SR20 ECU only sending 3.3v to Knock Sensor?

[ultimateirving]

CBH148

I know the hiccup you speak of, my SR used to do it too. Its almost like it idles a little high, then kinda skips a beat idle drops then it goes back..
Main things i have done to correct this is:

first and foremost The system has to be completely leak free, Get a pressure tester and pressurize the system over the desired boost level. This means making sure all the vacuum lines and t-fittings you have are not seaping.

Next is IACV functionality, until i changed my iacv it was really bad and my idle would actually be all over the place, dying on decel, etcetera. Verify the proper voltage is getting to it and that it is not gunked up or frozen.

Coilpacks also are a culprit in these old motors. They often times can fire a spark that will at least let the car run, but its not always up to par, the gap of the plugs plays a part of this too. I run about .028 gap with 19psi..

Knock sensor is something that can cause issues, but normally its under load.
I have bypassed my knock sensor with the little resistor and havent looked back. Eventually when i get my new tune, i plan to disable it entirely so i dont have to worry about my bypass. As long as your tune is solid and you keep an eye on the wideband... the knock sensor can be removed.
Besides by the time it starts to detect knock it may be too late.

Try these

[cbh148]

I would think that, geometrically speaking, if the CAS is in its place, then that tight fit only allows it to twist. Then by adding a single bolt, it's not able to have any motion at all. Doesn't feel like it's got any wiggle to it. I just assumed the 2 bolts were more for backup or reassurance, but not actually crucial to have both bolts. Maybe I'm wrong here?

Originally Posted by ultimateirving

CBH148

I know the hiccup you speak of, my SR used to do it too. Its almost like it idles a little high, then kinda skips a beat idle drops then it goes back..
Main things i have done to correct this is:

first and foremost The system has to be completely leak free, Get a pressure tester and pressurize the system over the desired boost level. This means making sure all the vacuum lines and t-fittings you have are not seaping.

Next is IACV functionality, until i changed my iacv it was really bad and my idle would actually be all over the place, dying on decel, etcetera. Verify the proper voltage is getting to it and that it is not gunked up or frozen.

Coilpacks also are a culprit in these old motors. They often times can fire a spark that will at least let the car run, but its not always up to par, the gap of the plugs plays a part of this too. I run about .028 gap with 19psi..

Knock sensor is something that can cause issues, but normally its under load.
I have bypassed my knock sensor with the little resistor and havent looked back. Eventually when i get my new tune, i plan to disable it entirely so i dont have to worry about my bypass. As long as your tune is solid and you keep an eye on the wideband... the knock sensor can be removed.
Besides by the time it starts to detect knock it may be too late.

Try these

Thanks for the insight!

My SR's idle seems to be pretty damn good, as far as never dying or changing much. Seems to consistently sit right at 800rpm's. Doesn't require any throttle to start up, starts up quick, and never dies on its own.

The hiccup that happens every half-second or whole second is hard to describe, but it's almost like each individual hiccup is a tiny little studder. You just hear it in the exhaust note of the engine. It's almost like, in that exact moment that it studders, the rotational speed of the crank goes from 800rpm to 500rpm then right back to 800rpm -- so fast that the tach couldn't even register it. I'm guessing that's a misfire?

Either way, every single time the hiccup happens, the timing marks (when viewed with a timing light) will jump about 4° or more to the right, then come right back. It's an individual flash of the timing light (maybe once every 3 flashes?) that shows the different timing reading some 4° advanced.

Brand new NGK BKR7E plugs, gapped tight to .8mm (.032 inches).

I'm assuming my IACV is straight since the actual idle speed seems to be great and under control (again, no random dying or random high-ass 1400rpm idling like my CA18 would do).

Definitely planning on deleting my knock sensor whenever I get the chance. Seems like a lot of people hate the idea and/or are scared to do it, but then everyone that's deleted theirs and/or understands how unnecessary they are (and apparently how ineffective they are) says it's a great way to repair/prevent random drops in horsepower since the ECU will pull timing if the knock sensor is acting up, and with no code (unless it's totally fucked), then you'll never get a code since the codes on these old ECU's is more for fixing and diagnosing the circuits rather than for fixing and diagnosing actual engine problems that the sensors claim they're picking up on.

You used a 1 megaohm 1 watt resistor? And just put the resistor between pin #27 on the ECU and a ground? (such as one of the black ground wires right there in the harness by the big blue ECU plug).

[cbh148]

Also, figured I'd share this video I made. It's a bunch of clips of my boost gauge when making a 2nd gear pull and several 3rd gear pulls (all done at 2500rpm cruising, then floored it).

Seems like my buddy's stock SR (like mine) pulls twice as hard, and shoots up into boost 4 times faster on his gauge. He sent me a video of the same pull 2500rpm 3rd gear pull and it's a lot quicker.

Perhaps if my ignition timing is somehow retarded then that makes boost build slower (as well as just making less power in general)? And if so, dunno if the ignition timing is retarded from me somehow setting the CAS wrong with all the hiccuping and whatnot, or cause my replacement knock sensor from a KA is still very old and has some little cracks in it (but it doesn't cause the code like my old SR knock sensor does immediately).



Youtube smoothed out the shakiness of the video and made the text captions spazz out like crazy lol.