Hey guys,

Having a frustrating problem. My Disco will run fine, and then all of the sudden it will sputter and buck on acceleration.

It has happened twice so far. Once while accelerating from low speed (maybe 25mph) a few days ago, and then tonight after I pulled over to let a fire truck go by.

First time it pretty much went away after I let off the gas for a few seconds. Second time was longer - It was idling really rough when I stopped, then felt like I had just a little bit of power with a lot of roughness for about half a mile - it almost cut out once.

It finally smoothed out, so when I got home I popped the hood to have a look, and eventually it ran just a tiny bit rough - then stalled altogether.

I have also had the "M and S" lights flash at me twice in the past week. Both times it happened right after start-up, and both times shutting off and restarting made them go away.

Any ideas?

My battery has an unknown history. It measured 12.5v the other night. I charged it last night, and it ran fantastic today until tonight when I came home.

I checked every line and hose I can think of. I have previously replaced both plugs and wires, replaced air filter, and did an induction cleaning per Mikes instructions. I have not done tranny service yet after getting it a few months ago.

What else should I look for? I am seriously thinking of doing the battery to see if that helps, but I want to cover all the bases.

Thanks - as usual, you guys rock...hopefully I'll get this thing sorted soon.

 

Found the date on the side of the battery - March 2012, so it isn't as old as I thought it might be.

 

Makes me wonder that you state it happens not at start but after you have been running for a bit and go to idle. Okay when sitting still your alternator is not working as hard as it does when at higher rpm so it may not be pumping out the power to keep up the charge. Therefore your getting the "m" & "s" lights and its wanting to dawg out.

 

Spluttering at low speed sounds very much like the IAC (Idle air control) valve. You may get away with cleaning it but probably long term needs a replacement

 

I put a meter on the battery while running, and it ranged from about 13.6 to 14+ volts while running in the driveway and giving it a little throttle.

I was wondering about that IAC - I haven't found a link to cleaning it yet, but I will do a search.

The other strange part - no codes - even with the M&S lights having come on, and it stalling last night in the garage - everything comes up clean on the scanner.

 

Fix your M&S lights. The ECM will not operate your idle air control valve unless you are in a gear other than N or P. Plus it's obvious that something is wrong there so I would fix the obvious first.