OK here's the deal fellas, I can't hold boost (maybe .5 psi max). Now here's the story. When I first installed my turbo I could boost 3.5 psi, and now I can't boost anything. A check valve is installed, but I dont think i need it. No exhaust leaks, and no MBC, runnin afc hack.
This is what I checked:
1)turbo exhaust side and dp seems dry, no oil, charge pipe has some oil, but nothing ridiculous, and the shaft has no side to side shaft play but has very little up and down shaft play, nothing that I think would cause no boost.-No scoring of the walls.
2)I am not burning any oil, at least I can't see any. Compression numbers are perfect.
3)I tested my actual piping from the charge pipe all the way to the piping that connects to the TB. No leaks, I could hold a lot of pressure via a bike pump.
4)tested wg, and it seems to be working fine, it closes well, and opens under 7+ psi it seems.
5)wg valve seems to have carbon on it, like it's been open, but I know what wg opening sounds like, and I should still be able to get SOME boost, i must be losing it somewhere.
Now as soon as I attach my TB to the intercooler piping, etc. It doesn't hold any boost, and air leaks through the wg hole on the turbo manifold, and I'm assuming the exhaust as well. Probably because the intake/exhaust valves are open in one or more cylinders.

Now what else can this boost leak be from? Can it leak through the TB? HELP


Modified by homesauce at 5:37 AM 3/26/2004

 

^

 

If you are running the afc-hack, you do not use check valves. If you do run the afc-hack, you need to have it properly installed AND tuned in order to run properly.

Now, which plugs are you running? Did you gap them to .030 like you are supposed to?

 

yes, im running the NGK's u recommended a while back. Actually I've done all of the install myself, and was actually on a dyno when I found out I was only hitting 3 psi, now it's zero. It's tuned for 3 psi. I don't know what u mean by "properly" installed, but I've installed everything correctly, as far as I know...Actually the shop that was tuning installed the check valve because they said they were getting a map sensor cel. I told them it shouldn't but maybe it was because they had the settings for air correction too high. Right now the settings are very reasonable, -11%->0% across the rpm band.

 

OK i figured it out. This is what was happening, because the shop installed a check valve, I didn't think about it, but because I was reading boost off of my afc, (which uses the map voltage) the check valve was bleeding off all of the pressure. So in actuality I was actually boosting, but afc wasn't reading it.

When I get past 4.5 psi, i throw the map sensor cel, probably because my settings aren't below -35%. They are more like -10%, but I need that much fuel because it was tuned at 3.5 psi, and now I'm running more than that. First things first, I think I will reinstall the check valve, install a separate boost gauge, and get it tuned again. There can be nothing wrong with having a check valve while running with the afc right, I guess it's not a "hack" anymore.


Modified by homesauce at 5:37 AM 3/27/2004