knock knock goes the jeep....

[Mark Romans]

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
>>>
>>>
>>
>