caravan up a steep hill without wind resistance or airflow considerations.
Road tuning, with all the data logging we do of AFR, EGT's, Knock monitoring, boost/vacuum, as well as all the ecu sensor levels, gives more data than available to a standard dynodynamics rolling road, but with the benefit of doing it actually on a road or track.
Polishing off the map on a dyno, means you can tune to MBT from power levels, as well as monitoring a currently secret variable which predicts the onset of knock, before it is detectable either in knock (from a sensor) audibly (via det cans) or from tuning to MBT alone... Which I have never seen someone tune to before, other than the guy who taught me the trick who worked in F1.. But I might let the cat out of the bag on this one someday
Some places just dyno tune them, but in that situation you are tuning the car to be the greatest car in the world at towing a caravan up a steep hill without wind resistance or airflow considerations.
Road tuning, with all the data logging we do of AFR, EGT's, Knock monitoring, boost/vacuum, as well as all the ecu sensor levels, gives more data than available to a standard dynodynamics rolling road, but with the benefit of doing it actually on a road or track.
Polishing off the map on a dyno, means you can tune to MBT from power levels, as well as monitoring a currently secret variable which predicts the onset of knock, before it is detectable either in knock (from a sensor) audibly (via det cans) or from tuning to MBT alone... Which I have never seen someone tune to before, other than the guy who taught me the trick who worked in F1.. But I might let the cat out of the bag on this one someday
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