00'gt

I have a 2000 gt that threw a misfire on cylinders 6&7. I changed the plugs but didnt do anything so i changed the coils from cylinder 6&7 to the outside cylinders 5&8 then a code came up as misfiring on cylinder 5. I got a new coil for that cylinder and then it threw a misfire on cylinder 8 so i changed the coil that i just replaced in cylinder 5 and put that in the 8th cylinder. The codes went away and the only code was 02 sensor bank 1 so i replaced that sensor now the car has no codes and still misfiring. does anybody have any ideas whats going on?

cliffyk

What condition are the COP boots in, do they feel hardened or smell burned? What condition are the spark plugs in?

A combination of hardened/burnt boot and worn plugs will cause misfires, and if not fixed cause the coil to burn out...

00'gt

The plugs are brand new NGK tr55 and the coil boots are in good shape. Im wondering if its possible to be the alternator because its reading 13.8v and the specs on the coils are suppose to be 14.5v to fire right. right before the car starting misfiring i was getting on it pretty hard and all the lights dimmed and then i let off the gas and they came back. thats the only time ive had that happen.

cliffyk

The COPs will fire quite nicely at anything more than 10.5V.

The generator should provide 13-15V at idle depending on ambient temperatue, more in colder weather less in hotter weather:



The shop manual docs for the charging system can be found on my site:

00'gt

thank you. I took the alernator off and got it tested and then put it back on and now it dosnt misfire so it must of been a connection problem maybe i dont know for sure. Do you have any idle hanging issues or the idle jumps up a little bit when you shift? i have the same 70mm plenum as you.

cliffyk

Electrical and radio frequency "noise" from the generator will interfere with the PCM's operation--sometimes just loosening and tightening connectors will disturb a bit of corrosion enough to clean up the contacts.

Nope, tuned them out with an IAC restrictor and the virtual dashpot settings in the tune. You may also want to verify the throttle stop screw setting, it was way off (too far open) on the PP TB when I got it--most are...

caaraa

The plugs are brand new NGK tr55 and the coil boots are in good shape.