Grumpy

The knock sensor is a diagnostic aid.
It's not intended to be a tuning aid.

It's not meant to replace plug reading.
Plug reading will tell you if you have real detonation or not.

Based on what the plugs tell you will dictate your path to cure the problem.

If it's false knock there are a million reasons for it, from broken engine mounts to too stiff of suspension, fractured serpentine belts, etc.

On the MEFI in marine applications, the cure is a 45d pipe fitting with 1/4 or is it 3/8 male and female threads on it.

You want to have it working right, if for street use.

A fast decay rate is usually always helpful.

Have alot of possible retard in case there is an unseen problem.

Getting Mickey Mouse with a K/S can really bite you unless you know what your doing.

Again, weither tuning Carbs, EFI, an aftermarket ecm, you need to be able to read plugs. just no way around it!!!.

On my car I have 24d timing limits, and a 200% recovery rate. YMWV. But, you have to get the mechanicals right....

Bobalos

hmmmmmmmm, intersting in light of the conversation we had the other day, re tuning timing curves & the measurement of gain or loss.

BW

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Bobalos
aka Bob W.
www.r71camaro.homestead.com
r71chevy@earthlink.net
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Grumpy

What do I need to clarify?.

The world is a constantly changing place, and my data base is expanding so, to some degree my statments do vary, thou, generally not too much or often.

Bobalos

Nothin', for the most part I think that we are all on the same page, just some of us like using Bookman old style & some like using Arial, & some like Times New roman.

BW

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Bobalos
aka Bob W.
www.r71camaro.homestead.com
r71chevy@earthlink.net
<><

e-man

Hey grumpy, would you know if the 90 and up knock sensor for a TPI350 is less sensitive than the 89 sensor they are different part numbers?

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89 350 TPI,comp cam,edelbrock intake base,SLP headers,highflo cats,flomaster cat back,accel 300+ ign,ported plenum and runners,ported maf,auto w/shiftkit,cold air induction,AFPR,Ed wright chip,3.23 posie best ET 14.011@98.72mph without cam/New best 13.926@98.27mph

Grumpy

The 90 uses a 730 ecm, and the K/S stuff is on the memcal, so it's basically a different set up.

On the GM Marine applications, the use a 45d male to female fitting as a standoff for the K/S to make it less sensitive. Several guys have been doing that with excellent results.

e-man

Is the 45deg brass or black pipe? I dont see any aluminum 45s in jegs or summit any catalogs

Homer

iTrader: (1)

Grumpy,
I don't get it. If you're supposed to read plugs instead of use a knock sensor to tune your car, how do you tell where on your spark map the knock is occuring? I guess you could use the oxygen sensor to tune the fuel, but how do you tune the spark?
thanks

Grumpy

You start with a very conservative timing table and then slowly row by row add timing, measure performance, and read the plugs.
Doing the timing table, for optimine best takes a whole bunch of time.
Folks like datalogging, and then back tracking from there, but that ain't the BEST way.
The K/S in oem form are designed to listen for major tip-in detonation / ping, and then up to about 3K RPM. The stock calibration is in part designed to be over rich above that to avoid detonation, and to keep the converter happy, at over 3K RPM. When you start tuning in that range, and making serious HP and solely rely on the K/S you can get into real problems, ie knocking the edges off the pistons.

87_TA

How well can you really trust plug raeding when todays fuels have so much garbage in them?

Grumpy

You'll find that once you get things right, plugs read just like they did 20 years ago. the games to keep the plugs looking so clean and lasting so long are mostly in the calibration.

Lean Cruise, running at Stoic, and with alot more advance then they need all help to defeat plug readings. And the cals are really taylored for catalytic converters.

Once you get to running Open Loop, and have things tuned correctly you'll see them read much better. MUCH!

Of course this is Off Road Only.

JPrevost

Grumpy, you need to make your sig read "Of course this is Off Road Only." That way you don't have to keep typing it .
I must say I have found little solice in looking at the knock counts, especially with the slower baud computers. I've been better off just starting with a hunch, going with it, runs better or doesn't, keep going if it's better or go backup. I haven't tried it yet but I'm thinking about raising the required knock counts for retard to like 10 from 2, this way if it is knocking I know it's knock and it isn't my tight suspension or other false issues. I noticed that when the car hits a hard bump it'll run funny for a split second. Maybe with lockers I can verify this is the case.