Bad knock, won't idle..

**lsgunner28** · 09-07-2013, 03:06 AM

Hi everyone, been a while since I posted, been busy with school.
So I started my camaro up the other morning to go to work and made it about 200 yards down the road and boom, it started knocking, wont run at an idle. It will start and run smoothly with a little throttle at about 2000 RPMs. Plugs 1,2,3,5,7 looked ok and no loose rockers under the valve covers. The codes I got where: Bank 1 lean, Bank 2 lean and Random misfire.
Going to continue the tear down today. Any known problems to look for?
thanks

***SMWS6TA*** · 09-07-2013, 05:35 AM

It may be your IAC has gone out. No sure way to test it except to swap it out with a known good one. That would be the first thing I would check.

Next would be fuel pressure at the rails. Should show a reading of around 56 ft lbs.

**lsgunner28** · 09-07-2013, 07:32 PM

What's an IAC?
Update:
All plugs look fine, good dark brown color. No metal in the oil

**35th-ANV-SS** · 09-08-2013, 09:20 AM

Idle Air Control valve

**2002ssslp** · 09-08-2013, 10:20 AM

You may also have an intake manifold gasket leak. If the IAC valve does not fix the problem try smoking the engine to look for a leak.

**lsgunner28** · 09-08-2013, 04:21 PM

Update:
I wish it was the IAC or manifold gasket.. I have much bigger problems. After a compression check i found cylinder 1 has no compression at all and will not even make the needle bounce. The rockers are moving and I am not getting any blow by under the valve covers.
Any guidance at this point would be great, otherwise I'm gonna start pulling the motor.

**2002ssslp** · 09-08-2013, 05:45 PM

Start looking for another engine.

**lsgunner28** · 09-08-2013, 05:49 PM

LQ9? how much can the LS1 be bored over?

**2002ssslp** · 09-08-2013, 07:04 PM

You have a steel liner in the LS1 so I would say .020 would be safe but I'm not sure. This also means all new pistons, pins, rings and bearings.

**redbird555** · 09-10-2013, 09:14 AM

Originally Posted by 2002ssslp

You have a steel liner in the LS1 so I would say .020 would be safe but I'm not sure. This also means all new pistons, pins, rings and bearings.

Nope, 98 blocks will only take a .005 hone. 99-01 blocks can go .010 safely. Op I would examine what you have but if it blew a hole in the piston its gonna need a bigger overbore than .010 so i'd strat looking for a motor.

***SMWS6TA*** · 09-10-2013, 10:46 AM

Originally Posted by lsgunner28

Update:
I wish it was the IAC or manifold gasket.. I have much bigger problems. After a compression check i found cylinder 1 has no compression at all and will not even make the needle bounce. The rockers are moving and I am not getting any blow by under the valve covers.
Any guidance at this point would be great, otherwise I'm gonna start pulling the motor.

Ouch, pull the head first. Most likely you'll end up pulling the block.

Originally Posted by lsgunner28

LQ9? how much can the LS1 be bored over?

Not much, barely a hone. They don't have much in the steel sleeve.

LQ4/9's are iron blocks and can safely bore out .030" over. Trade off is they are much heavier then an aluminum block.

Originally Posted by redbird555

Nope, 98 blocks will only take a .005 hone. 99-01 blocks can go .010 safely. Op I would examine what you have but if it blew a hole in the piston its gonna need a bigger overbore than .010 so i'd strat looking for a motor.

Correct.

**2002ssslp** · 09-10-2013, 03:20 PM

Very sorry for your loss.

**lsgunner28** · 09-10-2013, 05:30 PM

May have gotten lucky in a bad situation...

I pulled the intake, valley and head tonight. I found a piece of plastic in the intake, i think the clip that holds the brake booster to the back of the intake broke off. The piston and cylinder look fine, no signs of damage. The valves however do not seat the whole way and that's where I'm loosing the compression. I think it pinched a piece of plastic when the valves were closing and bent them. I plan to pull the motor, and put new rings, seals and bearings in, possibly pistons and replace the valves for #1.
Any suggestions? Should i upgrade the heads? I want to spend less than $2000 in parts if possible.
thanks

**2002ssslp** · 09-11-2013, 03:18 PM

Necessity is the mother of invention. If you want a little more go, I would do a head and cam swap.

***SMWS6TA*** · 09-12-2013, 08:29 AM

Originally Posted by lsgunner28

May have gotten lucky in a bad situation...

I pulled the intake, valley and head tonight. I found a piece of plastic in the intake, i think the clip that holds the brake booster to the back of the intake broke off. The piston and cylinder look fine, no signs of damage. The valves however do not seat the whole way and that's where I'm loosing the compression. I think it pinched a piece of plastic when the valves were closing and bent them. I plan to pull the motor, and put new rings, seals and bearings in, possibly pistons and replace the valves for #1.
Any suggestions? Should i upgrade the heads? I want to spend less than $2000 in parts if possible.
thanks

wow post some pics.

2k will get you a good cam swap.

I would wait first on seeing if the head is damaged. You should expect to have the valve guides and new valve if it is bent. Possible new springs to.

**initechpeter** · 09-12-2013, 09:42 AM

Wow....sounds like you got lucky.

**lsgunner28** · 09-12-2013, 06:31 PM

valves.jpg

**RONS98TA** · 09-13-2013, 03:41 AM

Depends on your budget. You can put a nice set of AFR heads on for around $2000. The bottom end of the motor is fine, you already found your problem so you don't need pistons or rings. If you do the work yourself, heads. cam springs, timing chain w gears, you should be a lil over $2k. Although it depends on what parts you go with. As with any purchase, you can go WAY higher with the best parts. Just my 2cents.

**RONS98TA** · 09-13-2013, 03:45 AM

I down shifted into the wrong gear once and over reved to 9k rpm's and bent up a few valves. I removed the heads, replaced all the valves, guides and put in some double valve springs with titanium retainers in the stock heads. been running fine for well over 5 yrs now. I would've love to have replaced the heads then, but $$$ didn't allow it.