69-chvl

iTrader: (11)

Continuing to shake the bugs out of the new build...

Running ~12psi at the moment, and getting what I'm pretty sure is spark-blow out. Engine popping and farting at WOT. I did have it initially, then I regapped the plugs to .027 from .035 (TR6's) which temp cured it, but it came back. Based on my searches I shouldnt be having this issue with low boost. Can meth injection (too much) cause this? Right now at max boost I have the meth contributing 10-12% of total fuel flow at max boost (Holley meth system, twin 1000cc nozzles).

Or, maybe this engine just wants .022-.024 or less gap???

denmah

iTrader: (2)

i gap right to 22 with a tr6

denmah

iTrader: (2)

if you have fresh plugs in, brand new, and your are still getting blowout in boost

you might have a weak coil or two

69-chvl

iTrader: (11)

They may of had 50 miles on them, maybe less. How can I test the coils - ohm them out? They may not work good when hot though. Guess I could swap them out - easy enough.

stevieturbo

What coils are you using ?

All LS coils are very powerful, so spark blowout due to lack of spark power is highly unlikely.



And yes too much meth could cause issues...as could too much fuel, too little timing etc etc

You make no mention of the actual state of the tune.

But 2 x 1000cc meth nozzles if actually spraying a lot...is a hell of a lot of methanol. Like massive amounts, probably about 5x as much as you could possibly need at 12psi

unnatrl

iTrader: (1)

Is this a Holley EFI system? If so, the early ones were known to have issues with spark blowing out under boost. Research the serial #, it's easy to find out if you have a problematic unit.

69-chvl

iTrader: (11)

Hey Steve,

These are just the stock coils that came with the engine (2002 5.3 truck, non-heat sink). Also using NGK wires with the TR6's.

State of tune = we'll, running 11.5 afr WOT and 12*. Runs awesome otherwise.

As far as the meth, its progressive and at 12psi its only contributing 8%.

ajrothm

Try the NGK BR7EF non protruding tip plugs, get them at O Reilys auto for $2 each. They come pre gapped around .026".. I tighten em up to .022". Never had a spark blow out problem.... And get less heat in the tip like a long tip plug like a TR6.

69-chvl

iTrader: (11)

That's where I'm leaning towards Alan

69-chvl

iTrader: (11)

Fortunately this is a new unit direct from the factory, so were good there.

Although, I'm using the chassis for ground with the engine, ECU is tied to the battery. May not be a bad idea to run a ground from the engine to the battery...easy enough to do. Those LS coils like a good ground...I found out the hard way before.

unnatrl

iTrader: (1)

Mine HP EFI is batty to body (batty in trunk), body to block, grounds in harness go to rear of each cylinder head. Power and ground to computer are directly to battery. No issues with 2004 LS1 GTO coils at ~11psi.

69-chvl

iTrader: (11)

Exactly how I'm wired

HRD

iTrader: (1)

Try it without the meth. At that boost level you should be safe. I'm running no meth 16psi, 14* with 93 octane and have no issues. Stock truck coils. 5.3L

Wicked69

It's both, not tight enough gap and too much meth at that low boost. .022 and one nozzle will be more than enough.

soundengineer

iTrader: (16)

make sure you have a resistor plug....
if you dont, you will have issues...
LS coils dont like non resistor plugs, and teh Holley ECU doesnt like non resistor plugs

I've many times solved issues like you are having just by putting in a resistor plug.


at 12 psi, a plug with a heat range 6 should be fine
get something non protruded tip and it will help as well
Br6ef or BR7ef

you also need a ground from the engine directly to the battery, the chassis is a dirty ground and can cause some issues
there is also a Holley Ignition ground that needs to connect to the engine
the main power/ground should go straight to the batter, or straight to your shut off switch/battery.

RonSSNova

iTrader: (3)

TR6 is a resistor plug

69-chvl

iTrader: (11)

Only other thing I can think of is that I just changed brands/type of meth...I threw the bottle out, but it said something like "-127*, windshield de-icer" and its purple. Not sure it makes a difference.

Going to rain today unfortunately so I'm not sure I can get out. But first thing will be to run a temp ground, then turn meth off, and finally tighten gap/replace plugs.

I also wonder if the 13:1 AFR idle is sooting up the plugs, but this is where I get the best idle and vacuum #'s. Oddly, 13:1 would of sooted-up the plugs in my BBC.

stevieturbo

Does it have a big cam, or is there any reason to run so rich at idle ? I doubt it would foul, but still seems excessive...but I can understand it probably feels like a very strong idle like that.

If battery is in the trunk, a cable direct from battery to block is less likely. It's still nice to have though.

IMO ground coils local to the coils on the head/block. Ensure block etc has a substantial ground, even if it is via the chassis. Bare metal surfaces and all that.

If your "methanol" has lots of water in it, then this could easily cause problems when spraying a lot.

At 12psi do you even need the meth ? Is it standard high CR ?

69-chvl

iTrader: (11)

Yeah it just likes it rich at idle, and I played with various afrs and timing figures and settled on 13:1 and 22*. Just a stock 5.3 and a ls6 cam. I will try and lean it some more. But I do have a separate grd wire to each head b/c I was chasing a misfire early on.

I was planning on running ~17psi on track days so I figured the meth was a good idea. Probably right though that it's not needed at this level and considering that there really isn't any sustainable wot around here.

RonSSNova

iTrader: (3)

I grounded the block to the chassis with a chunk of 1ga batt cable. Welded a 3/8" bolt upside down to the frame.
You really can't go overkill on grounds.

I guess I'll find out about TR6 plugs gapped at .035" and 14 psi on Sat. :-)

Ron