just got off the dyno, need advice

[hottscennessey]

Viper, try lowering the fuel pressure and upping the WOT (airflow signal).

This definately takes balance, you're not only trying to keep your AFR's straight, but also avoid fuel fut. The more fuel you add via airflow signal, the closer you get to fuel cut.

The theory behind this is, the more you pull fuel via airflow signal, the more your timing is advanced. This is because supposedly in the ECU your timing is determined by the airflow signal VS RPM, etc. So less airflow = more timing because the ECU believes there is less boost. Get it?

 

[zurud]

I'll say tune it to 11.0 afr or use methanol or water injection.

 

[MDCmotorsports]

Octane is a anti-knock agent that is added to gasoline, the tuner said more fuel will get rid of knock but I was almost positive it's the octane, maybe though mass amounts of fuel can do the same I will research that, that is news to my ears.

WOW.

Guys. Take note to this. Prime example of....

IF YOU DON'T KNOW - DON'T POST.

Wall of shame worthy right thar.

Just out of curiosity to the OP, what IC are you running? IC pipes or Boost Hoses?

 

[figgie]

ok i just pulled the spark plugs and they are white, so that means the cylinder temps are too hot. i assume this may be leading to my problem? should i try to find 1 step colder plugs?

Did you pull the plugs immediately after the pull? The pull should have been done to WOT and then engine "killed" so you can read the plugs. any idling will screw the readings up.

also the RPM when the "knock/detonation". Have a log of it? Reason is around 5000 rpm is pretty vague Also if you are detonating but read the plugs and saw no "black specs" or silver specs then it is hard to assume that you are detonating.

 

[grimreaper]

your compression is higher, and you stuck a turbo on it, and upped the boost. You think your higher compression might have something to do with it?

 

[figgie]

your compression is higher, and you stuck a turbo on it, and upped the boost. You think your higher compression might have something to do with it?

It can.

Only way to tell is to up the octane rating of the fuel and see if the knock still persists.

OP

forgot to ask. How are you "detecting" the detonation? A set of "cans" for listening?

 

[hottscennessey]

I'll say tune it to 11.0 afr or use methanol or water injection.

I agree methanol injection would help, and it works great on the MAF-T (from personal experience).

But, right now, I'd worry about getting the tune at hand straight, and not about using band-aids to fix the problem. We don't want to over-complicate the situation.

 

[grimreaper]

It can.

Only way to tell is to up the octane rating of the fuel and see if the knock still persists.

OP

forgot to ask. How are you "detecting" the detonation? A set of "cans" for listening?

Race gas to verify would be easy enough. how much timing does the ecu pull above 5700rpms (iirc) and why? Id expect kr in lower rpms where there is timing being added, not pulled.

 

[mecevans]

did you ever measure your compression? was the head ever decked, etc?

 

[figgie]

you giving advice on a 1.8 year old thread?

 

[mecevans]

its a question. didnt look at the date. My Bad.