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Amazing what opening the plug gap can do

S

SicSE

Veteran CEG'er
Joined
Sep 7, 2007
Messages
889
Location
Kennesaw, GA
Pics pretty much speak for themselves. Gap is in inches, I just shortened .051" & .060" to, 51 & 60.

Gapcomparison.jpg


Gapcomparison2.jpg
 
What's the 5300 / 5500? Almost looks like inverted secondaries (like they're closing) then.
 
Striker's right. I put it in the title so I can know at a glance where it happened. This way, it's easier to pick similar runs to compare.
 
Great numbers. I did see a comparison dyno on a 1999 cobra with a spark plug gap adjustment. They netted 5-6hp from the increase. I just thought it was a change between each run on the dyno:shrug:

Some % error plays a role, but it seems even if there is an error you showed atleast a few ponies that would be a consistent gain if you did this repeatedly.

Good job man.
 
The reason you picked up more power is your gap made a hotter burn because your car is runnig pig rich so you are able to burn more fuel to see results. If you tune the car and lean it out you can pick up the power you are losing bigtime. joey
 
BurritaSVT said:
The reason you picked up more power is your gap made a hotter burn because your car is runnig pig rich so you are able to burn more fuel to see results. If you tune the car and lean it out you can pick up the power you are losing bigtime. joey
Click to expand...

thats what i was starting to think.
 
BurritaSVT said:
because your car is runnig pig rich so you are able to burn more fuel to see results.
Click to expand...
My full-rich condition is not "enabling me to burn more fuel". My A/F goes full-rich when the PCM sees the problem and from that point on, power drops dramatically. The power gains shown are mostly from the increased gap, (bigger spark = bigger bang), and possibly some IAT influence.

BurritaSVT said:
If you tune the car and lean it out you can pick up the power you are losing bigtime. joey
Click to expand...
No doubt... though that may not fix the fault that is causing the full-rich condition. Which would put me back at square one.
 
SicSE said:
My full-rich condition is not "enabling me to burn more fuel". My A/F goes full-rich when the PCM sees the problem and from that point on, power drops dramatically. The power gains shown are mostly from the increased gap, (bigger spark = bigger bang), and possibly some IAT influence.


No doubt... though that may not fix the fault that is causing the full-rich condition. Which would put me back at square one.
Click to expand...


bigger spark means less time from spark to ignition. the power your picking up is because of that time difference. when the PCM stops advancing the ignition, the larger gap makes up for it slightly, giving you more power.

the fault thats causeing your full rich condition is your untuned SE PCM with a 3L. you need to get it tuned before you damage the internals.
 
good call striker. i'd be worried about washing down your cylinders,we all know duratecs can be bearing eaters,no need to help the cause
 
striker2 said:
bigger spark means less time from spark to ignition. the power your picking up is because of that time difference. when the PCM stops advancing the ignition, the larger gap makes up for it slightly, giving you more power.
Click to expand...
A larger spark helps creat a larger flame-front, therefor better burn... it's nothing to do with time - electrons travel at nearly the speed of light so time is not an issue with spark.

striker2 said:
the fault thats causeing your full rich condition is your untuned SE PCM with a 3L. you need to get it tuned before you damage the internals.
Click to expand...
Okay, so let's debate. A few questions about your idea of the cause here;
If it's just the PCM programming, why does it happen at different times on different runs?
Why is full-rich initiated at different RPM's, vehicle speed, MAF voltage, barometric pressure, IAT's, and ECT's?
What would be the logic behind programming a PCM to randomly initiate dumping as much fuel as the system could squirt out?

Fact is that no one has proven one way or another, exactly what causes SE PCM's to do this on 3L swaps.

IMO, a fault of some sort, (most likely detonation), is the root cause, NOT the PCM or prgramming contained therein. Support of this theory is witnessed by the drop in power just before the onset of the full-rich condition. The PCM sees the fault and initiates the full-rich fuel strategy to protect the engine from damage. This theory steps right in line with PCM programming and engine control strategy. Whereas the "PCM is the root cause" theory does not have any supporting data, and does not fit in with PCM programming and engine control strategy.
 
SicSE said:
A larger spark helps creat a larger flame-front, therefor better burn... it's nothing to do with time - electrons travel at nearly the speed of light so time is not an issue with spark.
Click to expand...
you dont get a flame front until the initial ignition reaches a certain size (.100 IIRC) the larger gap means its already closer to that size, thus the time to flame front is reduced by a few milliseconds (which is all a few degrees of timing will change it anyways)

Okay, so let's debate. A few questions about your idea of the cause here;
If it's just the PCM programming, why does it happen at different times on different runs?
Why is full-rich initiated at different RPM's, vehicle speed, MAF voltage, barometric pressure, IAT's, and ECT's?
What would be the logic behind programming a PCM to randomly initiate dumping as much fuel as the system could squirt out?

Fact is that no one has proven one way or another, exactly what causes SE PCM's to do this on 3L swaps.

IMO, a fault of some sort, (most likely detonation), is the root cause, NOT the PCM or prgramming contained therein. Support of this theory is witnessed by the drop in power just before the onset of the full-rich condition. The PCM sees the fault and initiates the full-rich fuel strategy to protect the engine from damage. This theory steps right in line with PCM programming and engine control strategy. Whereas the "PCM is the root cause" theory does not have any supporting data, and does not fit in with PCM programming and engine control strategy.
Click to expand...


its not randomly dumping fuel, its adding fuel becuase it likely sees knock. IIRC on each of the 3 runs you posted before the full rich came earlier on each succeding run. it did this because the cylinder temps were getting hotter on each run, likely due to detonation.

If there really is nothing wrong with the engine, since you cant seem to pinpoint anything, then the stock PCM strategy is the cause of the problem.

since you still think there is something wrong and its not caused by the PCM, read through this and check/double check everything.

what plugs are you running? what octane fuel? what are the specs of your 3L hybrid? it could be that you upped the compression to much for the SE PCM to handle without detonation occuring.
 
striker2 said:
it did this because the cylinder temps were getting hotter on each run, likely due to detonation.
Click to expand...
Agreed. I've bought into the detonation theory... but buying into it & proving it are different animals. I'm going to be experimenting with the knock sensor this upcoming week or weekend. I'm going to prove or disprove this if it kills me.

striker2 said:
what plugs are you running? what octane fuel?
Click to expand...
I'm running 1 step colder plug. I wasn't getting a very "happy" idle with the plug that's 2 steps colder, PLUS the problem still occured.
It's seen nothing but premium since the swap.

striker2 said:
it could be that you upped the compression to much for the SE PCM to handle without detonation occuring.
Click to expand...
That's a sad prospect for me, but one that's definitely to be considered. Worst part is... it's probably true. :blackeye:
 
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