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Discussion Starter #1
1997 Cobra. On the way home from work one day, I ran out of gas. Was between paychecks. I put cheap gas in. They next day, car had a bad knock. I immediately parked it, assuming it was something like a ring knock. But after reading quite a bit, could it just be cheap gas? I recently bought the car, it sat for years. Had to put it in shop to get it running. They flushed fuel tank, new pump, filter. Oil, filter, spark plugs. Now this... I cleaned imrc's. Drained oil, no metal. Checked under valve covers. Nothing unusual. About to work on pulling oil pan and check the rings. But a little complicated in my current situation. Few tools. No place to work on it. Very little money due to coronavirus bs..
 

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Yup, cheap gas..nothing more nothing less....might have had a little water in it too.
 

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Never put cheap gas in your car ...
 
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Welcome to AFM. You say you put cheap gas in. Define cheap gas what does that mean? Like low price station or what?
 

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Discussion Starter #5
87 octane I think. Ethanol, eww...Boss picked it up. 5 gallon can about 3 made it in. Middle of a tropical storm.
 

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What does the 97 cobra take premium only? If so the 87 is likely your prob as the older engines can't adjust like the newer cars.
 

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I believe it’s tuned for 91 octane when new.
 

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Says on dash, premium only. Seems to run fine, afraid to move it far, or even run it at all. Just below a quarter tank. Doesn't sound like dieseling. Persistent metallic tap. Louder when accelerating.
 

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Harbor freight sells a mechanics stethoscope for around $5. Get one and take a listen on the valve covers while it’s running.
FWIW I’ve ran 87 octane in my car that’s tuned for 93 and it didn’t act funny and mine can’t adjust timing on based on octane.
 

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Discussion Starter #10
Can clearly hear cylinder 5. No stethoscope needed. Painful to listen to.
 

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Drain the gas and see if that helps. If reg fuel in a older premium only car it will cause some issues. You say only a qtr tank so honestly if you can fill it up with premium that likely will solve the issue and no need to drain tank. I would if it were my car bring about 2-3 5 gallon's cans worth to it and fire it up from there to top the rest of the tank off. Though if you bring 3 5 gallons tanks worth it should be full. ha
 

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Drain the gas and see if that helps. If reg fuel in a older premium only car it will cause some issues. You say only a qtr tank so honestly if you can fill it up with premium that likely will solve the issue and no need to drain tank. I would if it were my car bring about 2-3 5 gallon's cans worth to it and fire it up from there to top the rest of the tank off. Though if you bring 3 5 gallons tanks worth it should be full. ha
Ah I dunno man. I’ve had 87 in my 93 octane tuned car and nothing happened. I’ve even had 87 mixed with a little denatured alcohol in the tank to pass emissions (it worked btw) and nothing happened other than passing smog.
I’d pull the valve cover off and see what I could see. I didn’t beat on it with the 87 and denatured but they ran it on the rollers at 3k rpm or whatever it was to do the “high speed” emission test. It was only a few gallons of 87 and the emissions place is only a few miles from the house though. After it passed I filled it up with 93.
How loud of a knock are we talking? It’s it a knock knock or a tick tick? However I do have an MSD box to where I can retard the timing. It’s usually on 0 and I dialed it to the 1 to where it’ll retard a little. But honestly I can’t tell a difference on either setting and they didn’t run it up to redline so I don’t know if the timing retard makes a difference at low rpm or not.
It sounds like this guy didn’t ping on 87 octane in his.
 

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Discussion Starter #13
I filled it with premium. Where do I smell gas from? Found out I have a tank leak as well...lol. Anyway, I ran it awhile, still knocking. Put Lucas in, 4 fresh quarts. Still knocking. Put it on Jack stands, tomorrow I will work on pulling oil pan. And check rings for damage. Good thing I am laid off because of covid. Nothing better to do.
 

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I filled it with premium. Where do I smell gas from? Found out I have a tank leak as well...lol. Anyway, I ran it awhile, still knocking. Put Lucas in, 4 fresh quarts. Still knocking. Put it on Jack stands, tomorrow I will work on pulling oil pan. And check rings for damage. Good thing I am laid off because of covid. Nothing better to do.
Did you pull the valve cover?
Did you see if you have any codes indicating rich or lean?
 

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Pulled valve cover, saw nothing unusual. No metal shavings. Cleaned imrc at same time. Nasty. Seems to run better. Is there a way to post video? Funny thing my daughter called me, " dad what is this sound on my car" really can't tell without being there. Anyone in Boca area?

Also, while cleaning old valve cover gasket, accidently dropped my razor blade. Dropped to oil pan. Have to go there anyway. Plan is loosen k member enough to go in that way. Motor mounts, lifting engine, 4x4 fender chain. The hard way in trailer park driveway. With limited tools.
 

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Can you retrieve it with a magnetic flex tool?
 
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Pulled valve cover, saw nothing unusual. No metal shavings. Cleaned imrc at same time. Nasty. Seems to run better. Is there a way to post video? Funny thing my daughter called me, " dad what is this sound on my car" really can't tell without being there. Anyone in Boca area?

Also, while cleaning old valve cover gasket, accidently dropped my razor blade. Dropped to oil pan. Have to go there anyway. Plan is loosen k member enough to go in that way. Motor mounts, lifting engine, 4x4 fender chain. The hard way in trailer park driveway. With limited tools.
Damnnit man... Yikes.
As far as videos go the only way I know how is to upload one on YouTube or the likes and then put the link in the post.
Yeah maybe try snaking down a magnetic rod deal and go fishing and hope for the best. When I was thinking under the valve cover I was thinking more along the lines of loose rockers.
 
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