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Old 07-11-2002, 03:40 PM   #1
IconCSprings
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Thumbs up Knock Sensor mod--No hesitation now...

I just wanted you all to know......after researching about the hesitation alot seem to have (including me), I got an idea from someone on the board about the knock sensor. His idea was that our knock sensors were over-sensitive to vibration (geez this sounds familiar....MAF's!) and they would think the engine was detonating when it actually wasn't, thus dumping the timing & causing the hesitation. Well, the fix was to put an oil drain plug gasket in between the block and the knock sensor to dampen some of the vibration. I went and bought one for .79 and did it. My hesitation has been gone for a good month now, with no signs of returning. Car feels like new again. I also did the grounding mod with 4 grounds, but it didn't help with the hesitation. For .79, I think you all should give it a try, it could work for you too.

Beau
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Old 07-11-2002, 04:43 PM   #2
BeavisNuke
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I wouldn't try this unless you had an aftermarket knock link with the bosch sensor. What if the stock sensor is numbed enough now to not recognize real detonation?

Also, where did you buy the oil drain plug? I'd like to try this.
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Old 07-11-2002, 07:39 PM   #3
IconCSprings
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Quote:
Originally posted by BeavisNuke
I wouldn't try this unless you had an aftermarket knock link with the bosch sensor. What if the stock sensor is numbed enough now to not recognize real detonation?

Also, where did you buy the oil drain plug? I'd like to try this.

I know what you mean with the knock sensor now being too dampened to where it won't recognize REAL detonation, but the oil drain plug gasket I used is only about 1/8 inch thick. I can't really see how this skinny of a gasket could dampen it too much to do that. It's just enough to dampen out engine vibration, road noise, etc......to make it stop THINKING its detonating, when it's not.

I got the gasket at Advance Auto Parts here in the Springs.....just ask for a Oil Drain Plug gasket about the size of a quarter with a hole in the middle so the bolt can go through. Oil drain plug gaskets are good because they also have heat resistent stuff on them to combat some of the engine heat...........even if it does crack or melt, it's only .79, small price to pay to rid yourself of the terrible hesitation.

Beau
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Old 07-12-2002, 02:32 AM   #4
HndaTch627
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Quote:
Originally posted by BeavisNuke
I wouldn't try this unless you had an aftermarket knock link with the bosch sensor. What if the stock sensor is numbed enough now to not recognize real detonation?

Also, where did you buy the oil drain plug? I'd like to try this.
actually this is bug that subaru knows about, MY99's had overactive knock sensors, MY00-01's have knock sensor that wouldn't pick up a hammer smacking the block. My99's run lean, MY00-01 run super rich...go figure *shrug*
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Old 07-12-2002, 08:55 AM   #5
Legacy777
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the overactive knock sensors have been an issue all the way back to the beginning of the legacies......I know I've got a 90 legacy.

They have updated the knock sensor over the years. The old knock sensor had a white plastic connector, the new one has a gray connector.

I bought Gary's electrical fix a while back, but I did not like the results. I picked up a drain plug washer the other day, lady gave it to me for free. I haven't gotten around to installing it, but will probably try this weekend.

Did you reset your ECU after installing the gasket?

Thanks

Josh
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Old 07-12-2002, 12:29 PM   #6
ciper
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One of the few times resetting the ECU will probably make a big difference. From what I read the ecu remembers when it had knock so it creates a new timing map based on this. Meaning with the washer in place you should let it relearn for a while.
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Old 07-12-2002, 01:00 PM   #7
Chav
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I have a link 2 ecu and have been running it for a while. I still get the 4200rpm hesitation. The knock sensor isnt picking up anything out of the ordinary and the a/f ratio is fine. I have talked to some people about it and they believe that it is a characteristic of the Pulses in the intake manifold and the cams. I have also read on here that people have datalogged with a obd2 scanner to see what was going on with the stock ecu and have noted that the ecu isnt retarding timing.

This has been a huge topic of debate. There are many different theories such as, the overactive knock sensor (I'm not inclined to believe this from the above data), switch from closed to open loop (wouldnt occur with the Link 2), and the pulses in the intake manifold.

-Chav
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Old 07-12-2002, 01:43 PM   #8
IconCSprings
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Quote:
Originally posted by legacy777

Did you reset your ECU after installing the gasket?

Thanks

Josh
Josh, I did reset my ecu after putting in the gasket. Like I said it's been gone for a month now. This may or may not work for you, I guess I was just lucky and FINALLY found something that fixed my hesitation after all the stuff I've tried.

Beau
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Old 07-16-2002, 07:02 AM   #9
danci1973
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Default Oil drain washer

What material should the drain plug washer bemade of?

All I can get here in that context is made of brass - and I doubt brass would dampen much.

D.
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Old 07-16-2002, 08:41 AM   #10
Legacy777
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Just a fiber type material.

I put mine in last night....what a fu@#kin pain in the ass that was. My stupid knock sensor wouldn't sit right, then it moved the washer around. I didn't want to put any sealant or silicone on there. But I did get it on. I need to reset my ECU in the worst way. I've got some SERIOUS hesitation now since changing my oil last saturday. The car feels like a freakin woofer.
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