Stock Turbo Overboosting

[Bowtie Mafia]

I recently purchased the RJC boost control. I installed it and it was working great. After a couple of weeks my '87 G.N. started running rich. I set it back to stock and the boost went off my gauge (stock gauge). I fixed the running rich and put the RJC boost control back in, it is fully closed and my boost is still off the gauge. Help would be much appreciated. Thank you.

 

[RIFF RAFF]

Lines backward

Most times .

 

[GNVYUS 1]

Well the stock gauge was never accurate in the first place, then considering the stock wastegate actuator is 12psi all by itself you probably need to take out all of the MBC screw and start over.

I'm assuming you don't have the stock solenoid in play here and you have the MBC hosed like ......
Compressor fitting to bottom of MBC
90 degree MBC fitting going to Wastegate

If you pull out all of the MBC screw (meaning it's barely threaded in there) the psi should be about 12psi. Now if I remember correctly, the factory gauge is off like 2psi so this might look like 14psi or the 15psi light barely flickers.

Here's an easy way to see if the factory boost gauge is accurate, just run a hose from the compressor fitting to the wastegate actuator. That should open gradually and achieve 12psi of boost. If your factory gauge shows something higher, you know it's not accurate.

 

[usetaboost]

mine shows 5psi at idle. how far off do you think it is LOL

 

[GNVYUS 1]

^ LOL, actually I thought that meant something like a hose or something concerning the MAP was unplugged etc.

 

[Bowtie Mafia]

Thanks a ton GNVYUS 1, I practically unthreaded the controller and it works great, like it's supposed to. For some reason I thought that would raise the boost. Thanks again!