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Discussion Starter · #1 ·
I have a ej2 civic with d16z6 motor I rebuilt, car has an oil pressure gauge now and that light doesn't always work right anyway, I had an engine run completely out of oil and the light never even flickered for a second. Always lit up under hard cornering tho lmao.

Anyway how am I gonna get this done? And can anyone tell me about using p72 ecu and NepTune Demon v2 RTP to allow for knock sensor? What's the software gonna be able to do??

93 Civic HB SI
1,720 Posts
Now if I'm reading the title of your post correctly, you ARE talking about "misfire" right? You seem to talk mostly about oil pressure in the post you submitted. I just want to make sure I'm replying correctly.

There really isn't anything in the realm of a normal user's ability to programmatically command an output to display/indicate/pick on ONLY cylinder "misfire" on an OBD1 ECU, at least not any OBD1 ECU I've seen and here are a few reasons why.

The ECU-specific fault code lists for (most) desirable Honda OBD1 ECUs that are useful to installing items like a Demon or some type of Hondata chipset do not support misfire detection and their related fault codes. If you look through a service manual for a car that a certain ECU came with, the manual usually only contains information on a limited subset of fault codes when compared to the Honda master OBD1 fault code list.

Misfire detection did not become mandatory until OBD2, but Honda was performing the R&D and perfecting the system by real-world field testing certain OBD1 ECUs somewhere out there in preparation for full roll out when OBD2 took over. I'm not exactly sure which OBD1 ECUs DO support OBD1 level misfire monitoring, but I've never personally seen these fault codes set on an OBD1 Honda vehicle though they do fall within the realm of the architecture as shown on Honda's master OBD1 fault code list:

Code 71
Misfire detected cylinder 1

Code 72
Misfire detected cylinder 2

Code 73
Misfire detected cylinder 3

Code 74
Misfire detected cylinder 4

Code 75
Misfire detected cylinder 5

Code 76
Misfire detected cylinder 6

Even if your OBD1 ECU DID support misfire detection, your ECU would automatically notify you via the CEL/MIL light in the dash. I don't know why you would want any other light to perform the task of notifying you that there are system faults, as the EPA has already forced manufacturers to include this handy little indicator on every computer controlled powertrain since 1986.

As for your oil pressure issue, it seems keeping the oil in the pan is the cause of the oil light being on lol. Here are a few things to consider doing if your going through a ton of oil on an engine you really like/want to keep going:

1. Seal all leaks
2. Perform an engine rebuild to slow down consumption
3. Verify your PCV system is functioning correctly and is not sucking your crankcase dry
4. Be more persistent in using the dipstick to check oil level

If all the above have been done in an attempt to keep oil in the pan, but your still concerned with being able to keep tabs on the oil that is actually present in the pan itself, you can install an aftermarket oil level sensor and gauge/light to monitor actual levels in the pan. Couple this with an actual oil pressure gauge to verify the instrument cluster light operation as a backup monitoring device, and you'll have double the ways of confirming the presence of oil! There are a number of ways/solutions to do all this, but honestly the cheapest is to just check your oil everytime you get fuel. It takes <2 minutes for piece of mind!

As far as your Knock Sensor question goes, Neptune/Hondata allows a user to manually enable/disable the Knock Sensor input from affecting ignition timing. If you have a Knock Sensor input-enabled factory ECU and install a Demon/Hondata to it, in the software you can click a checkbox to tell it to use the knock sensor input as it would in factory form OR remove the checkmark so the ECU ignores so it cannot affect timing.

Having a knock sensor installed and functional as part of the ECU's primary inputs, the ECU will have some ability to detect damaging knock/detonation/pre-ignition and the ECU will pull timing back to attempt to stop the knock.

One of the reasons why you would want to remove the knock sensor from the equation is to give a user completely FULL control of ignition timing and remove anything screwing with it in order for someone like a tuner to have predictable repeatable results when messing with the ignition tables. Remember, engines CAN take a SMALL amount of knock for very short periods of time before severe damage to components start. An experienced tuner will notice this occurring (some tuners use an external knock sensing device that they can attach to the engine block while tuning in order to keep an eye on things) and will adjust tables accordingly.

I don't know the extent Honda OBD1 ECUs go to try and control preignition when knock is detected in the way some modern ECUs on mid to high performance cars can do. Knock control systems on more modern cars will pull timing AND add more fuel AND purposefully create a misfire on each cylinder occurring every other spark event AND add a bunch of EGR in an attempt to lower in-cylinder temperatures as quickly as possible until knock goes away.

Pulling timing DOES work to control spark-induced-timing-initiated knock shockwaves, but it CANNOT control pre-ignition/detonation events caused by cylinder hot spots/in cylinder combustible contaminates as effectively as the systems that go further like mentioned above.

I haven't seen to what extent an OBD1 Honda ECU goes, all it could do is pull timing, command more EGR (when equipped) and richen fuel mixture to reduce available oxygen to the mix. Maybe someone can clarify this for me?? Don't mean to threadjack!

Hopefully this answers some of your questions.
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