Running Lean w/ EFI

[haseltonk]

While I was changing my front crankshaft seal on my 96 Metro I decided to pull the plugs and take a look at em since I think they have about 40,000 miles on them…and this is what I found.

http://www.webaphoto.com/pictures_vi...47567127010750

If you click on the thumbnail it will blow up the picture. This car has 110k miles, and is fuel injected (and yes it’s 3 cyl). From looking at the plugs it looks like it is running way lean to me. Since it’s fuel injected is there something that’s could be causing it to run so lean, bad sensor or something else? I'm used to fiddling w/ carbs so I don't have a clue where to start. Isn't the damn computer supposed to automatically correct the A:F ratio? When I changed the plugs last time I don’t recall it being bad at all so I’m pretty sure this is a new problem.

[fredjacksonsan]

Check out this site for spark plugs pics and diagnosis:

http://www.centuryperformance.com/spark2.asp

I think your plugs looked fine. How many miles were they in for? I'd look into changing them maybe every 15-20K, that 3cyl likely revs pretty good.

[Snow93]

plugs look good, no probs..

[Moppie]

They look alright.

When I first went from owning a Carbertted car to a fuel injected one I asked the same question when I first changed the plugs, as they came out looking like the car was running lean.
And compared to a carb engine it was.
But its ment to, EFI as a general rule provides more precise fuel metering, and allows the engine to run leaner resulting in much cleaner spark plugs.
However if you take a close look you will still see deposits around the ceramic, and on the ground electrode, they will just be much smaller than on a plug pulled from a carb engine.