290 mcx apex misses at full throttle.

[sebastien]

I did a full season last year with no issue and the only thing i change this year is a hallman boost controler. I check the injectors by adding pressure in mcx ecu, i did a leak test, change plugs with a 0.20 gap and check my fuel pump pressur and everything is OK. So what is next...it only misse at full throttle.

 

[DooAssassin]

Try going to .18 I had the same problem and .20 just wouldn't cut it.

 

[yooper1]

I agree, check you gap and lower it. At times a lot of boost will "blow the spark" out.

 

[sebastien]

Stock gap is 0.28 and i lower it to 0.2. Do you think that there is enough difference between 0.18 and 0.20? I ran a full year at 0.28 and was fine. I will try 0.18, dont know what else to chek.

Thanks,

 

[mbarryracing]

What plug part number are you running?

 

[sebastien]

Stock plug...CR9EB.
It's only doing it at full throttle no matter what boost. If i lower the boost with controler it will misse just after 10 pounds (WOT) and if i raise it, i can run up to 14 pouds as long as i'm not WOT.

 

[DooAssassin]

As you are increasing the the boost the spark is being blown out. I had blow out at .20 and was in disbelief when I regaped to .18 and it stoped missing. Make sure its really .18 too, when you gap you should feel alittle restriction when passing the gapping tool threw. Ither way its a spark issue from the way you are explaining it, so start with that.

 

[mbarryracing]

X2

 

[sebastien]

Thanks....will try that.

 

[TT]

If spark plug gap isnnot the problem, double check your vacum hoses on the boost controler. If routed wrong the Hallman will give you "unlimited" boost and you will hit the rev limiter ;-)

 

[DooAssassin]

is t going pop pop or more of a thud thud noise. Pop pop is rev limiter. lol And BTW the apex rpm gauge dosint keep up with the true rpm as it increases . ITs alittle delayed.

 

[sebastien]

I found my problem today....it was bad fuel. I stop at a different gas station last time. Got the tank empty and put new gas and there you go, was working like new.

Tank you for all your help.

 

[helmic]

boost

Your welcome...