Pontiac: 1997 Pontiac Bonneville SSEI misfiring, pontiac bonneville ssei, pontiac bonneville

Question
-------------------------
Followup To
Question -
I have a 1997 Pontiac Bonneville SSEI, 110,000 miles that seems
to have misfiring problem. Every 120 miles or so, the check
engine light come on (flashes, then goes on steady), I take it to
the shop, and they have to reset it. The computer indicates
misfiring (1-50 times) on one plug (different plug every time). I
had plugs and wires replace 10,000 miles ago, changing plugs
again did not help. One mechanic claims that there is a light
grey deposit on the plugs and suspects antifreeze in the oil (?). I
had the injector cleaned ($250) and it did not make any
difference. Car drives fine.

The mechanic wants to take the engine apart to change seals, I
think that I should try new wires (new coil?) and have the fuel
injector tested). What do you think, either or neither right?

Thank you for your help!

Thomas
Answer -
Since the misfire is on a different cylinder each time, I doubt that it is one of the coil packs.
There are some problems with the upper intake manifolds leaking coolant into the upper half of
the engine. When it first starts you will get random misfires, but as it gets worse, you will have a
hard time starting it and it will miss all the time until it eventually floods the cylinders with
antifreeze.

Follow-up question:
You will think that this is funny, but the check engine light is now off (lamp in dash board still
works). It was on for about 100 miles, then went off, then went on again, is now off). It is not
flickering, it appears that the fault has gone away. Does the computer re-set itself?

Also, can I add dye to the antifreeze to see on show up on the plugs? I don't see the typical
green, is there a more intense dye that I can add? Which dye should I use, will an auto supply
store sell it?

Thank you!

Thomas

Answer
Yes, the computer will turn the light off if the problem goes away after so many self tests, but there will still be a code stored in history.
The reason that you dont see any green coolant is because your car should have the pink/orange Dex-Cool in it. If you added any green antifreese you will need to flush the cooling system.
You could add a cooling system dye but I dont know if it will show up on the plugs. I just do a pressure test on the system after it is hot.