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05-13-06, 10:14 PM
|  | Founding Member | | Join Date: July 2001 Location: Kentucky
Posts: 849
| | | '03 Cobra Pinging
Hey guys,
I took the Cobra I planned to buy out on a test drive today. Took off fairly quick no issues, etc. Got on the highway had the car under load in 5th gear and heard some pinging. Come to find out some wrench monkey at the car dealer put in 87 octane gas. I guess its pretty decent 87 because it didn't ping until that engine was under HEAVY load. Sooo my question is, how much pinging can an engine withstand before real damage is done? I didn't know what it was so I had stepped on it a few times (only two where I heard that) before we narrowed the problem down. Think it could have done long term damage? The engine idling seems fine although now a belt is making some noise (squeaking) but besides that the car is in top shape. Deciding whether I should get it or not. |
05-13-06, 10:30 PM
| | Founding Member | | Join Date: June 2000 Location: Plano,Texas,USA
Posts: 419
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My thought is that the car is probably OK. The forged bottom ends are pretty tough. The computer will pull timing when the knock sensors light up. As for the tech, what a nimrod.
Last edited by midlifecrisis99cobra; 05-13-06 at 10:32 PM.
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05-14-06, 06:01 AM
| | Banned | | Join Date: June 2002 Location: Prattville, Alabama
Posts: 3,875
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Hard to say really... The upper ring lands are what get damaged by excessive pinging on these cars. The top ring land on the stock pistons is the weak point and if there's going to be damage it would be visible there. You may want to have them perform a compression & leak down test on the motor.
U.M. |
05-15-06, 04:43 AM
| | Member | | Join Date: April 2005 Location: SOCAL
Posts: 35
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maybe the dealership put in the wrong gas... |
05-15-06, 05:07 AM
|  | Official Member | | Join Date: August 2003 Location: Oly, WA
Posts: 1,782
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he said they put in 87.
as far as the car, i would have them inspect it fully and take note of the pinging before any purchase was made. if that checks out, go for it  |
05-15-06, 02:13 PM
|  | Official Member | | Join Date: April 2005 Location: OK, USA
Posts: 262
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well der....87 is your problem.
sounds like tip-in too.
You can cause severe oil consumption issues detonating at low RPM in the upper gears under load....geeze. I hope you didn't do that for long.
If you buy it, flush it out, put some 93/101 blend to be safe and let it run it's course.... |
05-15-06, 02:25 PM
| | Founding Member | | Join Date: July 2001 Location: Kentucky
Posts: 849
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I have them performing a compression and leak down test on it. We will see what they come up with.... Anyone have the specs of what I can consider acceptable norms for those tests? |
05-16-06, 12:10 AM
|  | Official Member | | Join Date: April 2004 Location: Bastrop,TX
Posts: 3,022
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If im not mistaken, 03-04 cobras dont have a knock sensor....just an AIT sensor that pulls timing dependant on air temps. Stock terminators are tuned pretty safe (note that you can gain freegin 40RWHP JUST from a tune)..low timing, rich AF. As long as it didnt ping @ WOT under alot of boost, it should be ok. |
05-16-06, 06:31 AM
|  | Official Member | | Join Date: May 2004 Location: Montgomery County,Pa.
Posts: 706
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Request an extended warranty with the purchase(if you buy it). It was traded for a reason.Hopefully it the owner was upgrading-not trading it in because of problems. |
05-16-06, 10:28 PM
| | Founding Member | | Join Date: July 2001 Location: Kentucky
Posts: 849
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Well I guess I was wrong..... They had the car for an extra day today (waiting on the broken spoiler lens) and they figured out what the noise I heard on the highway at low RPM's in 5th gear was..... At first I thought it was the exhaust rattling, but then they spoke of 87 octane so thats what I figured it was. Turns out it was a bad transmission mount they found today and are in the process of replacing it today. I don't recall hearing any other issues so maybe the car wasn't detonating at all.. Hell I don't know, I have never had a car detonate before. |
05-17-06, 12:57 AM
|  | Moderator | | Join Date: September 2001 Location: HOCKEYTOWN ® , MI
Posts: 6,313
| | Quote: |
Originally Posted by AmdMAN ...I have never had a car detonate before... | Similar to the sound of marbles bouncing around in a coffee can. Not good.  |
05-17-06, 05:10 AM
| | Banned | | Join Date: June 2002 Location: Prattville, Alabama
Posts: 3,875
| | Quote: |
Originally Posted by AmdMAN Turns out it was a bad transmission mount they found today and are in the process of replacing it today. I don't recall hearing any other issues so maybe the car wasn't detonating at all.. Hell I don't know, I have never had a car detonate before. | Let's hope that's really the problem and not just some story they concocted to keep you interested in the sale. We all know how honest and loyal car dealerships are... 
U.M. |
05-17-06, 05:44 AM
| | Founding Member | | Join Date: July 2001 Location: Kentucky
Posts: 849
| | Quote: |
Originally Posted by Uncle Meat Let's hope that's really the problem and not just some story they concocted to keep you interested in the sale. We all know how honest and loyal car dealerships are...
U.M. |
I agree with you, but this is Carmax, I don't know if you have dealt with them before, but they actually told me someone had put 87 in it, I would think most wouldn't have said that and made something else up. Like someone else said here though, I can always get the extended warranty which isn't expensive which leaves everything on their dime. It did sound like a rattling more than marbles and it sounded like it was coming from under the car not in front.. I will drive it again probably today as well as get the CT and LDT results. | | Thread Tools | | | | Display Modes |  Linear Mode | 
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