Ok, help me figure out this "miss"

[Anonymous_User]

I think I'm finally getting to a point where I can start saying the car is running pretty good, but I've got a high rpm under load miss kind of thing going on.

Today I put in a new set of Autolite 64's gapped at .025. I knew I had a bad plug and have just been taking it easy for a while. This made a helluva improvement.

1st gear - unusable
Grab 2nd - tires roasting wraps to 5000 pretty damn quick.
Grab 3rd - little tire chirping as the rpm climbs at about 3500 -4000 it starts to buck

4th and 5th act the same as 3rd only progressively worse.

Cruising at highway speeds in 5th, about 2700 rpm, I'm seeing 1350-1400* EGT and a nice bouncy A/F gauge. Punch it and the EGT drops to about 1100*, the A/F goes full rich, and then about 3500-4000 rpm the engine starts to miss bad and I start getting a CEL on Knock.

Right now I'm running the regular Blueberry scaled to +40's. I'm thinking:

1.) EGT at WOT is low. Take some fuel out of the WOT curve

2.) CEL on Knock and bucking might be too much ignition timing under boost?

Any other ideas appreciated.

[turbovanman²]

It could be your misfiring due to it being rich. What kind of spark advance did you program. I noticed when I ping, it miss's a bit.
How is the coil, cap and wires? Do you have the wires pushed all the way down?

[Anonymous_User]

Coil, cap, wires are all brand new, good stuff. All parts installed correctly (even with dielectric grease in the boots).

Hmm... If extra rich could cause it... but it's not like smoking rich.

[Anonymous_User]

OK, it is deteriorating. Now it does it in all gears. I can run up to redline as long as I don't boost above 15-16. At 15-16 at any RPM it stumbles REAL bad.

Weird 'cause I thought it was a failing spark plug. Put in new plugs and it ran good for a few miles. Now it is back to running bad.

I guess it's time to replace the cap/rotor/wires AGAIN.

[cordes]

What do you have your plugs gapped at?

[turbovanman²]

OK, it is deteriorating. Now it does it in all gears. I can run up to redline as long as I don't boost above 15-16. At 15-16 at any RPM it stumbles REAL bad.

Weird 'cause I thought it was a failing spark plug. Put in new plugs and it ran good for a few miles. Now it is back to running bad.

I guess it's time to replace the cap/rotor/wires AGAIN.

What kind of wires are you running? Anything other than Aurora is shitt.

[Anonymous_User]

Plugs gapped at .025

Wires - well I was running some junk parts store brand wires. Then I switched to some nice red wires I got in a box of misc. stuff I bought from someone. I don't recall the brand.

Saturday I said everything was new, but I forgot that the plug wires are actually unknown since I didn't personally purchase them new.

I just ordered a set of Magnacore wires.

[mw6886]

Fuel pump.

[BIGBRUDDA]

The problem is AUTOLITE plugs:nod: Ditch-um ,get Champion or better yet NGKs:amen:

[turbovanman²]

Nothing wrong with Autolites, used them with no issues. :nod:

[Anonymous_User]

I've used champions and autolites with no noticeable difference. I have run autolites in everything for years.

Today it didn't do on the way home from work. Hmmm.....

Well, hopefully the new plug wires will fix it for good.

[TurboBuggy]

up your overboost cut and see if that changes anything, it almost sounds like overboost cut. In a cal I did for my car I set the overboost to 24psi and for some reason I got cut at like 16psi, raised it to 27psi and the cut went away

[turbovanman²]

up your overboost cut and see if that changes anything, it almost sounds like overboost cut. In a cal I did for my car I set the overboost to 24psi and for some reason I got cut at like 16psi, raised it to 27psi and the cut went away


Overboost cutout isn't a miss, its like your head hits a brick wall, :banghead: :lol:

[amcpacer]

It sounds like a wiring problem. Perhaps when you get up to speed on the highway there is lots of turbulence in the engine compartment. Perhaps the wire to the hall effect sensor is swaying in the breeze and making the engine stumble badly.

[mech1nxh]

OK, it is deteriorating. Now it does it in all gears. I can run up to redline as long as I don't boost above 15-16. At 15-16 at any RPM it stumbles REAL bad.

Weird 'cause I thought it was a failing spark plug. Put in new plugs and it ran good for a few miles. Now it is back to running bad.

I guess it's time to replace the cap/rotor/wires AGAIN.

do you have access to an old analog scope? ck the ign sec voltage
doing a "snap wot test"...<40k...weak coil (this based on the assumption
supply voltage/chg syst is pristeen)