Boost Leaks!

[RiceKiller_TSi]

Got some, need to make a detector...
I didn't find the info at vfaq.


GOT LINK?

 

[RiceKiller_TSi]

I'm willing to bet that majority of the people claiming 190 will not overrun the fpr does not have a fuel gauge installed. As for the ebay fpr, people mostly pay for what they get...mostly, I would stick with a proven one.

You may be right. Btw do you think another stocker (fpr) will work?
What would be a proven afpr?

 

[oldman]

Btw do you think another stocker (fpr) will work?

I don't know but I doubt it. I also want to make it clear that I don't know if 14psi fpr overrun will cause high knock count at light throttle but one thing we know for sure, you have fpr overrun.

What would be a proven afpr?

Anything on this list except for B&M CommandFlo, the Megan unit is fairly new so I don't know anything about it.

 

[RiceKiller_TSi]

Well, I got my eBay brand fuel pressure regulator installed and it works great actually. My car now pulls pretty strong while under boost without knock... problem is I'm still getting that cruise knock.

As soon as I begin to open the throttle plate, knock kicks in, and the engine becomes spineless instantly. If I take my foot off the accelerator and then floor it, the boost kicks in and I bypass that knock region in my throttle.

Car runs pretty lean on idle but I've found no leaks. I'm leaning towards the tps since the idle is starting to bounce around a bit between 900-1500 when coming to a stop.

What are the signs of a bad tps?
EDIT: Nevermind... I forgot to search. Well I think thats what the problem is. Not sure doh. Does the 1g ecu not throw an error code for this? Geesh.

 

[RiceKiller_TSi]

Thanks to my boy from Atlanta I know how to check this thing out now. And I can just use my logger to do it. DUH! I'll post back.

 

[RiceKiller_TSi]

TPS checks out. What else could be causing this cruising knock issue?

Oh well. Boost is strong when it comes on so boost leak fixed.

 

[boostyGST]

what is the base fuel pressure supposed to be set @ on a 2G

 

[BREW]

Nice thread guys, I have learned much. However, after reading through it I still have some questions to things that don't make sense to me. I am in the middle of my first leak test on a completely rebuilt engine (yet to be started, first things first) I discovered when I pressurize the system at the turbo with an aircompressor, I have a leak at the throttlebody. Being that the gaskets I'm using are shotty to say the least, I kind of expected this, they will be changed. My questions...

1. I'm using my boost guage to meter the pressure in the system, since the throttleplate is closed and the boost guage is tapped to the intake manifold, wouldn't the air need to "work harder" to fill that intake manifold to get an accurate reading.
i.e. More pressure before the plate than in the manifold. Leak is before the plate therefore escaping before entering the manifold to be metered.

2. A follow up to question 1. Wouldn't it be more accurate with the throttleplate open?

3. In a properly pressure holding system, where should the air leak out from?

thanks for the help,

Brew

 

[oldman]

Sorry guys, it has been a crazy couple of days.

1. I'm using my boost guage to meter the pressure in the system, since the throttleplate is closed and the boost guage is tapped to the intake manifold, wouldn't the air need to "work harder" to fill that intake manifold to get an accurate reading.
i.e. More pressure before the plate than in the manifold. Leak is before the plate therefore escaping before entering the manifold to be metered.

There are other passages around the throttle plate which will allow pressure to fill up the intake in no time. The reason there is a difference in pressure during idle is because the engine is swallowing up air fairly quickly, this is not a problem during a static pressure test.

2. A follow up to question 1. Wouldn't it be more accurate with the throttleplate open?

See answer 1.

3. In a properly pressure holding system, where should the air leak out from?

It's normal for pressure to get past the turbo seal under a static pressure test, usually in the form of gurggling sound under the oil cap. Assuming the test is done at the beginning of the licp instead of the turbo inlet, some blow by through the ring should be the only leak, this leak should be minimal as only one set of intake valves should be open as long as the compression numbers are good.

what is the base fuel pressure supposed to be set @ on a 2G

43.5 psi without the vacuum line. A simple search would have answered you question in no time.

TPS checks out. What else could be causing this cruising knock issue?

Let's do a recap on your situation. You have changed the fuel filter, knock sensor, installed an afpr (ebay ), what was the fuel pressure with vacuum line attached. Anything else you like to add?

 

[RiceKiller_TSi]

Let's do a recap on your situation. You have changed the fuel filter, knock sensor, installed an afpr (ebay ), what was the fuel pressure with vacuum line attached. Anything else you like to add?

Okay, okay, okay I've learned my lesson. The eBay afpr is going back. It turns out that it only worked good for the first day. I was able to lower the fuel pressure to around 35psi and the car actually ran great that day...uh, for a little while. But then the knocking came back. And when it did, I immediately checked the afpr guage and it read like 45psi and I could not lower it any more.

(Side note: I dont know how this happened but my base timing somehow got advanced to about 10* btdc. I put it back to 5* and the real knock went away on the WOT runs.)

I've been playing around with my fuel settings trying to eliminate this "phantom" low throttle knock with no success.

low trims indicate a lean condition between 107%-139%. When I add fuel, the car feels totally gutless on acceleration and it still knocks.

Mid and high trims are at 97% and 98% currently. (at least thats what the datalogger says). The car pulls mad strong at wot and there is no knock problem there. The knock problem ONLY exists when the car is fully warmed up and/or accelerating at part throttle. If I start the car and drive it before the engine temps come up it will drive like a dream.
I am currently reading threads from 3+ years ago on dsmtalk trying to get a grip on this.

I did "however" retest for boost leaks last night and found a good amount of air leaking from my bov. It leaks out where the bov dumps back into the intake. I plan to replace it.

 

[oldman]

Okay, okay, okay I've learned my lesson. The eBay afpr is going back. It turns out that it only worked good for the first day. I was able to lower the fuel pressure to around 35psi and the car actually ran great that day...uh, for a little while. But then the knocking came back.

Bastard was going to keep it quite if I didn't ask. Is this knock the same knock you're talking about. If so, isn't it clear that you need a real afpr?

 

[RiceKiller_TSi]

Bastard was going to keep it quite if I didn't ask. Is this knock the same knock you're talking about. If so, isn't it clear that you need a real afpr?

Bastard? You go moderator on me and getting anal already?
Next you'll be telling me that my grammar ain't (isn't) good enough.
, Is butt retention a requirement for being a mod? j/k

Nah, I'm humble enough to admit that I made a crappy decision to buy an eBay afpr. (If you ask )Live and learn.

Yeah, I got to get a real afpr... I didn't want to spend a couple hundred for one just yet. I'm gonna have to deal with it for another couple of weeks, then I plan to get a new bov and afpr. In the meanwhile though, I'm going to clean the combusion chamber with some MCCC and see if it helps eliminate any knock.

I might have a lot of build up due to dumping all that fuel for a week.

 

[oldman]

Bastard? You go moderator on me and getting anal already?
Next you'll be telling me that my grammar ain't (isn't) good enough.
, Is butt retention a requirement for being a mod? j/k

I just checked my moderator handbook and yes, it's rule number 3 so I did the right thing.