Gunner823

iTrader: (2)

I'm stuck between a rock and a hard place. I'm currently running a procharger with about 11psi of boost. my car has a very loud exhaust, so there's lots of noise under the hood. the issue i'm having is when my knock sensor is plugged in the car runs like ***. I get all kinds of hesitation at low throttle cruising (bucking) and when i nail it you can just feel the car hesitating and surging. This all goes away when i unplug the knock sensor- however, because my car tends to get pretty warm after 20 minutes of highway driving in the summer (220 or so) getting on it at all throws an immediate code 43 and I go into limp mode until I shut it down and restart.

Is there anyway to get the ECM to ignore the knock sensor WITHOUT throwing a code 43 at warm temps? Or better yet, a way to plug the sensor back in and stop it from pulling so much timing because of my supercharger/exhaust noise. The car is NOT detonating, I've dynoed it and my A/F ratios are in good shape.

jethawk

wire in some resistors instead of the knock sensor! no more code 43!

Gunner823

iTrader: (2)

Can someone walk me through that? I saw a diagram earlier but didn't quite understand it.

Damon

Clip the plug off the knock sensor wire, attach it to a cheap 3900 Ohm resistor like you get at Radio Shack for $.25 and attach the other wire from the resistor to a good ground- block, frame, etc.

You better stay REAL conservative on the ignition timing once you do this. Hot engines, boost and full timing is a custom-made recipe for detonation.

Your knock sensor might just be saving you butt right now, even if it makes the engine run like crap.

Please note many people say that the ECM "tests" to see if the knock sensor is actually working by occasionally over-advancing the timing to force knock, which it then listens for to confirm the sensor is actually working. If it doesn't hear any it throws the penalty flag. I can't say I've actually seen that kind of behaviour when I've done this mod before (which is several times) but I never say never or discount the greater knowlege of people who have actually crawled around inside the chip progrmming of these car's computers.

Gunner823

iTrader: (2)

Thanks.

I shouldn't have any issues. I'm running a mix of 94 and 100 octane, 30# injectors, an FMU that boosts my fuel pressure to 70+ lbs at full boost and my compression has been lowered from stock to 8:1. I've also got a set of 14" fans on order and I'm going to remove my A/C condenser ASAP, the combination of which should drastically lower my operating temps.


As for the ECM, it certainly checks for something- I have verified time and time again that if I leave the sensor unplugged, once I get over about 200 degrees I can't play with it past 3000rpm at _all_ or it will throw an SES code 43 every single time. Doesn't do this at all with the sensor plugged in.

86Z

iTrader: (4)

i was having similar issues, i did a tpi swap, before my procharger when i hit the gas the engine would just flatten out like i hit a wall, i hooked up the laptop and found the knock sensor was retarding my timing up to 11.40 degrees, i disabled the knock sensor in the code and it all went away, although i would like to have it hooked up, i'm still working on that.