another boost loss thread...
 

I have search the forum, and I have not found what I need.

During the ride home from Travis AFB last weekend, I stopped to get gas at Applegate, after starting back up and driving, I noticed a massive boost loss, I was at 8-9 PSI, and now im at 5-6. I checked the following:

-Wastegate
-charge piping before intercooler
-intercooler
-charge piping after intercooler
-all couplers for damage
-all clamps
-vacuum lines
-boost gauge

Anything else? The one thing I did find today is that my Greddy BOV needs a new diaphram, since it started to flutter that same day driving home. But I slapped on a cheap egay BOV on and still boost loss.

Its does not act like a leak, since it doesnt peak and then drop, it just never gets passed 6 psi, even with the wastegate vacuum line disconnected.

Define 'checked' couplers. Visual inspection does not count. Pressure test does, and it also allows you to test the wg hardware.

Having said that it does not sound like a leak on the intake side. Did the engine's note sound any different? Anything unusual about pulling in or out of the gas station? How is boost controlled? Any odd electrical things crop up?

I have checked the couplers with pressure and soapy water, and no tears or cuts, I did replace one coupler that was scraped by something, but no luck. The engine note sounds the same to me I guess, but now I think I will compare it to my sound clips I have recorded in the past. I have a cheap manual boost controller, plumbed from a barbed fitting before the TB, then to the wastegate. Even with it disconnected the wastegate should open at 7 psi. The most recent electrical issue I had after this was my injector harness two days ago, I was driving home from work and the car just died, after a start from the stoplight. I coasted into the parking lot, tried to start it, and it hesitated for a bit, then I randomly jiggled the injector harness and it started like it always did. Got home and replaced the harness, no problems after. I was told it could be a broken wastegate valve, or a massive crack in the exhaust housing... is this true?

Okay I got to use one of those fancy cameras that is similar to those used to shove up your ass, and I found out that the wastegate flap is chipped, is there any way to replace these things? Or do I need to replace the exhaust housing?

You can usually change out a flapper, larger ones are sometimes fitted with a ported passage for mis-guided souls who dont want go external ;)

So probably no need to replace the whole housing.

When you said that the WG opened at 7 psig with 'it' disconnected, did you mean it opened with just straight boost pressure to the wastegate actuator or that the wastegate opens with no boost line to the actuator at all?

If that thing is opening with 0 boost signal to the actuator, then that's your problem right there. It would take a pretty huge chip on the flapper to really cut boost. Where a blown out actuator would explain this perfectly.

Im sorry, i meant that the wastegate is a set stock 7psi actuator, but with it connected to a signal it barely reaches 5psi, and with it disconnected it reaches just above 5. That would suck if I have to change the housing, but I thought of laying a sheet of aluminum or copper behind the flat flush side of the flapper, and filling in the chip with globs of steel weld, and dremeling it down to look semi-pretty. I also have a T25 chinacharger I could use, but I was hoping to sell it.

alright now im worried. I replaced the turbo with a complete t25 chinacharger, and still the same boost loss... what can be wrong?!

Did you extend your WG arm any? did you put the same WG actuator on the chinacharger, or use a different one?

What kind of manifold are you using?

Is your EGR valve functioning correctly?
(Direct exhaust injection FTW!)

What are your AFRs?

-The chinacharger has its own chinagate, supposed to be 7psi...

-Using S4 BEGi SS exhaust mani, stock intake mani

-EGR valve has a block off plate... NV doesn't have very strict smog regulations.

-sadly, still running band-aids... o2 clamp, MSD boost timing controller, boost referenced FPR, etc.... stock o2 sensor showing "rich", which is a lie anyways.



edit: I am also starting to fear severe blow-by, I am tooo busy to pull the motor to replace rings and other shit... would this cause such boost loss?

Compression test will confirm/deny that.

Also check your EGR blockoff plate, if one side came off it could be causing what you described.

Betting on EGR plate issue. You would need blow-by of massive proportions to loose boost like that, to the point of your distick blasting out etc. Comp test to be sure, but I doubt it is that serious.

I would pay to see that.

You have a boost leak. Check the hoses to the TB, (IAC in particular) it took me 20 minutes to find one of those off, because it didn't look like it had blown off.

Bad meter. Your car is fine ;)

Hang out with DSM guys for awhile. We always have blow-by issues and crappy PCVs like just about every other OEM turbo I-4. So we just crimp the end of the dipstick tube a bit to hold the thing in place.

Which works great untill a PCV check valve sticks or something. Oil everywhere, lots of smoke. Very exciting.

MY brothers stealth was like that too, he shouldnt have ben crazy and ran 20 psi. Damn dsm's over boosting their cars.

I just noticed some oil smoke coming out of the crank case breather filter when goosing the throttle a little bit... But its hot here and I have my winter oil still in the car, so does this mean anything?

new light has been shown upon me... My wife reminded me that on the way back from sac, in its glory hot heat, that my car overheated, thats the first reason I stopped in applegate is when I just realized that my car was overheating I did an emergency 3 lane pull off. Is is there anything that I should check that would cause a boost loss? There is a slight tick in my engine, but I checked the timing and everything is where it should be, so I assumed its just hot outside these days and the oil is super thin. I have an extra head I can bolt on, but I dont want to go through the labor if its not even a slight possibility. help! I am an automatic driving retard!

how hot did you get it? did you peg the thermostat? if you were really really bad, you may have warped the head. this can lead to 'sticky' valves that dont want to open/close as easily/fully. A sticky valve will make a solid-lifter head sound like a bad HLA head. You may also get coolant into the cylinders, as well as a host of other problems that are generally associated with a blown head gasket.

Take your bypass valve off and see if you can cap where it came off. Try and remove the BPV from the system for a pull or two to eliminate a 'leaky valve' as a potential problem.

I didnt have anything to block it off with, and I couldnt find a piece of piping lying around that would just replace the section of plumbing, but all I could do to at least TRY and block it off, was disconnect the vacuum line and set it to the tightest it could go, and still same problem. It doesnt help that I trusted my car to a piece of shit valuecraft thermostat, now it may be causing a world of hurt. Lesson learned. The car's stock temp guage was reading a little past the hot bold mark, thats how hot, and I noticed it when my speed at 85mph was decreasing, and I freaked when I saw it. If its the whole head or just warped valves, im in luck to have an extra head lying around, and I am kinda glad I didnt sell any of the parts yet.