Hey everyone, I'm down quite a bit of power, and I'm trying to figure out why.

Last summer i got tuned at 18psi and hit 454whp. Then last fall i ran on a dyno (same brand, but not sure of corrections), and only hit 405 at the same boost level.

I also recently ran another fd that had 390whp and I was barely able to pull on him, which makes me think I'm really down to 400whp.

This is on a street port with a T78 turbo, so i should be well over 400whp at 18psi.

My gauge will go up to 18psi and hold, so the peak level hasn't changed. I bought a boost leak tester and will be testing tomorrow, but is it even possible for my guage to still show the 18psi with a boost leak that results in 50 less hp?

I haven't changed the plugs in a while, so i'll be doing that as well.

Is there anything other than a bad engine that could cause this type of power loss?

 

what were your compression numbers before and after?

 

^^^ i was talking with the OP and he was wondering if that could be it to.... lets just hope its not down on compression.....

 

i also remember saying something about your air filter.. but try changing that out or cleaning it up a bit.. could cause a few hp but doubt it will find you the 50 hp youre missing...

 

i was around 110 on all sides before the tune, and it seemed fine all through the tuning process when we stopped at 18psi. I haven't had any problems with the car since, it was a fresh engine with 1500 miles of break in with very little boost prior to being tuned.

I havent tested the compression since though, i'm really hoping thats not it.

I'll be changing my filter as well, right now its got the old greddy foam type filter, i'm getting a K&N to replace it.

 

Check spark plugs.

thewird

 

was this on the same dyno?

 

I think I may have found the problem.

I changed the plugs today, they are BR10QEG. They look pretty bad, I replaced them with BR10EIX (iridium version):


Trailing:


Leading:




Now the real problem:

You'll notice the wire on the left has no metal connector in it. It must have pulled out last time i changed the plugs, funny thing is, I still have the old plugs and the connector is not on one so it must have flung off when i changed them. Has this ever happened to anyone else? And in the pic of the leading plugs above, you can see that they look pretty different.

This problem wire is the front rotor Leading plug wire, its still making around 400whp, and it made it all the way to deals gap and back with no problems, how could it run ok without a good contact to the plug? Could the spark just be jumping from the end of the wire through the plug so that it doesn't matter that its missing the metal connector?