Miss on Big End

[Chuck]

After what I saw last night at the track I don’t know about this, I still think it’s plugs or coil packs. Here’s why.

I have changed the plugs absolutely no difference then installed my stock coils didn’t change a thing
I know you don’t like the Brisk plugs but I have been using them for years with no problem
So I guess we’ll try something else

 

[16GoManGoHC2]

Just got a email the injectors are all good have one that is right on the borderline
He told me it wasn’t my problem the miss is somewhere else
So on to the next thing replacing all the sensors
Debating about replacing ECM

It’s a spark issue, coil packs for 135$ is a no brainer. My buddy just went through this this past week, replaced plugs and coil packs and problem solved. Think about this, O2 senses lean when it senses oxygen in the exhaust stream, oxygen in the exhaust stream comes from a leak or not enough fuel in the mix to burn up al the oxygen in the mixture. When there’s not spark NONE of the oxygen gets burned in that cylinder it happened in and it mixes in with the others and O2 sensors pick it up as lean. O2 sensors DONT sense gasoline, they sense oxygen . Once I saw what I saw last night on my wide band a light went off to your problem. Add this, when I hit the rev limiter up top at 7,500 rpms guess what’s seen on my wide band? LEAN not rich, it’s carbureted so it keeps fueling the engine, the sensor doesn’t see the fuel at all, it’s not made too!! It senses OXYGEN. If my car was computer controlled it’d be throwing a CEL for too lean, but not from a fueling issue, from a spark issue. Your injectors came back with a clean bill of health, one more thing to say it’s not from a cylinder being starved for fuel at the big end, the spark can’t keep up at the firing rate at high rpm, CHANGE THE PLUGS AND COILS PACKS!! It’s most likely a coil back not a plug, the stock coil packs are not that hot, at high RPM’s and increased cylinder pressures they can’t build up enough energy in the short amount of time allotted (milliseconds) to generate enough voltage to bridge the gap. I’m an electrical engineer, this makes perfect sense to me. Add to that my buddy just had your same issue and coil packs and plugs took care of his issue. I may be wrong but it would be what I would be changing next.

 

[Chuck]

I will give it a try makes sense the way your explaining it

 

[16GoManGoHC2]

If I get a chance later today or this weekend I’ll take a video of my Capri up against the rev limiter for launch control and get the wide band display in the view of the video as well and you’ll see it go off the chart as a lean when spark is interrupted not rich. It’s my 22nd wedding anniversary today so there’s no playing with my cars to get such today if I want to get lucky later LOL

 

[Bboyd]

I have the same problem breaking up thru out the run? Changing plugs first... will post results....

 

[zhc]

A severe misfire will normally show as a LEAN condition. This is because the o2 sensor detects oxygen, not fuel. So if a mix isn’t lit, that’s extra unused o2 picked by the sensor. It’s gotta be pretty severe for it to show up that way though. Minor misfires are normally imperceivable.

 

[Mean Cat]

It’s a spark issue, coil packs for 135$ is a no brainer. My buddy just went through this this past week, replaced plugs and coil packs and problem solved. Think about this, O2 senses lean when it senses oxygen in the exhaust stream, oxygen in the exhaust stream comes from a leak or not enough fuel in the mix to burn up al the oxygen in the mixture. When there’s not spark NONE of the oxygen gets burned in that cylinder it happened in and it mixes in with the others and O2 sensors pick it up as lean. O2 sensors DONT sense gasoline, they sense oxygen . Once I saw what I saw last night on my wide band a light went off to your problem. Add this, when I hit the rev limiter up top at 7,500 rpms guess what’s seen on my wide band? LEAN not rich, it’s carbureted so it keeps fueling the engine, the sensor doesn’t see the fuel at all, it’s not made too!! It senses OXYGEN. If my car was computer controlled it’d be throwing a CEL for too lean, but not from a fueling issue, from a spark issue. Your injectors came back with a clean bill of health, one more thing to say it’s not from a cylinder being starved for fuel at the big end, the spark can’t keep up at the firing rate at high rpm, CHANGE THE PLUGS AND COILS PACKS!! It’s most likely a coil back not a plug, the stock coil packs are not that hot, at high RPM’s and increased cylinder pressures they can’t build up enough energy in the short amount of time allotted (milliseconds) to generate enough voltage to bridge the gap. I’m an electrical engineer, this makes perfect sense to me. Add to that my buddy just had your same issue and coil packs and plugs took care of his issue. I may be wrong but it would be what I would be changing next.

Is there a better aftermarket Coil Pack other than oem ?

 

[cole3986]

It’s a spark issue, coil packs for 135$ is a no brainer. My buddy just went through this this past week, replaced plugs and coil packs and problem solved. Think about this, O2 senses lean when it senses oxygen in the exhaust stream, oxygen in the exhaust stream comes from a leak or not enough fuel in the mix to burn up al the oxygen in the mixture. When there’s not spark NONE of the oxygen gets burned in that cylinder it happened in and it mixes in with the others and O2 sensors pick it up as lean. O2 sensors DONT sense gasoline, they sense oxygen . Once I saw what I saw last night on my wide band a light went off to your problem. Add this, when I hit the rev limiter up top at 7,500 rpms guess what’s seen on my wide band? LEAN not rich, it’s carbureted so it keeps fueling the engine, the sensor doesn’t see the fuel at all, it’s not made too!! It senses OXYGEN. If my car was computer controlled it’d be throwing a CEL for too lean, but not from a fueling issue, from a spark issue. Your injectors came back with a clean bill of health, one more thing to say it’s not from a cylinder being starved for fuel at the big end, the spark can’t keep up at the firing rate at high rpm, CHANGE THE PLUGS AND COILS PACKS!! It’s most likely a coil back not a plug, the stock coil packs are not that hot, at high RPM’s and increased cylinder pressures they can’t build up enough energy in the short amount of time allotted (milliseconds) to generate enough voltage to bridge the gap. I’m an electrical engineer, this makes perfect sense to me. Add to that my buddy just had your same issue and coil packs and plugs took care of his issue. I may be wrong but it would be what I would be changing next.

You basically agreed with me and added the science behind the O2 sensors, nicely done.

 

[Bboyd]

Is there a better aftermarket Coil Pack other than oem ?

would like to have coil packs adleast in the trailer! anyone have any ideas?

 

[16GoManGoHC2]

would like to have coil packs adleast in the trailer! anyone have any ideas?

Like earlier in the post I posted these, these are the ones he used, made by MSD for this company, same part as MSD part but without MSD logo on them for half the price

 

[16GoManGoHC2]

Is there a better aftermarket Coil Pack other than oem ?

ideas?
Like earlier in the post I posted these, these are the ones he used, made by MSD for this company, same part as MSD part but without MSD logo on them for half the price

 

[16GoManGoHC2]

You basically agreed with me and added the science behind the O2 sensors, nicely done.

Unfortunately it took such Detailed explanation to convince
Hopefully coil packs takes care of their problems, I would not have suggested them if it where not where I’d be spending my own money myself if I was having the same issue.
I agree it’s a hard one to grasp, computer saying lean, you dump more fuel on it, O2 sensors are still saying lean, you start to think WTF impossible, sensors must be bad, but you could pour gasoline straight on the O2 sensors and if they still see Oxygen they are going to keep saying lean, Because they sense oxygen not gasoline lol. Took me a while to grasp that as well, all good, I’m just trying to help.

 

[Bboyd]

thanks, i ordered them! just OCD! trying to get it worked out for challenger fest? ???

 

[Mean Cat]

ideas?
Like earlier in the post I posted these, these are the ones he used, made by MSD for this company, same part as MSD part but without MSD logo on them for half the price
View attachment 24007

These coil packs ^^ are the cheapest I've seen, My question on coil packs is what is the voltage output ?
I read some where the stock is 25k volts. Not sure if that's true. Defiantly don't want less volts than stock.
Accel is 33k volts, $428
MSD is 36k volts, $481
Performance Distributors SOS is 40k volts, $379

 

[Bboyd]

LOL... what if maf sensor was unplugged?? just saying i know a guy>>>> lmao

 

[Mean Cat]

LOL... what if maf sensor was unplugged?? just saying i know a guy>>>> lmao

So did you cancel CP order ? LOL

 

[16GoManGoHC2]

These coil packs ^^ are the cheapest I've seen, My question on coil packs is what is the voltage output ?
I read some where the stock is 25k volts. Not sure if that's true. Defiantly don't want less volts than stock.
Accel is 33k volts, $428
MSD is 36k volts, $481
Performance Distributors SOS is 40k volts, $379

Unfortunately don’t know voltage on these, their supposedly made by MSD.
Myself, I’d probably buy genuine MSD, I come from the school of hard knocks and you get what you pay for. For testing purposes or back up spares I’d use the cheap ones, for performance upgrade, longevity, and especially high boost applications I’d use genuine MSD

 

[Bboyd]

So did you cancel CP order ? LOL

No I put them in the trailer..for spares...

 

[Mean Cat]

No I put them in the trailer..for spares...

Well it's good you found your problem.

 

[Mean Cat]

Unfortunately don’t know voltage on these, their supposedly made by MSD.
Myself, I’d probably buy genuine MSD, I come from the school of hard knocks and you get what you pay for. For testing purposes or back up spares I’d use the cheap ones, for performance upgrade, longevity, and especially high boost applications I’d use genuine MSD
View attachment 24010 View attachment 24011

I agree, you get what you pay for normally, that's why, if I needed them, would buy the PD's SOS (Sultan of Spark) with the 40k volts at $379, not bad compared to the others.

I've noticed that if they don't say the voltage, it's probably not that impressive.