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LT1 just pegged itself to red line and grenaded!!!!

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LT1 just pegged itself to red line and grenaded!!!!

 
Old 02-19-2019, 10:33 AM
  #1  
jimxms
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Default LT1 just pegged itself to red line and grenaded!!!!

Ugh, I can't believe I'm back here again - staring yet another rebuild in the face!

I'm taking the car out for a shake-down after installing a new intake manifold and a few other bits (new tune loaded to take all of this into account). After warming up I got the car down a straight, put about 75% throttle in 2nd, went to about 4.5-5k rpm, de-clutched, was about to change into 3rd when a car changed lane in front of me, so I let off the throttle and the car just decided to peg itself to the red line!!!!.

I had no foot on accelerator, clutch was totally in and it totally scared the **** out of me! I gave it a second to see if the revs were gonna drop (they didnít) so I put it in 3rd and they instantly fell.

Almost immediately after I hear the dreaded knock. Pull over and from the passenger side of the engine I can hear a knocking coming from down low. I start unplugging the coilpacks and isolate it to Cylinder 6. My guess is another spun bearing!!!

WTF caused my car to peg the red line when I had zero throttle input???
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Old 02-19-2019, 11:41 AM
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Well that sucks! Drive by wire failed? Tune related?
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Old 02-19-2019, 11:46 AM
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Floor mat??
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Old 02-19-2019, 11:49 AM
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Originally Posted by Danengraham View Post
Floor mat??
I like your thinking, so I've gone and checked - my mat is secured with the tabs.

This is definitely something that the car was doing itself.

I had the rev matching enabled at the time. It was almost like it thought I was going to change down for some reason, and blipped the throttle, but as I was already at 5k it blipped to the limiter and then just got stuck in some kind of crazy loop!

Had I have selected 3rd immediately I don't think it would have happened, but because I had to abort my change to 3rd at 5k rpm due to the driver in front pulling out on me, I was in a bit of a limbo. I'd taken my foot off the throttle and was waiting for the revs to drop to engage 3rd so I could slow down behind the car in front, but instead it hit the red line.

Last edited by jimxms; 02-19-2019 at 11:56 AM.
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Old 02-19-2019, 12:01 PM
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Originally Posted by jimxms View Post
after installing a new intake manifold
Seems like an 'elephant in the room' starting point...
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Old 02-19-2019, 12:43 PM
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Originally Posted by redzg View Post
Seems like an 'elephant in the room' starting point...
Yep you're right. It would seem I jumped the gun. The gaskets provided with the headers looked **** and I should have never used them as they were some kind of squashy fabric ones with a metal finish. It looks like one of them has literally blown apart!!

That said, I still want to know why my engine hit the limiter and stayed there...
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Old 02-19-2019, 03:18 PM
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Just one of those crazy things, are you may have just from the crazy guy pulling over on you without thinking about it went to hit the brake & hit the gas paddle . Robert
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Old 02-19-2019, 03:55 PM
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Originally Posted by robert miller View Post
Just one of those crazy things, are you may have just from the crazy guy pulling over on you without thinking about it went to hit the brake & hit the gas paddle . Robert
100% sure. I had a passenger at the time and turned
to them and said ďI aint doing that, look, look at my feetĒ
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Old 02-19-2019, 05:24 PM
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Originally Posted by jimxms View Post
100% sure. I had a passenger at the time and turned
to them and said ďI aint doing that, look, look at my feetĒ
Just putting something out here I did this once in the c5 and said O ****. Robert
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Old 02-20-2019, 10:22 PM
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New tune, look at your numbers, maybe a bad edit/bad math issue.
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Old 02-20-2019, 11:39 PM
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OMG Jim!!! So is the engine actually damaged or was it just the gasket causing the sound?
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Old 02-21-2019, 03:01 AM
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Originally Posted by FYREANT View Post
OMG Jim!!! So is the engine actually damaged or was it just the gasket causing the sound?
hey man, I removed the gasket yesterday and it has a big hole blown in it, so Iím pretty confident that is what it was. Iím going to get some OEM mls gaskets and use those going forward.

im gutted that I wasnít logging on hpt at the time as Iím nervous to take the car out again with the red lining issue
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Old 02-21-2019, 08:17 AM
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1 user suggested looking into the install of a new intake manifold as a starting point for the throttle issue and then you replied to that with the quality of your header gaskets? Maybe I just read it wrong.

*edit: I re re re-read it. Seems now the low quality header gaskets may be to blame for the "spun bearing sound" but still no progress in the throttle issue

Did you happen to install a new throttle body with the "other bits" you installed with the intake manifold? Just throwing out ideas here but if you installed a 95mm or 103mm throttle body into an intake manifold meant for a stock TB I would guess there's a chance the blade could get hung up on the manifold

Last edited by 555ctsv; 02-21-2019 at 08:19 AM.
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Old 02-21-2019, 08:35 AM
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My car has done this before actually. I was racing in a WGF event in Dallas and have a habit of driving with my left hand at 9 oclock while I am getting up to speed. As a slid my hand to 9 oclock I hit the rev match and the moment I stabbed 2nd it just went to the RPM it though I needed to be at and yes I spun all over the place. Almost wrecked the car actually.

Rev match is the devil. I would disable it if I could.
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Old 02-21-2019, 12:12 PM
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Originally Posted by C7&7 View Post
My car has done this before actually. I was racing in a WGF event in Dallas and have a habit of driving with my left hand at 9 oclock while I am getting up to speed. As a slid my hand to 9 oclock I hit the rev match and the moment I stabbed 2nd it just went to the RPM it though I needed to be at and yes I spun all over the place. Almost wrecked the car actually.

Rev match is the devil. I would disable it if I could.
95% of the time rev match is consistent and works as well as I could ever rev match. However, there are times when goofy things do happen with it that I've noticed. Either unnecessary revs or not rev matching when it should.
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Old 02-21-2019, 02:05 PM
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Originally Posted by C7&7 View Post
My car has done this before actually. I was racing in a WGF event in Dallas and have a habit of driving with my left hand at 9 oclock while I am getting up to speed. As a slid my hand to 9 oclock I hit the rev match and the moment I stabbed 2nd it just went to the RPM it though I needed to be at and yes I spun all over the place. Almost wrecked the car actually.

Rev match is the devil. I would disable it if I could.
Glad itís not just me 😮 I normally enable rev matching every time I drive, just because I love the auto blip. But I think Iím going to have to leave it disabled from now on if it wants to do that! Maybe the switches can be unplugged in the steering wheel?

Interestingly I also looked over a lot of my previous HPT log files, and on many occasions I noticed the ECU blipping the revs during a gear change EVEN when I was already over 6k RPM! Same situation - clutch in, mid gear change, 0% TPS. Instead of revs simply dropping they would drop a bit, increase again, then drop.

I thought the Rev match was supposed to be for downshifting only? If the car doesnít understand that at 60mph in 2nd gear at 6k RPM that Iím going to shift to 3rd not 1st then itís total crap!
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Old 02-22-2019, 09:52 AM
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By any chance is P0068 turned off in the ECU calibration?
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Old 02-22-2019, 12:02 PM
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Originally Posted by TurboLX View Post
By any chance is P0068 turned off in the ECU calibration?
MAF/MAP throttle position correlation? Yes itís set to no error reported and SES is disabled. Whatís the deal?
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Old 02-23-2019, 10:49 AM
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Did you edit the driver demand tables and if so, did you alter any negative values?
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Old 02-23-2019, 11:22 AM
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Originally Posted by JHEBERT View Post
Did you edit the driver demand tables and if so, did you alter any negative values?
I've had a pro do the tuning for me, so I don't really know how to check that.
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