Upgrade spark plugs for tune Mercedes
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Joined: Mar 2016
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From: Orlando, FL
2020 AMG GT63S 4dr Coupe
Renntech replaced my plugs 1300 miles ago due to the misfires I was having, and sold me a diverter valve. I've had 5 misfire cel's since. So it's not just changing for new plugs. I only wish.
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2014 E63s amg 4matic, 2009 C63, 2006 E55 AMG , 2001.5 AUDI S4 stg 3+ w/meth
coil pack or other part of the ignition system, vacuum leak , bad injector or clogged fuel system, failing fuel pump, or low cylinder compression (bad rings or warped or burned valves) worn lobes on a camshaft; a leaking head gasket or intake manifold gasket...etc, etc...
A cylinder needs three things to fire, proper fuel mixture, proper spark and sufficent compression. If any one of those are not present, you will get a misfire
if plugs didnt fix your misfire then time to look at next possible reason (coil packs)
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2014 E63s amg 4matic, 2009 C63, 2006 E55 AMG , 2001.5 AUDI S4 stg 3+ w/meth
i dont get whats not working for you? you car driving super slow or sputtering around town going into limp mode?
how many times do you misfire per day and have to clear codes?
Last edited by gaspam; Mar 23, 2016 at 03:22 PM.
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E63
maybe preface-lift m157's dont work as well with stock plugs then.... plus didnt you have 2 bad-coils causing your misfires and once you got them replaced you said your cars was smooth in your other thread?
i dont get whats not working for you? you car driving super slow or sputtering around town going into limp mode?
how many times do you misfire per day and have to clear codes?
i dont get whats not working for you? you car driving super slow or sputtering around town going into limp mode?
how many times do you misfire per day and have to clear codes?
After new plugs went in, I got a misfire within a week only under WOT and usually around 3-4000rpm (ie when i lay into it). It comes and goes. Its pretty infrequent. In fact on one dyno session, I made 12 plus pulls in an hour and did not have a single misfire. However a couple of weeks later, I got two misfires. Always happens when I am either pushing hard or going WOT. Never when I am driving around town.
So back she went to the dealer for new plugs yet again. Since it had a CEL, a whole lot of crap got replaced including two coils, my accelarator pedal and module, etc etc. Honestly I do not believe any of those had anything to do with the misfire. When you get misfires, you tend to get some unrelated codes like O2 sensors and some other crap. This time I re-gaped the plugs down to 0.021/0.022. Its been a month plus and no misfire no matter how hard I push her
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E63
ever think misfire could be caused by something other than a spark plug? especially since you had it before and after spark plug replacement...
coil pack or other part of the ignition system, vacuum leak , bad injector or clogged fuel system, failing fuel pump, or low cylinder compression (bad rings or warped or burned valves) worn lobes on a camshaft; a leaking head gasket or intake manifold gasket...etc, etc...
A cylinder needs three things to fire, proper fuel mixture, proper spark and sufficent compression. If any one of those are not present, you will get a misfire
if plugs didnt fix your misfire then time to look at next possible reason (coil packs)
coil pack or other part of the ignition system, vacuum leak , bad injector or clogged fuel system, failing fuel pump, or low cylinder compression (bad rings or warped or burned valves) worn lobes on a camshaft; a leaking head gasket or intake manifold gasket...etc, etc...
A cylinder needs three things to fire, proper fuel mixture, proper spark and sufficent compression. If any one of those are not present, you will get a misfire
if plugs didnt fix your misfire then time to look at next possible reason (coil packs)
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E63
To add to what I said about my car.....The brand new in the box stock plugs I re-gaped myself AND the new ones that were removed from the car had wider gaps on average than the old 30k miles old plugs that were removed from the car. I still have both sets in my garage and I have verified.
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From: miami / delray beach
2014 E63s amg 4matic, 2009 C63, 2006 E55 AMG , 2001.5 AUDI S4 stg 3+ w/meth
in my experience, misfires across random cylinders and random misfire codes usually means vacuum leak and the air/fuel mixture is running lean. whereas cylinder specific misfire would more indicate that spark is missing
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From: miami / delray beach
2014 E63s amg 4matic, 2009 C63, 2006 E55 AMG , 2001.5 AUDI S4 stg 3+ w/meth
To add to what I said about my car.....The brand new in the box stock plugs I re-gaped myself AND the new ones that were removed from the car had wider gaps on average than the old 30k miles old plugs that were removed from the car. I still have both sets in my garage and I have verified.
if i am following this timeline correctly, then dealer didnt check gap or correctly gap set 2 ?
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E63
are you are saying that original plugs (set 1) had no problems and 30K on them.... you decided to get new ones (set 2) dealer installed then got problems...went back to dealer and they replaced a bunch of stuff (including coils).... then you bought another new set (set 3), gapped them yourself, installed and now no problems correct?
if i am following this timeline correctly, then dealer didnt check gap or correctly gap set 2 ?
if i am following this timeline correctly, then dealer didnt check gap or correctly gap set 2 ?
I have the second (new un-gaped and used for about 1000miles) and first (stock 30k miles) set in the garage right now. I have gone through and checked the gaps on all 16. The new out of the box that was taken out is on average 0.003 larger gaps than the 30k miles set. That was also the case for the set that I gaped myself.
So recap. The 16 new sparkplugs I bought in the last 2 to 3 months had wider gaps out of the box than the 8 plugs that had 30k miles on them. Yes this is despite 30,000 miles of wear! they still had gaps of 0.024-0.026 leads me to believe they may have started life with smaller gaps than that.
Last edited by kponti; Mar 24, 2016 at 11:46 AM.
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E63
Except none of those things have cropped up again since installing new regaped stock plugs
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Large companies say stock. If you dont have a problem, leave them alone. If you change them, request the dealer check the gaps and set them to 0.022 - 0.024
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From: Fort Worth, Texas
2016 E63 S
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From: miami / delray beach
2014 E63s amg 4matic, 2009 C63, 2006 E55 AMG , 2001.5 AUDI S4 stg 3+ w/meth
renntech recommends stock and weistec recommends their own plugs so curious as what AMS recommends
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Joined: Mar 2016
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From: Orlando, FL
2020 AMG GT63S 4dr Coupe
Diverter Valve / Spark plug gap ??
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.
I can now run the heck out of my car without the misfires, I'm confident after having it back for over 3 weeks now and putting it to the test.
My car runs better with the diverter valve and adjustments, but I think reducing the gap in the plugs is the key and obvious first choice for anyone having the misfire issue with a tune.
The stock plugs were set between .027 and .028
FYI, RENNTECH really stepped up and took care of my issue and I will stick with them in the future.
Last edited by tlowry; May 9, 2016 at 09:25 AM.
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CLS63 PP
Since I continued to have the misfires on my cls, renntech arranged to bring my car in for more troubleshooting. They had my car for 3 weeks. They had another car in with the same problem. They changed out the diverter valve they had installed with one they could make more adjustments to. Finally they also gapped my plugs under .025.
I can now run the heck out of my car without the misfires, I'm confident after having it back for over 3 weeks now and putting it to the test.
My car runs better with the diverter valve and adjustments, but I think reducing the gap in the plugs is the key and obvious first choice for anyone having the misfire issue with a tune.
The stock plugs were set between .027 and .028
FYI, RENNTECH really stepped up and took care of my issue and I will stick with them in the future.
I can now run the heck out of my car without the misfires, I'm confident after having it back for over 3 weeks now and putting it to the test.
My car runs better with the diverter valve and adjustments, but I think reducing the gap in the plugs is the key and obvious first choice for anyone having the misfire issue with a tune.
The stock plugs were set between .027 and .028
FYI, RENNTECH really stepped up and took care of my issue and I will stick with them in the future.
I don't know why the " big tuners" are not doing tighter gaps as a matter of basic course when modding these motors for more boost. Its common practice on every other boosted platform. There is effectively no downside to gapping down to around .022. Tighter still, and you "may" get some idle harshness, but a small trade off for consistent ignition firing, which is literally the only job a spark plug needs to do.
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CLS55 2006, CLS 63S 2015
I don't know why the " big tuners" are not doing tighter gaps as a matter of basic course when modding these motors for more boost. Its common practice on every other boosted platform. There is effectively no downside to gapping down to around .022. Tighter still, and you "may" get some idle harshness, but a small trade off for consistent ignition firing, which is literally the only job a spark plug needs to do.
surly if tighter is better they would have done it no?
The spark plug issue is not new, was there with the first generation and hence why the newer ones have different plugs, so just got me wondering
the one common theme is its mostly the ecu tuned guys the complain the most about it and all tuners suffer from it including brabus
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From: miami / delray beach
2014 E63s amg 4matic, 2009 C63, 2006 E55 AMG , 2001.5 AUDI S4 stg 3+ w/meth
So why if i may ask are the stock ones set the way they are?
surly if tighter is better they would have done it no?
The spark plug issue is not new, was there with the first generation and hence why the newer ones have different plugs, so just got me wondering
the one common theme is its mostly the ecu tuned guys the complain the most about it and all tuners suffer from it including brabus
surly if tighter is better they would have done it no?
The spark plug issue is not new, was there with the first generation and hence why the newer ones have different plugs, so just got me wondering
the one common theme is its mostly the ecu tuned guys the complain the most about it and all tuners suffer from it including brabus
A gap that is too small means that the spark duration will be very quick and the spark will be thin and weak. If the gap is set too large, the ignition system will not be able to cope with the demands and a misfire situation will occur.... in the past people would set the gap manually by opening it very large and then closing in increments until misfires stopped. goal is to have as wide of gap as possible that doesnt misfire
rule of thumb is reduce the gap about .004" for every 50 hp you add over stock system... conversely if you add higher powered ignition system the gap can be opened more
Last edited by gaspam; May 10, 2016 at 10:41 AM.
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2014 E63 AMG S
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.
Seems Brisk MR12S would be great on a Renntech platform if running decent boost. I have these on a very different platform running over 2.5 bar boost- been performing great. What does Renntech run in their kit (stage 3 I think)? Something like 1.5 bar? I never asked...
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From: miami / delray beach
2014 E63s amg 4matic, 2009 C63, 2006 E55 AMG , 2001.5 AUDI S4 stg 3+ w/meth
Curious how the Brisk MR12S are doing for you? Was having all the issues mentioned in this thread, troubleshot based on experience with other platforms since I don't have anything to read codes... Interestingly, many of these symptoms are similar to other component issues so spark plugs didn't occur to me until it was a "duh!" on my part. Have a Renntech kit with stock plugs per their recommendation (they stated same reasons listed in this thread but I thought odd since generally went against common practice on any other platform). Right around 15k miles I started seeing symptoms, periodic limp mode right after WOT pulls, etc. Guess I missed that part of their recommendation.
Seems Brisk MR12S would be great on a Renntech platform if running decent boost. I have these on a very different platform running over 2.5 bar boost- been performing great. What does Renntech run in their kit (stage 3 I think)? Something like 1.5 bar? I never asked...
Seems Brisk MR12S would be great on a Renntech platform if running decent boost. I have these on a very different platform running over 2.5 bar boost- been performing great. What does Renntech run in their kit (stage 3 I think)? Something like 1.5 bar? I never asked...
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