andjmalo

Hi all,

I have a 93 f150 that is giving me some troubles. First some background -

For the past year or so I've been living out in New Mexico where I would drive country roads going 60-70 most of the time. Truck and I loved it. For the summer I've been living in Chicago and driving city streets. I noticed it was running rough almost right away after getting here. Then it would run real rough around 35-40 mph after being driving for about 45 minutes and it would stall a few times at stop signs or lights. It has been doing that for the past few weeks, though I took it on a 150 mile round trip ride (mostly highway) yesterday and it didn't stall at all - only with city driving. The check engine light is not on except when it stalls. I did run code once when it was not running and got one related to the EGR valve. Did a few maintenance things - fuel filter replacement, air filter, etc. Replaced the egr valve and no change (ended up returning it as it was expensive for my wallet).

Finally took it to a shop for a diagnostic and they said it was probably clogged catalytic converter and recommended replacing spark plugs and charged $100 for that information. Took it to a well reviewed muffler shop and they asked if I wanted to straight pipe it vs get a new cat. I took them up on the offer as I wasn't sure I trusted the shop that told me about the clogged cat (though it did make sense with the symptoms to me) and would rather spend a lot less in case it isn't fixed - turns out was probably a good choice for now... After that, I did the spark plugs and wires, drove it on that 150 mile trip and today did some city driving and it stalled several times at stop signs and was running real rough just at idle off and on. It has never left me stranded but it is threatening to - though it is intermittent.

Any ideas on where to look or what to do next? Don't really want to, nor can I afford to, throw money at random parts.

Thanks in advance. - Andrew

fomoco998

Check codes again and check for vacuum leaks.

andjmalo

Checked the codes - engine off code (does not have check engine light on when running for the most part). I was getting one check engine, then two quick, two quick. Pause then same thing - I took that to mean 22 - which seems to be related to a MAP sensor. I replaced it because I figured I could return it easily if it doesn't work - it didn't work. Once it gets heated up and driven for at least 20 minutes - it dies almost at every stop sign or stop light - which isn't a good thing in Chicago!

Also, haven't heard any hissing or anything to indicate vacuum leaks - also don't really understand how vacuum leaks would cause such an issue only when warmed up.

Any suggestions?

Thanks for the help again

fomoco998

Probably not reading codes correctly. Invest in a code scanner $35 well spent. Heat can effect vacuum lines due to their age.

andjmalo

Thanks. I went and got a scanner - I'll look into it tomorrow and take a closer look at the vacuum lines.

andjmalo

Ok Think I made progress. Getting a continuous memory code of 122 and so was looking at wiring around the throttle position sensor. I found when I mess with these wires pictured - I could get it to stall pretty consistently. My theory is when the truck gets warmed up and I rev the engine the vibrations was causing the wire to rub against the very hot radiator hose going into the TPS as they were very close together. When I got it to stall and had the check engine light on I checked it and got code 122 in the engine off on run position mode so confirming my theory I think. Does this seem likely?

If so, how to I go about testing the wiring and/or replacing it? Also what is it? Read somewhere it could possible be the wiring into the idle air bypass valve but not sure on that. Electrical is not my forte but do own a multimeter.

Thank you again - saving me tons of money hopefully by not sending it to mechanics who don't know anything about pre 95 cars anyway it seems.




What is this and how do I replace wiring on top? The thing closest to the alternator, not the one connected to egr valve. Thanks!

andjmalo

Did a bit more research and seems the part is e4tf-9c915-aa - a vapor canister purge valve. I am still unsure exactly where the problem is but I know that is I move that canister around I can get the engine to stall. I attempted to get some reading with my multimeter to see if voltage was in fact going down but couldn't get anything concrete. I put my black wire on the negative battery and red I poked into the electric that was hooked up to the canister - I would lose some strength here and there but nothing consistent and it looked more like because my red wire was getting off a connection.

Any suggestions or help with replacing wiring and/or possible solutions?

Thanks again!

sdmartin65

Pull the connector off the purge valve and use a paper clip to short across it while the truck is running. If the engine dies then one of the wires under that wrap is cracked and shorting. Unwrap the wiring and look for the bad spot or spots. I'm betting it will be easily seen.
Edit. It could also be the connectors are corroded. Most all under hood connections have a rubber insert to keep water out but many times the rubber piece doesn't get put back in when the connector is unplugged.

andjmalo

Just an update - I tried to short the wire and nothing happened. I then looked down below the throttle body and noticed a connection - some sort of temp sensor or something - where the plastic piece was partially pulled off so it kept coming off, I think. I put it on tight and drove it around all day today and yesterday and everything seems fine. So perhaps it's solved?! Hopefully it is! Thanks for all the help!