Maximum Negative FMFR Correction Fault p1177

[Thomasmacer]

Hi,

can anyone help. I have a 98 Range rover and the check engine light came on, my local mechanic downloaded the fault code p1177 Maximum Negative FMFR Correction Fault - what does this mean? and can anyone let me know what might be causing the problem? i doesn't start real well in the mornings but once running it's seems fine. also sometimes has small missfire when starting hot.

thanks

[shiftech]

Just read a similar post on a UK forum.
Adaptive mass fuel flow rate is to high,(running rich)It means that the adaptive values are at their limit and cannot rectify the problem.A good place to start is the misfire as this will be picked up by the lambda sensor as a rich mixture.
Check the plugs on the lamda sensor are clean and secure.
I can give you the pin outs to test the lambdas and narrow the problem down and if it only occurs on 1 bank of cyinders/which bank etc.I'm not sure if this fault will reset the check engine lamp if it has cleared or wether its a trip to the dealers.

[Badger1]

My guess would be a mass air flow meter is dirty or bad. Had the same codes pop on my 97 Disco with a 4 liter V8(prob. the same motor you have). In my case the codes popped up after I took in some mud/water into the intake system while wheeling, but just from everyday driving some dirt and grime can accumulate on the wires. The MAFS is what tells your computer how much air and what temp that air coming in is, then the computer adjusts the fuel mixture using that info. I bet when you start your truck in the mornings it is running rich and you can smell it too. Try buying some mass air flow sensor cleaner at any local auto parts shop. Take off your positive battery cable, undo the wires going to the sensor, undo the two clips after your airbox, and the hose clamp on the other end, and spray that out. Hopefully that is all it needs.

[Badger1]

Also if you live in the States, and have an Autozone by you, they can test the codes for free(usually, depends where you live I guess). You could also rent a code reader for a refundable deposit too. That is a good way to go because then you can reset the check engine lights yourself.

[Rovin4life]

check fuel pressure to make sure its within tolerances. if not then also check that the fuel pressure regulator vacuum line isnt damaged, pull it off and inspect it for cracks.