SL ECU Major Differences or Why NOT to Use an SL ECU

[Drummer]

Well if green is right, then once the sl ecu is flashed to vr4, it will use the circuit like a vr4 should. But 99vr4 says there are differences. Need the final answer here!

Any idea what the ecu's will cost when ready for sale as a kit? Flashed for the correct 99 revision, and ready for install with harness?

[Jesters Deadd]

Well if green is right, then once the sl ecu is flashed to vr4, it will use the circuit like a vr4 should. But 99vr4 says there are differences. Need the final answer here!

Any idea what the ecu's will cost when ready for sale as a kit? Flashed for the correct 99 revision, and ready for install with harness?

Worked fine for me... just saying...again. NO one else has said it hasn't worked for them.

[95gto]

Well if green is right, then once the sl ecu is flashed to vr4, it will use the circuit like a vr4 should. But 99vr4 says there are differences. Need the final answer here!

Any idea what the ecu's will cost when ready for sale as a kit? Flashed for the correct 99 revision, and ready for install with harness?

There is a hardware difference in the knock circuits and the easiest way to think about the issue would be to think of it like having a non-matched gauge unit and sending unit.

So say you have an Apexi oil pressure gauge (round unit with the needle) but a Greddy oil pressure sending unit. The two parts may work well enough together that it is not an issue (ie it could read accurately enough) but I would personally prefer to use a matched gauge and sending unit.

The difference in the knock circuit is similar in that it may work well enough but its not correctly matched. Whether or not you want the matched set or the "should be okay" set is your call.

[Drummer]

There is a hardware difference in the knock circuits and the easiest way to think about the issue would be to think of it like having a non-matched gauge unit and sending unit.

So say you have an Apexi oil pressure gauge (round unit with the needle) but a Greddy oil pressure sending unit. The two parts may work well enough together that it is not an issue (ie it could read accurately enough) but I would personally prefer to use a matched gauge and sending unit.

The difference in the knock circuit is similar in that it may work well enough but its not correctly matched. Whether or not you want the matched set or the "should be okay" set is your call.

Ok I get that, but what Im wondering about is how they differ. If greens information is correct, the sensor circuits are identical. Is there something else in the path that is not? Another part of the circuit? Im just trying to make sense of it. Perhaps the sensor itself is not identical in older models? I have not yet opened up my SL ECU, and I now own a VR4 ECU. So Im just asking ahead of time to save me the trouble. I will take a look personally in the end, as I have the correct values and locations.

[95gto]

Ok I get that, but what Im wondering about is how they differ. If greens information is correct, the sensor circuits are identical. Is there something else in the path that is not? Another part of the circuit? Im just trying to make sense of it. Perhaps the sensor itself is not identical in older models? I have not yet opened up my SL ECU, and I now own a VR4 ECU. So Im just asking ahead of time to save me the trouble. I will take a look personally in the end, as I have the correct values and locations.

Based on a side by side comparison the knock circuits on the ecu boards, vr4 versus sl, are not identical. There are differences in the surface mount hardware and that circuity impacts the knock signal your ecu sees from the knock sensor. So going back to my metaphor, the ecu = the gauge and the sender is the knock circuit.

I'm not sure who Paul's very reliable source is but I know that Brett is first hand comparing a VR4 ecu to the others, not to mention that Paul's source may be some of the folks that Brett is already talking to.

[green-lantern]

I'm not sure who Paul's very reliable source is but I know that Brett is first hand comparing a VR4 ecu to the others, not to mention that Paul's source may be some of the folks that Brett is already talking to.

It’s Jeff, it’s why I’m a bit baffled that I’m seeing conflicting information about it. It’s not like these guys haven’t talked to each other a lot about the ECU research.

[prop7459]

If this is the case, then why not stick with the 99 SL Rom and use the 99 knock sensor to prevent false readings?

[ChargerX3]

Interesting to see if this phantom knock will make itself known. Ive got a 98 Diamante ecu and a 99 vr4 ecu on the way. Will be glad to test this all out once i get hard wired in.

[95gto]

It’s Jeff, it’s why I’m a bit baffled that I’m seeing conflicting information about it. It’s not like these guys haven’t talked to each other a lot about the ECU research.

That's what I figured so I will bug Brett again about it.

[95gto]

If this is the case, then why not stick with the 99 SL Rom and use the 99 knock sensor to prevent false readings?

The issue isn't the sensor, the issue is the circuit on the ecu board. The knock sensor output does not directly go to a chip in the ecu there is other hardware in the circuit that the signal has to go through first.