[Z06] help with dieseling problem
Thread Starter
Racer
Joined: Feb 2008
Posts: 290
Likes: 0
From: Sammamish WA
help with dieseling problem
my C5 Z06 2003 with 30k miles started dieseling today.
it isnt a severe dieseling issue. it lasts for about a 0.5-1 sec at most.
i replaced the plugs and wires the weekend before last, with
Iridium tipped plugs (0.04 pre-gapped) part # 12571164
Red wire kit part # 89017270
Gas is (always) 92 octane filled recently.
I have been running fuel injector cleaner for the past 3 tanks but not the current one.
When i had purchased it (as used) a month ago, it had an odd ping (once or twice as opposed to severe detonation) on cold start and in low rpm and low speed situations. So i have been running injector cleaner for a while and i didnt hear any ping.
i did a search and found the following causes:
1. carbon build up (i havent been driving it hard; too much traffic; snow/mild-heavy showers. But i doubt this could be the issue since mileage is 30k only)
2. Hot plug (iridium tips are ok as far as i know. But this set could be defective. Should i have had the plugs replaced with the platinums that the car came with?)
3. faulty/failing injector (
4. timing (unlikely)
i did a search here and it seems that this could be
1. normal issue with these cars (disengage clutch to avoid sputter/dieseling)
2. Throw out bearing
Any clues what could be running hot or what could be causing this?
it isnt a severe dieseling issue. it lasts for about a 0.5-1 sec at most.
i replaced the plugs and wires the weekend before last, with
Iridium tipped plugs (0.04 pre-gapped) part # 12571164
Red wire kit part # 89017270
Gas is (always) 92 octane filled recently.
I have been running fuel injector cleaner for the past 3 tanks but not the current one.
When i had purchased it (as used) a month ago, it had an odd ping (once or twice as opposed to severe detonation) on cold start and in low rpm and low speed situations. So i have been running injector cleaner for a while and i didnt hear any ping.
i did a search and found the following causes:
1. carbon build up (i havent been driving it hard; too much traffic; snow/mild-heavy showers. But i doubt this could be the issue since mileage is 30k only)
2. Hot plug (iridium tips are ok as far as i know. But this set could be defective. Should i have had the plugs replaced with the platinums that the car came with?)
3. faulty/failing injector (
4. timing (unlikely)
i did a search here and it seems that this could be
1. normal issue with these cars (disengage clutch to avoid sputter/dieseling)
2. Throw out bearing
Any clues what could be running hot or what could be causing this?
Last edited by shaggy911; Apr 22, 2008 at 04:04 AM.
Safety Car
Joined: Sep 2007
Posts: 3,816
Likes: 16
From: Anchorage Alaska
St. Jude Donor '08-'09-'10
DOes it only happen at shutdown?
If so, what you are hearing only SOUNDS like dieseling, but is really what we affectionately call "the death rattle". I think it might be coincidence that it started around the same time you changed plugs and wires, but not related.
If you do have the death rattle, it will sound like dieseling but is alleviated if you hold the clutch down while you shut the engine down. The explanations I've heard for this is that the various drivetrain parts rattle against each other as they stop spinning; and having the clutch pressed will disengage the components so that they can stop spinning freely of each other... and therefore, not produce the rattling / dieseling sound.
Of course, you could have an entirely different issue... but I know the "death rattle" is very common and often misinterpreted as diseling.
If so, what you are hearing only SOUNDS like dieseling, but is really what we affectionately call "the death rattle". I think it might be coincidence that it started around the same time you changed plugs and wires, but not related.
If you do have the death rattle, it will sound like dieseling but is alleviated if you hold the clutch down while you shut the engine down. The explanations I've heard for this is that the various drivetrain parts rattle against each other as they stop spinning; and having the clutch pressed will disengage the components so that they can stop spinning freely of each other... and therefore, not produce the rattling / dieseling sound.
Of course, you could have an entirely different issue... but I know the "death rattle" is very common and often misinterpreted as diseling.
Race Director
Joined: Aug 2006
Posts: 12,581
Likes: 13
From: Colorado
St. Jude Donor '16 thru '26
If your Corvette is in fact dieseling at engine shut down as with any modern fuel injected engine, it has to be getting fuel with the key off.
I would suspect it’s most likely a leaking injector or a bad fuel pressure regulator.
It needs further hands on diagnosis to pinpoint it. I hopes this helps.
I would suspect it’s most likely a leaking injector or a bad fuel pressure regulator.
It needs further hands on diagnosis to pinpoint it. I hopes this helps.
Instructor
Joined: Feb 2008
Posts: 138
Likes: 0
If your Corvette is in fact dieseling at engine shut down as with any modern fuel injected engine, it has to be getting fuel with the key off.
I would suspect it’s most likely a leaking injector or a bad fuel pressure regulator.
It needs further hands on diagnosis to pinpoint it. I hopes this helps.
I would suspect it’s most likely a leaking injector or a bad fuel pressure regulator.
It needs further hands on diagnosis to pinpoint it. I hopes this helps.
Thread Starter
Racer
Joined: Feb 2008
Posts: 290
Likes: 0
From: Sammamish WA
DOes it only happen at shutdown?
If so, what you are hearing only SOUNDS like dieseling, but is really what we affectionately call "the death rattle". I think it might be coincidence that it started around the same time you changed plugs and wires, but not related.
If you do have the death rattle, it will sound like dieseling but is alleviated if you hold the clutch down while you shut the engine down. The explanations I've heard for this is that the various drivetrain parts rattle against each other as they stop spinning; and having the clutch pressed will disengage the components so that they can stop spinning freely of each other... and therefore, not produce the rattling / dieseling sound.
Of course, you could have an entirely different issue... but I know the "death rattle" is very common and often misinterpreted as diseling.
If you do have the death rattle, it will sound like dieseling but is alleviated if you hold the clutch down while you shut the engine down. The explanations I've heard for this is that the various drivetrain parts rattle against each other as they stop spinning; and having the clutch pressed will disengage the components so that they can stop spinning freely of each other... and therefore, not produce the rattling / dieseling sound.
Of course, you could have an entirely different issue... but I know the "death rattle" is very common and often misinterpreted as diseling.
If the fuel pressure regulator/injector were faulty would i get a diagnostic code?
Thanks!
Intermediate
Joined: Aug 2007
Posts: 48
Likes: 0
That's the death rattle... now that I think about it, it does sound like a diesel... but my car has done that since the day I got it, haven't ever worried about it. It does get some strange looks in parking lots, but I don't really care...
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Vettes that have been babied too much and never tuned, even with out 30,000 miles may have carbon build up.
The best way to clean this out is put in a tank of 93 and drive it hard for the whole tank, then get it dyno tuned, factory settings are way too rich, then another tank of 93 and drive it hard again.
That will clean everything out. Dont even think about that green chit or any other decarb except plain old carborater cleaner with is ether
The best way to clean this out is put in a tank of 93 and drive it hard for the whole tank, then get it dyno tuned, factory settings are way too rich, then another tank of 93 and drive it hard again.
That will clean everything out. Dont even think about that green chit or any other decarb except plain old carborater cleaner with is ether
Race Director
Joined: Nov 2000
Posts: 17,103
Likes: 39
From: stop the fun suckers
it might be important to point out you should never use "carb cleaner" on your throttle bodies... Throttle bodies have a special finish on them that will be removed with carb cleaner (I forgot how this effects performance.. but I remember reading it someplace - maybe the service manuals). If you do choose to clean your throttle body make sure you use only "Throttle Body Cleaner"..
just something to consider.. BTW: there is a TSB about the noisy throwout bearing during shut down.. IIRC the solution was shut down the car with the clutch depressed..
just something to consider.. BTW: there is a TSB about the noisy throwout bearing during shut down.. IIRC the solution was shut down the car with the clutch depressed..
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Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Our drive trains and clutch components are all splined together. The clutch disk rides on a splined shaft. All of those splined shaft tolerances add up to (in mechanical specs) a LOT of clearance. When you shut down any engine,, as the fuel and ignition are stopped, the engine still continues to spin and lose RPM. As it approaches Zero RPM, the cylinder pressures and cylinder vacuum cause the crank shaft to oscillate slightly in a back and forth in a CW & CCW movement. If you leave the clutch engaged thats what your hearing. That clutch disk and some of the tranny gears moving in that designed tolerance. It wont hurt anything except your pride. Is become second nature with most of us to secure the engine with the clutch depressed. if we forget, we know what the noise is and don't worry about it.
BC
BC
