possible vacuum leak?

[beeman212]

so when car is cold at idle the boost gauge shows 7 or 8lbs of vauum and once it warms up it will show 10lbs of vacuum at idle..
is this normal or is that a vacuum leak?
car is 2000 Pontiac Bonneville ssei supercharged

[nos4blood70]

It's normal.

Any other issues or symptoms making you think there's something wrong?

[beeman212]

yea cars had a miss since I bought it and I,ve changed everything from the normal plugs wires coil packs icm and headgasket kit. heads where pulled cleaned and new valve seals..
but it misses when it wants to and only when first started after it runs a few mins it goes away and you never know if its gonna miss or not.
cold hot dosent matter you could drive it and park for a min shut it off come back and its a 50/50 chance if it will miss or not and it likes to miss on cylinders 3/4 but not always... sometimes its just 3 or 4 or both or it wont miss at all...
any ideas?
also I think the reason for boost gauge to do that is because cold idle is higher and prob makes it read under -10 when cold idle but other than that car runs great other than P0300 code that passes/fails on my tech 2 scan tool

[nos4blood70]

I'd look at the injectors for those two cylinders.

[96 SSEi]

I would pull the plugs and check gap again- did you use the copper or iridium plugs? for vacuum leak diagnosis, you can use propane or smoke test. I rigged a home- made tester with a smoker and an air pump

pull a line on the system, I pulled the u hose from throttle body to engine rear bank. get the smoker to fill the hole in throttle body for about 5 min- drag- blow into hole then you connect the low volume cheap tire pump and look for smoke escaping from the system. do this with the hose also.....good luck

are you getting po171/174 dtcs........that would be one moreindication of a vacuum leak

[beeman212]

I had copper plugs in it for 1500 miles or so then got iridium plugs after that with new ac delco wires and plugs..
I did ohm test the injectors and they tested good and they all ohmed almost identical numbers on all 6 injectors... also I used an automotive stethoscope and listened to all the injectors and they all seem to be working and all sound the same while car is running..
in process of testing for vacuum leaks with a handheld vacuum pump/ automotive test and bleed kit that has instructions on how to test for vacuum leaks and by what the vac gauge reads its supposed to be a good test for everything from vac leaks to burnt valves and lots of other tests that can be done with this tool...