[Mana_MGT]

Originally Posted by Eagle2000GT ...If you are on a limited budget and you need to get the car fixed quickly then you need to go to a salvage yard and get a replacement motor...

This (or at least a replacement of damaged parts)

That's exactly what i've did when i replaced my cylinder heads (due to bad tune which cause extreme hot spark plugs)

[WickedSnake00]

When Eagle mentioned blowing lots of motors I expected a 5.0 in there somewhere. All the 5.0 guys I know usually have a disposable mentality. Boost the shit out of their motor, or spray the hell out of it till it pops, then go get a new one. Why re-build when you can get a salvage?

Which is also a strength with our 4.6's. They're everywhere in the junkyards. Better still you can get an Explorer which is effectively the same, but with an aluminum block.

I tried talking a friend of mine into getting a MKVIII motor when he popped one of his pistons on nitrous. He refused, and ended up spending more to repair his than a MKVIII swap.

[Mike Hadz]

Is there any chance that an extremely deteriorated timing chain holder ( the orange plastic peice ) could have caused this to happen?

also, the car was running an sct flash tune 91 oct which was specified for all my modifications, i'll just assume if it wasn't the timing chain housing thing, it was that the fuel injector was bad?


i think at this point i'm just going to have the cylinder re-honed, possibly bored out slightly (like some of you have suggested) and get it running again, if all appears well after a while hopefully i'll start running some low amount of boost

[WickedSnake00]

Originally Posted by Mike Hadz Is there any chance that an extremely deteriorated timing chain holder ( the orange plastic peice ) could have caused this to happen? also, the car was running an sct flash tune 91 oct which was specified for all my modifications, i'll just assume if it wasn't the timing chain housing thing, it was that the fuel injector was bad?

I highly doubt a timing chain guide would cause that. If your timing chain goes out of whack, your intake/exhaust valve timing is off. If anything this would promote something like PTV, not detonation. Not to mention it would affect all cylinders in that bank, not just one.

Now for detonation, the main factors are AFR, ignition timing, compression, octane, IAT's, and swirl/squish. Your compression, IAT's, swirl, octane, and swirl are the same across the entire bank. Since the injectors are independent, it could be a bad injector causing a lean AFR.

It could also possibly be ignition related, but this is a long shot. I don't think I know of a failure mode that causes premature ignition, normally ignition failure results in late/no spark, which is a misfire. The only other thing that could happen is if a valve got hot enough to cause pre-ignition due to carbon deposits, but this is something you see in race cars, seldom street cars. Looking at the valves in that cylinder may not hurt though.

And I'm sure someone else can chime in about how agressive or conservative the SCT 91 tune is.

[Mike Hadz]

Originally Posted by WickedSnake00 I highly doubt a timing chain guide would cause that. If your timing chain goes out of whack, your intake/exhaust valve timing is off. If anything this would promote something like PTV, not detonation. Not to mention it would affect all cylinders in that bank, not just one. Now for detonation, the main factors are AFR, ignition timing, compression, octane, IAT's, and swirl/squish. Your compression, IAT's, swirl, octane, and swirl are the same across the entire bank. Since the injectors are independent, it could be a bad injector causing a lean AFR. It could also possibly be ignition related, but this is a long shot. I don't think I know of a failure mode that causes premature ignition, normally ignition failure results in late/no spark, which is a misfire. The only other thing that could happen is if a valve got hot enough to cause pre-ignition due to carbon deposits, but this is something you see in race cars, seldom street cars. Looking at the valves in that cylinder may not hurt though. And I'm sure someone else can chime in about how agressive or conservative the SCT 91 tune is.

now that you say that my car sounded like it was missing slightly on ignition for a few weeks before this happened, didn't sound quite right, but after it was started it would run smooth, so really did nothing about it, as i tried to show the sound to my mechanic it wouldn't make the noise, typical...

what could the problem have been? my plugs? i had just replaced them with ngk platinum plugs

[stal94gt]

email tune mixed with a bad injecter could have alot to do with this. even though people say they are safe there is no real data on your car vs info that they think they have. 91 octane tune could have been confused and sent out as a 93 tune. or you could have gotten some bad gas which happens sometimes. i do my best to fill up at the same gas station where i got my tune from

[Mike Hadz]

Originally Posted by stal94gt email tune mixed with a bad injecter could have alot to do with this. even though people say they are safe there is no real data on your car vs info that they think they have. 91 octane tune could have been confused and sent out as a 93 tune. or you could have gotten some bad gas which happens sometimes. i do my best to fill up at the same gas station where i got my tune from

yes i pretty much always fill up at the same station that i know sells good gas

[WickedSnake00]

Originally Posted by Mike Hadz now that you say that my car sounded like it was missing slightly on ignition for a few weeks before this happened, didn't sound quite right, but after it was started it would run smooth, so really did nothing about it, as i tried to show the sound to my mechanic it wouldn't make the noise, typical... what could the problem have been? my plugs? i had just replaced them with ngk platinum plugs

Sure that noise was missing and not more of a you know, marbles rattling in a coffee can kind of noise? Because that would be detonation.

Like I said, if your coil or plug craps out on you, it usually causes a misfire, which WILL NOT cause detonation. Especially with the fact you have new plugs I don't think this was a factor.

You may have been hearing very slight detonation, and when you romped on it, that was the straw that broke the camel's (or piston's) back.

[Mike Hadz]

Originally Posted by WickedSnake00 Sure that noise was missing and not more of a you know, marbles rattling in a coffee can kind of noise? Because that would be detonation. Like I said, if your coil or plug craps out on you, it usually causes a misfire, which WILL NOT cause detonation. Especially with the fact you have new plugs I don't think this was a factor. You may have been hearing very slight detonation, and when you romped on it, that was the straw that broke the camel's (or piston's) back.

Thanks! it sounded like a big tick or something, hard to sound it out.