knock knock goes the jeep....

[CSH-HQ]

Boy it would be nice to have an adjustable knock sensor.
Just to take the edge off of it's sensitiveity, not that there aren't 
mechanical means to do it, but to have it tunable from in car.
  Anyone have any thoughts about increasing the EST test advance, and then 
using a simple resistor divider network for tuning down the sensitivity?.
Grumpy


>Hi Bruce:  I have played with est decay and recovery rates.  Kind of
>interesting.  I pretty much found that if I slowed how fast the timing was
>pulled out it caused the knock to keep getting worse.  I put that back to
>stock.  I have modified how fast the timing in put back in though.  Mainly
>at the higher rpm's.  The car seems to run best with the knock sensor just
>being tickled a hair.  If I sent you a gdf file and you graphed rpm, LV8 and
>Knock you would see the ecm putting the timing in quicker than stock.  Kind
>of a series of very fast downhill spikes.  If they are uphill it means the
>detonation is getting worse and you need to pull out some timing.  If I try
>to eliminate all detonation the car feels flat.  It apparently needs/likes
>the timing sometimes and doesn't others so I make a small compromise I
>guess.
>Mark
>-----Original Message-----
>From: CSH-HQ <nacelp at jvlnet.com>
>To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
>Date: Thursday, December 30, 1999 12:56 PM
>Subject: Re: knock knock goes the jeep....
>
>
>>Did you mess with the EST recovery rate?.
>>Interesting strategy.
>>Grumpy
>>
>>
>>>If you have Terry Kelly's GMe Pro you can print the actual spark map and
>>>plot where on it you were with rpm and load and plot the actual advance
>that
>>>the ecm should be putting out.  If it is different then you could be
>>>experiencing PE spark advance, or HWY spark advance or HWY fuel problem.
>>>>From what little experience I have with a friends 89 TPI with Vortech, we
>>>pulled the boost retard out and allowed the ecm to take out up to 14 deg
>of
>>>timing when in pe and with only about 5 psi of boost the ecm rarely pulled
>>>out more than 5 deg of timing when on the throttle and the car ran much
>>>better without the boost retard.
>>>
>>>I graph (Using diacom) rpm, LV8 and spark knock, 02 sensor voltage,
>>>commanded afr and tune the spark map from there.  I have also noticed that
>>>the 02 sensor still reads high (Over 850mv)  but the car just seems to lay
>>>down if it's not rich enough.
>>>
>>>Took me a while to find PE spark advance (Now all zero'd out) and I have
>>>been playing with hwy spark and hwy fuel.  I only put in about 4 deg of
>hwy
>>>spark and have hwy fuel set at  16.0 to one.  It seems to surge a slight
>>>amount on very slight decel, but other than that, no detonation.
>>>
>>>Hope this helps.
>>>
>>>Mark
>>>-----Original Message-----
>>>From: Peter Fenske <Peter_Fenske at bcit.ca>
>>>To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
>>>Date: Thursday, December 30, 1999 9:25 AM
>>>Subject: Re: knock knock goes the jeep....
>>>
>>>
>>>>
>>>>
>>>>Hi John
>>>>
>>>>Been a while but I think you gotta disable the hwy spark..
>>>>What happens GM tries to eak out the best CAFE MPG by advancing
>>>>the timing at steady state.. Also there is a hwy fuel enleanment
>>>>function which can give you AFRS of 17 to 1. all for MPG.
>>>>
>>>>I am not sure if these functions are enabled in your cal.. check em out
>>>>
>>>>:peter
>>>>
>>>>
>>>
>>
>