DIY 94-97 to 98-99 Patch Harness Parts

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Originally Posted by 99 vr4

jester . . . for an experienced tuner such as your self . . . the lack of a completely functional knock sensor is apparently a non issue. But for the normal DIY, this should be an area of concern. Big concern.

I am not saying that having a completely tunable ECU is a bad idea. Having a completely tunable ECU in which you THINK the knock sensor is working 100% is a bad idea. Would you remove your knock sensor completely and keep driving your car? I don't think so. If you knew your knock sensor was bad would you throw caution to the wind and say forget about it? Maybe you would. But you shouldn't.

I will try to shed some light on this in non-technical terms. The knock sensor is a piezo element which generates an electrical signal in response vibrations very much like a microphone generates electircal signals in response to sound waves. Think of the knock sensor circuit like an amplifier, audio filter, and signal processor. The filters and amplifers are hardware based while the signal processor is software based. If your filters and amplifers are not tuned the sound you get will be junk. You can't fix it the signal processor. Lets say your have a new audio amp for your car. It can pump 300 watts from 20 to 20K. But your speakers are rated from 70 to 15K. So you throw in a filter but miscalculate and your filter passes 50 to 5K. So now you have no high end (sounds like shit) and your driving too much bass to your speakers. Does it work? Yes. Does it work well? No. Will your speakers last? Time will tell. Probably if you don't drop any deep bass at high power.

I know you would never really mismatch your shit like that, but you are if you use an unmodified ECU. If you say its a non issue - then I wouldnt let you near my car if you paid me. I know your a smart man. I know your an experienced tuner. I also know that no one else has reported this problem. But you have heard of the Diamante and Montero "wierd" knock issue. Well guess what? Its the same circuit as what is in the SL ECU. Its only a matter of time. Sorry to bust your bubble. - Brett

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I know everyone involved in this appreciates the works you have put into this project. And for the record I totally agree with you... except the test results I gave should be taken into consideration also. I realize you are speaking from a review of the hardware side of this and reviewed the circuit differences. However, I tested this on my car and got the same amount of knock on the same program on the same road with in an hours time as my 99VR4 ecu at the same locations on the graph... it wasn't 100% scientific but it was very repeatable. That's real world testing to 18 plus psi. What would be nice is if we test the circuit to see the hz window the knock sensor sees. Then we can be able to tell if it is cutting off part of the window or if it is just narrower or shifted.

Great work guys! I should be able to test the knock sensor on a diamante ecu versus a 92 ecu soon. Its going to be next to impossible to get any good comparison, but I've tuned enough to know if something is fishy with the knock counts.

Jester, from what I can see is that the knock issue with the Diamante and Montero ECU's seems to affect some people more than others. Some people swear they don't get knock, and others get all sorts of issues with these ECUs. Knock itself is not always able to be duplicated. Lets say some guy in NY is getting knock. I could load his tune and not get any knock. There is so much more here than just the tune and fuel delivery.

You have to take into account fuel formulations. Not all gas is equal. And even if you buy Amoco Gold here in St. Louis you can bet it is not formulated the same as Amoco Gold in Florida or New York. Although the EPA mandates RFG vs CG in high polution areas, they also limit the Reed Vapor Pressure (basically the rate of boil off) so RFG will be formulated differently in the winter vs. summer vs. elevation for each major area. Frequent Questions | Reformulated Gasoline | US EPA Then you have to take into count air temperature, density, barometric pressure (elevation), and humidity. Throw all of this into the mix with your tune and thats how you might not get knock or you might get knock. :)

So although I am sure that your real world test yielded no additional knock, its not 100% because there are more variables. As far as the filter circuits are concerned, I am sure that Mitsubishi, if they could have cut corners (and cost) by using the same knock sensor circuits, they would have. Even though we are talking a small handful of parts, the engineers designed it, tested it, specified it, and signed off on it. It is there for a reason.

As far as working the math for the filter circuits, I hate laplace transforms and I don't see myself working out that math any time soon.

Interesting information per the 99 service manual...
"The knock sensor generates a voltage proportional to the magnitude of cylinder block vibration due to knocking and inputs it to the engine control module. Based on this signal, the engine control module provides retard control of the ignition timing."
So maybe it doesn't need Laplace transforms just a little V=IR.

Has anyone found a source for OBDII and Mitsubishi flash plugs other than junk yards? We don't have any 3S's around here or DSMs for that matter so I have to resort to another source to get at least the flash plug.

Any 96+ Mitsu will work. Eclipse, diamanté, montero... Surely they had something there.

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Originally Posted by Greg E

Any 96+ Mitsu will work. Eclipse, diamanté, montero... Surely they had something there.

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Nope. :(

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Originally Posted by TurboSinceBirth

Has anyone found a source for OBDII and Mitsubishi flash plugs other than junk yards? We don't have any 3S's around here or DSMs for that matter so I have to resort to another source to get at least the flash plug.

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You don't need the flash plug... Lol

Open port has a mini jack for the flash port on the side. They supply a stereo mini plug cable which plugs into the open port and then plugs into the mitsu re-flash plug. Just bypass the mitsu connector.

My harnesses are set up this way and include the obdii when needed.

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Originally Posted by 99 vr4

You don't need the flash plug... Lol

Open port has a mini jack for the flash port on the side. They supply a stereo mini plug cable which plugs into the open port and then plugs into the mitsu re-flash plug. Just bypass the mitsu connector.

My harnesses are set up this way and include the obdii when needed.

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While I was searching for somewhere to buy the plugs I ended up finding Ceddy's page where he listed this mod. I just got about 12 male to male mini stereo cables to do just that. They were cheap and I plan to build more than one harness.