Boost goes up and down during mid acceleration

[Garrett Powered]

I have new pics of my engine bay on page 2 of my car domain link below. The vac. lines are all air tight. How common is it for the aluminum intake to crack on the 3.1? Starting to run out of ideas on what this could be. I had the upper intake off to do the timing chain and the injectors. My good friend who is a mechanic torqued the intake on so I would not think it would crack normally.

Is there a way to check the manifold for leaks or a possible crack in the metal behind the motor where I cant see? We have a vac pump tester I think. What should I do or expect when testing? Never had any luck with this one so it is dragging on now and time to fix it.

Sorry I have to do this by trial and error, I don't have a cable to hook up to the computer to find out what really is going on. But I do have access to a Snap-On set up at my friends garage. Just need to know what to look for so I can rule out a manifold leak.

The turbo gets good boost most of the time I just cant figure out why the gauge needle goes wildly up and down sometimes. I know it sounds weird.

[TGPilot]

When the gauge flips out...does the car feel like it too is flipping out? 8)

[Garrett Powered]

It still accelerates with really good power. it seems to like wot more than partial acceleration. I forgot to mention I have cruise control problems. It is all air tight on the fittings but it will not stay off once engaged and I hit the brake. Would this be the switch (turn sig.)or the cruise unit (maybe got too hot one day) I only mentioned that because it seems like everytime there is problem with the cruise, there is a problem with boost.

Its more like when I lift up on the gas even slightly during acceleration and I get this sssshushushush leaky piss me off sound. :x

The factory and aftermarket gauge do the same thing so they got to be leak free and everything. I think I am going to take out my new bov that I don't like anyway until I fix this. It needs to weld on near the TB.

[Garrett Powered]

OK I read the other thread. I saw the list of things and decided I am just going to buy a new wg sol. and install my new map. I did not hook up my new map because I was going to return it and they won"t take it back after it has been installed. but I did put on the one off my other parts car, and the wg sol. too with no change. In fact I swapped over the cruise unit too with no change. The only swapping that actually did something good was the turn sig. switch.

So in goes the $50 map sensor and cross my fingers. If no gains there then wg sol, then cruise unit. and go from there. At least I am not paying hundreds more for a pro mechanic to do this.

[TurboGTU]

I think you aswered your own qs. The BOV. I would set the spring tention higher on it if its ajustible. Many people assume BOV won't leak if under the BOVs opening pressure. Not true. Some ajustibles need more ajusting due to engine vacume beeing more than what the BOV makers thought it would be.

 

Well anyway..I think skalor also has this problem but I don't think he knows. On his dyno run..I can swear I can hear the BOV leaking and then closing when the rpms are shotting up by the end of the dyno (you can hear the air leaking..and then everything silents up and car keeps reving) :?:

[Garrett Powered]

Ok sounds like a plan. I gotta go to bed man I will try that tomorrow.

[Garrett Powered]

Others have been doing knock sensors lately, I think I am going to try one, since the map sensor did a little good but wasn't the problem. I guess the ecm could be pulling the timing like TGPilot said.

[Garrett Powered]

All it was this whole time just a old rubber tee that I overlooked and never replaced. It was on the fuel pressure regulator just like Jeff M said to me repetitively but I didn't have to test the fpr at all...just get a new tee from Schuck's. Vacu-tite! soft vacuum "T" 47415 7/64". a needlenose plier and cram it on there hella tite.