First off I have to pump the gas pedal several times after van has been sitting overnight. Once started it idles smoothly and everything seems ok. If I gently depress the gas pedal it accelerates fine and sounds good. If I quickly depress the gas pedal the engine sputters hesitates and backfires. It also does this when I am driving it. With gentle acceleration it seems ok but under load or up hill or on quick acceleration it again hesitates loses power backfires and sounds like its only running on 4 cylinders. Occasionally the check engine light comes on but never seems to want to be on when I go to Autozone. It was on one time when I stopped at Advanced Auto parts but they told me it was too old for them to scan!! Somebody told me it sounded like an O2 sensor so I went looking for it from the manifolds to the tips and could not locate the sensor!! Autozone says its on the manifold but they are wrong and the Ford dealer says its on a pipe but didnt know where exactly???? Any ideas or suggestions would be greatly appreciated! Thanks dbg

 

heres the sensor on a 93 f150


yours i believe are on the back of the exhaust manifolds. right above where the exhaust pipe bolts on. only accessable if you take the engine cover off. i'd check fuel pressure. how olds the fuel filter? you could manually read the codes. using a paper clip or piece of wire connect the self test input, which is the loose wire, to the signal return pin, which the one on the taper side of the connector, its the closest one to the shorter taper. i'll get a pic up here in a minute i cant explain it better.

 

here you go

 

Thank you for responding.I pulled the cowling/engine cover and didn't see the sensor. As far as the fuel filter that was replaced within the last year. I considered fuel pressure also. I was advised to pull the vacuum hose to the fuel injector pressure regulator and see if fuel ran and it did not. I am staring to wonder if maybe it is a weak fuel pump or the screen/filter may be clogged with debris. I don't envy the thought of dropping my tank to verify and clean. Is there a way to test the fuel pressure to rule out that possibility?

 

Concerning the self test....how do I interpret the results once I have made the connection you suggested??

 

yup get a fuel pressure gauge and hook it to the shrader valve on the fuel rail(gotta pull engine cover again). should be at least 30 psi at idle with a good pump. do a couple snap throttles to test the regulator. it should jump up. and then pull the vacuum line off the regulator and it should once again jump up. if it doesnt jump up for either then its either a bad regulator or the pump is very weak.

sorry bout that. you gotta turn the key on and watch the cel flash. each time it flashes is one number in the code. a slightly longer pause between flashes divides codes into 2 or 3 digits. there will be about a 6 second pause between each trouble code.
example- code 32= flash 3 times- short pause- flash 2 times- then a 6 second pause to start the next trouble code.

if you dont get the codes written down in time then just turn the key off then turn it back on and it'll repeat itself. if you cant understand it right away i'll completely understand because i was never very good at reading it with this method. i think there is actually a code reader for the odb1 systems for like 30 bucks somewhere. i'll look for it real quick and i'll post the link.

heres one
http://www.amazon.com/Equus-3145-For...6474309&sr=1-1

 

Thank you for all your great advice. I have ordered the code reader from Amazon as suggested. I really appreciate you taking the time and effort to help me resolve my problem. Have a great holiday weekend. dbg

 

Finally found the oxygen sensor it was well back of the manifolds where the two pipes came together and it was connected between the two exhaust pipes.Someone cut the wires to my O2 sensor about 1/2 inch from the male connector. .It was obvious that it was cut with wire cutters,all four wires were squashed and crimped at the same location! ..My question now is should I splice it back together or should I just get an OEM replacement?? I have a feeling it was done by a garage my girlfriend took it to @ one time. Second question is there are 4 wires one black one gray and two white wires,does it matter which white wire goes to the other white wire??

 

i'd just go onto rockauto.com and get a bosch or motorcraft brand sensor. the wires do have to match where they go.