525 EFI plug fouling
 

my 525 efi is fouling all the plugs every now and then?????it starts off with a rough idle and then it worstens and then i have to change the plugs. its done it twice in the last 25 hours, does anybody have any thoughts

Fixx
 

how many hours?? may be time for valve springs, lifters and a valve job???

only 260 hours real easy hours too

its the water temp sensor or air temp sensor. either bad sensor itself or wires to it. if the water temp sensor plug is off or bad then the system stays on full rich cold start and does what you say. will also do this if the water never warms up
( no or bad t stat)

i am not suggesting this is a carved in stone answer but is the answer 8 out of 10 times in circumstances you describe with all else being equal.

im in the process of changing those 2 sensors (one on order) i also cleaned the air filter . just waiting on the temp sensor to show up,hopefully this will fix it, thanks for your imput,confirms what i thought also

if you are going to have an efi motor you have to have a scanner. you could be buying sensors that don't need replacing at all. buy yourself a scanner for your birthday. it will pay for itself very very quickly.

It could also be the IAC air filter is plugged if these models have that. It would look like a brass cone shaped male plug with a very course texture. The engine at idle gets its air from there and if its plugged could cause a rich rough idle. Mine would harldy idle at all, would actually die when put into gear until i cleaned them.