ok my car evolve a high rpm miss few months back, and it does it around 5000 or so. i have had about everything we can think of replace. it has a new fuel racetronix system 255 walbro, and on the dyno A/F stay perfect all the way threw the missing up to the rev limiter. have tried all diff coils, new plugs, new plug wires, it has new valve springs,has new cam and crank sensor, alternator replaced today with a higher out put one. has all new tenisors and belts. even had the engine wiring harness replaced. it only does the miss sometimes one day it might do it all day next want do it any. i had the alt replace today cause the voltage gauge wants to jump from 11 or so up to 14.5 volts. and we checked it from the battery same thing. with the car in netural and the E brake up it reads bout 14.5 and when u let it down it read little over 13 volts. i dont know if that has anything to do with it or not. but i dont know what else to check. i have 2 computers to one tuned for 250 shot and one tuned for 150. acts the same either way. ... PLEASE HELP ME!!!! I believe it is something electrical not a fuel issue.. But it did first when i came back from goin to get it tuned the first time and couldnt because it was running out of fuel. so we replace the pump and has new 42lb injectors to.... sorry for all the bad typing LOL

 

Anyone?

 

what plugs are you running and whats your compression ratio?

 

Why are we guessing, rather than discussing scan results such
as knock detects?

Don't tell me you don't have the tools, when you throw all that
money trying random parts and anybody's software will let you
scan for the borrowing.

 

Sometimes it misses and sometimes it doesn't......

Loose PCM to engine-block ground wire.....check it.

And of course, the old age problem with missing like that....make sure no spark plug wires are touching the exhaust manifold piping...AT ALL.

.

 

I have log it and logged it. Seems to be the wire on the ALT that tells it when to charge. I'm check to see if ts gettn the constant 5 volts to it and go from there and I'll check the ground wire from the PCM to. Where it's located at?

 

But you don't tell us a thing, about what you see in the logs.

 

It hasn't showed nothing in them. And I don't have the logs myself. I'm call and see if he can send them to me

 

What mods...?

 

408 stroker,5.3 prc stage 2.5 heads42 pb injectors, 85mm maf,Taylor 10.5 wires , racetronic hot wire kitand walbro 255 pump and lower pulley and nitrous

 

AnyOne. I think it's losing voltage somewhere and something is breaking down

 

Might be losing CKP signal.

 

everytime i had a miss it was the plug wires. and when i used Taylors which was twice It developed a miss within a month and not a thing was touching the headers. Just my experience. MSD Wires solved that problem

 

just took msd wires off lol and replaced them with taylor, cause it was doin it im try another new CKP sensor

 

when my sensor the Crank postion Sensor went it just plain quit on me.

 

Don't just try another CKP sensor... have a look at the 3 wires and the connector... are the pins not making good contact, are the wires ok.

 

If the scan data is inconclusive...CKP errors usually show up as RPM data inconsistency, jumping around...I'd pull the valvesprings and have them verified on a spring dyno at **BOTH** installed height and max lift height.

I always dyno new valvesprings prior to installation and occasionally find 1-2 springs in a set yielding low pressure relative to the rest of the set.