Hey guys i am experiencing weird misfires. I have a fully built evo 9 with an aem ems. As far as iginition goes i am using: buschur mini-battery, hks dli2, and ngk lfr6a11 plugs. Now before we go crazy, i am also using a buschur double pumper, aquamist alcohol injection, and a few gauges hooked up to the mini battery.

My question to the community is what is average battery voltage during a single 3rd or 4th gear pull? Using aem to log, i currently see 11.15-11.30 volts throughout full boost.(42psi)

My current tune is spot on,plugs have been changed and gapped to .022. c-16 and 42psi breaks up horribly. I even went as low as 32psi and it is the same. One pull can be fine, the next breaks up, and so on.

I am going to assume everyone is telling me the hks dli2 is crap and i should get a COP which i am ready to pull the trigger and order one asap.

Thank you for everyones input, my main concern is average battery voltage with the above mods i have listed above.

 

Can not expect a good ignition with low voltage. Make sure that your alternator is working properly.

 

There is only 15,500 Miles on the alternator, its original. I have only heard of one other instance but i believe the alternator was older.

 

Can anyone give me battery voltage readings on a 650-750whp build?

 

I think the goal would be to keep battery voltage as consistent and near 14V as possible.

A local kept losing motors because of a similar issue from voltage drop. The voltage dropout would make the fuel pressure drop in an unpredictable manner and cause ignition misfires.

He finally went up to a higher current alternator and has had much more consistent results since.

 

Battery voltage should be the first thing you should look at when diagnosing that kind of problem. It looks like you have found the problem with the question in your first post. 11 V is way to low, looks like your alternator isn't even working.

 

thats a bit low, but also the aem reads the voltage about .50 lower then it actually is from what I heard. I had similar issue with mine since my fuel pump takes so much amp's. Once I fixed the voltage to be in the 12's, my afr's dipped into the 10's.

I would try switching the battery and logging the volts again. If that doesn't fix your misfire I would consider changing to a cop.

 

I appreciate your input. I did run two batteries in parallel with each other on the dyno and it did not make a difference. I am considering the alternator is shot but i haven't heard of this before at all. Thanks again

 

I am going to swap alternators tommorow with another set of plugs. If that does not fix the problem, a COP will be on its way, and if that doesnt fix it the car will be crushed because this is getting old!!!!!

 

Other than Dan's fuel pump causing a voltage problem and getting his voltage back in the 12's, that was the only answer i have gotten from a high hp evo in terms of battery voltage.

Can anyone else give me their Battery Voltages during a pull?

 

anyone else???

 

hey
Did u find the issue

 

Total necrobump 11 year old thread

 

i would check your grounds in the charging system, recently had the same issue. moved the ground by the battery started seeing 14+ volts. my car makes 600whp.