1997 Ford Explorer Repair Question
Asked on November 29, 2010
Ford explorer sport engine light and code 171 and 174
I have a 1997 ford explorer sport 4.0 motor i brought it to auto zone to scan it and it came up with code 171 and 174 and it seem to run fine just really bad on gas and dont seem to have the power it should and in 2 gear if you give it gas when its cold it makes a pinging noise what would be the problem
Asked by strawAnswer
Replied on November 30, 2010
Check for vacuum leaks
check and clean MAF sensor
MAF sensors can get contaminated from a variety of sources: dirt, oil, silicon, spider webs, potting compound from the sensor itself, etc. When a MAF sensor gets contaminated, it skews the transfer function such that the sensor over-estimates air flow at idle (causes the fuel system to go rich) and under-estimates air flow at high air flows (causes fuel system to go lean). This means Long Term Fuel Trims will learn lean (negative) corrections at idle and learn rich (positive) corrections at higher air flows.
