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HELP: noise upon acceleration


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EarlJ
Novice

Nov 5, 2016, 6:38 PM

Post #1 of 15 (946 views)
HELP: noise upon acceleration Sign In

I have a 1993 Corvette coupe with about 60,000 miles. I recently started hearing a strange sound that only occurs upon acceleration when driving.

The best way I can describe the sound is the way a diesel engine sounds when it's idling. Like a clackety-clack sound.

I only hear the clackety-clack sound when I'm driving and the throttle is pressed slowly to a certain point. With further depression of the throttle (and more fuel) it goes away. When I back off the throttle and slowly press it again I hear it again. The clackety-clack sound gets louder when under load like going up an incline. During the point of throttle depression when the clackety-clack noise occurs it loses power. When I step on the throttle hard to get up to speed quickly I don't hear it and it accelerates fine.

The sound seems to be coming from under the car on the front passenger side somewhere near the front quarter-panel and/or engine area.

My first thoughts are:

1) Bad catalytic converter - it's located near the noise. Although it just passed smog test the other day.

2) Engine knock or ping.

I always use high octane premium gasoline. Oil and filter has recently been changed with mobile one per the owner's manual. It has new injectors, plugs and wires. No smoke from the tailpipe and it's not burning oil. Fluid levels are fine.

Had the car for 3 years and it was running fine.

Any ideas?


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Nov 5, 2016, 7:00 PM

Post #2 of 15 (941 views)
Re: HELP: noise upon acceleration Sign In

Without being there to hear the noise and try to pinpoint its location all we can do is guess.

Have you had your mechanic take it for a drive? Maybe get it in the air and do some visual inspections of the exhaust/heat shields.

Any trouble codes stored in the ECM?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


EarlJ
Novice

Nov 5, 2016, 7:05 PM

Post #3 of 15 (937 views)
Re: HELP: noise upon acceleration Sign In

I haven't taken it to the mechanic yet.

Is there a way to read codes with OBD1?

Would loose heat shields only make noise with certain depressions of the throttle?


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Nov 5, 2016, 7:12 PM

Post #4 of 15 (935 views)
Re: HELP: noise upon acceleration Sign In

Yes, that one has flash code diagnostics. You jumper A to B in the ALDL (diagnostic connector) and then turn the ignition on. The check engine light will flash stored trouble codes.


Quote
If the test terminal is grounded with the ignition on and engine not running, the system will enter the diagnostic mode. In this mode, the computer will display a Code 12, three consecutive times, by flashing the "CHECK ENGINE" or "SERVICE ENGINE SOON" light. A Code 12 consists of one flash, a short pause, then two flashes in rapid succession. After Code 12 is displayed, any stored trouble codes will be displayed by flashing the "CHECK ENGINE" or "SERVICE ENGINE SOON" light. All codes are displayed 3 times each then a code 12 will repeat. In the diagnostic mode, the computer will also energize all computer controlled relays and solenoids.



Its possible for different loads and rpms of the engine to influence vibration differences in the exhaust system that may resonate certain components.

It could be a detonation issue also, but it would be important to verify that before troubleshooting.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Nov 5, 2016, 7:13 PM)


Hammer Time
Ultimate Carjunky / Moderator
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Nov 6, 2016, 5:11 AM

Post #5 of 15 (914 views)
Re: HELP: noise upon acceleration Sign In





~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



EarlJ
Novice

Nov 8, 2016, 4:33 AM

Post #6 of 15 (895 views)
Re: HELP: noise upon acceleration Sign In

I recently had the oil changed at one of them there quick lube places. A bunch of kids were working there. Now I'm a not accusing anyone but I hear stories of them doing stuff to nice cars out of spite and jealousy and sometimes just pure dumbness. I'm a just a sayin do you all think they could have messed something up on purpose while under the car changing the oil? Is the an O2 sensor or something like that accessible under there.


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Nov 8, 2016, 5:18 AM

Post #7 of 15 (893 views)
Re: HELP: noise upon acceleration Sign In

Have you or someone done a visual under there? Why start assuming someone may have sabotaged your vehicle if you don't even know what is wrong?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Nov 8, 2016, 5:21 AM)


EarlJ
Novice

Nov 8, 2016, 10:25 AM

Post #8 of 15 (874 views)
Re: HELP: noise upon acceleration Sign In

I aint a sayn anyone's sabotaged my car, I'ma just asking a question. I reckon I'ma gonna have to take it to my mechanic 'cause I ain't a gettn any idears to what that noise is here except take it to yer mechanic. What's the point of askin heres before going to yer mechanic if nobody is good at troubleshootn.


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Nov 8, 2016, 11:22 AM

Post #9 of 15 (865 views)
Re: HELP: noise upon acceleration Sign In

Most of us are really good at troubleshooting. Read some of the other threads in here. It is difficult to troubleshoot a problem like that over the internet. Troubleshooting noises over the internet is almost impossible. The first thing you should do is have your mechanic drive the vehicle to see what kind of noise it is making and to find it where it is coming from. From what you described it could be detonation, but it would be nice if someone could verify that.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 8, 2016, 11:36 AM

Post #10 of 15 (863 views)
Re: HELP: noise upon acceleration Sign In

OK, smartass.............

You come to an Internet forum to diagnose a noise that nobody can hear and you thing WE"RE the problem!!!!!!!!!!!!!!!!!.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



EarlJ
Novice

Nov 10, 2016, 1:24 PM

Post #11 of 15 (842 views)
Re: HELP: noise upon acceleration Sign In

Now don't ya go gitten yer suspenders in a bunch. I appreciate yers all help. I aint calln anyone names so dont be hollerin. I think the cars a pingin. But it aint doing it now. So what can cause part throttle pinging? It would be right nice of ya all If you can help me. I cant goes to the mechanic right now.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 10, 2016, 1:28 PM

Post #12 of 15 (839 views)
Re: HELP: noise upon acceleration Sign In

  1. Timing too far advanced
  2. Engine running too hot
  3. Low octane fuel
  4. Inoperative EGR system
  5. Compression too high due to carbon buildup on piston.



I don't know if that hillbilly routine is something you think is funny but there aren't too many hillbillies in Sacramento CA. where you are.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Nov 10, 2016, 1:31 PM)


EarlJ
Novice

Nov 10, 2016, 4:54 PM

Post #13 of 15 (830 views)
Re: HELP: noise upon acceleration Sign In

Now remember.. an arrogant bug is a cocky roach.

Thanks I'll check into them things.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 10, 2016, 5:06 PM

Post #14 of 15 (827 views)
Re: HELP: noise upon acceleration Sign In

That's two. You won't get three.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Wrenchly
User

Nov 17, 2016, 1:53 PM

Post #15 of 15 (798 views)
Re: HELP: noise upon acceleration Sign In

Your description sounds like pinging. Typical causes for pinging are overheating,
egr inoperable, carbon buildup, timing set too advanced, lean fuel mixture, low octane fuel.

Check coolant is full. Head gaskets fail from age on this engine.

The easiest thing to try is high octane fuel (93) and one bottle of techron in the gas tank.






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