Is there way to do this manually without reflashing the chip. I want to see if my new knock sensor is pulling timing, this might explain why I have lost a half second in the 1/4 mile!

 

You can simply unplug the knock sensor if you want to take retard out of the loop.

 

Wont that turn the engine light on, causing the computer to run in a "limp home" mode???

 

I "think" if you unplug the ESC module the ECU would go into limp home mode. Unplugging the sensor would be the same as if the knock sensor wasn't hearing any knocks.

I could be wrong, though.

 

Thanks for the reply.

Can anyone else shed some light on this??

 

Well I guess I will just have to give it a try and post my results.

 

Yes, you can unplug the knock sensor without any code or other problems, except detonation if you are actually getting knock.

 

Not necessarily, depends on the motor. The TBI motors (at least some as I'd hate to make a universal statement) will do a self test of the knock sensor circuit on start up. The ECM will advance the timing until it detects knock at the KS. If the KS is absent or unplugged the ECM won't see this knock during its self test and subsequently throw a code and run limp home timing. I don't know if TPI, or some of the TPI, will react similarly. I'm fairly certain (based on empirical evidence) that the carb'd motors don't.

On many of these systems shorting pins A and B at the ALDL will disable spark retard. Don't know for sure it will work on your particular model, nor which particular motor you're running.

 

having the knock sensor unplugged will throw a code, but it will NOT put the ecm in limp mode.

 

You may be right, I can't say with certainty- I'm going by recollection. Easy enough to check though. Let us know what the file says.

 

I ran my supercharged TPI with the knock sensor unplugged for a year, and it never once threw a code. I did this because the whine/squeal from the blower housing set off the sensor repeatedly and the car ran like crap. The diagnostic test that the ECM does referencing the knock sensor is specific to engine operating temp (around 190-220 degrees) and load, at least on TPI cars. And if you do get a low or no voltage reading at that point it WILL go into limp-home mode. Just unplug it and see what happens, it is not hard to find and if it does throw a code (which I doubt) just plug it back in.

 

Doesnt set a code on my car.Mine is picking up a lot of knock and pulling timing.It`s saying like 20 degrees of knock ,maxing out the table in datamaster,but I hear no knock.I have a small exhaust leak but I cant hear any knocking or pinging or anything.I disconected mine just to listen and see if it ran differant.It ran better,I guess,cause it wasnt pulling timing.If I was getting that much knock wouldnt the car run like crap or I would hear something.Oh,sorry to highjack the thread but I`m still having this problem.I did some searching and saw where some people wrapped a shop towel or something around it.Some said it helped some said it didnt.I`ve also read it can be put in too tight which can make it overly sensitive,or just be the wrong one.

 

I screwed up above. To disable spark retard you need to jump A and B with a 10K ohm resistor, not short the pins.

 

I had similiar issues with knock retard due to header noise in the block. I bought a new knock sensor, extended the connector so it could reach near the battery area. Then I found a fitting so I could run a ground wire from the threads of the knock sensor to the battery. Then I cut open a beer can, sprayed some expanding foam in it and stuffed the knock sensor into the foam in the can. Haven't had any problems since. The foam keeps noise from the sensor, and I just bungeed the can to the battery. It also leads to interesting conversation because no one can figure out why the beer can has wires running to it. Just make sure you put tape around the connector so it doesn't come off or get ruined by the foam. Or you can just do the resistor thing.

 

My problem is I cant figure out whats causing the knock.I`ll have to give the beer can thing a try.Should I be able to hear the knock if it is indeed true knock.

 

After re reading your post I`m not exactly sure what you did or how you did it.Is your knock sensor still in the block or strapped to the side of your battery in the beer can foam.

 

...or you can ground your knock sensor wire lead thru a 3.3 K Ohm resistor.

 

Not familiar with that.Guess I`ll search around and see what I can find.

 

A 3.3K Ohm resistor to ground can be used to replace the KS and 'confuse' the ecm into thinking it's still connected.

 

Hold on a sec! You mean that if you stick a 10K ohm resistor in the A&B connectors to the adlc connector inside the car, the car will not pull timing? I want to try this but I'm afraid of shorting out something by having the car running with a resistor plugged in. Has anyone else tried it. Also, where is the knock sensor on my 89 formy 350 tpi? I can't find the ****!

 

Yes.

KS installed in pass side block drain. You'll see it just forward of the starter.

 

I'm going to radioshack in 15 minutes to get some 10K ohm resistors. Thanks and I'll try it and let you know what happens.

 

Why would you want to trick the ecm into thinking the knock sensor was there.Why not just unplug it?It doesnt cause a code or ses light.Atleast not on my car.I want mine to work properly and do the job it was designed to do.I do not want it to detect false knock and pull timing.Why spend money to do the same thing unplugging it will do.I`m 99.9% sure mine is picking up false knock.

 

Replacing the KS with a resistor is a diagnostic tool. It allows you to ensure that the wiring to the KS is not triggering false knock from some source other than the KS. The sensor wire can transmit signals that the ECM interprets as knock that are bleeding over from proximity to bad plug wires, as one example.

In your case, if you temporarily install a resistor and you are still experiencing false knock, you'll know it's NOT the knock sensor. Kinda a process of elimination, if you will.

Next check may be to temporarily ground the KS sensor wire at the ESC with a resistor, bypassing the sensor wire thru the loom. If the false knock goes away you'll know you've a bad sensor wire or it's too close to a source of stray voltage.

Sounds like you're already 99.9% on top of all that though?

 

thanks for explaining.Was wondering.So is it a 3.3 or 10 kohm resistor?Or,is one for the ks and one for the esc.Also,I`ve asked several times in differant posts,should I be able to hear the knock?At work we have a 3500 chevy truck with 454 tbi that knocks and pings some and the ks for some reason it want stay connected.We can tell when it comes off cause it knocks and pings really bad.Thats the knock it`s hearing to pull timing right?detonation,right.If We dont run 93 octane in our 06 maxima it does it a little too.The knock table on dattamaster can max out at 20 degrees on my car but I hear nothing with the ks connected or dissconected.Just trying to figure this problem out.thanks

 

3.3 K ohm will replace the KS at the sensor wire and 'confuse' the ecm into thinking it's still there.

10 K ohm across A and B will disable spark retard in the ECM. At least on most models. I can't make a universal statement that it will work on every ECM. I've done this on some of the ccc models and some TPI/TBI.

There's a lot of this spark retard stuff on the prom tuning board.

 

I believe I may be having a similar problem if not the same!! I upgraded my 88 305 z with a 355 with a noisey gear drive. When I go to start it cold I have to crank it, stop , crank, stop and crank somemore then it fires up. There is no exhaust on it yet, just open headers. Would the gear drive spinning tell the ks to pull timimng on initial start up.

 

The KS is not going to pull timing on initial startup. The timing is, however, designed to be retarded during starting to reduce the load on the starter and make cranking easier. The KS is not your problem. You may actually have the timing too far advanced (although it's likely the problem lies elsewhere). Did you set your base timing to zero with the ESC disconnected at the dist? New burn or are you running the old 305 chip?

 

Yes I have the 305 chip in it, do I have to disconnect the esc, is that the plug by the heater box?

 

You could try this, even though it's for a vette I'm sure the principal is the same

http://www.inthehook.com/paul.html

 

Ok,so just put the 3.3 resistor on at the wire conector instead of hooking the wire to the knock senso?This will make the ecm think the sensor is in line and it will record real or false knock?

 

I`ve been doing some searching and seen it may be a 3.9k ohm resistor or a 3.3.Anyone sure which one?So can do I just put the resistor where ks is or do I have to cut the knock sensor wire or something to put it inlinr with the esc to ground or the ecm?

 

I know this is an old post, but I just found it while searching, so I figured I'd throw in my $.02.
I had a noisy cut gear drive in one of my motors that would cause false knock to be detected. I moved the KS from the right side block drain to the left side rear oil pressure port above the oil filter. The oil provided a little more damping than the coolant and got the sensor further away from the timing gears. Problem was solved. I've since gotten rid of that horrible gear drive and moved the KS back to stock location.