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Just an update. I decided to try a set of Brisk Mr12s non projected tip plug here they are compared to a stock plug. Thread reach and body are a perfect fit, only difference being the non projected tip. The reason for this is a shorter ground electrode has less distance to pull heat out, and the tip doesn;t become a glowing ember out in the combustion chambers during high boost. Note the difference in center electrode. These babies should be damn near impossible to blow out under load. My only question is part throttle/idle behaviour where projected tips are usually better. Only one way to find out, installing this coming weekend and I'll report back.
KLR you will NOT have blowout under any form of boost with those babies!!! Jeez talk about turtle necking the electrode!
I would recommend opening them up a bit though....maybe around 0.025 gap (closer to stock plugs) rather than 0.022 or narrower. I have stockers gapped down to 0.022 and it completely changed the way the car drove. Waaaaaaay smooth, almost to the point that I feel its too smooth lol. Also I do not think our ECUs learns as aggressively as say the BMW one. I should have had more timing advance by now but I have only had very little change.
I've had this misfire/limpmode issue for a year now, I traded in my last CLS63, a 2013 for a 2012 with less miles and PP to start over, thinking my firsr car was a lemon. I only had the tune on my first, so in order to ensure a great running car, I had the Renntech tune, downpipes, exhaust and cooling installed on my 2nd.
A month or 2 after the install i had the pleasure of anoither misfire/limpmode in my current car, this was approx. 2 monthes ago. All my work was done at Renntech since I'm in Orlando and only a couple hours away. I took it back to RT, for a day of troubleshooting, they changed the spark plugs first, but it misfired on the dyno after. They noticed some boost spikes and sold me a diverter valve that they felt addressed the issue.
I left feeling good, but a month later experienced another misfire, I had been using shell gas, RT has always brought up gas regarding the issue, but I didnt want to hear it. The owner agreed with me that Shell and Chevron were goood choices but asked that I try Sunoco. As soon as I filled up with the Sunoco the misfires started (WOT) it happed 3 or 4 times with that tank. I was scheduled to go back to RT, but after putting shell back in, i was running smooth again .
I did have 1 misfire thru 2 tanks of shell, I'm now buying form a very busy Chevron, on my 2nd tank now and giving it hell, so far so good.
I think gas may be part of the problem with this tune, or at least in my case. I'm sure the plugs are part of the problem as well. I've only used stock plugs per RT.
I think the problem has very little to do with gas or spikes or whatever else the tuners are coming with. We are already past the limits of what the stockers in their out of the box configuration can do. I do not even think a colder heat range plug will suffice. I believe a gapped low 0.021-0.022 range is what is needed stock or otherwise.
Heat range and gap spacing address different issues. A "colder plug" pulls more heat out of the combustion process by utilizing the shell of the plug as part of the conduction of heat into the head material to dissipate it. A colder plug will tend to prevent the ground electrode from becoming a constantly glowing ember that leads to pre-ignition/detonation where the combustion occurs due to the hot electrode and not correctly timed spark.
The misfires most seem to have are related to spark blow out from the combination of high compression of the DI motor, and high pressure from he onset of boost. Under these conditions you can only combat with 2 things. Increasing spark energy to the gap, or closing the gap up to give it the shortest distance to bridge the gap. Ideally , you do both. ( why I went with the Brisk plugs I posted ). Now there are trade offs with the smaller gap. OEMs like a large gap and projected tip to put the flame kernel deeper into the combustion chamber to ignite faster. This usually positively affects cold startup and idle characteristics. The trade off is under extreme loads, its more susceptible to blow out. In a tuned motor you always want the most stable spark you can get, so that trade of is always worth it to me. Different motors behave diffently, but for example in the case of my 700whp CTS-V, moving from a projected tip Iridium tr7ix at .032 to a non projected tip copper BR7EF with .024 made no difference in idle quality and solved my blowout missfire issue completely. Car ran better than ever in fact.
Here is KLR's rules for tuned M157s:
Run plugs with the highest spark energy you can. Gap them under .025 and change them every 20K. I guarantee that avoids all blowout misfire issues. If you worry about the cost, buy the tools and learng the skills yourself. It's hardly rocket surgery.. ;-)
The misfires most seem to have are related to spark blow out from the combination of high compression of the DI motor, and high pressure from he onset of boost. Under these conditions you can only combat with 2 things. Increasing spark energy to the gap, or closing the gap up to give it the shortest distance to bridge the gap. Ideally , you do both. ( why I went with the Brisk plugs I posted ). Now there are trade offs with the smaller gap. OEMs like a large gap and projected tip to put the flame kernel deeper into the combustion chamber to ignite faster. This usually positively affects cold startup and idle characteristics. The trade off is under extreme loads, its more susceptible to blow out.
how are you getting blowout on stock boost of 18.8 psi ? the canned tunes dont increase stock boost, they just hold it longer.... its not like its increasing boost from 19 to 30
i dont see it happening unless you have w4 turbo kit or something similar?
What he said except for one major issue, unlike Donald trump, I do not have tiny little fingers so changing plugs on this car is like rocket surgery to me
how are you getting blowout on stock boost of 18.8 psi ? the canned tunes dont increase stock boost, they just hold it longer.... its not like its increasing boost from 19 to 30
i dont see it happening unless you have w4 turbo kit or something similar?
Even with a W4 turbo, I do not see a whole lot of increase in boost being commanded by tuners. More efficient boost, yes. A whole lot more boost....remains to be seen
Also note that these are the same plugs used in the 4.7l TT, and a few of the 6 and 4 cylinder engines. Different combustion chamber characteristics, same spark plug.
how are you getting blowout on stock boost of 18.8 psi ? the canned tunes dont increase stock boost, they just hold it longer.... its not like its increasing boost from 19 to 30
i dont see it happening unless you have w4 turbo kit or something similar?
Blowout happens under transitional loads not just due to peak boost. And its not about absolute boost or CFM, but cylinder pressure. In fact high load, low RPM ( IE just as boost is ramping in) is the most common place to experience it. The motor may run fine for a bit once tuned, but it will happen eventually. Mine has only done it that I have noticed on my very first dyno pull, then din't on subsequent. Broke up hard at about 3500 rpm and dumped fuel. Dyno showed huge dip, but it did not set a code. Next three passes fine and power and toque climbed on each subsequent pass.
Now, not to say it isn't happening on the street here and there, but maybe just not enough to notice it. Having experienced it on my CTS-V, and spent lots of time chasing it, I know better now that the right plugs, at the right gap are a relatively cheap and easy was to avoid problems and aggravation.
the m157 uses multi-spark ignition enabling 4 sparks to be discharged in rapid succession within one millisecond, creating a plasma with a larger spatial expansion than conventional ignition... even if there is blowout on first spark, there are 3 more sparks backing it up.... seems unlikely an extra 60hp to 100 hp from a tune is creating that much more load to cause blowout.... not like we are going from 300hp to 600hp, nor are we running a conventional ignition system
all the issues with m157 plugs i have seen have been more electrode cracking and then subsequent misfire
Don't you think that a vehicle with multispark that is essentially a long duration spark at high rpm (think glowing ember) will be even more sensitive to the type of plugs or gap used?
FYI my first misfire episode occurred at around 4000rpm. Was very minor, a quick restart and all was well. Did not happen again until after a few weeks
the m157 uses multi-spark ignition enabling 4 sparks to be discharged in rapid succession within one millisecond, creating a plasma with a larger spatial expansion than conventional ignition... even if there is blowout on first spark, there are 3 more sparks backing it up.... seems unlikely an extra 60hp to 100 hp from a tune is creating that much more load to cause blowout.... not like we are going from 300hp to 600hp, nor are we running a conventional ignition system
all the issues with m157 plugs i have seen have been more electrode cracking and then subsequent misfire
Most modern coil on plug ignition systems are multi spark. This has no bearing on the blow out problem. My lsa motor had multi spark coils. MSD aftermarket coils in fact. You know MSD(multi spark discharge) inventors of multi spark ignition systems? Did you miss where gapping down the stock plugs solved kponti problem?
Not sure why you are adamant this isnt the problem when you don't have it? There is tremendous evidence of these cars misfiring on new and old plugs of different manufacturers pretty consistently. Are you saying there is a bad manufacturing epidemic out there with oem and aftermarket plugs cracking insulators?
As for boost, My cts-v made 16 lbs of boost. It has nothing to do with boost for the last time but transitional cylinder pressures. This isn't a new problem for boosted cars. It's pretty common knowledge actually and the only reason this thread exists is because certain. Tuners were charging crazy prices for spark plugs when there are other options and it's frankly a no Brainerd to do. Anyhow, I'll report back on my actual experience with these plugs.
the m157 uses multi-spark ignition enabling 4 sparks to be discharged in rapid succession within one millisecond, creating a plasma with a larger spatial expansion than conventional ignition... even if there is blowout on first spark, there are 3 more sparks backing it up.... seems unlikely an extra 60hp to 100 hp from a tune is creating that much more load to cause blowout.... not like we are going from 300hp to 600hp, nor are we running a conventional ignition system
all the issues with m157 plugs i have seen have been more electrode cracking and then subsequent misfire
Engines do not see horsepower increases, just torque. HP is just a function of that with rpm. All of which I know you are aware of. So using your argument, we increased torque on this engine by well over 200 to 250 ft/lbs
Now that's a lot
Did you miss where gapping down the stock plugs solved kponti problem?
Not sure why you are adamant this isnt the problem when you don't have it? There is tremendous evidence of these cars misfiring on new and old plugs of different manufacturers pretty consistently. Are you saying there is a bad manufacturing epidemic out there with oem and aftermarket plugs cracking insulators?
and yeah i know msd invented msi.. and yeah modern cars now have msi.. and they get tunes and they dont have to get new plugs when you get the car from the dealer or add a tune.... "here's your new car buddy, we put the wrong plugs in, go figure out what the right ones are on your own" ....and yeah changing gap too small can prevent misfires because it ensures a spark but also can give a spark to weak for complete combustion, so less power, but smoother... gapping down is usually a band-aid to bigger problem
and yeah there is lot of evidence of our cars misfiring in the past (like year 2012 and 2013) and the conclusion a long time ago was it wasnt the temp of the plugs or gap , but the service life of the plugs in our engines when tuned.... previously it was believed to be about 30K but its been found to be about 10-15K on tuned engines... this is why rennntech discontinued and stop recommending their one step colder plugs, because they realized that wasnt the issue and it was more of a shorten service interval issue.
you act like there is a new "misfire CEL" thread every day on here.. i've seen like 2 in past few months
my car's plugs started misfiring on que at 15K miles on them and one of them even had cracked electrode.... no gapping down would of solved that... it was age related.... have new stock plugs now and 4000 miles on them with my super crazy tuned power and no misfires
the tuners arent stupid... they tested other plugs and found stock ones work best... dont you think renntech/ams/gad would love to sell you $500 plugs if they could justify it?
yeah changing gap too small can prevent misfires because it ensures a spark but also can give a spark to weak for complete combustion, so less power, but smoother... gapping down is usually a band-aid to bigger problem
and yeah there is lot of evidence of our cars misfiring in the past (like year 2012 and 2013) and the conclusion a long time ago was it wasnt the temp of the plugs or gap , but the service life of the plugs in our engines when tuned.... previously it was believed to be about 30K but its been found to be about 10-15K on tuned engines... this is why rennntech discontinued and stop recommending their one step colder plugs, because they realized that wasnt the issue and it was more of a shorten service interval issue.
you act like there is a new "misfire CEL" thread every day on here.. i've seen like 2 in past few months
my car's plugs started misfiring on que at 15K miles on them and one of them even had cracked electrode.... no gapping down would of solved that... it was age related.... have new stock plugs now and 4000 miles on them with my super crazy tuned power and no misfires
the tuners arent stupid... they tested other plugs and found stock ones work best... dont you think renntech/ams/gad would love to sell you $500 plugs if they could justify it?
Weistec does recommend their own plugs.
According to word from another tuner who has examined the Renntech files, Renntech is one of the most maxed out in boost of the most tuners out there.
I have had a dealer installed brand new plugs on my car and I barely made it past 100 miles before misfiring
When I had Weistec plugs installed while I had them do a B service with LSD and transmission service ( even with less than 18,000 on the odometer ) I had my dealer gap it at 0.022 as per recommendation and even asked them to take photos of all the plugs gaped at 0.022 even though I didn't buy the OEM plugs from my dealer.
and yeah i know msd invented msi.. and yeah modern cars now have msi.. and they get tunes and they dont have to get new plugs when you get the car from the dealer or add a tune.... "here's your new car buddy, we put the wrong plugs in, go figure out what the right ones are on your own" ....and yeah changing gap too small can prevent misfires because it ensures a spark but also can give a spark to weak for complete combustion, so less power, but smoother... gapping down is usually a band-aid to bigger problem
and yeah there is lot of evidence of our cars misfiring in the past (like year 2012 and 2013) and the conclusion a long time ago was it wasnt the temp of the plugs or gap , but the service life of the plugs in our engines when tuned.... previously it was believed to be about 30K but its been found to be about 10-15K on tuned engines... this is why rennntech discontinued and stop recommending their one step colder plugs, because they realized that wasnt the issue and it was more of a shorten service interval issue.
you act like there is a new "misfire CEL" thread every day on here.. i've seen like 2 in past few months
my car's plugs started misfiring on que at 15K miles on them and one of them even had cracked electrode.... no gapping down would of solved that... it was age related.... have new stock plugs now and 4000 miles on them with my super crazy tuned power and no misfires
the tuners arent stupid... they tested other plugs and found stock ones work best... dont you think renntech/ams/gad would love to sell you $500 plugs if they could justify it?
Do you know why your "age related" plugs were misfiring? Because the gap and electrical conductivity eroded to the point of no longer giving the necessary spark energy to overcome the high cylinder pressure to fire correctly....which is also known as.....wait for it....spark blow out!!! Yes a tighter gap has the practical effect of reducing timing advance since the flame kernel isnt out away from the head as much and reduces power marginally, but we are talking a few hp, well worth it for a properly running car
This whole thread started because tuners were doingg exactly that. ..charging $350 plus for ****ing spark plugs, and people were asking for options. I just wanted to add some facts and alittle research on options since many on this forum have a love of the amg performance, have the money to play but don't have a lot of hands on experience mod ding cars themselves so frankly don't know any better than what the "tuners " recommend. Which news flash..they recommend what makes them money.
Anyhow my points is made. I'll review these plugs and confirm their performance once installed. If hey don't work I'll try something else but all I have to waste Is my time and my money. If it helps add some science and fact to what has largely been speculation on this topic then it's money and time well spent
I drive my cars pretty hard and have the dealer do A service every 4,500-5,000 miles. This is the second documented B service for 18k. I like how smooth the car drives after LSD and transmission service let alone a A service.
Especially after the transmission service the shifts are smooth and crisp.
Originally Posted by dav461
why u changed LSD and transmission oil at 18k ? its should be 50,000 KM.
Do you know why your "age related" plugs were misfiring? Because the gap and electrical conductivity eroded to the point of no longer giving the necessary spark energy to overcome the high cylinder pressure to fire correctly....which is also known as.....wait for it....spark blow out!!!
lol exactly... at that point is when.... wait for it.... you replace your plugs! instead of tightening the gap to compensate for erosion
just like when the active material in my car battery plates can no longer sustain a discharge current, i buy a new battery.... i suppose you try and add more active positive plate material though as a band-aid, instead of buying a new battery.
if you want to add some different plugs and feel like your customizing your car then great, but dont go acting like everyone needs to go get different plugs or else we are going to get spark blowout because its been proven time and time again that stock plugs are fine in tuned cars and good for about 15K miles...
Seeing how you had a cracked insulator, and several others have burned off the ground strap, that indicates to me, that no...stock plug are not fine, and that colder more robust plugs are required. I'm really struggling to understand what your point in all this is. We agree that plugs are being blown out do to insufficient spark energy to overcome cylinder pressure. We agree on regular frequent replacement. I am not advocating for taking out your plugs when you are misfiring at 15 or 20K, and gapping them down. I'm saying to avoid misfires, and potentially detonation related issues replace with a better quality, colder plug and gap to .025 at most. That was what I exactly stated above in my KLR's rules for plugs. Sounds like you are agreeing, but think people should only use stock plugs. I am saying I believe you can get a better option, that may in fact prevent the problem form occuring at all with a minor trade off of maybe a few hp left on the table. You want to keep your stock plugs great..go ahead and replace them every 15K, or when you eventually cook the insulators or ground strap off. I choose to go the route of safer and better.
03-21-2016, 02:52 PM
and no misfires
instead of tightening the gap to compensate for erosion 
