Question about 1991 Ford F150
LOSSING POWER SEEM TO BE LOSEING POWER WHILE DRIVEING
1) Go to parts store and check error codes set by computer if Check Engine light is lit. If the converter is stopped up enough to affect power, a code should have been set, maybe even 3 or 4. Most parts stores do this free. Do not reset the error codes, unless you have high mileage and haven't replaced the air filter--if it's seriously plugged up, you're going to be sucking gas, losing power, and setting codes. If it's just the air filter, replace it and have them reset the codes. Same thing with the fuel filter, and even the fuel pump.
2) P0420 is a good indication converter(s) is/are bad. P0300 (random misfire) is a death knell for converters. P0131 and P0133 indicate bad O2 sensors, which can cause P0420. P0101 indicates mass air flow sensor, but none of these codes are guaranteed to identify the actual problem--there are over 30 things that can cause these codes. When the problem is actually a stopped-up converter, it is because the engine killed it somehow, usually due to misfiring, way rich fuel mixture, or bad gas. Bad gas kills converters double-quick time. Still, as with major surgery that may leave yo paralyzed, you want a second opinion to confirm or deny your problem, so the next step is:
3) Take vehicle to manufacturer dealer (Ford) and have them put it on the engine analyzer. Usually less than a hundred bucks, but it pinpoints the problem MUCH better than the OBD-II check at the parts store. Whatever they tell you is going to be right, because they want to fix it for $$$. If you want to fix it yourself, tell them thank you, but I'll pass on the repair, it costs too much for my wallet at this time (and it WILL). Do it MUCH cheaper yourself.
4) Ask anonther Fixya question for instructions on how to do the repairs if you aren't sure you can.
Posted on May 25, 2014
Disconnect exhaust at manifold flanges and see if engine runs better... yes it will be very loud
Posted on May 24, 2014
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Posted on Jan 02, 2017
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