ESC module question

Turbo6Smackdown

Well-Known Member
Ok, I read Gbodyparts's descriptions between the two ESC modules that come on the 86 vs the 87 model year GNs. The concensus is that the 87's module is a bit more sensitive than the 86's, though in the ATR tuning and chip guide they said the program inside is EXACTLY the same; who's right?
 
the 86 esc marked BLO has 4 pass filter while the 87 esc marked HKP has 2 pass filter... I read that Buick made changes to ESC in 87 due to senstive false knock readings so they made the 87 less sensitive. Hence less filtering. would like to hear others take on it. Either one will work in our cars. I have (2) BLO as spares and (1) HKP in my 86 TtYpe now with zero issues
 
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the 86 esc marked BLO has 4 pass filter while the 87 esc marked HKP has 2 pass filter... I read that Buick made changes to ESC in 87 due to senstive false knock readings so they made the 87 less sensitive. Hence less filtering. would like to hear others take on it.

from Gbody Website:

ESC Spark Knock Module 1986 & older GM Electronic spark module. Will work on 87 Turbo Buick & 1989 Turbo Trans am. The difference is in the sensitivity setting or level. The 1987 ESC Spark module was twice as sensitive as the 86 ESC module. 1984-86 BLO sticker had a 4 pole low pass filter. The 1987 HKP Sticker was 2 pole. Less sensitive to Knock. Both are interchangable. GM Part Numbers 1987 & 89 TTA GM#16051654 Delco# 216-42 1984-86 GM#16022614 Delco#216-33 $139.95 New $ 95.00 Used

Soooo...... Now what.
 
The difference between the BLO and the HKP modules is the HKP module does not attenuate (reduce) the knock frequencies as much as the BLO module which results in a broader frequency band it passes through. The program in the computer chip is the same for either module. The way the chip identifies knock is the number of knock counts from the ESC module over time. This means the chip must see a certain number of knock counts from the ESC module in a certain period of time. The HKP module will pass more knock counts than the BLO module for the same condition.
 
Pass more knock counts meaning... Pass them along to the ecm, or pass more as give it a free pass and not count it torward the total. Basically I want the one that isn't as knock sensitive.
 
Are you seeing some false knock?
I just worked on a Stage 1 car that was showing a lot of false knock. The car had knock blips and counts popping up during normal part throttle driving and during WOT pulls too. First and foremost knock is processed through an electrical circuit with power and ground feeds. I went through and checked the ESC ground, the power feed, and the signal line to the ECM. No problems there. Checked out the knock sensor and found that it was very loose and gobbed up with teflon tape on the threads. I didn't think much of it as it's a very common thing to see. Guys do that to "dumb it down". I started heading down the path of "something might be wrong with this motor", like bearings or valve train or transmission noises (even thought it sounds great to the ear). I figured I would need the knock sensor at maximum sensitivity in order to identify any issues with the motor or driveline, so the sensor came out and got all the tape cleaned off and then reinstalled at 14 ft*lbs. Guess what that did??? Completely eliminated all false knock issues. The tape/looseness was weakening the knock sensor ground with the engine block and making it send false signals to the ESC.
 
Brand new knock sensors come with a locking coating on the threads. Is that helping or hurting? I know on many engines the sensor is in the water jacket and needs to seal from leaks. Ours does not.
 
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It doesn't seem to hurt. I have that factory applied red stuff on mine.

The sensor on the problem car in question was generously gobbed with teflon and barely more than hand tight.
 
So since ours doesn't seal a hole, should I just try to yank off the tape and tighten to 14 and try again?
And tell me how a bad ground would make MORE electricity... A bad ground would make less, thus less knock counts would it not? You need both power and ground to make any sensor work; take one away and you're not getting a false anything.
 
The ESC signal is 9V to the ECM when there's no knock to report. When knock happens, the signal from the ESC drops to 0v

If you have a powerlogger, watch the knock counts immediately after you keyoff to see it in action. That's when the ECM shuts off power to the ESC and forces the signal to drop out
 
A capacitor , or filter circuit passes part of the signal to ground, hence a bad ground , not as much filtering taking place, so the signal is stronger and would produce more knock , in simple terms.
 
The ESC signal is 9V to the ECM when there's no knock to report. When knock happens, the signal from the ESC drops to 0v

If you have a powerlogger, watch the knock counts immediately after you keyoff to see it in action. That's when the ECM shuts off power to the ESC and forces the signal to drop out

I don't mean the esc module, I meant the knock sensor itself. If there's no ground to the knock sensor, how's it putting out voltage to the esc module?
 
I don't mean the esc module, I meant the knock sensor itself. If there's no ground to the knock sensor, how's it putting out voltage to the esc module?
weak or intermittent grounding. the knock sensor is a piezo electric crystal which responds to frequency. messing with the grounding can interfere with the frequency which the sensor "thinks" it sees. this is just my opinion.....

if there's absolutely no grounding at all, then yes there should be no signal whatsoever and the ESC should report 9V all the time, no knock retard and no knock counts. Same as having the knock sensor unplugged.
 
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