Rich exhaust and smoke

TRX2FIVEO

MEMBER
1992 FORD F-150
V8
2WD
AUTOMATIC
148,000 MILES

Hello, this will be my first post here. I have the truck listed above with a 5.0Liter, it's been sitting for about 1 1/2 years I have already done a complete tune on it plugs, wires, cap, rotor, fuel filter and air filter. My issue is that for one the truck will not accelerate if you floor it. If you ease on the throttle, it will eventually get to 55. Lol. The second issue is while it's sitting you can't stand to be anywhere near the truck for the rich exhaust and smoke. I have cleaned the throttle body, checked for vacuum leaks, cleaned the EGR passages and replaced the MAP. I have added seafoam to the fuel which I feel may be the whole issue since it's stale? Any insight would be most helpful. Thanks in advance.
Moose

3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

There are a couple of things that will cause the engine to run extremely rich even in these older trucks.

Basically, any computer-controlled engine relies on correct sensor reading.

This means we need to know the correct amount of air that is coming in and the correct fuel pressure. The PCM uses these two things including all the temperature sensors to properly match the amount of fuel needed.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

The PCM can only control the amount of fuel so it needs to know how much air and at what temp to get the proper air fuel mixture.

Lastly it relies on the o2 sensors to tell is exactly what it is doing so that it can make adjustments based on rich or lean exhaust.

So, we need to check all these sensors and see if they are showing that the air is coming in and proper fuel pressure and temperature.

Then we need to see that the o2 sensors are seeing that the exhaust is rich. If it is not, then the o2 sensors are the issue.

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor

If all this checks out, then more than likely the PCM is the issue, and it is not able to adjust things properly even though it is getting correct info.

Let's start with this and go from there. Thanks

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