About Grant Mcleod Expertise ford 7.3 diesel and most ford technical problems excluding, automatic transmissions and air conditioning. I have access to all current technical service bulletins and shop manuals
Experience I have worked in ford dealerships for the last 20 years as a technician, service manager and shop forman, as well as working with ford on solutions to some technical problems
Automotive - Engine Repair/Troubleshooting; '93 Ford Explorer
Expert: Grant Mcleod - 8/24/2004
Question Hi Grant,
I would greatly appreciate your repair help with my truck which is a '93 Ford Explorer. I'll provide you with a little history first that may help you in answering my questions.
About 3 weeks ago, I started to have problems with the Explorer. It would run rough and some black smoke was coming out of the exhaust once it arrived at normal operating temp. During this time, the "Check Engine" light would come on and off periodically. As I would accelerate, the engine would run better but at idle, like at a stoplight, it would run really rough. This would happen intermittently over a period of a few days. In fact, one morning, 5 miles into my 12 mile drive to work it ran great but then all of a sudden it started to run rough and emit black smoke again. Then it changed to running rough all the time, either cold or hot to stalling at idle, to not being able to start it now. I have sinced checked, with a meter, the (IAT) Intake Air Temp sensor, the MAF sensor and the Idle Air Control Valve and all appear to have the correct readings for either voltage or resistance. I have a Scan Tool and have checked the DTC and the stored codes are 113, 157 and 158. Code 113 is IAT sensor circuit open, or reads -40F. Code 157 is MAF sensor circuit below minimum voltage. Code 158 is MAF sensor circuit above maximum voltage.
Do you have any recommendations what I should do now? Can a faulty oxygen sensor(s) cause this problem? What about a bad or clogged catalytic converter? What may cause it not to start now?
Thanks in advance for your help. It is greatly appreciated.
Brent H.
Answer Hi Brent
Did you go through any large puddles or very heavy rain before this started?
A bad IAT may cause a slight drop in fuel economy but no real change in performance. check the vac line to the map sensor and all vac hoses for leaks. I would suspect a severe vac leak, bad mass air flow or map sensor or low fuel presure
I doubt the O2 sensor is causing your problem.
