Running Rich

[ViPER1313]

All right, I'm trying to think of reasons a car can run rich. My SHO is getting around 11mpg in Harrisonburg. I have already:

-Replaced the O2 sensors (~7k miles ago, old ones were throwing a lean code)
-Cleaned the MAF with brake cleaner
-Replaced spark plugs
-Re-grounded engine
-Replaced thermostat
-Run a tank of STP complete fuel system cleaner

To do-
-Plug wires (although the ones I have are supposedly 30k miles old and are OEM quality)
-Fuel filter

Here are the previous spark plugs - the car still seems to be running rich at this point (black soot all over the exhaust & pretty dark black smoke under hard acceleration, poor gas mileage.) Any ideas?? Cause I'm out of them and tired of thinking.

[mpg9999]

Thats some pretty bad gas mileage, which makes me think it may be the o2 sensor. What did you replace it with? I replaced mine once with a crap track auto one and it went bad only a few months later. Its easy enough to check the voltage to be sure thats not still causing you problems.

-Mike

[JohnC]

All right, I'm trying to think of reasons a car can run rich. My SHO is getting around 11mpg in Harrisonburg.

Does that car have a distributor? Cap and rotor are cheap and easy to replace too. My money is on the 02 sensor as well...

[JackoliciousLegs]

Either way, the o2 is an easy check. If you need a DMM, stop on by 363.

[CaptainHenreh]

Just boost it.

The pressurized air will use up the extra fuel.

[JackoliciousLegs]

he knows what he's talking about... DO IT!

[CaptainHenreh]

he knows what he's talking about... DO IT!

:wink:

[NTIman]

Just for reference,a few things that can cause a rich condition are:
-Leaking injectors
-ECT sensor bad
-Thermostat stuck open
-Plugged air filter
-Restricted air intake
-High fuel pressure

[Andy]

Those plugs don't look rich nor do they looked fouled. From what I've been told, when plugs get that whitish, it due using too much fuel treatments.
I, however, don't know enough about fords to surmise what could cause a v6 to average 11 mpgs though it looks like you got your bases covered with 02 sensors and the like.

[Kaan]

ummm... those plugs are fine... thats what they should look like... and its not the detergents being added like the STP fuel cleaner or whatever... its just normal.

[Evan]

plugs look fine to me. they should be light grey

[ViPER1313]

I'm not worried about the ceramic color - the whitish is probably due to the fact the old O2 sensors were throwing a lean code. I'm worried about the thick black soot that is coating the surrounding metal. I'm just beginning to think I can't expect better mileage in H-Burg, even though I don't drive it that hard around town (I get 300+ miles to the tank while driving on the highway). Must be the short driving cycles and cold weather .

[Kaan]

I'm worried about the thick black soot that is coating the surrounding metal.

its called carbon... :roll: .... most motors will have that built up inside them over time :wink:

i'm not exactly sure whats going on to cause the poor mileage... BUT i dont think you need to worry about your plugs and IF they are telling you anything.

[Krush]

Those are some of the CLEANEST plugs I've seen.

First, 11mpg arond town....do you have a lead foot? The most you would prolly expect around town is 17 or so. Heavy foot will KILL it.

You need to find somebody with a scan tool and check all the parameters of your sensors. Example: my s10 blazer (4.3) was running like shit, spitting out black smoke and stalling. Turned out to be a bad connector to the temp sensor....computer thought coolant was at -50 (open circuit reading), so it was running super rich.

Crap in, crap out....that's how computers work.

[Rex4life]

i think 11 mpg in town is pretty good

take that thing to a dealership and get it hooked up on a diagnostic if you have a good connection. it might cost some $$$ but you will know what is wrong instead of throwing more money into it.

[JackoliciousLegs]

damned rotary engines....

[ViPER1313]

take that thing to a dealership and get it hooked up on a diagnostic if you have a good connection. it might cost some $$$ but you will know what is wrong instead of throwing more money into it.

It's OBD1, I have read the codes - there isn't anything a dealership can really do for me. What I need to do is take it to a dyno and get the A/F ratio read across the board (unless a club member has a wideband tailpipe O2 that I can borrow).