crazy missfire under boost

[boostcrazyawd]

the problem is that my car is missfiring like crazy when under boost, no boost leaks, brand new ecu, and iam gonna put some new plugs in it tonite and check out the plug wires for arc holes. is there anything else i should look for?
another problem i am having is when my car has sat overnite when i go to start the car it will start then stumble and die, this happens a few times until it kinda warms up then it seems to run fine with the exception of stupid idle surge

 

[yekrahs]

I had the exact same problem as you. I bought new brp6es's and it did the same thing, then I tried some 8ES's and the studdering stopped. I'm running 25psi so buy according to what your running but sounds like plugs.

 

[boostcrazyawd]

hmm i bought some more 6es's but if that doesnt change then ill try the 8's

 

[yekrahs]

well I'm not saying go directly to 8's becuase 7's should be sufficient for most applications, but I'm on a 72trim and runnig 25 psi of boost so I need a lot more spark than a 16g on say 19 or 20psi needs.

 

[Quasimondo]

If your car has problems starting when cold, you should look into replacing your ECU coolant temp sensor.

How much boost are you running when your engine misfires? Did you check to see if they were gapped properly?

I would go with BPR7ES instead of 8ES. If the spark plug is too cold, it can't burn off the combustion deposits effectively and that can lead to misfires.

 

[boostcrazyawd]

it missfires at boost over 10 psi i run 18 max boost, yea ill take a look at that temp sensor i blew my upper rad hose and ever since that it has been doin that cold start problem so maybe the connecter is crudded up. .28 is the correct gap correct? i am gonna put the new plugs in tomarow and ill come back with the resaults

 

[boostcrazyawd]

well its all fixed now put some new taylor wires and new plugs and runs awsome, and as for teh starting problem one of the wires on the coolent temp sender was broke off, put a new end on it and starts perfect and no more idle surge!!!! thanks for all your help everyone i would of never guessed that sensor could of caused that