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  1. #1
    Insane SVT Poster
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    Over reving the engine... what can happen?

    Bare with me.... this is long.

    Went to the woodburn drag strip today. Not a good day for racing as temperatures was above 90. 1st run... 15 minutes after getting off the freeway, I ran a 12.5 @ 116+ MPH. On my 2nd run, I over reved the damm engine while doing a quick burn out to clean my tires. Staged and ran a 15.4 @ 102 MPH. No I didn't miss any shifts. I felt the car lost about 300 RWHP in 1st and 2nd gear, then 3rd gear comes up and it accelerates quicker than 2nd gear! I though maybe the computer hicupped and pulled timing or something. So I let her cool down for about 1.5 hours. Went out and ran a 13.5 @ under 110 MPH (forgot). WTF? My buddy and I reset my ECU by disconnecting the battery and trying to crank, etc... Let her cooled down for another 1.5 hour or so... 12.8 @ 106 MPH. WTF?

    Came back and listened to the car -- it sounded rough like it was missing. No more runs for me. Went home later and I could feel the car shaking and acceleration was not there as before. Still had boost and the car is still driveable but it felt weird. Kept off the boost and when I got home, I took out all the spark plugs (NGK-TR6). The part that surrounds the electrode was white, the electrode itself was dark, the metal curved tip was greyish white on the outside. I think I'm running lean? But how? The previous NGK-TR6 plugs that I used, all five were black, except three. The other three had reddish porcilin. (Porcilin is that ceramic part that surrounds the electrode, right?).

    I installed the old plugs back on, started her up and seems to sound fine. Went out and took a test drive and the car seems to pull hard again...

    I am at a lost as to what could possibly have happend. So here are my questions.

    1) What happend? Did I fry a coil pack? Did I fry a spark-plug? I took a flash light and looked at all the plug holes. One of the piston top had black residue. All the other ones didn't or I didn't see any. What the heck does this mean too?
    2) Why was the porcilin on all the plugs white?
    3) Why was the porcilin on the previous 5 plugs black?
    4) Why was the porcilin on the previous 3 plugs dark reddish?
    5) I didn't check the computer chip, but could it have fallen off and forced a lean condition? (It can't cause I tapped the damm thing and there's no room to move on top.) Did the chip go bad then?
    6) The car SEEMS to run normal again after putting in the old previous plugs. That brings up question 1, can a spark plug become bad in someway even without anything breaking off?

    The shitty part about all of this is that I lost to a 2001 Z06 when I should have whooped his ass hard! He ran a 12.9 @ 109 MPH to my 12.8 @ 106 MPH. He got the better reaction time so he finished first. Sorry I let all of you mustang brothas down..... My car was probably only running on 6 cylinders or something.

    Sorry for the long post, but any help or insight as to what the heck happend, I would greatly appreciate it.
    Last edited by Forbidden Snake; 06-28-2003 at 02:08 AM.
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  2. #2
    Civil PE 03blackCOBRA's Avatar
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    Dang that sucks! I wanted to go today but my freaking helmet isn't in yet and the 90+ temp would have been a bad choice for my first time at Woodburn in the 03.

    If I remember right you raised your limiter over stock via the chip? What is it set at?

    I smoked a coil pack on my 97GT, but it used 2 packs for all 8 cylinders and the cobra is coil on plug. In my GT it cruised ok but absolutely no power at all and bad bad idle. I thought I smoked the motor at the time. In the cobra it would be much less sever if you lost just one cylinder with the coil on plug design compared to my 97GT. Seems like your car recovered somewhat, so that is a good sign.

    I believe you have to check the plugs right after a hard run with the unleaded gas we use today to read them correctly. I don't know how to, but I think thatís what a hard-core drag racer told me.

    If it were me I would dump the NKG and go with Denso 22's for your mods. I would also find someone who can look over the car that knows what they are doing or take it into the shop. It would be a shame to smoke an engine because you don't know whatís wrong and continue to run it till it pukes. Let me know what shakes out. Good luck!
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  3. #3
    Insane SVT Poster
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    Thanks bro. There was another black cobra there -- I thought it was you, but it wasn't. It was a 99 or 01 cobra. I think he ran mid or high 13s. Other than that, there were tons of Turbo Buicks! Must of seen about 15+ buicks.

    It was a sorry day for me. I was hoping to do more practice and get high 11s with stock F1 tires, but no cigar as my car crapped out on me. Well, it was my fault.

    Rev limit on my car is 7500 RPMs. I normally shift at 6500 RPMs, but during that burn-out, the revs climbed up too quickly. Before I knew it, the car hicupped and thats when I looked down and saw that the RPMs where above 7000.

  4. #4
    zzzZZzz roushraven's Avatar
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    Rev limit on my car is 7500 RPMs. I normally shift at 6500 RPMs, but during that burn-out, the revs climbed up too quickly. Before I knew it, the car hicupped and thats when I looked down and saw that the RPMs where above 7000.
    Forbidded Snake


    Re: over-revving the motor and I'm not saying that this happened to you; but serious damage can result. I have personally witnessed a guy lose his motor under the same conditions ie over-revving his motor doing a burnout at the drag strip. Immediately after he too noted that it felt like power was way down and he felt it (the motor) shake/knock and immediately after his run the car shut down --- for good. Turns out he spun a few bearings due to oil starvation. The oil starvation in his case was because the oil pump gear in the stock pump shattered in five pieces causing the oil pump to stop spinning therefore no oil was supplied and viola the spun bearings.
    I understand the reasoning tuners raise the rev limiter (ie so that you don't bump it during a run.) However a 7500 rpm limit seems extreme to me given that the weakest link in all mod motors regardless of piston and rod type is the stock oil pump. I'm not 100% positive but I do not believe that the '03 pump is any different than on any other Cobra or GT which is a shame.

    As for your plugs, how did the electrodes look? Do they appear melted at all? Any part of the electrodes missing? Those would be indicators suggesting serious detonation. Dark coloured porcelain electrodes and threads on the plug (like an oily or sooty deposit) can indicate fouling from a number of things. Good luck, I hope you get it sorted out.
    Last edited by roushraven; 06-28-2003 at 06:03 AM.
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  5. #5
    200+mph Boss-O-Matic! racerat's Avatar
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    A similar thing happened to me this week. The shaking, especially at idle and under load and just didn't feel right.
    It was a single bad plug...mostly likely caused by firing the car up without a chip. I'm running NGK TR6's too but will soon be switching plugs.
    When we pulled the plugs all were fine except one was a bit darker than the other 7. Replaced them all and life is good again.

    Hope that's all your problem was too.
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  6. #6
    Insane SVT Poster
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    Originally posted by racerat
    A similar thing happened to me this week. The shaking, especially at idle and under load and just didn't feel right.
    It was a single bad plug...mostly likely caused by firing the car up without a chip. I'm running NGK TR6's too but will soon be switching plugs.
    When we pulled the plugs all were fine except one was a bit darker than the other 7. Replaced them all and life is good again.

    Hope that's all your problem was too.
    I hope so too.... cause it seemed to be running okay again after I re-installed the old TR6 plugs.

    Should I invest in a leak-down test or cylinder compression test? How much does that cost?

    roushraven... all the plugs looked okay. No missing or chipped off pieces. The electrode looks dark. The metal curved tip were greyish white and the porcelin was white, however, which leads me to believe it's running lean. I'm going to pull the old plugs out later on today and see if it resembles the ones I ran with yesterday.

    Thanks for your help and racerat's help. Any more ideas or possibilities? Anybody? The car still runs strong so I'm hoping it's not a spun bearing. If it was, I could hear it right?

    I appreciate the help guys and gals...

  7. #7
    little moddie Poisonous Mods's Avatar
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    http://www.svtperformance.com/forums...4&goto=newpost

    The NKG's color is a bit different then the stock one. Grayish color means good operation...mine were looking whitish at first but after a week of running the car around it was getting to its Grayish state.

    Make sure u give it at least 500miles before u check...i was freaking out at first due to the whitish color.

  8. #8
    Insane SVT Poster Griffin's Avatar
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    Dump the Tr-6s. They aren't a cold enough plug for the boost you are running. I had the same problem with my L. I didn't even bother with the TR-6s on the 03'. I went straight to a colder plug....
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  9. #9
    Crazy SVT Poster
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    Sounds like my snowmobile when she burns a plug out.
    Mind you it only has two cylinders in the first place.
    clugs and sputters along on one but when she has two good ones, she is good to go.

  10. #10
    Authorized Vendor CobraBob's Avatar
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    This brings up another question that probably has entered the minds of many who have visited local dyno shops.

    If the dyno operator runs all the way to redline, the computer will cause the engine to shut down fuel supply. And the engine misfires. Right? And do custom chips do the same thing?

    Does this hurt the engine if it is happens on two consecutive pulls?

  11. #11
    Interested Party needspeed's Avatar
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    I don't know how you can over-rev the motor since you have a rev limiter. The only way I know of is downshifting into the wrong gear. Unless your chip has way upped the rev limit.......Steve
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  12. #12
    Ford Fanatic 94SVT Coupe's Avatar
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    Originally posted by CobraBob
    This brings up another question that probably has entered the minds of many who have visited local dyno shops.

    If the dyno operator runs all the way to redline, the computer will cause the engine to shut down fuel supply. And the engine misfires. Right? And do custom chips do the same thing?

    Does this hurt the engine if it is happens on two consecutive pulls?
    That's why I told them to stop the pull at around 6000-6200 rpms. No need to go to redline for me, I don't shift that high.

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