i have a 1989 gta L98 my car didnt seem that fast as it should be so i unpluged the knock sensor and used some octane boost and the car seemed to be alot faster is this possible? and why? so now i put the knock sensor back on and put some octane boost in and it feels slower again.

 

Chances are your knock sensor is bad. When theyre bad, they tell the ECM that there is audible knock, which inturn retards the timing. Replace your knock sensor with a brand new one and you should be good to go!

 

How do you test teh knock sensor - is there a way?
Can I just unplug it and see how the car runs with it unplugged?
I noticed that my car seems to loose LOTS of power once it warms up. This is one of VERY FEW sensore that I haven't changed..
How expensive are they?

oh, and will cool and/or oil flow out when I remove it?

Thanks,

 

The knock sensor screws into the block drain, so yes, coolant will come out when you unscrew it. Unless of course there is so much rust sediment in the block that the hole is covered.

As for just unplugging it, that will lead to a trouble code. The right way to unplug it is to bypass the sensor with a resistor (100k ohms for MAF, 3.9k for SD) so the ECM simply sees no knock.

 

Cool, so I can put a 100k resistor in place and run ...

THanks,,

 

Hmm. I didn't have any coolant come out when I replaced the one on my IROC, and that motor only had a couple thousand miles on it.

 

That can't be good. It is suppose to be in the coolant drain hole, which is defenately suppose to poor out coolant when removed. I would look into that. Just for safe sake that is.

 

Ed, would it be possible to put something like that on a toggle switch? Run it unbypassed on the street w/ 93 octane, and make use of the resistor as a track only item w/ 100 octane unleaded. Or would the gains from something like that be negligible? TIA

 

well, you could set it up on a switch, but i don't see much real value to doing so, except you eliminate knock retard as a variable in your tuning. I run mine bypassed for just that reason. Since up until now i didn't have a scan tool for tuning, i was using my old fashioned KS (also known as 'ears') to pick up knock.

But i guess if you wanted to leave the KS functional for the street in case of bad gas or whatever, then yes you could use a double throw switch to toggle between connected or bypassed. Then at the track just bypass it to ensure that you're not working against any KR. No need to run 100octane though, higher octane isn't going to make you go any faster.

 

Thanks for the info, now to just figure out how to go about wiring that up. I could be wrong, but I figured my high compression motor might like the extra octane.

 

Just a thought but wouldn't the knock sensor throw a code if it sensed something was amiss in terms of knock?
I think if the timing was retarded enough to hurt performance, you would definitely see the SES come on..

 

i have to say i unpluged my knock sensor and ran octane boost and my car was faster and i did not get a check engine code or light.

 

hmmm, we may be on to something here.
Where does the knock sensor plug into (on the harness side not on the block). As far as I remember, one end is down on the lower passenger side of the block (white plug). Where is the other end?

 

The other end stops at the ESC module.

 

Someone wanna refresh me where that is. I've been working on the bike for the last few months so my head is somewhere in japan.
Does it go through the firewall and behind the dash on the passenger side?

 

i unpluged mine from the block on the passenger side.can anyone tell why when unhooked and octane boost put in it would be faster?

 

this is for 88 ws6 trans am. i have a chattering noise at high rpm maybe the knock sensor is picking it up so a new sensor wont work what should i do?

 

I dunno. It's been thousands of miles since I did the swap, and the car runs as cool as a cucumber. I don't think I'm gonna screw with it.

 

I don't blame you Jim. That long and no problems. I'd leave it too.

Here Steve. Hey you should check out our Ontario site too if you want. www.sogm.ca

 

Thanks!

 

i have a ? how come when you post something other people just take over your post!

 

I really don't think anyone took over your post. You ask a question and it was answered! Replace your knock sensor. What more do you want?? Seriuosly though. Now you tell us you have a clattering sound, fix it! These post aren't specifaically for you. When you ask a question you open a door for others with the same questions. Yours was already answered so we move on the the next question. That's all, it isn't menat to make you feel left out or anything.

Have your ECM checked for codes and go from there,

 

Your best bet is to read, pay attention, and learn!

 

i dont feel my ? was answered yet but thats your opinion but anyway. i think the chattering noise may be inside the enigine but i dont have the money to fix that right now and the engine runs strong.what can i do for now leave the knock sensor unhooked? i dont mean to be rude i know others have to ask ?s just sometimes you post something and you get knocked out of the box.

 

I understand where your coming from, don't worry. Well if you have a engine noise internally I would get it fixed no matter what.

Now you say this noise is at High RPM..Do you mean under Heavy load?? Like when you mash her to the floor?? If so. You need a new Knock sensor. Most likely what you are hearing is detanation, or engine ping. The timing is being thrown off cause the knock sensor is not performing correctly. Either that, or your ESC module is going for the dogs. It is most likely your Knock sensor. I would have that replaced and see what happens.

 

no its not a ping its a chattert if you have the car in park and raise the idle to say 1500-2000 you can hear it then if your driving and between 4000-5400 or so you can hear then when it shifts it goes away,but the car runs great it doesnt even smoke but woh knows i just dont have the money to take it apart right now.

 

That sounds like ping! knock sensors csot $50 here in Canada so ther they should be more like $30 + an hour labour to install. Barrow the $$ and go have it replaced and see how things go.

 

dude im possitive itrs not ping i know what ping sounds like i have had a few mechanics look at it and they say either wrist pin or flywheel so its not ping. so what do i do maybe just unhook the damb knock sensor and run octane boost?

 

Well I guess. It will cause more problems in the long run. Heck a Flywheel make a knockning noise like a bad rod, not a chatter. Not trying to knock you mechanics, but something doesn't sound right. Wrist pins and cracked flywheels sound nothing alike. Sounds like they are just trying to take you for some $$$ Go to another mechanic. One you know you can trust.

 

well the wrist pin noise was my friends idea i didnt really by that one myself the mechanics all said flywheel it chatters not knocks.