I agree with your mechanic if you were listening for the right thing. I'm assuming this engine is pretty quiet. With so many misfires I would expect an audible hiss and I would expect lean/rich codes. I have pulled my fan just to listen for leaks They sometimes take longer to show up than misfire codes.

I don't believe in throwing parts at issues, either. But I'm lucky enough to have some extras and a friend with a disco so I'm able to borrow things like an MAF. Several years ago I had misfire issues and called Disco Mike. He listened to all I had done and suddenly announced that I needed a new MAF. I thought he was full of beans and I ignored that advice then did some other things, all of which were unsuccessful. In desperation I borrowed my buddy's MAF and the problems disappeared. Instantly. Mike was right.

You have so many new things in the engine bay and have done so much work, there are few things that could be causing the misfires at this point. With that many misfires, I'm thinking it could be the MAF. Bad knock sensors can also cause the computer to think you have misfires, but when mine have gone bad (or the wires melted) I had an instant code. I use the amazon cheapie MAF and have not had any problems.

I just accidentally went back to page 1 of your thread. Beautiful Disco!

 

I'm currently transitioning from Vermont back to the seacoast area; switching jobs and looking for new place to rent so any future investments in parts or service for my truck are on hold until I get my **** squared away. I have been "eyeballing" a replacement MAF sensor for awhile now...

Thank you Charlie_V for the tip and compliments on my truck. Myself I do like throwing new parts in my truck because it does give me piece of mind and it quickly eliminates possible causes of issues. But money dictates.

How does everyone else feel about the MAF sensor as being the likely culprit? FYI I have cleaned it with MAF cleaner afew times since ownership of the truck and most recently during the tinkering I did. The sensor does not look damaged or appear to have any contaminants on the sensitive element inside the sensor.

 

See if you can get a replacement MAF that can be returned if it doesn't solve the issue. It's possible for both new and used items, either of which will solve the problem if the MAF is the cause. If it's not the MAF, you might not be out more than the cost of shipping.

 

Triarii you are a detail oriented person and probably already knew this, but for others, cleaning the MAF requires that you let it completely cool down. I read a discussion on the elements and learned that it can take hours. If not, when the spray hits it, element gets microscopic cracks.

I'm not that patient so I've just gotten new ones and cleaned the old one for a spare after a successful drive.

 

It's not that complicated. If you understand how the MAF works, it's simply a piece of wire that's heated up exactly like a wire in your toaster. The hotter it is, the more resistance it has to current flow. As more or less intake air flows over it, it is cooled, changing the resistance. The resistance is measured to estimate the airflow.

It does not take any longer to cool off than a toaster wire. It will cool off in less than five minutes. It simply doesn't have enough mass to store heat longer than that. It's a tiny wire.

Cleaning it with a solvent cleaner like MAF sensor cleaner, non-chlorinated brake parts cleaner, acetone or something like that doesn't accomplish a lot. The hot wire itself will burn most contaminants off just like the wires in your toaster. It's the housing surrounding the wire that can accumulate dirt and grunge. The solvent cleaners can remove that without leaving a residue on the wire.

You could make the wire brittle by heating it up and then immediately cooling it off too rapidly like with a spray of cold solvent. If that doesn't break it, it will likely be annealed (softened) when it is reheated. There isn't much need to worry about microscopic cracks because of this annealing.

Wire element failure is not the only thing that can cause a bad MAF. There can also be wear, damage, and failure of measuring and electronic components (there's a circuit board on the side). There isn't a lot you can do to prevent or cause these failures. It's often just a result of time, age, vibration, and other stresses.

 

I'm rubber, you're glue.

I read that somewhere.

 

I understand how the MAF sensor operates and like I said I have used MAF cleaner. Have not used any other cleaners on the unit. I dont recall ever using MAF cleaner while the truck was hot though. But perhaps you guys are right about the MAF sensor housing itself that could be bad now. I hope the cable that plugs into the MAF sensor is not the problem. I will source a used sensor when I can and test it out for a week and see what happens. Ill keep this posted. Thanks again for the tips.

 

ARB Awning finally installed. Mounting hardware/brackets were missing from packaging so I had to improvise. Setup is pretty straight forward - requires a step stool for the vertically challenged but still a one person setup/put away job. Worth the investment.

 

Wow. That's nice! And not just the awning. Very nice looking Rover.

 

Nicely done. I have mine mounted on the drivers side but it extends a little further.
Did you end up resolving your misfire woes? I could loan you my spare MAF if you wanted to eliminate the MAF from being the root cause.