Knocking/Pinging on 99 T/A

[6t9deville]

Hey everyone, I just joined today and hope I can get some help on this issue. Have a 99' T/A (5.7L) and have noticed a knocking/pinging sound (yes I got that description from the Haynes) when I get on it. Some times are worse than others, and some times I don't hear it at all? The sound is exactly like the sound you would hear when the timing was out on cars that used to have distributor caps, but don't think you can adjust timing these days. Also have noticed what seems to be a "whistling" sound after I hit the gas and then let off it? Power steering pump? I know there are folks here with 110% more knowledge of motors etc. than me, so I would appreciate any help I can on any of these issues. I wanted to check my vacuum but can't seem to find the right spot to hook up the gauge to on the intake? Thanks in advance...

Dale

[Rhode Island Red]

First LS1's do build up carbon quite good from driving at the lower RPMS's 2k and under and from general use -it's unavoidable... Odds are that your pinging and knocking is a bad case of this. It's worth the $17 at the GM dealer to buy some GM top-end cleaner. Simply start the car, allow to get warm. Take off the pcv valve and slowly pour in the top end cleaner into the Throttle body (using a funnel helps a lot), keeping the rev's up so as to prevent it from stalling. When ~1/2 the bottle is poured in, dum in all the remaining cleaner all-at-once and turn off the car if it doesn't stall. Let sit for 1/2 hour and restart the car and watch the smoke fly (it will smoke up the neighborhood so do this where it won't cause issues) . Twice a year is what I do, and I always have a bottle on hand. Top end cleaner should be considered, regular maintenance for LS1's (btw my pinging would develop in 6th gear, under acceleration...then it would migrate to 5th, then to 4th...then be noticeable at any gear when I accelerate)

And yes the Power steering does whine... I've seen a 2001 SS had to have it replaced uder warrantee as it eventually died. I've taken my car, while it was under warrantee, to the dealer about the whining power steering. They saw nothing going bad... 4 years later I am still driving on the same PS pump (a mod is to port it - which I want to do ) Just accept it will whine and keep an eye on the fluid level. The fluid level should not change (unless you auto-x - that's when I noticed a fluid drop)

It's worth a shot at the top end cleaner... it must be GM top end cleaner ... everything else is junk at the stores..

[fastTa]

Hey everyone, I just joined today and hope I can get some help on this issue. Have a 99' T/A (5.7L) and have noticed a knocking/pinging sound (yes I got that description from the Haynes) when I get on it. Some times are worse than others, and some times I don't hear it at all? The sound is exactly like the sound you would hear when the timing was out on cars that used to have distributor caps, but don't think you can adjust timing these days. Also have noticed what seems to be a "whistling" sound after I hit the gas and then let off it? Power steering pump? I know there are folks here with 110% more knowledge of motors etc. than me, so I would appreciate any help I can on any of these issues. I wanted to check my vacuum but can't seem to find the right spot to hook up the gauge to on the intake? Thanks in advance...

Dale

The whistling sound is indicative of a vacuum leak which also in turn could be a substantial contributing factor to detonation. This is likely the "pinging" noise you hear. Vacuum is highest with the throttle closed so this is why you hear the "whistle" noise only when you get out of the gas.

Look at your vacuum diagram and start tracing for leaks. It is common on the LS1's for a leak to occur at the air check valve near the fuel rail or where it connects to the backside of the manifold.

[6t9deville]

Thanks for the quick replies. I'll look into both suggestions. If the whistling (vac leak) is the cause of the knocking (detonation) then using the top cleaner could only make it even better... I'll let ya know how it goes. I didn't see a vacuum diagram under the hood though?

[SixtyNineFbody]

Hey everyone, I just joined today and hope I can get some help on this issue. Have a 99' T/A (5.7L) and have noticed a knocking/pinging sound (yes I got that description from the Haynes) when I get on it. Some times are worse than others, and some times I don't hear it at all? The sound is exactly like the sound you would hear when the timing was out on cars that used to have distributor caps, but don't think you can adjust timing these days. Also have noticed what seems to be a "whistling" sound after I hit the gas and then let off it? Power steering pump? I know there are folks here with 110% more knowledge of motors etc. than me, so I would appreciate any help I can on any of these issues. I wanted to check my vacuum but can't seem to find the right spot to hook up the gauge to on the intake? Thanks in advance...

Dale

we all know a lot about engines....