So I'm detonating...

[LaureltheQueen]

I'm almost completely sure. When we swapped in the TD05 and dp and ic and everything, my car started making a pulsing or flapping noise. I had not turned up the boost, but since the car ran fine and I wasn't throwing any codes, I assumed it was just loud injectors, as Art's stock STi made a similar sound(although a tad quieter).

Another theory is that the car was detonating, and for some reason my computer wasn't picking it up. This was confirmed when Nick(555bcturbo) took a ride in my car and verified that something just isn't right.

I'm going to throw a gallon of xylene in the tank and see if that fixes anything. If it does, then I know that it's definitely a fuel system problem. It should also be noted that I'm fairly certain that I'm in need of an oxygen sensor due to my poor gas mileage situation, which is likely tied into this.

We have an STi fuel pump sitting in our spare bedroom collecting dust as we got it in a package of things from someone parting out their STi. As Art can't use it on his legacy, I was wondering if it's worth it to swap it in, so I did a search, and here's what I came up with.

EJ257 STi fuel pumps are specified to flow at least 145 liters per hour at 43.5 psi with a 12 volt power supply.

GD/GG WRX stock fuel pumps are specified to flow at least 130 liters per hour at 43.5 psi with a 12 volt power supply.

BC/BF Legacy Turbo stock fuel pumps are specified to flow at least 150 liters per hour at 43.4 psi with a 12 volt power supply.

It seems to me that the STi's fuel pump isn't better than ours. But, my fuel pump also has 175k miles on it, and a new, even stock specification fuel pump may help out in getting fuel to my car. Thoughts, comments?

also on the list is a rrfpr, and new injectors

[BAC5.2]

Are you sure it's detonating?

What are the conditions? What exactly is going on? You should run the VRG3 Scanner and try to diagnose what is happening. If it's detonating, the knock sensor should be picking it up and pulling timing.

Another theory, is simply wastegate fluttering as boost is building. STi's are notorious for this with aftermarket exhausts and the stock VF39. I've seen it with 16G's too.

Does the car feel slower? What kind of gas mileage are you getting? Poor performance could simply be related to WAY too much fuel from a dying O2 sensor.

[napphappy]

My vote is wastegate flutter or compresor surge. I have a VF-8 and a 3in DP. I get a "pulsing or flapping noise" when Im building boost. that is in between 0-5psi.
if you were getting this noise at full boost I might suspect detonation.

[evolutionmovement]

If you're running rich you're not likely to be detonating either, though it wouldn't hurt to clean out the combustion chamber.

I vote wastegate also.

Steve

[206er]

go with toluene and not xylene

[555BCTurbo]

go with toluene and not xylene

Toluene is getting rather hard to obtain around here because of its use in the cooking of meth, and Xylene is chemically similar to Toluene and seems to work just as well in my experience...


On another note...Laurel...I agree with the guys about the wastegate flutter...as when you mentioned that the STi did it as well...Which is a very common STi thing...so I doubt it is detonation...

My diagnosis was a bit on the incorrect side

Thanks for letting me crash for a few days...was totally awersome!!!

[LaureltheQueen]

Wastegate flutter sounds right. fwew. I'm so relieved. The fluttery sound is only between 0 and 5 psi too, that's one of the reasons I was so confused.


Beautiful. I'm glad my car's not trying to kill itself.

The wastegate flutter however, that's not good, is it?

[vrg3]

I suppose it's not especially good; however, it is to some degree normal.

I don't think you should be using your stock 175000-mile-old fuel pump with your other modifications. As you guess, the STi pump will be better since it is new, but I would actually recommend a higher-capacity pump, like a Walbro 255lph pump, or one from a MkIV turbo Supra.

Can you tell me more about your plans for the future which involve both injectors and an RRFPR?

[LaureltheQueen]

well, I want to increase the boost at some point, as well as get the liberty twin cam heads. Probably eventually get a walbro, and bigger injectors so my engine doesn't go boom

[vrg3]

Hmm... I think you should think through what you're doing with fuel -- you may find that for the moment you want to keep stock injectors (though having them cleaned and having their soft parts treplaced might be good) if you're going to use a rising rate fue pressure regulator.

[Legacy777]

Mine does something similar...as well as my budy's turbo forester.

Here's my thread
http://bbs.legacycentral.org/viewtopic.php?t=24185

[tris91ricer]

For what its worth, Nick told me I was detonating, as well.

Not at full boost, either.

I'm not trying to discredit him, its just that I know for a fact that I'm not detonating.

My knock sensor isn't stepping in to pull timing, as the select monitor has indicated on more than one occasion.
Why not do a run with the select monitor, just to find out? Stop stressin', yo.

[555BCTurbo]

I still believe that what you have IS detonation Tristan...especially based on the fact that you don't have a turbo fuel pump. The sound that Laurel's car made and your car made were very different...and while her I was questioning about detonating...I would put money on the fact that yours is...because it was making that very sharp, knocky sort of noise, up in the RPMs and on boost.

Just because your knock sensor isn't pulling timing doesn't mean that you aren't detonating...

Once again, as in Laurel's case, I am not 100% sure about it, but my experience leads me to believe so.

btw...it was great to meet you! Had lots of fun!

[Legacy777]

Tristan.

I've got a turbo fuel pump sitting in my garage. Let me know if you want it.

[evolutionmovement]

Tristan, the knock sensor doesn't always work! I'm damn sure from experience. I had a melted exhaust valve and found a cracked knock sensor and I don't believe in coincidence. The computer didn't pull timing at all - the car was running balls out until the exhaust note started sounding funny.

Steve