Dodge Challenger Forum banner

1 - 11 of 11 Posts

·
Registered
18 challenger r/t
Joined
·
2 Posts
Discussion Starter #1
I have a 18 chally m6 I just slapped on a Vortech v3 running about 5 lbs .. it’s diablo tuned I have a wideband and boost gauge . Car starts up and idles perfect. Once I get into boost the CEL will flash then reset itself a few moments after it will come back on and stay on and I get that stumble feeing in the pedal and obvious power loss. Code is for cylinder 8 misfire .. I checked every mechanical issue (plugs,coil packs,intake bolts,injectors.) all good .. don’t believe I ya e a leak because my boost pressure is good .. I have a oem 3 bar map sensor . I know some say swap it out for the ProCharger 2 bar one!! Also I noticed I was running at about 12.3 on my wideband at WOT recently got a updated tune for that but haven’t drove it yet .. wanting to know if anyone else has ran into this issue and could help . Thanks
 

·
Vendor
Joined
·
12,053 Posts
do you have a borescope?? would look at the piston
 

·
Registered
Joined
·
1,890 Posts
Flashing CEL indicates a rich misfire. This arises from incomplete combustion. This suggests the plug or coil of #8 is at fault.

While the fuel is probably not responsible for the misfire, have to bring this up: How fresh is the fuel? With a high compression engine fresh premium fuel is critical. And of course you must use the proper octane of fuel. But toss in boost and the right gasoline and fresh gasoline becomes super critical.

Not sure how you can check a coil other than look it over for obvious signs of a problem. With one of my cars -- a turbo charged car I might add -- there were no misfires but out of curiosity I had the coils and plugs changed. The plugs were about 10K miles away from their change by mileage but the tech advised doing the plugs while he was there and I agreed.

After new plugs/coils the engine ran noticeably better. The plugs were changed several times before every time based on miles and the engine never reacted favorably to the new plugs. Also, the tech was asked to look over the coils and if he found any suspect to replace them all and he never noticed any thing.

It could be the coil (or coils) is (are) marginal. In the stock engine it was ok but with boost it is not. I say "coils" because the #8 coil/cylinder may just be the tip of the iceberg so to speak. It is the weakest cylinder but still acceptable and it misfires first. You "fix" it and then another cylinder misfires.

Also, I would hope you started with fresh plugs and the right plugs and ensured they are gapped correctly.

Have you done a compression check? Maybe just say cylinders 7 and 8 or 4 and 8 just to see if #8 compression is close to that of a cylinder that is not misfiring.
 

·
Registered
18 challenger r/t
Joined
·
2 Posts
Discussion Starter #4
I don’t have a boroscope the car has less than 20k on it .. I don’t think it’s a piston issue.. I put new plugs in it . Brisk 14s . To check the coils I swapped one with the next cylinder and unhooked it . Cel popped up indicating it was a low circuit on the coils .. coils are good .. I haven’t done a compression check. It just weirds me out to think I have piston or combustion issues on a brand new car .
 

·
Vendor
Joined
·
12,053 Posts
simple test, swap coil, injector and plugs to a different cylinder, each a different cylinder, record position, drive, if the code change cylinders, you have a winner, if not, borescope, good luck
 

·
Vendor
Joined
·
12,053 Posts
not to be negative person, good chance you have a broken ring land, especially with a canned tune
 

·
Registered
Joined
·
1,890 Posts
I don’t have a boroscope the car has less than 20k on it .. I don’t think it’s a piston issue.. I put new plugs in it . Brisk 14s . To check the coils I swapped one with the next cylinder and unhooked it . Cel popped up indicating it was a low circuit on the coils .. coils are good .. I haven’t done a compression check. It just weirds me out to think I have piston or combustion issues on a brand new car .
Brisk plugs is not a brand I'm familiar with. I did a bit of research and one source has the Brisk heat range numbers going up for a "hotter" plug vs. for instance NGK, which for a hotter plug the numbers go down. So if you bought Brisk plugs and decided to go a step colder and going by the NGK and bought a higher number Brisk plug you have a hotter plug, not a colder plug.

I have to say too my second hand experience with plugs other than the brand recommended by the factory is the plugs are often not up to snuff. I recall in one case with another brand of car after new plugs were installed the engine ran terrible. Turns out while the plugs the owner bought were considered -- at least by their manufacturer -- to be compatible with the factory recommended plugs, at least the plug chart showed this -- the plugs were not.

Either the onwer posted a pic or I looked up the plugs based on the brand name and plug number. The difference in appearance was striking. The factory plugs have an extended tip. The extended tip at low engine speeds runs hot and thus this keeps the plugs "clean". Under higher engine speeds the extended tip is in the path of the incoming charge and is cooled by this thus the plugs do not run too hot.

BTW, I ran the factory plugs -- with the extended tips -- in two of my cars of the same brand and even after 60K miles and upon being replaced the engine never ran any better. It was clear the plugs even at 60K miles were not in the least bit degraded.

But in the case of this owner and his car, the replacement plugs had a recessed tip. Oh my. The owner replaced the plugs with the ones recommended by the factory and the engine symptoms went away.

A coil not being connected is not a test of the coil per se, only that something, like the engine controller, can detect its absence.

The coil's "test" comes from being able to deliver a good spark under all operating conditions and this of course includes an engine under boost. So in my opinion the coil is still a suspect.
 

·
Vendor
Joined
·
12,053 Posts
ps, would stick to Brand name spark plugs, NGK etc

had to google Brisk and Speed Channel has been gone for years
983413
 

·
Registered
2016 Jazz Blue A8 Scat
Joined
·
622 Posts
Where did you get the "Diablo tune"? Is it from Vortech or a custom tune from a tuner? Why aren't you running the 2 bar map sensor that is supposed to be on it?
 

·
Registered
2015 RT 5.7 M6
Joined
·
6,131 Posts
No need to run a 3 bar if you are planning to run below double digit boost levels. Downside to running a 3 bar is your PE table resolution is decreased. Also 12.3 at WOT is too lean for FI...should be more around low 11's. Like Luke said, scope the cylinder for damage...also check the plug insulator for damage or aluminum deposits. Most FI kits recommend running 1 step colder plug as well. If the cylinder/piston is ok then you really should have a knowledgeable tuner look a the tune to make sure everything looks good. Although at 5 psi I would not expect it causing much problems on a 5.7 unless the tune is really out of wack like knock sensors deactivated or too much spark and not enough fuel.
 

·
Registered
Joined
·
738 Posts
Who hasn’t heard of brisk plugs?! All I use in my nitrous hemis.
If you have done everything you said, it is time to look in the cylinder. You can buy cheap camera snake attachments for phones off Amazon too.


Sent from my iPhone using Tapatalk
 
1 - 11 of 11 Posts
Top