I purchased a Land Rover Disco 2 with 137,000. I think I have a few issues going on...

Coolant Issues
The previous owner had replaced the radiator and I assume it had previously overheated. I filled the coolant tank because it was very low.... I've driven it for about 100 miles and I recently had to add more coolant. I could hear it boiling out of the overflow tube tonight when I was driving 60 mph uphill... I plan on checking it again tomorrow morning to see how much coolant I lost... I don't see any smoke from the exhaust and the oil seems fine.

Misfire Codes
I was receiving misfire codes 300 and 308 (and 413) and could see sparks at night when looking at the plugs. I replaced the plugs / ignition coils last night. After the plugs / coil were replaced I received the 300 / 305 codes. During my 10 minute test drive, while driving 55-60mph, I had one occurrence of feeling like the engine was sputtering for a second the Check Engine Light flashed, then returned to driving. It feels like I have some lost power, but can sustain speeds of 70mph.

I drove about 75 miles today and still am getting the 413 / 300 / 305 codes. During my hour drive I had two occurrences of the engine
sputtering for a second when I was driving 55-60... Then no other problems...

I use a OB2 App on my iPad. I was watching the MAF (Cycled from 65 through 10 reading), Coolant Temps (held at 183 the whole time)... The
one item that seemed out of normal was the Vacuum gauge, it was cycling from Positive 15 to Negative 15. I'm not sure if that's normal or what
that even means...

Any ideas? The engine runs quiet and idles around 600rpms.

 

There isn't a MAP Sensor on the D2... is this a separate gauge you installed, or was it an OBD reading?

Did you replace the wires, along with the plugs and coils?

 

We replaced the plugs and wires, sorry, not the coils...

I plugged in a used Mass Air Flow Sensor (from my old Rover I use for occasional parts)... That cleared a code and now returns a reading on my app gauge...

I think I have a vacuum leak, so I plan on checking the bolts and hoses tomorrow.

Any advice is much appreciated!

 

If you're losing coolant from the reservoir the first thing to do is replace the reservoir cap. It's a $15 part and they do eventually fail to hold pressure. If that doesn't stop the coolant loss we'll move on to other possible causes.

 

You might want to invest some time is a cooling system pressure test and a cylinder compression test. Both machines can be rented or loaned

 

That would be a good next step after replacing the cap, but if it is a bad cap the pressure test won't reveal it because the pressure tester screws onto the reservoir in place of the cap.

 

The 413 is coming from the vacuum solenoid valve that operates the secondary air system (if you have SAI, if not ??). It's located behind and below the idle air valve - a connector may be wonky. If you have a vacuum leak in the system, you should be getting a 171 or 172 code. Make sure you're not losing coolant out of the throttle body heater, which drips on the LH valve cover and runs to the back, sometimes evaporating before it gets to the ground. A 301, 307, 302, or 308 misfire could indicate head gasket since they're next to the coolant path and relate to coolant loss.

 

If the coolant appears to be "boiling" in the overflow tank, it could be a crack in the block and a slipped cylinder liner. The cylinder compression is forced around the liner, through the crack in the block and into the cooling jacket and into the cooling system, appearing to overheat. ..very common on these engines..

 

Hey Guys,

So... I took off and cleaned the throttle body with throttle body cleaner. I also put a can of the bg44k stuff in a full tank of gas...

I've driven about 1/4 of the tank and already noticed a great difference. The throttle seems much more responsive, flashing Service Engine light is gone, and no codes for misfire (drove for 2 hours with no misfire codes)... I can still sense a very slight hesitation, but it is 90% better than before. I'm hoping the injectors will keep being cleaned over the last 3/4 of the tank...

I'm down to one last code, 413.. I opened a new forum thread for that...

Thank you again for your feedback and comments.