PREMIX High RPM bog/grind - (not your average "help me" thread)
 

So I just recently gutted my cat (was horribly clogged), and also replaced coils/plugs/wires/battery because my car had gotten really sluggish in higher rpms (when engine is warm) and extremely hard to hot start.

To make a long story short:

Gutted cat and drove home (seemed to have more power).

Wouldnt start the next morning.

Ordered plugs/wires/coils. Bought battery.

Changed p/w/c/b. (there was fuel sitting in the old plug/chamber)(badly flooded)

Had my dad pull start behind his truck, cause it was easier than doing the de-flood method.

Drove car awhile but once the engine warmed up it would start losing power above 5500 and start that grinding/puttering sound, also above 5500.

Read around the forums a bit, read almost the whole Oil/Fuel Premix thread and decided to try it, thinking maybe the OMS wasnt functioning correctly, or just simply not enough.

Filled up today with 93 and premixed 5ozs of Lucas 2stroke Semi-Syn and WOW. :Eyecrazy:

So my final question is,

Would premixing really have made THAT much difference??? I mean the car seems to have more power than its ever had...maybe its psycological.... :squint:

Premix has nothing to do with power.
However, you could be experiencing low compression, and the premix help to "seal" it a bit. It's a temporary fix. Have you had your engine tested? Are all of your plugs/coils connected properly/ in correct order?
Are you getting any CEL's?

Yes I doubt it's the premix, you could have also just cleared up the cobb webbs. But just drive it a bit and see how it goes. With a clogged cat the damage could have already been done. Only time will tell. I would also reset your sensor profiles (brake stomp method).

I agree with you both. I just couldnt imagine how premixing would have made this much of a difference. I am still getting a CEL, but I'm guessing that its because of gutting the cat. Im going to get codes pulled this weekend so Ill have a little more info.

I reset the fuel trim (brake stomp) last night also. Maybe this cleared things up.

Drove it more tonight (about 20 miles), got to normal operating temp and its still running very well. Pulling very hard and Im not getting that terrible grinding/sputtering at high rpms.

Im hopeful thats it not compression, but I'll probably go ahead and have it tested after I pull codes.

Well if it's driving well then it's probably good to go. The CEL is likely from the Secondary O2 due to the gutted cat. But get the codes pulled just to see.

Filled up today with 93 and........

My guess (that's all we can do without a code) would be a plugged primary fuel filter.
The high rev sputter, and the total difference when you get some fuel pressure by filling up are the clues.

^That's actually what I was thinking, after re-reading the OP.

So barring the codes tell a different story, I should look into replacing the fuel filter? Or would it be ok now?

This actual makes me feel a heck of alot better that its not the dreaded "C" word.....

Updates OP?