carlu

Got a stock 1985 Maxima SE that just started running very rough. Smells like it's burning very rich. Step on the gas and it spits and dies. Hardly maintains an idle. Can't even drive it. ECU codes indicated a 12 for MAF sensor. It was bad, replaced it. Still have same problem and still getting a ECU code for MAF. Checked new MAF per Maintenance Manual works great. Replaced ECU, no help. Ohmed wires from MAF TO ECU, checked ok. Owned this car for 18 years and have never had any major problems before. Gave it a fresh tune-up a few months back. ( plugs, wires, cap, rotor, coil etc.) If anyone has any ideas I sure would appreciate it.
Thanks

maximase86

iTrader: (24)

Have you check to make sure you seated the MAF sensor in to the vaccum chamber portion of the intake piping. From experience, if air gets in after the MAF sensor, the engine will start running extrememly rich. Have you check the mixture ratio on the ECU? Any other codes being thrown like a CHTS?

S

Charles Bisel

Also, how far can you rev up the engine. If the MAF is broken, the car won't rev past 2000 rpm. It should rev up fine until you get to that point, then it'll start stumbling. That's because the ECU isn't getting the correct information from the MAF, so it uses a preset fuel/air mixture up to 2000 rpm so you can 'limp home'. Also, do as Sarin said and make sure there are no air leaks anywhere, that can also cause the condition you are describing.

-C-

carlu

Got a new MAF, checks ok per the manual. Can't really rev the engine up, it runs so bad. Haven't been able to check mixture ratio for same reason. Looked for vacuum leaks but haven't been able to find any. Probably better take a closer look at that. Thanks for your input, this is really starting to drive me crazy.

86Wagon

Just an outside thought... changed the fuel filter or air
filter lately?

Just thought they might have been overlooked...

Might want to check your fuel pressure as well

Scott