Rod(?) knock on cold accelerate
Thread Starter
Cruising
Joined: Nov 2007
Posts: 12
Likes: 0
From: Sacramento California
Rod(?) knock on cold accelerate
Hey Ya'll:
My bone stock 178K mi 90 knocks slightly on soft acceleration when cold. Moderate and heavy throttle when cold is fine. Timing is right, gas is right, recent oil change, no codes....Once warmed up, all is perfect again. Appreciate your thoughts.
My bone stock 178K mi 90 knocks slightly on soft acceleration when cold. Moderate and heavy throttle when cold is fine. Timing is right, gas is right, recent oil change, no codes....Once warmed up, all is perfect again. Appreciate your thoughts.
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
Melting Slicks
Joined: Feb 2008
Posts: 3,286
Likes: 6
From: Palm Beach
Piston slap is usually associated with forged pistons due to the increased clearances. It goes away as the piston warms up and expands. It is not a big deal.
Rod knock, on the other hand, is.
I don't think 90s had forged pistons.
Rod knock, on the other hand, is.
I don't think 90s had forged pistons.
Race Director
Joined: May 2006
Posts: 10,691
Likes: 71
From: Phoenix Arizona
I would go with piston slap, wrist pin, or cracked piston. Could last for years. I'd just drive it, it probably won't cost any more later than now. I've got that in my hunting truck, starting on the seventh year like that.
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
Piston slap. Be e gentle and warm it up and it will last a long time. Now is the time to start planning for a rebuild or replacement. I spent months looking for good deals when I decided to do mine. If money is an issue you may want to do the same.
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Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
w/Zr1Fred...Drive it. Cast pistons here with 146k. Piston slap when cold, goes away when warmed, have no issues leaning on it once everything is up to temp.
If a motor is going to "go" it will do it wether you baby it or not.
Personally I wouldnt sweat it .
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by go-olds
Thanx Fella's. Got a "knock sensor" code last week, hoped that may have something to do with it, but after I changed it, still knocking/slapping this morning. Oh, well.
RACE ON!!!
Thread Starter
Cruising
Joined: Nov 2007
Posts: 12
Likes: 0
From: Sacramento California
Duh, Yes you've mis-read and like some, you have jumped to the conclusion that everyone else is stupid. The Check Engine light lit, code retrieved indicated the knock sensor had failed. Occassional throttle surge has now gone away. I didn't indicated that this had anything to do with the subject at hand nor what pressure the RR tire should be set at for racing or even which wiperblade was the most affective at high speed.......I was only hoping that the two may have had been related in some fashion, and relaying my thoughts to the my fellow Corvette owners. Geeez, one shouldn't stow thrones Dude.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Hey Duddie,
I haven't jumped to any conclusions. I read:
That reads to me, an awfully lot like you changed the knock sensor because you got "a "knock sensor" code". If not, that was the IT that you changed? I didn't want to before and I don't want to now, mis-read you you. That is why I asked in my first post and I am asking again. I am trying to understand what you are trying to say.
You STILL haven't stated for certain whether you changed the knock sensor or not, but even in this post, it sounds more as if you did.
Tell us what you think stopped the "Occassional throttle surge". Just for your information, there IS no code that indicates that the knock sensor has failed. Your FSM will tell you what conditions it takes to set each of the codes and how to trouble shoot them to avoid throwing money (the wrong parts) at the problem.
RACE ON!!!
Originally Posted by go-olds
Duh, Yes you've mis-read and like some, you have jumped to the conclusion that everyone else is stupid.
Originally Posted by go-olds
Got a "knock sensor" code last week, hoped that may have something to do with it, but after I changed it, still knocking/slapping this morning. Oh, well.
You STILL haven't stated for certain whether you changed the knock sensor or not, but even in this post, it sounds more as if you did.
Originally Posted by go-olds
The Check Engine light lit, code retrieved indicated the knock sensor had failed. Occassional throttle surge has now gone away.
RACE ON!!!
Racer
Joined: Dec 2007
Posts: 312
Likes: 0
From: San Antonio Texas
!!!
!!!
Former Vendor
Joined: Jan 2006
Posts: 698
Likes: 0
From: Social Circle Georgia
Stone stock LT1 except the headers here with 168k. I've had piston slap for tens of thousands of miles now. Doesn't pull so hard on the top end anymore so I'm thinking valve springs and oils seals while I am in there. Aside from that it runs like a champ once warmed up and doesn't use oil. Take care of the engine and it'll take care of you.
Racer
Joined: Dec 2007
Posts: 312
Likes: 0
From: San Antonio Texas
, but in case you aren't......you have a fueling issue.Running Lean = not enough gas for the amount of air in the combustion chamber.
KW
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by LouisvilleLT4
Hey guys, I just got a "running lean" code. Where is the "running lean" on my engine and how do I replace it?
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Drifting
Joined: Aug 2006
Posts: 1,326
Likes: 18
From: Los Angeles California
I think I found my running lean. Turns out it was just dirty!
I cleaned it up and as you can see now it looks much better. I haven't started the car back up yet but hopefully this will fix all those codes I'm getting!
I cleaned it up and as you can see now it looks much better. I haven't started the car back up yet but hopefully this will fix all those codes I'm getting!
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
The pix aren't too clear. If you have any crusty deposits left, they cam be dislodged with a ball peen cleaning tool. It helps loosen them for the power washer. Kind of like how you might treat an uncooperative MAF.
RACE ON!!!
RACE ON!!!