Not boosting up...

[sims76]

My setup has been running GREAT at 6PSI. I am very happy, but of course still want to turn up the boost. Even at 6PSI, I can smoke em through first and part of second (impossible with my previous NA setup.)

 

Question #1:

I was unable to up the boost using a MBC, so I disconnected the vacuum line to the wastegate actuator and took it for a ride (carefully watching the boost gauge) to see if I could get it over 6PSI. Same boost as before.

 

This tells me that the wastegate actuator was never moving and the wastegate puck was likely in a slightly open position (I do have it mounted at an odd angle) causing a constant leak that regulated boost to 6PSI. Correct?

 

Question #2:

I removed the wastegate actuator and put as much tension as I could on the wastegate puck arm using cable ties, but then I could only get about 2PSI. How much tension is required? I had the arm pulled pretty tight.

 

Tonight, I'm going to re-mount the actuator in a better location so that It can put a lot of tension on the puck arm. I hope this solves my problem.

[Jersey]

Sounds like it could be the WG Actuator but, do you have a POV? Is your BOV leaking? IC silicon connections in good shape? Just some quick thoughts.

[sims76]

Jersey,

 

I don't have a POV, I'm using my stock '76 intake.

 

I didn't even consider the BOV (1G DSM) because everything I've read says they are good to 12PSI or so before you have to even think about crushing them. I will consider this also, maybe I'll plug the outlet of the bov so It can't vent as a test.

 

I'll double check the IC connections. They seem well and I'm using sturdy ss T clamps.

 

Thanks for the input.

 

Here is more food for thought...a datalog that I took a few days ago....

From this you all can see the boost response (the lavendar "MAP" line). Is this response typical of a wastegate regulating or a leak? By the way 136kpa on the MAP signal is approximately 5PSI.

 

Ignore the A/F ratio line, it's skewed because of the datalogging interpreter. It stays at 11.1 - 11.8 under boost.

[sims76]

I took a few hours and made a decent WG actuator bracket out of 1/8 steel stock....It looks like crap because I'm a terrible welder, but at least it's sturdy.

 

Took it out for a spin, and still no boost. I came back, fixed the IC pipe that slipped off. I took it back out and carefully did a 3rd gear pull. HOLY CRAP, 12psi no problem. The car surged forward like a rocket!

 

I didn't floor it because I'm not sure that it was going to stop at 12psi and I didn't have a passenger to watch the AFR and boost gauge. I think I now have too much pre tension on the WG actuator arm. I will loosen it a turn and hopefully have regulated boost tomorrow. I'll then put the MBC back on and work my way back up.

[Guest bastaad525]

I have run up to 15psi on a stock non crushed 1g DSM BOV w/o any leak problems... I had heard you shouldn't have to crush it until you get close to 20psi. I currently run a little less boost than that on that same BOV, non crushed and have been for quite some time... no leaks. Crushing isn't good if you dont have to do it, because it will make the BOV respond slower and let the turbo surge a little before all the excess pressure can be released... don't crush it unless you know for sure it's leaking.

[Clifton]

I use a bike pump with an accurate guage T-d in to test wastegate and other stuff. I would make sure it is not opening to soon. The WG shouls have some tension, enough to keep it firmly closed but you don't need to pull 1/2 the travle out of the diaphram. It should open at 7psi. The puck on the WG flapper could also be broken, missing or there could be a crack. Are you running the stock pressure relief/saftey valve still? It could be your problem too.

[sims76]

Thanks Clifton and Bastaad,

 

I did pull the housing just to check the condition of the flapper and it was fine. No safety valve as I using a 76 intake. I have a threaded WG arm, so I loosened it a turn and will try again tomorrow (it's raining now). I'll report back.