Spark plugs: black, shiny, wet

[KevAndAndi]

'81 FI with 117k miles. Finally got around to pulling and checking the spark plugs after 11 months of ownership.

The car had been sitting for a week. The plugs all looked the same way: shiny and wet with a thin coating of black that mostly wiped off. The gaps on all were too wide - around 0.035" (I reduced to 0.029" before cleaning and replacing the plugs).

Since the AFM was professionally rebuilt this summer, wife reports that "it doesn't smell like gas so much anymore" during drives. Before the AFM rebuild, the flap didn't move inward at idle, and I'm sure the air/fuel ratio was messed up for who knows how long. Even so, it ran well for us. With the refreshed AFM, it now runs even better and the idle is no longer wildly variable. It's around 1100 with no stalling at stop lights anymore. The idle speed screw is fully seated, so I may still have a vacuum leak somewhere.

The coolant temperature sensor is new. Cold start injector and throttle position sensor have been tested per Brad's guide and seem to be operating OK. I have a new O2 sensor in hand but have not installed it because I didn't want to do so until I was sure that the air-fuel mixture was right. I have not yet checked timing, compression, or valve clearance.

What are the spark plugs telling me? Looking at similar descriptions and photos, I presume this is a too-rich situation? What should I check first? Might I have leaking injectors?

[bradartigue]

If you don't know the history and they ran with a bad AFM then replace them and drive it for a while, then take a look. That or wire brush the hell out of them until they have no gook on them.

They should be brownish-white with fuel injection. More white than brown.

[KevAndAndi]

Thanks, Brad. I think I will replace the fuel-fouled Bosches with NGKs. Maybe I will also try some Techron in the gas tank to clean the injectors.

[bradartigue]

Thanks, Brad. I think I will replace the fuel-fouled Bosches with NGKs. Maybe I will also try some Techron in the gas tank to clean the injectors.

Burn the techron with the old plugs. Get down to about 1/2 a tank and put a bottle of techron or seafoam in there. Drive it keeping the RPMs high for about 1/2 hour. It won't run great but it will clean up everything. Then top off the tank with super unleaded. Then change the plugs.

[KevAndAndi]

Thanks! Will do. I have the Techron and plugs on order. I may be able to do it this weekend. Tank is already at the 1/2 level.

I'm sure the injectors have never been replaced or serviced. Longer term, maybe I should have them refurbished or install new ones? I see that one of our vendors has USA-made injectors at $200 for a full set. Assuming it's a quality product, it seems just about as cost-effective as refurbishing.