My coworker gave me a 1999 Discovery II as a project a month or so ago. He was... lackadaisical about maintenance, so I've been working all of the bugs out.

When I got it, it was showing the following codes:
P1590, P0733, P0734, P0134, P0171, P0174, P1300, P0300-P0308, P1171, P0800

Having no idea how long those codes were on there or whether any work had been performed, I just reset them, but they may be useful to know.

Work done so far that may be relevant to the issues I'm having:
STI 8mm wires
E3.48 plugs
New PCV valve
New upper intake gasket
New fuel pump
Cleaned MAF sensor (with throttle body cleaner, which may have been a mistake)
Cleaned throttle body and IACV

So here's the issue I'm having. When the vehicle is first started, the transmission does not seem to engage properly. When you attempt to accelerate, it will get to about 20 mph in what I believe is second gear with what feels like a lot of slipping. If you put the pedal down all the way, it won't downshift, won't accelerate, and starts to throw misfire codes. Once the vehicle has gotten up to operating temperature... all of these problems go away.

After driving it for a couple days, the following codes have come back:

P1590 (It has the 3 amigos, which I'm in the process of dealing with)
P0134
P0171
P0174
P0734
P1300
P0300
P0301
P0303
P0305
P0307

So P0134 is a bad O2 sensor - real time scan showed abnormal voltages from the sensor, so I'm assuming it's dead. I believe P0171, P0174, and P0734 correspond to a bad MAF sensor. But I'm trying to figure out if the misfires and transmission behavior are related to those things or are caused by something else. It's safe to assume the transmission fluid has never been changed in the 215,000 miles that have been put on it. And all the misfires are on the same side as the bad O2 sensor, so could that be it?

Thanks in advance for any help.

 

You have a full bank of misfires and on O2 snesor code. Those are related.

You cleaned a MAF with throttle body cleaner. Yea, that's cooked.

215k with no service on the trans. Thats gonna be a mess if you open it up.
https://www.scribd.com/doc/254865544...-Repair-Manual

Link to the transmission manual. From your description, it may be very low on fluid or the torque converter is fubar.
Either way, you may be looking at a new(to you) trans and torque converter.

 

 

When I took the MAF sensor off, the adhesive holding the sensor together had disintegrated, so I figured it couldn't make things worse.

I haven't had the chance to look at the transmission fluid, but I'll be doing that shortly.

And I will also try cleaning the o2 sensor before I replace it.

Thanks for the suggestions!

 

So I have to walk back the transmission thing. I reached out to my coworker, and he says the transmission was serviced last summer, which is somewhat miraculous, as nothing else was serviced. Is this something that would happen if the transmission wasn't filled all the way? I understand the LR transmission can be difficult to fill if you're not familiar with the process.

 

Yea, sounds low on fluid till it warms up. Also, easy way to check your 02 sensor vs misfires it so swap the sensors left to right and clear the codes, see if they follow the sensor. You can unplug the maf sensor completely and it will default to using the TPS and rpm, not ideal but might run a little better till you can get a replacement. I recommend you buy a second disc and pull the maf out of it to test

 

Anyone have the transmission manual download without signing up for the BS account from scribd? I can host it on m site for free if someone has it.