Okay so heres the deal my car misses and pops at WOT 5800-6100rpms. It has been doing this every now and then but it has been pretty sporatic. But now its doing it every time since i went to the track last night. It does it worse in 1st and 2nd than in 3rd and 4th but it does in in all 4 for sure every time now... NOW, everything and i mean EVERYTHING in the ignition has been replaced within the last year because it was like a dominoe effect not too long ago. The only thing in the ignition that is semi old are the wires(taylor 8mm street wires) which are 3-4 years old. Also i have had the hotcam kit in the car for a couple of years so maybe the LT4 springs are getting worn out and causing valve float?? Maybe that would make sense because the LT4 springs are rated at .525 and thats what the lift is on the hotcam... Lastly I am still on stock injectors and stock fuel pump so maybe that is what it is... I am getting NO CODES on the LT1 SCANMASTER so I think we can all rule out the opti... Plus it is less than a year old. So I know this is really hard to track down but I have put sooooo much money into this car and I feel like it NEVER works correctly for any period of time. But in poker terms I am "commited to the pot" by now so any help is much appreciated... Sorry so long.

Chris

 

Do u hear valve float? Have you checked your fuel pressure in wot? What's your duty cycle at?
(assuming 12% loss M6):371*.12=45
(flywheel hp):371+45=416
(hp*bsfc/#of cylinders*flow rate lbs/hr= duty cycle):416*.5/(8*24)=108% duty cycle!!!

note to self don't do calculations when tired!
-b

 

Honestly I don't know the sound between valve float and detonation.... I just know that my car is missing in the high rpm's..... So i guess what I am asking is this.... If I am in fact maxing out my current fuel situation, if I go with the Racetronix setup, should i go with OEM replacement injectors or go with higher pound aftermarket ones? If I have to get the car tuned then so be it...

 

My car started doing that last week, and it got worse and worse until it was misfirning at pretty much all RPM's and loads. Turns out my Mallory 685 was toast. I plugged in the bypass connector and my car has ran flawlessly for the last four days.

 

Does it sound more like a rev-limiter hitting or a popping out the exhaust? I had a miss at 5800-6000 that felt like I was hitting the rev-limiter. I replaced the coil and battery and the problem's fixed. Now I just have valvefloat at 6300+rpms, which I knew I would have since I'm running the CC612 springs with my XE230/236 cam.

 

Mine had a terrible miss up high, turned out to be my fuel pump. Check fuel pressure.

 

Whats a mallory 685??

And I have a new coil and battery....So it looks like all signs point to fuel pump...

 

You shouldn't have valve float with the 612s and that cam. I have the same setup, except I'm running a 233/239. No float till 6800, the highest it was reved.

5800-6000 sounds like the opti to me, but it may be some other ignition related component like a coil.

 

It's an ignition box, like an MSD or Crane. I didn't know if you had one or not, so I thought I'd throw it out there.

 

Check your fuel pressure, mine would miss up top because it was slowly going bad. WOT (w/vacum line off) should be around 43. Mine was reading 38 when i started having problems.

 

RACETRONIX FUEL SYSTEM
Full Plug & Play weatherproof harness - no cutting / splicing required - Boosts pump performance by as much as 25%.

High-Pressure 255L/Hr integral Walbro pump - supports high horsepower levels easily
All components come pre-assembled
Stainless steel hardware
Installation hardware
Instructions included (on some kits)
Harness is performance upgrade ready!

Ordered! Hopefully that is the problem but if not.....My old fuel pump is goin on 11 years anyways so I'll look at it as preventative maintenance