speed_demon
New Member
- Joined
- Aug 21, 2007
- Messages
- 18
- Reaction score
- 0
- Points
- 0
- Age
- 43
- Vehicle Year
- 91
- Make / Model
- Ford
- Transmission
- Automatic
I just bought a 91 Explorer 4.0 "as is" advertised as being a good runner but slowly lost power and eventually would stall with the application of throttle. I figured if the fuel pump cycles its a plugged filter. The pump cycled but sqealed a little. I then thought install the filter and see how it goes. Sure enough the old one was plugged bad and after cycling a few times the fuel pump sounded better. It runs and idles but stumbles and misses. At lease I know the IAC is working. As it warms up the miss gets worse and I see a black spot in the grass where the exhaust exits. I pull a vacuum line to induce a leak and it runs better but still rough which confirms it's rich.
I figure its probably a temp sensor, a dirty mass airflow sensor, or possibly a bad or fouled o2 sensor. I'm also guessing the rough idle is due to fouled plugs as a result of the rich condition.
Which of the two coolant temp sensors is in charge of the fuel mixture?
How do I test? Can I use a multimeter to check resistance cold and hot? What should it be reading?
How do I test the MAF sensor? ohm specs needed.
What else should I check?
That isn't all though. At idle the voltage bounces around when the engine stumbles. The battery seems strong so I figure maybe a bad chassis ground but can't be sure with all the other issue happening at the same time.
Thank you so much for any help. I'm kinda screwed if I can't get this truck running well. I have to pass emissions and I'm a little nervous right now.
I figure its probably a temp sensor, a dirty mass airflow sensor, or possibly a bad or fouled o2 sensor. I'm also guessing the rough idle is due to fouled plugs as a result of the rich condition.
Which of the two coolant temp sensors is in charge of the fuel mixture?
How do I test? Can I use a multimeter to check resistance cold and hot? What should it be reading?
How do I test the MAF sensor? ohm specs needed.
What else should I check?
That isn't all though. At idle the voltage bounces around when the engine stumbles. The battery seems strong so I figure maybe a bad chassis ground but can't be sure with all the other issue happening at the same time.
Thank you so much for any help. I'm kinda screwed if I can't get this truck running well. I have to pass emissions and I'm a little nervous right now.