On Boost Collapse

Is there a tell all for spark.

I think every thing is working but the car quits at 5-6 lbs.

Gapped ar 45 a little over 300 hp higher compression.

It's ongoing so any input would be appreciated.



Paul

you mean a misfire under boost? I would think you need a closer gap. I run a ngk tr6 copper plug .030 gap with my set up.

I'm not even sure what to call it.

It truely is a total collapse.

I'm thinking I have to regap to find out.

Paul

Before you yank the plugs , which is always a fun job, take a look and make sure all the plug wires are properly seated and that none of the wires have exposed wire. Check both at the plugs and on the Coil pack

loosing spark as boost comes up is an indicator of an ignition system problem. As already said check the spark plug wires. Bad insulation on one wire could easily cause the spark to jump. Check the coil and make sure it's grounded properly as well as the DIS module.

If the wires look good, it may be a cracked spark plug. You'll need to pull them to check.

Check the ground straps for the engine and all the harness wires to make sure they are not binding from the engine moving as you build power. If your motor mounts are going bad, excessive engine movement could strain a wire harness for the ignition system.

Mike8675309 said:

loosing spark as boost comes up is an indicator of an ignition system problem. As already said check the spark plug wires. Bad insulation on one wire could easily cause the spark to jump. Check the coil and make sure it's grounded properly as well as the DIS module.

If the wires look good, it may be a cracked spark plug. You'll need to pull them to check.

Check the ground straps for the engine and all the harness wires to make sure they are not binding from the engine moving as you build power. If your motor mounts are going bad, excessive engine movement could strain a wire harness for the ignition system.

Click to expand...

Mike

Motor is a yr old (4000 miles) with solid mounts.

I haven't checked the ground straps but because of the detail going into the install don't honestly suspect them.

It has historically burn't the boots off #6. I relaced that wire maybe 6 times and it is my go to check when I suspect ignition issues.

This doesn't feel like past arcing on the header.

It literally shuts down to the point where your thrown towards the steering wheel. Once I back off its starts building boost again.

I have floored it in 5th under load at 2500 rpm and do not get the collapse.

Can the knock sensor pull enough timeing to shut it down at high rpm?

Overall it is running as good as it ever has. I just can't beat on it.

Paul

If you are certain in your correlation of boost pressure and the problem the only thing can be ignition problems. That means one or more of any ignition devices including but not restricted to, plugs, plug wires, coil, dis, cam sensor, crank sensor, and wiring between any of them.

Did you check the codes yet?

Did you paint the accessory brackets?

Did you check the ground strap from the left motor mount over to the chassis?

Why gap so large?

KMT said:

Did you check the codes yet?

Did you paint the accessory brackets?

Did you check the ground strap from the left motor mount over to the chassis?

Why gap so large?

Click to expand...

It is not throwing any codes.

Keep in mind the build is a yr old and has been dyno'd at last yrs ShootOut as well as tracked.

DD pointed out the knock sensor during the dyno pulls as well as the AFR being rich at 10.0

All I have done recently is go from 73-70 CAI to 76-75. I also changed out the S Port and put on a home ported unit.

This cleared up most of the afr issues and added about 1.5 lbs of boost which is now at 12.5

As far as the gap. Stock was in the 50's and I thought 45 would be about right for the build.

I under estimated the final HP by about 40.

Paul

Got it, thanks.

Is this the issue where the tach signal drops out and comes back suddenly?

If you can't isolate an issue, I'd start reducing the gap to see if it helps at all.


Good luck and keep us posted, thanks.

Ken

Mike8675309 said:

If you are certain in your correlation of boost pressure and the problem the only thing can be ignition problems. That means one or more of any ignition devices including but not restricted to, plugs, plug wires, coil, dis, cam sensor, crank sensor, and wiring between any of them.

Click to expand...

Well I'm plucking the feathers to eat crow tonight.

Turned out problem was a bad coil.

Literally never a sign of problems unless it went into boast.

I'm safe to pass again.

Paul