Hi, I have a '98 disco with 135,000 on it. about 1-1/2 months ago, my CEL came on. My scanner said "1178". My research shows its "max positive AMFR correction". Which I was told basicaly means it's running lean and the ECU is trying to correct for it by richening the fuel mix. The tailpipe has a nice coating of black soot, which tells me its running rich?? So far, i have replaced fuel and air filters, cleaned the MAF with the good kind in the gray can specifically for MAF's(properly following the directions), replaced both pre-cat o2's, eliminated any source of vacuum leaks with the exception of the intake manifold gasket. I have replaced the plugs and wires, I cleaned out the T-body as instructed in other posts. The car runs really good. It takes anywhere from 1- 3or4 days after I clear the code before it pops up again, and it almost always comes on with the car idleing and not driving down the road.

I have come to the conclusion that I'm looking at either an intake manifold gasket, since it did spout a small coolant leak. That tells me it aint in very good shape. Or a new MAF sensor. I am just confused why the ECU thinks it has to richen the mix(if that info is correct) when there's so much soot on the tailpipe.

Any input or info would be gratly appreciated. And thanks to those who have already helped with other issues I've corrected by reading other posts, It's been invaluable. I want to get this corrected before all that soot starts to clog my cat's( I've already priced them).

 

Well, oddly enough, i changed my oil and tranny fluid. When I did the oil, i added some thick seal conditioner and stop smoke(leaks oil but no smoking) And strangly enough, this code hasen't come back in a week. Hope i didn't just jinx myself.