Spark blowout? Short log within.

[yetterben]

Here is a short log. Basically when i go wot i get a small stutter around 3-4 grand. Rpm goes up 400 down 50 in the log in some spots. Can anyone verify? its a pretty short log few minutes at most. Thanks guys.

datalog201004111648.rar

Edited May 27, 2010 by yetterben

[cygnusx1]

Ben, can it be some bounce in the dizzy shaft? Does it smooth out if you stay WOT? Might try damping the rpm signal in general setup in megatune. Lower the number. Try around 50 or less to test the theory.

[yetterben]

Running fuel only. Nah its not the dizzy shaft as i pulled it out to check when i dropped in my new dizzy. It does not smooth out unless i back off the throttle a hair. say to 85% or so.

 

Using a zx dizzy locked at 18 total advance. Flamethrower coil. Plugs gaped to .020. Can't gap any smaller without a way to measure. Running br7es. Was gonna try the protruded plug to see if it makes a difference.

Edited May 27, 2010 by yetterben

[yetterben]

gaped them down to .015 and issue is gone.

[cygnusx1]

Time for BIG sparks that you can map!

[yetterben]

After i have faith in my fuel setup i will go spark as well.

Edited May 27, 2010 by yetterben

[yetterben]

welp ran good for about a hour. till it barfed oil out the vents motor is on floor waiting to be cracked open.

[cygnusx1]

ouch, detonation???

[yetterben]

no clue like a gun shot....if yah hear it...youre not dead. I heard notta

[Noddle]

I though I might add to this, since I had this problem after moving my engine form one car ( 4 door) to my coupe,

 

short story,

specs

L24, 440 cc injectors, Megasquirt (MSExtra), EDIS, Intercooled, 3 inch exhaust.

 

before I removed the engine from my 4 door, I recreated the engine harness, plugged it in to test, all worked fine, then I removed the engine from my 4 door, this sat in my shed for about 5 months while the weather cleared up,

 

once the weather got better, I moved it to my coupe, with some changes to the waste-gate, went from internal to external, (went from 15 psi to 7 psi for now)

 

fired it up and had some plugs fouled on me, so I cleaned them,

 

I had problem of the engine cutting when coming on boost, AFR went learn, it would pop and fart, took my foot of the throttle , dropped under boost, then it all ran normal, I could lightly run the engine up to high revs, but once boost came on, it died, like hitting a wall.

 

so I did a heap of searching on this site, and came across this post, I changed the gap on my plugs from 0.7mm (0.28) to about 0.5mm (0.20), and this made it run up to about 4 - 5 psi before the problem came back,

 

I put new plugs in it, and that fixed my problem, not sure why it played up, since it was running fine in my other car.

 

I should have know better, I have seen spark blow-out on a old spark-plug clearer when I was younger (it was a nice bit of gear)

 

Hopefully this may help someone else who has this type of problem.

 

Nigel

[mobythevan]

We had a lot of problems with NGK plugs in our talons under boost. I just went to autolites and never looked back. They create a much wider/larger spark between the electrodes, yeah the trade off is that they eat themselves up faster, but it has fixed all of our spark blowout. We still gap them down, but over several different applications under boost I like the autolites (I know, flame away .

[BLOZ UP]

Or those stupid Bosch platinum plugs, I've only known of one turbo car that those actually work well in.