Using the old balloon

[perrytime]

Refering to my last post about long term fuel trims, my conviction i had a hidden vacuum leak problem with lower intake manifold was waining. I had been trying to think of a poor man's DIY substitue for the smoke machines, maybe my fog machine. So i came up with this idea. pulled off air cleaner and rubber banded part of an old balloon over throttle body opening. I knew the PVC valve would leak, so i pull vacuum tap to that and connect a hose whose other end was connect to inflated ballon. I didn't know what to expect, some air must flow past open valves and into chamber, but how fast would it leak past piston? I heard a small air flow, turns out the IAC motor has a black plastic cover over a small bleed hole, removed and sealed that hole. Back on with a newly inflated balloon. I heard no noise, and it was very slow to deflate. I surmized I had no serious vacuum leak, at least not some simple opening. I knew I wasn't applying much pressure with the balloon, I replaced it with air wand, run compressor just long enough to be at only 4-5 psi, as verified by manifold vacuum gage. Had to hold hand over throttle body to keep ballon on. I could hear air flowing, but was this normal? it seemed to be under the upper intake manifold, I soapy watered everywhere, finally found it blowing air out near upper/lower manifold joint near fuel pressure regualator. removed upper plenum, closer inspection revealed small nicks in the 3 orings for upper plenum, apparently in all my years of working on this I carelessly slid the manifold around till it seated, slightly gouging the orings with the dowel pin locators. I did a temp fix, silicon on orings and put it back together while new orings were ordered. Next day it didn't seem like my long term fuel trim was fixed, but I will wait till new orings are in, and repeat pressuring testing manifold. Long term fuel trims may or may not be fixed, hot soak rough idle may or may not be fixed, time will tell.
Assuming the problems are not fixed, and the next pressure testing of manifold reveals no problems. My next plan to fix the hot soak idle issue, is to add a vacumm solenoid in line to FPR, and circuit to keep it from energizing first minute of engine operation. To prevent FPR from seeing vacuum first minute of operation after start. This should work as i have verified rough idle is made much better with FPR vacuum removed.

end of chapter one of fixing cars with balloons