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Discussion Starter · #1 ·
i've been trying to get my 83 UR coupe quattro that i just picked up running again after 11 long years of sitting. figured i'd inspect the ECU and see what sort of shape it was in. to my amazement i found a superchips sticker on top, i got curious and opened it and and found a chip inside with a superchips label. has anyone ever seen or ran a superchips modified ECU? i find this to be a bit odd as its modified by superchips.





 

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Wow. This is interesting. Was it running before?
 

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Discussion Starter · #3 ·
Yes it ran 14 years ago before it was put in a warehouse. I got the car to run last night too.

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vwnut8392 said:
to my amazement i found a superchips sticker on top, i got curious and opened it and and found a chip inside with a superchips label. has anyone ever seen or ran a superchips modified ECU? i find this to be a bit odd as its modified by superchips.
*interesting* indeed...!

Interesting, as the only thing the Mac-02 ECU does is run ignition timing, and control the fuel pump (and do O2 sensor stuff)

As such, I'm not sure how much you *can* do to the ECU, except change the conditions when the fuel pump will cut out (like increase the boost cuthout threshold).

As such, "some" chip 'tuners' just did a hardware hack (the "Zener Clamp") that clamped the signal coming from the pressure transducer to a level just below the fuel pump cutout point. So, under high boost, pump wouldn't cut out. At teh same time, the ECU wouldn't know about the higher boost (as signal was clamped), so wouldn't adjust timing accordingly either..

On the other hand, some modified the ECU by re scaling the pressure sensor output using a resistor divider and re mapping the internal EPROM for this new sensor output, and also raising the overboost fuel pump cutout map inside the EPROM code.

Would be be very interesting to hear what other have to say about what you have.. :)
 

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Discussion Starter · #5 ·
i've considered doing a read out of the eprom but i dont have a stock one to see what they might have changed. i'll have to hunt and and see if i can find someone with a stock ECU. there's actually 5 other UR quattro's in my area and one of the other owners should be willing to let me borrow their ECU for a stock read out.
 

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Not quite true. There are pretty much three ways the ECUs could have been "mod'd". First, as you explained was the Zener diode. All this did was effectively remove the boost cutoff and limit any timing/fuel control over the MAP value corresponding to the voltage the MAP sensor was clamped to. A long term effect was that this would eventually kill the MAP sensor.

The "resistor mod" divided the MAP sensor output to some fraction of the true output and is the most common modification done to the older ECUs. Unlike the zener diode mod, this effected timing across the full MAP range, as well as the boost limit. Depending upon the resistance values used, this also can kill the MAP sensor. From a performance standpoint, this is very simple, effective and actually works pretty well in practice, although more so on the later ECUs as resistor mods will eventually kill the MAP sensor in MAC-02 ECUs. It does take a lot of work remapping an EPROM to get the same or better results as the resistor mod effectively increases ignition advance at a given MAP value as it puts the timing into values of lower MAP than actual. You must run premium at all times as the MAC-02 has no knock sensing. It does NOT turn a 2 bar MAP sensor into a 2.5 or whatever MAP sensor. From all the ECUs I have seen, no one used a reprogrammed EPROM along with it. If you reprogrammed the EPROM, there is no reason to rescale the MAP sensor, you just do it in the calibration tables.

Last was reprogramming the EPROM. This allows you to change timing, mixture enrichment, boost cutoff, warm-up enrichment, etc. I've never seen a Superchips modified MAC-02, but it looks like they may have actually reprogrammed the EPROM, which IMO is the correct way to recalibrate the ECU. One thing I found helpful was to get rid of the lean mixture at a certain temperature when the engine was warming up. This helped warm up the cat for emissions, but made the engine slow to respond to the throttle transitions when the engine was not up to temp, which I found to be a PITA in winter. Theoretically, you could swap in a different MAP sensor, maybe a 2.5 bar, and rescale everything properly, but these engines and fuel systems can't handle the extra boost possible by doing this, so I don't know anyone who has done it. It can be done quite effectively on the later MAC-11s and -14s as those engines and fuel systems can handle it if done correctly.

Steve

Katman said:
vwnut8392 said:
to my amazement i found a superchips sticker on top, i got curious and opened it and and found a chip inside with a superchips label. has anyone ever seen or ran a superchips modified ECU? i find this to be a bit odd as its modified by superchips.
*interesting* indeed...!

Interesting, as the only thing the Mac-02 ECU does is run ignition timing, and control the fuel pump (and do O2 sensor stuff)

As such, I'm not sure how much you *can* do to the ECU, except change the conditions when the fuel pump will cut out (like increase the boost cuthout threshold).

As such, "some" chip 'tuners' just did a hardware hack (the "Zener Clamp") that clamped the signal coming from the pressure transducer to a level just below the fuel pump cutout point. So, under high boost, pump wouldn't cut out. At teh same time, the ECU wouldn't know about the higher boost (as signal was clamped), so wouldn't adjust timing accordingly either..

On the other hand, some modified the ECU by re scaling the pressure sensor output using a resistor divider and re mapping the internal EPROM for this new sensor output, and also raising the overboost fuel pump cutout map inside the EPROM code.

Would be be very interesting to hear what other have to say about what you have.. :)
 
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