New to the forum so it will take me a minute to figure out how this works. We bought a 2004 C5 convertible last month. We drove it two hours home and there was a very loud knocking. Lifters they say. The dealership came and got it the next day and said that the engine was trashed. They replaced it with a brand new LS1 - they said we couldn't upgrade because of modification problems.

We got it back last week after 3 weeks of waiting. We drove cautiously while putting the first 100 miles on. We then changed the oil to get rid of any shavings. We worked her a little bit more for another 400 miles not getting over 4k rpm. We changed the oil again to clean her out. She has been running great, but there is a light pinging coming from the engine. You can hear it much better from underneath on the driver's side. The dealership listened and said it wasn't anything to worry about and it would be fine. I read all kinds of input on how it can be real bad. This is a brand new engine and we need to know what to do. It isn't a knocking, kind of like a soft air conditioner clicking. Yes, it is happens when the air is off. Help us please.

 

Surely someone has had the same problem and could offer some ideas. The dealer said it is fine after listening to it, but we want to make sure because the noise wasn't there for the first 500 miles.

 

id try a new fuel filter,
maybe clogged and making it ping.

but surely doesnt explain the clicking.

 

The Iron, the hard part from where we all sit is, we can't hear over the internet.

 

You maybe hearing injectors, valve closure, exhaust leak, etc.. When the dealer took a look, what did they say the noise was from?? When you say it is a new engine, was it a complete engine or a short block? If it was a complete new LS1, chances are you will be fine. They are very reliable engines.

 

If its pinging, you'll only hear it under a load, usually heard in a higher gear with a mdeium throttle command. I would look at the gas you are using if its pinging. Make sure its the highest you can get in your area. Out here, all we can get is 91 which causes pinging whereas those in other areas of the country, lucky enough to have 93 available, don't seem to talk about pinging as much.

 

Does it happen when the engine is cold, hot, or both? Can you hear it when driving, idling, or only when you stick your head under the car? Does it vary with engine RPM?

 

Good morning guys. It was a complete engine direct from GM. 91 Octane is all we can get here. I don't see any exhaust leaks, but still have to get it up on the ramps to double check.

If it is the gas problem, should we start using octane booster or something like that?

 

Noise comes on when the engine is hot. No, you can't hear it when you are driving - you can at idle if you are outside of the car on the driver's side. Doesn't seem to vary with rpm.

Have to tell you guys that this forum is great. Thanks for everyone's help. I have a thousand questions as this is our first vette.

 

On a stock LS engine, you should NEVER have to use octane booster. Unless something is horribly wrong, the engine should run fine on 91. Hell,,it will run on 87 if you were in a pinch.

Check your DIC for any DTC. If your scratching your head wondering what I'm talking about,,,,here you go:

READING YOUR Engine Diagnostic Codes (DTCs)

The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open etc…)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.

Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes)
If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, C or ;H. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present;
press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET
To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.

Here is very good site of DTC definitions:


http://www.gearchatter.com


Make sure to include the H or C suffix!!



Post your DTCs if you have any. You can CLEAR all of them and see which ones come back.

Where do you live. Maybe someone can drop by and help you figure it out.