Loud pop from under the hood

[Bens87tr]

Just installed the 2 nozzle SMC and Bstc (Thanks a bunch SalvageV6 !!!!!!!!!!!). Here's my problem: On occasion the car will mis/backfire under WOT. Boost drops and then rises again really slowing the car down. The sound is horrible when it happens.My setup:

FP 45 line off
trans + set to 2% rich at WOT, +4 degrees timing at WOT = 23/21
boost 24# alky on at 14#
pump speed 8
60/40 alky to water mix
no knock on scanmaster when it happens O2s in the 750 range
Car pulls like a bastard when it doesn't happen

Can this do damage to the car? Any suggestions to make it go away? Plugs are the 43s standard gap.

Any help would be greatly appreciated.

 

[alkyboost]

gap plugs to 035.
same problem till i did it.
if u missfire under load, remember the coil fires on exhaust stroke also.
the slow return to power is probably from flooding.
also, 60/40 is a lot of water.

 

[salvageV6]

Hey Ben, sign up for race day and I can check your coil pack with the Caspers tester.

I'd gap at .034 or so if you have a good gap tool.

Check your wires as well for good contact to the coil and plugs.

Never had the pop problem with alky.

 

[blackbuick87]

When was the last time the car was run at high boost on race gas?

 

[Bens87tr]

I last ran at high boost at the track at the GMHTP shootout in July. Actually, I was having miss problems on that last run there, but no popping like I have now. Plugs have since been changed. Coil pack was new at the beginning of this season. Wires have 3 years on them and about 10K. Hmm..........

 

[blackbuick87]

Thats the same problem I had, ignition couldn't handle high boost. After changing everything it ended up being the module.

You can try closing the gap to .030. It might make the car idle rougher, but see if it helps the top end. Then you know its ignition related

 

[salvageV6]

Ben I'll bring the Caspers tester raceday.

Might want to check the wires if you have a good ohmmeter.

I've got a spare module but never tested it, (used).

Spare coil pack too.

If you have spare ign. parts swap them out one at a time.

 

[Bens87tr]

Al,

Burkhart has a coil tester so hopefully I'll test it before Wed. I just ordered some wires from Red today. Plugs are almost new and coil pack was replaced right before dyno day. I'm going to look into buying a Delco module tomorrow. Big bucks I know, but I've already gone this far and that's the last piece of the puzzle. So you guys are pretty convinced it's the ignition, right? I hope you're right because my wallet is taking a beating trying to get ready to race. Thanks for all of your suggestions.

 

[salvageV6]

Ben, don't buy the module until you use the Caspers tester on it.

Unless you really want a spare, not a bad thing just $$$.

You could double check the cam sensor operation and install....

 

[blackbuick87]

Since Salvage has a tester try that first. Could also be an O2 sensor among other things.

 

[DMan]

Ben,

This sounds like the same problem I was having. For me, it turned out to simply be a corroded plug wire contact.

I highly recommend you borrow a buddies wires and try them out.

And contrary to an earlier post on this thread, 60/40 is not a lot of water. Myself and others run 50/50 with no issues.

Denis

ps - we're going to NED tomorrow. C'mon up. Bring Joe.

 

[Bens87tr]

Doh... Can't go tomorrow. Installing line lock, wheel cylinders, etc. Getting Drag radials from Cotton on Monday. Getting the 235 BFGs. Don't laugh, size isn't everything. (at leat that's what I keep telling myself). I know a lot of people will think I'm stupid for getting tires that small, but F'em, it's my car.

I got new wires on order from Red A.

 

[salvageV6]

Hey Ben, you're stoopid for buyin' such small tires.

Want me to bring up some 275/50's ???

Won't fit prolly with all my other junk in the car.

I'm sure you can smoke them up as good as any other tire.