Unbolting the knock sensor
05-20-2009, 12:06 PM
#1
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Unbolting the knock sensor
It appears that our knock sensor is very conservative and sometimes determines normal engine noise and vibration as knock. The ECU then pulls timing which results in power loss. If you are not FI and always run premium fuel knock should not be an issue and we may gain power from unbolting it. On the other hand, if you were to experience knock I doubt it would hurt an NA motor.
Here are some quotes from Racing Beat's Site:
“We have also tested the knock sensor system and found that though it is good, it can cause minor problems. The sensor seems to detect normal engine vibrations as “knock” (pre-ignition), and because if this, the ECU retards the timing. Unbolting the knock sensor from the #2 rotor housing (do not disconnect it electronically - this will cause an ECU fault and retard the timing.) usually adds a small amount of power (often 1+HP) by eliminating the random, unnecessary retarding of ignition. Of course, if the engine should experience knock, your unbolted sensor will never know it- but cars ran for many years without these sensors and survived!”
Knock Sensor – “The reason for unbolting the knock sensor is that our testing has shown that the ECU sometimes randomly retards the ignition even when there is no actual detonation occurring. (Detonation - pre-ignition combustion of the compressed intake charge.) The difference is only 1-2 HP, but this is more than the differences we are looking for. We obtain more consistent test results by unbolting the sensor (but leaving it connected electronically so that it doesn't cause a fault in the ECU); thereby preventing it from feeling the vibration it mistakenly thought was detonation.”
Thoughts?
Here are some quotes from Racing Beat's Site:
“We have also tested the knock sensor system and found that though it is good, it can cause minor problems. The sensor seems to detect normal engine vibrations as “knock” (pre-ignition), and because if this, the ECU retards the timing. Unbolting the knock sensor from the #2 rotor housing (do not disconnect it electronically - this will cause an ECU fault and retard the timing.) usually adds a small amount of power (often 1+HP) by eliminating the random, unnecessary retarding of ignition. Of course, if the engine should experience knock, your unbolted sensor will never know it- but cars ran for many years without these sensors and survived!”
Knock Sensor – “The reason for unbolting the knock sensor is that our testing has shown that the ECU sometimes randomly retards the ignition even when there is no actual detonation occurring. (Detonation - pre-ignition combustion of the compressed intake charge.) The difference is only 1-2 HP, but this is more than the differences we are looking for. We obtain more consistent test results by unbolting the sensor (but leaving it connected electronically so that it doesn't cause a fault in the ECU); thereby preventing it from feeling the vibration it mistakenly thought was detonation.”
Thoughts?
05-24-2009, 01:08 AM
#4
this is what some guys at our dyno day were saying might be happening to my car. it was pulling like 20-25hp less (142-144) than similarly configured cars (165) and then ran once much closer to the other guys (155). This was out of 6 pulls. I have new plugs, ignition coils, wires, and good compression.
do you think this could be part of the problem or is there something else i should look into?
do you think this could be part of the problem or is there something else i should look into?
05-24-2009, 01:14 AM
#5
this is what some guys at our dyno day were saying might be happening to my car. it was pulling like 20-25hp less (142-144) than similarly configured cars (165) and then ran once much closer to the other guys (155). This was out of 6 pulls. I have new plugs, ignition coils, wires, and good compression.
do you think this could be part of the problem or is there something else i should look into?
do you think this could be part of the problem or is there something else i should look into?
Just to make you feel good,, you have less HP then my 4 Port AT.
I would say that the dyno may not be calibrated correctly.
05-24-2009, 01:20 AM
#7
That's till pretty low on the scale. I've seen mine range about 25 whp on different dynos on different days.
I've also seen a stock AT do 155 whp. While mine did 145 with intake exhaust and BHR coils and an Accessport. Some 8's just have more HP. I don't know why.
Try some injector cleaner in it. Se if that helps.
I've also seen a stock AT do 155 whp. While mine did 145 with intake exhaust and BHR coils and an Accessport. Some 8's just have more HP. I don't know why.
Try some injector cleaner in it. Se if that helps.
05-24-2009, 01:24 AM
#8
That's till pretty low on the scale. I've seen mine range about 25 whp on different dynos on different days.
I've also seen a stock AT do 155 whp. While mine did 145 with intake exhaust and BHR coils and an Accessport. Some 8's just have more HP. I don't know why.
Try some injector cleaner in it. Se if that helps.
I've also seen a stock AT do 155 whp. While mine did 145 with intake exhaust and BHR coils and an Accessport. Some 8's just have more HP. I don't know why.
Try some injector cleaner in it. Se if that helps.
i suppose this fails w/o pics though.. i'll try to scan the graphs.
05-24-2009, 01:45 AM
#10
we did the first part on the dyno in seattle and he told me the coils were bad so i got the bhr ones and recently got those working well so i put it on the dyno again. my plan is to datalog again now and send that in for another map to see if it helps at all.
i can't scan now, scanner's not working, so i'll get them up tomorrow.
i can't scan now, scanner's not working, so i'll get them up tomorrow.
05-24-2009, 10:25 AM
#12
Dondo's numbers are from a Mustang dyno. We had 3 8's dyno back to back to back with my car being the 3rd car. I pulled 163 with new OE coils and plugs. I also have RB intake and Corksport exhaust. What is a bit interesting is Dondo's graph. He peaked earlier than the 3 8s that pulled in the 160s where others still climbed.
Note: I believe we had 6 8s get on the dyno. 3 in the 160s, 1 157, 2 in the 140s.
Note: I believe we had 6 8s get on the dyno. 3 in the 160s, 1 157, 2 in the 140s.
05-24-2009, 01:39 PM
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Dondo's numbers are from a Mustang dyno. We had 3 8's dyno back to back to back with my car being the 3rd car. I pulled 163 with new OE coils and plugs. I also have RB intake and Corksport exhaust. What is a bit interesting is Dondo's graph. He peaked earlier than the 3 8s that pulled in the 160s where others still climbed.
Note: I believe we had 6 8s get on the dyno. 3 in the 160s, 1 157, 2 in the 140s.
Note: I believe we had 6 8s get on the dyno. 3 in the 160s, 1 157, 2 in the 140s.
Here is mine for comparison.
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