Help GN is over boosting?

[my85grandnation]

Ok Heres the deal. I have an 85 Hotair GN. The only thing done to it is an ATR pitbull chip, no cat or muffler, and a k&n air filter. Other than that it is a stock car with about 100k miles on it. Anyways the speedometer has been bouncing so I decided to take it out and grease it up, after I put it back togther I went to drive it to see if the speedometer bounced. It was fine at low speeds, but I decided to get on it and see if it bounced going to a higher speed, and thats when my problem occured. It down shifted and took off and all of a sudden I noticed that my boost gauge went over 15lbs. It will normally only go to about 12lbs cause it has a cracked passenger side manifold. I thought it was just a fluke so I tried it a few more times and each time it would go right past 15lbs, and I would let off cause I was affraid that it was to high. I checked all my boost line to the wastegate and dont see any problems with it. What could be causing this to happen? Thanks for your help. Dusty

 

[my85grandnation]

Ttt

 

[cool 84]

So the only thing you changed was pulling the speedo? Do you have an aftermarket boost guage? The stock boost guage isn't very accurate. By pulling the speedo you could've disturbed something in there and made it even more off.

 

[my85grandnation]

I do have an aftermarket boost gauge, and with the speedo the only thing I changed was the botom part of the cable. I didnt even mess with taking the dash apart.