89Vert

I disabled code 43 on my cousins car (91 TPI),
he had a knock code and his car with a fresh motor was running like terrible because of it,

he put a new knock sensor in, and tried a different prom and ecm from a friends car(same year/motor/trans), still had a code
I went out to take a look it, my scanner siad it was pulling 20* of timing in knock retard with no knock occuring, I didn't have a multimeter to check voltages etc. and could figure out what was wrong with it

we needed the car to run well so he could properly break in the motor,
I had a brainstorm to eliminate the knock sensor code,
can ran like a dream, after I disabled the knock sensor


what do people think about this as part of a permanent tune?

JP86SS

iTrader: (1)

Maybe bad gas.
I started up mine this week after sitting since roughly October and the fuel in the tank made it run like crap.
Got lots of counts, idle sucked.
Once I got to the station and filled with 92, everything straighted right out.
Other than that I'd say look for another cause. I wouldn't leave it that way.
Might be picking up some loose valve lash or something if it is always reading at any rpm/load.
Make sure its the 305 sensor too. Try dropping some spark or adding some fuel if you can see any issues that could cause the knock as well.
Then go back over the tables to clean them up when you're done.
Check the plugs to confirm if there is a problem. (Clutch noise ??)

89Vert

its not calling knock, ie no counts,
but its retarding the timing and it had ses light on,
he had a 350 sensor it was new but we checked the part number and found they sold him the wrong 1, put the 305 sensor in and still had code,

its not a mechanical problem, motor runs fine, no shaking or knock noise at all,
its a fresh race built balanced and blueprinted 305(i know 395 wouldn't be my choice either), it ran fine with a carb on the engine dyno

jstoll

Check to see if the secondary fan switch is not swaped with the knock. The connectors look similar and hook up to each other. The fan will turn on when the connector is grounded plus it is a 12v sourch and the knock is only 5v. I know cause it happened to me.

Grim Reaper

It's not uncommon to have the Knock Sensor detect a lot of "knock" that is unaudible to the human ear as it works on a difference frequency. But there is something not right if you are getting a Code 43 all the time. And it's NOT just limited to the KS.

The two things more to check are the wiring (especially the engine ground on BRN 486 - they may have not missed this) or the ESC Module itself may be faulty.

89Vert

I put an different ESC module/memcal and a different computer from same year same motor/trans combo car, its not sensing knock, I have a snap-on diagnostic scanner, it was pulling like 5-20* timing all the time and not sensing knock(no knock count)

the ecm does a couple test to the knock sensor at start up, its failing 1 or all of the tests, and the engine light is coming on right away with code 43

once the car was above 3000rpm it ran perfect under 3000 it was a dog and it was lugging the motor, which is really bad for a fresh rebuild,

I went over the timing table I have setup for the car with my other cousin who built the motor, he specializes in drag racing and sprint car motors
he siad it looks good as long as I knock out some timing when I do the nitrous tune for it,
he wasn't all that concerned about no knock sesnor since 90% of the motors he builds don't have 1,

the fixing of the knock sensor isn't an issue for me, I'm a deisel mechanic and specialize in electronic trouble shooting, I just didn't have any of the right tools with me at the time

I was more interested in what people thought about eliminating the knock sensor?

Grim Reaper

Well, you can think of it this way, "What did us old guys do in the good ol' days when there was no such thing as Knock Sensors & EFI"? But in your situation, there is a problem there and based on what you have done, it pretty well leaves the wiring.

Personally, I am NOT a fan of flat-out eliminating the KS. There are many times where I found the KS "has done its job". A hot summer day, driving up a long grade (like the Coquihalla) can trigger pre-ignition very easily. I have another car that does not have any "electronic doo-dads" and I find I have to adjust the timing on hot summer days for this very reason. My brother has found similar detonation in the summer on an older vehicle.

I have on occasion "limited" the KS retard in WOT to just a few degrees as I find many L98 TPI cars seemed to be extremely prone to knock in WOT. I have found a GOOD spark curve is the BEST THING you can do to maximize performance. A good spark curve can permit running a little extra spark (and make more power).

I have found a lot of L98 TPI responds very nicely to just a little extra spark. Funny thing, the total spark ends up being WAY LESS than the stock spark tables too! 24*-28* seems to be optimum for the L98. I find that when the KS kicks in, it destroys spark curve and this seems to make the engine even more sensitive to ping where it can't seem to handle even 22* without incurring detonation.

This is just my experience with tuning L98 TPI systems. I find the more you start to modify the L98 (bigger cams, better heads, different induction), the less prone the engine becomes to detonation - both audible and as detected the KS.

But if you can, I would try to retain the KS system for at least part-throttle cruising. You never know when you may get a bad tank of gas (as it has happened to me) and by taking it easy in part-throttle, I was able to get to another gas station where I able to top up my tank with enough 94 octane to stop the ping.

89Vert

yeah I was wanting to get it working properly for him,
especially if he puts it on nitrous,

I got his timing pretty agressive out of the hole like as much as 40* but then it falls off to like 24-28* higher rpm and higher loads,
and they guy who built the motor even bumped it up 2* at the distributor and he was liking it alot better

have to see what happens, hes got a switcher maybe I'll set him up a performance chip with out a KS and a daily driver with 1,
and then have another chip for nitrous depending on what jet he uses

it is a forged bottom end so it will take a pretty hard detonation with out taking out the rings or piston,

I guess we'll have to see what happens