Notices
4.6L V8 Technical Discussions Any questions about engine, transmission, or gearing can be asked here!

spark plug blowout?

Thread Tools
 
Search this Thread
 
Old 09-22-2009, 08:01 AM
  #1  
shanec
4th Gear Member
Thread Starter
 
shanec's Avatar
 
Join Date: Aug 2008
Location: Mississippi
Posts: 1,679
Default spark plug blowout?



I think I have some spark plug blowout at the end of this run. You see it easily where the red curves has some brief dips in power and dips toward richness. We could also see black puffs of smoke out of the exhaust at this time.

I was a little bit surprised at this, as I don't see people complaining about this much.
shanec is offline  
Old 09-22-2009, 02:40 PM
  #2  
HaneyMotorsport.Com
Banned
 
HaneyMotorsport.Com's Avatar
 
Join Date: Apr 2006
Location: Goodyear, AZ
Posts: 1,631
Default

I would say detonation/pre-ignition. If you have a misfire, "spark blow out", etc. the WB is going to read lean, not rich. Little puffs of black exhaust is generally an indication of detonation.

By just going off of the A/F readings, the tune needs some work.

Casey
HaneyMotorsport.Com is offline  
Old 09-22-2009, 02:48 PM
  #3  
shanec
4th Gear Member
Thread Starter
 
shanec's Avatar
 
Join Date: Aug 2008
Location: Mississippi
Posts: 1,679
Default

There was no pinging. Timing is only at 20 peak.

Blowout = no spark = unburnt fuel = rich, right? We also saw black puffs of smoke that would confirm unburnt fuel.

Wouldn't data logging the knock sensors indicate something if I had detonation?
shanec is offline  
Old 09-22-2009, 03:08 PM
  #4  
onederful100
6th Gear Member
 
onederful100's Avatar
 
Join Date: Jul 2007
Location: Honolulu, HI
Posts: 6,130
Default

got this from tricktuners website
http://www.tricktuners.com/detonation_explained.htm

Detonation, also known as pinging, pinking, or knocking, is a serious motor destroying event. It sounds different on many cars but it can sound like slapping metal wires against the motor, a rattle in the dash, shaking popcorn kernels in a coffee can, and when it’s real bad it sounds like marbles in a coffee can. It has a rhythmic sound much like a diesel (technically its very similar to a diesel). When you hear detonation GET OFF THE GAS IMMEDIATELY! Detonation is not the same as pre-ignition although they often occur at the same time. Detonation can be caused by too much spark advance, high IATs, lean mixture, dry air, high ECTs, low octane, etc. It occurs when the spark ignited flame front compresses the reaming air fuel mixture till it reaches critical temperature and pressure to auto ignite the mixture on the other side of the cylinder. The two flame fronts then collide with a giant explosion causing the audible knock sound. The cylinder temperatures and pressures increase drastically beyond the normal combustion temperatures and pressures causing burned holes in the pistons, bent or broken rods, damaged crankshaft bearings, and complete and total destruction.



Pre-ignition occurs when the mixture ignites on some hot spot (spark electrode, spark plug threads, a sharp point, carbon build up, etc) before, or at the same time the spark fires. The flame fronts do not always collide, the destruction comes from extended burn time in the cylinder. Pre-ignition does not produce the classic knock or ping, more of a dull thud, but it is often caused by detonation and therefore associated with the pinging sound. Pre-ignition is more dangerous than detonation because it occurs earlier in the engine cycle causing more temperature build up due to the extended burn times. It can also cause “runaway advance” where the hot spot gets continually hotter causing the explosion to occur earlier and earlier in the engine cycle. It can also be caused by detonation events heating up a hot spot to the point where the detonation then turns into pre-ignition to cause some serious destruction. This is why its very important to get off the gas when you hear or feel anything “funny” at WOT.



Detonation is affected by many things including ECT, IAT, octane, timing, compression ratio (or boost), RPMs, and AF. Increased coolant temps or air intake temps will increase the chances of detonation. Too much advance can also cause detonation resulting from increased burn times. Too much compression will cause detonation that can be eliminated with increased octane or in the case of forced induction by lowering the boost and or intake air temps. Octane is the easiest factor to control detonation. Octane is the fuels resistance to auto ignition (detonation and pre ignition). Sufficient octane will solve nearly all minor detonation problems. High octane fuel burns slower than low octane, and high octane is much more resistant to higher pressures and temperatures. Engines are much more prone to detonation while “lugging” when at high loads and low RPMs. This is mostly due to the extended burn times at low rpms and usually a motor will not detonate under the exact same conditions, but with a higher RPM. Lean AFR mixtures are also very prone to detonation and rich mixtures can sufficiently cool the cylinder to reduce or eliminate detonation. A motor might run great at 11.5:1 and detonate like crazy at 12.5:1 on the same octane. The goal to eliminating all detonation is to keep things cool and use sufficient octane for your appropriate boost and timing requirements. Water methanol injection can drastically reduce detonation by cooling the chamber as well as adding octane. Methanol has a pump octane rating around 100. The formula for calculating your octane level when mixing gas is:

[(Volume 1 * Octane 1) + (Volume 2 * Octane 2)] / (Volume 1 + Volume 2)



Volumes must have the same units such as gallons. Example: Mixing 7 gal of 91 octane with 3 of 100.

[(7*91)+(3*100)]/10=93.7
onederful100 is offline  
Old 09-22-2009, 04:23 PM
  #5  
HaneyMotorsport.Com
Banned
 
HaneyMotorsport.Com's Avatar
 
Join Date: Apr 2006
Location: Goodyear, AZ
Posts: 1,631
Default

Originally Posted by shanec
There was no pinging. Timing is only at 20 peak.

Blowout = no spark = unburnt fuel = rich, right? We also saw black puffs of smoke that would confirm unburnt fuel.

Wouldn't data logging the knock sensors indicate something if I had detonation?
No, a oxygen sensor reads/senses (actually more to it) oxygen content in the spent exhaust gases. So, if you don't have ignition, the air / fuel mixture does not burn, which means the oxygen is still there. Hence reading lean.

This is also the same with the factory SB O2's. You can get lean codes, but in reality the engine is running rich.

Casey
HaneyMotorsport.Com is offline  
Old 09-22-2009, 06:41 PM
  #6  
shanec
4th Gear Member
Thread Starter
 
shanec's Avatar
 
Join Date: Aug 2008
Location: Mississippi
Posts: 1,679
Default

Is there a SCT parameter I could log that would indicate detonation or pre-ignition?
shanec is offline  
Old 09-22-2009, 11:32 PM
  #7  
mygt500
Multi-Tasking Moderator!
 
mygt500's Avatar
 
Join Date: Nov 2006
Location: Detroit Rock City!
Posts: 15,618
Default

Originally Posted by onederful100
got this from tricktuners website
http://www.tricktuners.com/detonation_explained.htm

Detonation, also known as pinging, pinking, or knocking, is a serious motor destroying event. It sounds different on many cars but it can sound like slapping metal wires against the motor, a rattle in the dash, shaking popcorn kernels in a coffee can, and when it’s real bad it sounds like marbles in a coffee can. It has a rhythmic sound much like a diesel (technically its very similar to a diesel). When you hear detonation GET OFF THE GAS IMMEDIATELY! Detonation is not the same as pre-ignition although they often occur at the same time. Detonation can be caused by too much spark advance, high IATs, lean mixture, dry air, high ECTs, low octane, etc. It occurs when the spark ignited flame front compresses the reaming air fuel mixture till it reaches critical temperature and pressure to auto ignite the mixture on the other side of the cylinder. The two flame fronts then collide with a giant explosion causing the audible knock sound. The cylinder temperatures and pressures increase drastically beyond the normal combustion temperatures and pressures causing burned holes in the pistons, bent or broken rods, damaged crankshaft bearings, and complete and total destruction.



Pre-ignition occurs when the mixture ignites on some hot spot (spark electrode, spark plug threads, a sharp point, carbon build up, etc) before, or at the same time the spark fires. The flame fronts do not always collide, the destruction comes from extended burn time in the cylinder. Pre-ignition does not produce the classic knock or ping, more of a dull thud, but it is often caused by detonation and therefore associated with the pinging sound. Pre-ignition is more dangerous than detonation because it occurs earlier in the engine cycle causing more temperature build up due to the extended burn times. It can also cause “runaway advance” where the hot spot gets continually hotter causing the explosion to occur earlier and earlier in the engine cycle. It can also be caused by detonation events heating up a hot spot to the point where the detonation then turns into pre-ignition to cause some serious destruction. This is why its very important to get off the gas when you hear or feel anything “funny” at WOT.



Detonation is affected by many things including ECT, IAT, octane, timing, compression ratio (or boost), RPMs, and AF. Increased coolant temps or air intake temps will increase the chances of detonation. Too much advance can also cause detonation resulting from increased burn times. Too much compression will cause detonation that can be eliminated with increased octane or in the case of forced induction by lowering the boost and or intake air temps. Octane is the easiest factor to control detonation. Octane is the fuels resistance to auto ignition (detonation and pre ignition). Sufficient octane will solve nearly all minor detonation problems. High octane fuel burns slower than low octane, and high octane is much more resistant to higher pressures and temperatures. Engines are much more prone to detonation while “lugging” when at high loads and low RPMs. This is mostly due to the extended burn times at low rpms and usually a motor will not detonate under the exact same conditions, but with a higher RPM. Lean AFR mixtures are also very prone to detonation and rich mixtures can sufficiently cool the cylinder to reduce or eliminate detonation. A motor might run great at 11.5:1 and detonate like crazy at 12.5:1 on the same octane. The goal to eliminating all detonation is to keep things cool and use sufficient octane for your appropriate boost and timing requirements. Water methanol injection can drastically reduce detonation by cooling the chamber as well as adding octane. Methanol has a pump octane rating around 100. The formula for calculating your octane level when mixing gas is:

[(Volume 1 * Octane 1) + (Volume 2 * Octane 2)] / (Volume 1 + Volume 2)



Volumes must have the same units such as gallons. Example: Mixing 7 gal of 91 octane with 3 of 100.

[(7*91)+(3*100)]/10=93.7
That is an awesome explanation!!!!!! thanks
mygt500 is offline  
Old 09-23-2009, 02:25 AM
  #8  
Jersey Stang
2nd Gear Member
 
Jersey Stang's Avatar
 
Join Date: Jan 2008
Location: NJ
Posts: 401
Default

Originally Posted by shanec
Is there a SCT parameter I could log that would indicate detonation or pre-ignition?
Yup, I don't remember with PID's they are exactly but you can monitor each cylinder seperately for pinging and timing
Jersey Stang is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
BOB ROME
5.0L (1979-1995) Mustang
3
07-26-2023 01:54 PM
lincolnshibuya
V6 (1994-2004) Mustangs
9
12-08-2015 04:37 PM
firehorse02
Archive - Parts For Sale
1
11-16-2015 11:28 AM
Dathan
V6 (1994-2004) Mustangs
4
10-05-2015 05:52 AM
breaking
Audio/Visual Electronics
5
10-02-2015 01:27 PM



Quick Reply: spark plug blowout?



All times are GMT -5. The time now is 08:53 PM.