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Old 09-13-2005, 10:15 AM   #1
ODGC8
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Default Knocking Please Help!!!

My engine makes a knocking sound.. It normally ONLY happens when the engine is under a load, such as when you hit the gas or let the clutch out. I can usually get the sound in the morning by blipping the throttle a bit, and its definately present when im driving at lower rpm. I have had the hood open and gotten it to make the sound and its NOT coming from either cylinder bank im sure of that. I have it pinpointed to somewhere in the center of the engine, top or bottom i dont know...( guess i dont have it THAT pinpointed). Anyway....once the engine gets up to OT the sound gets much fainter and sometimes isnt even there.... I have had a few people tell me that it could be a rod bearing, call it denial, but i just want to hear if theres anything else this could be... One person in the troubleshooting section mentioned that it could be the oil pump...? If anyone has the same problem or has had it at some point let me know...

The only things that I have done recently, or since about the time i noticed the knocking was to change the oil ( i do it religiously) and replace the spark plugs, and PCV... And i have a drop in K&N, i know none of that prob makes a diff but thought i would throw it out there..

Owen
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Old 09-13-2005, 10:20 AM   #2
cefoskey
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did this get moved, or is it a double post?

anyway, still wondering what octane you're running
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Old 09-13-2005, 10:21 AM   #3
ODGC8
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um, i posted it in two places...i need answers haha.. I run 87 all the time, i was told by the previous owner that running anything higher would detroy your knock sensor... i have run 89 once but i had the car LOADED with school stuff...
owen
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Old 09-13-2005, 10:25 AM   #4
cefoskey
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running higher than 87 will destroy your knock sensor?

Im no RS expert, but I think that sounds like BS. We need some GC8 guys in here to confirm that. I would instantly have thought you are getting detonation running 87.
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Old 09-13-2005, 10:28 AM   #5
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^^^confirmed. I ran 89 all the time and my knock sensor went bad. I've used only 87 since then and its been fine (over 30k mi since)
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Old 09-13-2005, 10:30 AM   #6
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yeah i havent had any probs with running 87...well i do have this knocking sound....any other ideas?

owen
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Old 09-13-2005, 11:16 AM   #7
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i always use 89 octane, and teh engine ran smoother, but no problems otherwise

i would bump the octane up a lil if your car is pinging.
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Old 09-13-2005, 12:14 PM   #8
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If by knocking you mean ticking, then thats normal. Should sound like the wheel of fortune or a stick along a fence.

Its the lifters. Try changing your oil and see if it goes away for a while. Also, try using 5w-30 in the cold months.
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Old 09-13-2005, 12:42 PM   #9
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Quote:
Originally Posted by sha_zapple
If by knocking you mean ticking, then thats normal. Should sound like the wheel of fortune or a stick along a fence.

Its the lifters. Try changing your oil and see if it goes away for a while. Also, try using 5w-30 in the cold months.

I agree with this statement. From what you describe it sounds like your lifters. Do you change your oil regularly?? That can make all the difference.
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Old 09-13-2005, 01:06 PM   #10
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that reminds. me i always had a clicking that sounded like somebody taped a 3 of hearts to the cam gear. annoying, and kinda ratchety sounding, but i never had any problems related to it.

as for teh source? no flippin idea
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Old 09-13-2005, 03:13 PM   #11
ODGC8
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na guys, i know lifter tick when i hear it i used to have a 94 probe gt and they have more HLA tap than anything... Its definately not that althought i appreciate the ideas... Im gonna take it to a garage soon and hopefully get it checked out...except for the whole Money thing...

Owen
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Old 09-13-2005, 09:13 PM   #12
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Quote:
Originally Posted by kastkc
^^^confirmed. I ran 89 all the time and my knock sensor went bad. I've used only 87 since then and its been fine (over 30k mi since)
Are you serious? I only have 4000 miles on my car, and all of that has been on 89, but jsut today for the first time I filled up with 87 because of the soaring gas prices. The engine did feel a bit grumpy for the first few miles, but its been fine the rest of the day...how would you tell if your "knock sensor" has gone bad?
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Old 09-13-2005, 10:33 PM   #13
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Pardon me, but I think the 87 octane ruining a knock sensor really seems like crap. It's a piezoelectric microphone bolted to the engine block. Changing the octane by a single grade doesn't create an extra violent vibration or loud denotation enough to damage the knock sensor. If that happens, there's something more to it. Most people run 87 octane as this is the recommended grade.

As to the knocking, could it be piston slap? I know you said it didn't seem to come from any specific cylinder, but this a common problem mistaken for knocking. I have it with my #2 cylinder especially. It does get better after it warms up. Mine has gotten worse and is now burning oil. FYI, Subaru said it wasn't bad enough to fix under warranty. It's been 20k miles since then.

I've done the grounding mod, upgraded the wire set, spark plugs and air filter. This has made a difference even in how much better it sounds.
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Old 09-14-2005, 12:17 AM   #14
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If it is from the center front check your timing belt tensioner.
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Old 09-14-2005, 07:16 AM   #15
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That's crazy. I've run everything from 87 to 110 octane in mine, and I ran nothing but 91+ for about 2 years.
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Old 10-17-2005, 03:09 PM   #16
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Keep this thread going. My NA 2.5l Saab 9-2x has a spark knock that bothers me. Dealer said nothing wrong, but it has gotten worse. Does it at low speeds around town, but I took a trip this weekend, and it does it at 70mph highway speeds too. I have experimented with different grades of gas, to no effect.
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Old 10-17-2005, 03:39 PM   #17
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I highly doubt running 91 or 93 will kill anything on your car. Ran 93 octane on my '97 L for almost a year straight, my car is fine.

As for cars running "grumpy" after going from say 93 Octane down to 87, I believe it's just your ecu remapping or recycling to compensate for the lower octane.

After running 93 octane for about 3 months I changed to 87 and shortly after the car started running like carp and threw a CEL. After I let it run a while, turned it off, ran it again the CEL went off and engine ran great. This happened twice.

It has ran perfect not one complaint besides those two times I switched grades.
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Old 10-17-2005, 04:54 PM   #18
Brandon24
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Default hmm

Quote:
Originally Posted by craigz
Pardon me, but I think the 87 octane ruining a knock sensor really seems like crap. It's a piezoelectric microphone bolted to the engine block. Changing the octane by a single grade doesn't create an extra violent vibration or loud denotation enough to damage the knock sensor. If that happens, there's something more to it. Most people run 87 octane as this is the recommended grade.
Yea, i didnt want to get all technical, but a knock sensor works off vibrations through crystal plates. I with CRAIGZ on this one.......how does the octane ruin the knock sensor?

Last edited by Brandon24; 10-17-2005 at 07:25 PM.
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