When I first start spraying at 3000rpm, I get really bad detonation for about 1000rpm's, then it goes away.

Aynone have any ideas?


Jason

 

No one has any ideas?

Any at all would be helpfull.

 

Jason,
Is there a fuel pressure drop?If there is it could be causing a lean condition creating the knock.
Dave

 

Not sure? I don't have a gauge to measure the fuel pressure. I am thinking as well that I might need a fuel pump. The weird thing is, when the rpm's get higher I get richer, at 5600 rpm I was at 11.0 A/F, ending up at 10.4 at 5900rpm.

About the pressure drop, someone said you have something called an accuator(sp), that would not empty my fuel rails when I spray.

 

Jason,
Sorry I cant remember which kit you have.What kit is it?
As for it getting rich later on in the run.
That is jetting.However if you are running a stock pump it sounds like a fuel pressure drop.We are talking about a sudden drop in volume.The best way to tell would be to put a machanical fuel pressure gauge on it to see if there is a drop in volume when the system comes in.If there is upgrade the pump.It may not be able to keep up with the needed supply but then recovering and the system running rich from the jetting.If this is the problem you will never get it tuned right because you are fighting two different problems.
Dave

 

True...how much is a pump?

 

What happens when you try to turn it on at 4K instead of 3K?

 

Same thing...detonation. I tried spraying at 3500, 4000 and 4500 rpm's. It starts with detonation, then it goes away. This is all with a 100 shot.

Sometimes it won't detonate at all. I am at a loss for what is going on...even Ed has no idea what it could be. It seems to not detonate when the bottle pressure is around 1000psi...but that would make no sense, if it detonates when the bottle is at 900psi?


Thanks for the reply...

Jason

 

Maybe your not feeling detonation but a extreme rich condidion, The easyest way to tell is wideband the car.

 

I never thought of that? If it was really rich, would it still make noise like is was detonation? Right now I have 100 shot, 52-31...do you think I should change the fuel jet to a 28 and run 52-28?

It's weird, when the bottle pressure is right around 1050-1100, I don't seem to have much of a problem. When the bottle pressure is lower ie:950-1000psi, it seems to make noise.

When it was on the dyno, I got a really bad lean spike when I first starting spraying, but my window switch was not working.

 

Are you sure its detonation? Sometimes your tires throw out all the stones on initial power that sounds like detonation. If you run again the stones are all out so it does not do it. I have this happen at the track as the pebbles swing off the tires and hit the exhaust. You should get a dynotune fuel pressure gauge to monitor that pressure or a wideband... Even a narrow band a/f Gauge should catch a very lean spike.
Dan

 

Get your car on a wideband dyno... It's not worth the risk guessing if it's lean or rich. If it is lean, you could try changing the fuel filter. If you can, get a fuel pressure gage on it while dynoing to make sure pressure doesn't dip on the hit. If it does, the filter may still fix it, otherwise the pump might be weak.

 

Jason,
Have you pulled your spark plugs?
Why dont you give me a call so I can ask you a few questions.This is not worth playing a guessing game.
1-866-648-7637
Dave

 

That's what I was going to ask. What kind of spark plugs are you running and what fuel are you using?

Like everyone else said, stop spraying until you get it all sorted out.

 

TR 6 gapped at .038. Stock fuel system with Chevron 91 octane.

 

Well, I just changed the gap to .035...I am gonna change the fuel filter in the next couple of days. Hopefully that will make some kind of difference. If not, I will check the fuel pressure.

Huge props go out to Nitro Dave for helping me with my problem, you are the man!!!

Thanks,

Jason