kettemr

2001 convertible stock engine with Z06 cat-back exhaust. 6 speeed with 33k miles.

I have had a pinging issue under hard acceleration for quite some time. At the top end of 1st and 2nd (above 4,000 rpm) WOT after engine is at operating temp.... Coolant 194 degrees and oil 220 degrees. No codes.

I have cleaned the MAF and done the Sea Foam cleaning multiple times. I always run 93 octane. It still pings. The cats went at about 30,000 miles and I replaced them. I'm guessing this is all related. The car runs great and strong but keeps pinging. Knock sensors maybe? I have heard that it may need to have timing and/or fuel mixture adjusted but this is a stock set-up so the computer should take care of this right? Does anyone have any other suggestions? I need to fix this before I damage the engine badly. Thanks in advance.

099blancoss

fuel filter?

All_Motor_C5LS6

Have you tried some fuel system and injector cleaner? Have you tried checking your spark plug gaps?

NURVUS

I had the same problem with a 2002 6spd I recently picked up with 59,xxx miles. I read all the posts about seafoam, oil in the intake, oil catch cans, etc. A GM tech I know figured somewhere along the line someone downloaded an aftermarket tune. After he reflashed the computer with a stock tune, all the pinging went away! It runs fantastic and no more spark knock.

dankhts

check your tune! get some one who knows what they're doing to check it out.. I've also seen pinging probs when the wrong heat range plugs are used....

~Josh

The seafoam didn't do anything to the carbon on your piston tops and exhaust valves.

I've got pictures of mine either here or in the Zo6 section when I took off my heads. Even with a seafoam treatment 100 miles earlier there was tons of carbon buildup. After physically removing the carbon you can be assured it wont ping.

chevy406

You could possibly have a bad injector (or two). Or if you just have bad spray patterns it could be causing the detonation. Does it run OK without the AC on?

Do you still have 1-to-4 skip shift? If not was it tuned out (i.e. the car has been custom tuned). A quick data log would give you a lot of answers, too bad you aren't anywhere near north Alabama.

ICULUKN-C5

Check your injectors, fuel pressure, or possibly carbon on the piston..
If all else fails add some torco.

n8dogg

I would not drive it if shes pinging until you fix the issue. You are just asking for an engine failure. Strongly recommend data logging. This is driving the vehicle while recording engine parameters. This way you can go back and take a look at your log and view 02 sensor, fuel trim, ignition, MAF, and injector duty cycles.

You can do this with most tuning software like HPT or EFI Live. Tech-2 and Predator scan tools also can do this.


Do you know if the car has been tuned? If you say it only happens under heavy acceleration then it sounds like it happens under Power Enrichment. You may be running too lean, too much timing, or in some cases carbon build up can get hot enough to detonate the intake charge.

Considering you already went through a set of cats with the low miles you have, my guess is you are running lean. Catalytic converters fail when exhaust is too hot.

Where is Williamsville? I am in Rochester and would be happy to help determine what the problem is. I use EFI Live so I have full scanning and tuning capabilities.

tsts

Sounds like the right course to take!

84REDCROSSFIRE

Might be your MAP sensor going bad. Good Luck

kettemr

Hey n8dogg... I just sent you a pm.... I am thinking the same as you but need to get some help from someone I can trust.... I do NOT trust my local dealer. Take a look and let me know how I can contact you. Thanks.

kettemr

Thanks to all for your help.... I have considered all this stuff and need some real expert advice.... The car is stock, never retuned that I know of or suspect.

~Josh

The cliffnotes of my past experience was that I had hptuners and I logged a heavy street driving session. It was indeed knocking at 3/4 throttle between 3800 and 4100 rpm. It was pulling the max 4 degrees of timing in those cells before eventually dropping the car into the low octane table.

It turned out that hard carbon was caked on the piston, combustion chamber, and built up on the necks of the exhaust valves. Physically removing that will surely take care of pinging.

Keep in mind, you have an '01 like me with the "bad" piston rings.

tjwong

There is an updated GM engine calibration that addresses spark knock. Check with your lcoal dealer to have them check if your car needs this update.

retired cop

Had the same problem have a good tuner look at it.

Quicksilver Vert 01

It's interesting, and also unusual, that your cats needed replacing at that low mileage. Does your engine have excessive oil consumption?

Oil consumption can cause contaminated catalytic converters, and also carbon build-up on pistons and valves.

Dave68

A small percentage of 01s had this problem. I wouldn't tell people that they ALL did.

However, given the fact that the cat needed to replaced so early may be an indication of bad rings.

kettemr

The car was delivered to the original owner in April of 2001 so I think it was one of the earlier models that had the ring problem and I don't think it was repaired. I didn't realize this issue with 2001 models until after I had owned it a couple years (ugghh).

What is involved with manually cleaning the carbon deposits and changing the rings? I'm not a mechanic..... Any idea on how many hours of labor I would be looking at?

Thanks to all.

cruisemon

Look on the forum for how to dump codes on the DIC and report back here what codes you found. That will help get started down the solution path.

Charlie