Hello, I need a little help figuring out an issue. I have a 98 disco with 168k on it. I am seeing codes 1193, 0451, and 1508. Here is what is happening: She will start fine and run fine for a few days, then go through a phase where she either won't start or will stall out soon after putting her in gear and then not start again. To make it start, all I have to do is unplug the main harness from the fuel pump and plug it back in. I know that sounds strange but it consistently works. FYI, the fuel pump is new, the fuel relay is fine, and the idle control valve has been pulled and cleaned (I have a new one to install when/if the time comes). Also, after running about town for an hour or so, the idle will get rough, almost stall out. I welcome any educated opinions on how to fix this, thank you.

 

1508 is an idle speed control unit failure, have you cleaned both the t/body and the IAC?
1193 is a 02 sensor heater circuit open downstream, have you ever replaced all 4 02's?
451 is a evap control system pressure sensor out of range.
How do you know the relay is OK, there are 3 separate relays in that one black box and you can only determine if all 3 are working with an OHM meter.

 

I have not cleaned the throttle body, just the IAC. I have not replaced the O2 sensors yet. I opened the relay box, tested each and observed them working. I thought 0451 was a Fuel Tank Pressure Sensor Signal Error Fault, is that saying the same thing?

 

Same thing on the 451.
Can't say the 02's will fix your issue but you are way past do for them.

 

I had the valve cover gaskets replace and while they had it it would not start for them and they said, "they unpluged something on the firewall passenger side and it started. After I got it home I went to start it and show it to someone who wanted to buy it and it would not start. The next day it started. I drove it and while driving it it stopped running, I pulled off the road and it started back up. Drove it home and after parking I want to move it and it would not start. Later I went out and it started. Please any help I can get it's a 98 disco.
Thanks

 

I agree on the O2 sensors Mike. My best guess on the situation is that I should go ahead and replace the IAC valve and get the adaptive memory reset. Does that sound unreasonable to anyone?

 

If they unplugged something it was probably the inerita switch on the passengers side of the fire wall.

 

When was the last time you replaced the fuel filter?
Replace the fuel filter if not done receently, and hook up a fuel pressure gauge.
fuel pressure should be around 38 psi. If it starts to drop off or is low you need a fuel pump.

 

Mike, I had came to the same conclusion that you had posted inerita switch. Purchased one off E-bay for less then $20. Will let you know if that takes care of the problem thanks.