# 8 Cylinder Failures - Tuned Coyote

[Whipped Snake]

Hearing reports (small population) of failures with tuned/modded 5.0's...Appears some have experienced broken piston rings and toasted ring lands on cyl #8. Could this be like the infamous #7 issue on 03/04 Cobra's...I doubt it!

With that, my guess is it's tune related! And what's wrong with the tunes that's causing this? My suspicion is a tuner using global spark adder (have my reasons), but would like to hear everybody's input.

[Synister500]

My response to this on other forums has been a combination of the 2 points you have mentioned. My reasoning is this:
1. All failures that have come with pics of ring lands show almost the exact same failure in the exact same area of the piston.
2. This has lead to the theory that it must have been a run of bad pistons. Ok if that is the case then why have there been no other failures in any other cylinders? I actually sat down why my statistics professor and worked out a general probability for just 10 bad piston to end up in the same cylinder by chance. The probability is so infinitely small that it would be considered impossible. I even remember some mouthing off that their friend's, brother works with a guy, who knows someone that had lunch with the wife of the guy at Ford that said they knew about it but covered it up. Haha but yet in the days of the Internet where the Gov can't even keep documents secret Ford has some how found a way to do so. Therefore we have no proof.
3. The new 5.0 block uses oil squirters to aid in cooling the cylinders in the GT but not the Boss motor. Why? The Boss motor uses forged pistons to handle the repeated abuse of high rpm and road racing. Not something the regular GT was meant to endure.
4. Is it possible that the #8 cylinder receives less cooling than any other cylinder? Absolutely. If it were possible I'd like to see what the individual cylinder temp is on a coyote motor at operating temps.
My theory is as follows. If there IS less cooling to the #8 cylinder, is this a possible design flaw; no, because we have not seen any untuned #8 failures. Is it a possible design weakness; yes, but only when it is tuned outside of its designed limits. My reasoning for adding the cooling problem resorts back to point 1 above. All damage to the piston appears to be relatively similar in location and appearance. This could suggest that there is a "design weakness" in #8 cylinder, creating a "hot spot". Is it possible that variables such as repeated abuse and global tuning compounded the effects of less efficient cooling causing premature failure; absolutely yes. In my opinion my theory is supported by the fact that no FI coyote motors have had a reported failure, nor have any Boss motors. Obviously the Boss motor because it uses a stronger forged piston and for FI cars; they have more fuel added to the cylinder, this makes the cylinder run richer, cooler, and decreases the chance of pinging and detonation, which do increase heat in the cylinder and end in failure.
There are 2 basic type of tuners out there. 1 that takes a base file from a company like SCT and tweaks it, then you have others that build a custom tune from the ground up. Obviously building custom tunes from the ground up are more time consuming and more involved. Some "new" tuners to the Ford market may only know how to adjust the original SCT files and not build custom tunes (I myself have been a victim of this). This is another reason why some charge $300-$400 for a tune and others charge $50. Those charging $300-$400 know how much their time is worth and charge accordingly, others make money off the shear volume of sold tunes. I know I know, this is not always the case but this is where research on the side of the consumer can really pay off. I also want to add that dynos do help and should be used for fine tuning of optimal performance, but they are just another tool to be used by the tuner. If he doesn't know what he is doing the dyno is not going to save your motor. I know of many motors that have taken a shit on the dyno from bad tuning, during the tuning process. Sorry for the soapbox rant about tuners.
Finally, have we found 1 of the possible design limits of this motor; yes. Is a design limit a design flaw; no. Should Ford be responsible for replacing a motor that you knowing had tuned beyond their design limits of the motor; no. This would be no different then a 3v owner putting a Kenne Bell SC on his car with 15psi of boost, popping his motor and trying to get it fixed under warranty. Is it likely we recognize this weakness because of the use of global tuning; yep. Have a lot of tuners gone back and changed how they tune because of this; you bet ya. I'd bet anything if they still use global tuning they have added more fuel across the board and pulled some timing. Will a tuner ever admit they may have caused this failure; hell no. Is it possible we can see this problem again; yes, but I'd say it will be less and less. If you are worried about your warranty then DON'T MOD YOUR CAR unless "No" is a risk you are willing to take from Ford. Find and use a reputable tuner you trust after you have done your research. 1 simple thing to to is pick up the phone and call them. If they sound like Billy Bob from Sling Blade, chances are you do not want him tuning your car. Ask questions, for the love of God you are a paying consumer, if he can't answer your questions then look else where. Just for reference I asked my new tuner a ton of questions, spent over 20 min on the phone with him, then an entire weekend at the track during a national event he was racing his own car at, tuning my car. My car was tuned at the track because his dyno is more than 800 miles away from me. I understand this is highly unusual but many reputable tuners will work with you on either remote tuning or tuning from datalogs. I know this is more than you asked for OP but I hope I made it all relevant.

BJ

[cmygtfly]

My response to this on other forums has been a combination of the 2 points you have mentioned. My reasoning is this:
1. All failures that have come with pics of ring lands show almost the exact same failure in the exact same area of the piston.
2. This has lead to the theory that it must have been a run of bad pistons. Ok if that is the case then why have there been no other failures in any other cylinders? I actually sat down why my statistics professor and worked out a general probability for just 10 bad piston to end up in the same cylinder by chance. The probability is so infinitely small that it would be considered impossible. I even remember some mouthing off that their friend's, brother works with a guy, who knows someone that had lunch with the wife of the guy at Ford that said they knew about it but covered it up. Haha but yet in the days of the Internet where the Gov can't even keep documents secret Ford has some how found a way to do so. Therefore we have no proof.
3. The new 5.0 block uses oil squirters to aid in cooling the cylinders in the GT but not the Boss motor. Why? The Boss motor uses forged pistons to handle the repeated abuse of high rpm and road racing. Not something the regular GT was meant to endure.
4. Is it possible that the #8 cylinder receives less cooling than any other cylinder? Absolutely. If it were possible I'd like to see what the individual cylinder temp is on a coyote motor at operating temps.
My theory is as follows. If there IS less cooling to the #8 cylinder, is this a possible design flaw; no, because we have not seen any untuned #8 failures. Is it a possible design weakness; yes, but only when it is tuned outside of its designed limits. My reasoning for adding the cooling problem resorts back to point 1 above. All damage to the piston appears to be relatively similar in location and appearance. This could suggest that there is a "design weakness" in #8 cylinder, creating a "hot spot". Is it possible that variables such as repeated abuse and global tuning compounded the effects of less efficient cooling causing premature failure; absolutely yes. In my opinion my theory is supported by the fact that no FI coyote motors have had a reported failure, nor have any Boss motors. Obviously the Boss motor because it uses a stronger forged piston and for FI cars; they have more fuel added to the cylinder, this makes the cylinder run richer, cooler, and decreases the chance of pinging and detonation, which do increase heat in the cylinder and end in failure.
There are 2 basic type of tuners out there. 1 that takes a base file from a company like SCT and tweaks it, then you have others that build a custom tune from the ground up. Obviously building custom tunes from the ground up are more time consuming and more involved. Some "new" tuners to the Ford market may only know how to adjust the original SCT files and not build custom tunes (I myself have been a victim of this). This is another reason why some charge $300-$400 for a tune and others charge $50. Those charging $300-$400 know how much their time is worth and charge accordingly, others make money off the shear volume of sold tunes. I know I know, this is not always the case but this is where research on the side of the consumer can really pay off. I also want to add that dynos do help and should be used for fine tuning of optimal performance, but they are just another tool to be used by the tuner. If he doesn't know what he is doing the dyno is not going to save your motor. I know of many motors that have taken a shit on the dyno from bad tuning, during the tuning process. Sorry for the soapbox rant about tuners.
Finally, have we found 1 of the possible design limits of this motor; yes. Is a design limit a design flaw; no. Should Ford be responsible for replacing a motor that you knowing had tuned beyond their design limits of the motor; no. This would be no different then a 3v owner putting a Kenne Bell SC on his car with 15psi of boost, popping his motor and trying to get it fixed under warranty. Is it likely we recognize this weakness because of the use of global tuning; yep. Have a lot of tuners gone back and changed how they tune because of this; you bet ya. I'd bet anything if they still use global tuning they have added more fuel across the board and pulled some timing. Will a tuner ever admit they may have caused this failure; hell no. Is it possible we can see this problem again; yes, but I'd say it will be less and less. If you are worried about your warranty then DON'T MOD YOUR CAR unless "No" is a risk you are willing to take from Ford. Find and use a reputable tuner you trust after you have done your research. 1 simple thing to to is pick up the phone and call them. If they sound like Billy Bob from Sling Blade, chances are you do not want him tuning your car. Ask questions, for the love of God you are a paying consumer, if he can't answer your questions then look else where. Just for reference I asked my new tuner a ton of questions, spent over 20 min on the phone with him, then an entire weekend at the track during a national event he was racing his own car at, tuning my car. My car was tuned at the track because his dyno is more than 800 miles away from me. I understand this is highly unusual but many reputable tuners will work with you on either remote tuning or tuning from datalogs. I know this is more than you asked for OP but I hope I made it all relevant.

BJ

I actally think that is the knock sensor placement. The back driverside sensor is not picking up the number 8 cylinder as was machined and designed in to block. THen the tuners are desensitizeing the knock sensors that is where they are running into problems. IMO