Help. Disco running rough and rich
 

Hey I have a 98 disco 1 and it is running really rough until you get to about 2000 rpm and even at that it isn't smooth. When I slow down it will stall out if the gass isn't depressed. I got a maf from a junk yard and still no luck. Also there is no lights on the dash?? Please help.

Extra info

New alt and charge wire.

First of all.. Did toy expect a MAF from the junk yard to fix your problem?? You should always get known working parts from a parts supplier to rule out your issues.

Give me more info - how do you know it's running "rich"? also is your check engine light on?

Start with a tune up.

I know I shouldn't get used Parts ,but I was using just to see if that was the problem.

I know it's running rich by the smell.

There is nothing wrong with used parts, but you need to know what is wrong before you buy parts.

High probability is the O2 sensors are shot and it is running rich because the ECU is reacting to bad inputs from O2's.

Have you puulled a few plugs to see what they look like?

New plugs, plug wires, clean the plenum ports really well including the IACV and it's porthole, the TPS porthole and the other ports on the plenum from the charcoal cannister/purge valve line as well as the main air input and butterfly valve and throttle linkages.

If you bought it with lots of miles and unkown care, it probably needs a complete going over. And use premium gas.

Wouldn't the o2 sensors trigger the check engine light??

That depends, if they are non responsive, or reading out of range then yes, they will set off the CEL.
If they are working but not giving the correct signal then no.
They can be covered in soot and not set off the CEL.

How does one go about checking an O2 sensor to verify it is working properly?

If you download the GEMS manual in link in my signature, see pages 33-53 for detailed explanation of what the engine computer is doing, in terms of constant checks and tests of the O2 sensors. It is based on precise voltage measurements and comparison to stored previous readings and standard min/max values. So a lot of ECU time is taken up with these tasks. Doesn't mean it will catch everything or not be fooled by certain conditions, like sensor fouled by whatever.

Here's a link to a video of how sensors should look, and a bench test with volt meter and torch. Auto Repair: Oxygen Sensors - Testing and Replacing (1 of 2) - YouTube

And some plain text write up of testing - Oxygen Sensor Information

And a handy tester that works in or out of the car - Amazon.com: GTC ST05 Oxygen Sensor Tester and Simulator: Automotive