I've looked through old threads and can't help but wonder if these two are related given their respective functions. Replaced MAF Saturday. Test drove for 15 miles and worked great. Monday and Tuesday great. Today, not so much (about 45 miles after MAF install). Rover felt slow unless I put the pedal down on the way to work. Same after work on the way to an appt. Leave the appointment and now rough idle. Had another stop, start again and normal idle... Go to Autozone for codes and get the P0734 and P0441 (purge valve) but no 0171 or 0174 like I did have. The 0441 is new. Unplugged the Rover for 45+ minutes, start and still rough/weak idle.

So here are the questions, did one mask or cause the other to fault? Why still the implausible 4th gear ratio (P0734)? Faulty new MAF? Purge valve will go in quick.

Thanks.

 

Who made the new MAF, where did you get it? PO734 is usually still a bad maf code. Check all your connections at the sensor plug, maf housing connections, make sure that huge o ring is seated good and that the air box cover is sealed well. Not sure about the purge valve code.

 

Everything is tight.

 

Got it from RockAuto, reman. I cleared the codes Wednesday, nothing back yet. Checked gas cap. Hopefully the ecu just didn't fully recognize the new maf. The lean codes were gone though.

 

441 is an incorrect purge flow in your evap system which will not cause a bad running engine.
My money is on a bad MAF. Disco's are real sensitive about MAF's. I have never seen anyone sell rebuilt MAF's . Your truck won't even run well on an after market or generic MAF. Send the one back to where ever you bought it and get one from British Parts of Utah and you will be fine.

 

Think that's what I'll do. Hopefully RockAuto isn't a pita to send this thing back. The guy at bputah has been good to work with in the past.

 

I tried 3 aftermarket maf sensor's (Lucas) from 2 LR parts suppliers before I got a geniune Bosch maf and my codes finally went away. Very frustrating.