Check Engine...P171/P174

Check Engine...P171/P174

I had this problem for awhile now and I finally found the resolve to it. I had changed the fuel filter,plugs,wires but no improvement. I replaced the battery(knowing it was bad) hoping that due to the low charge it was causing the PCM to fail, but no improvement. Then the idling started getting rough and stalling constantly. Took it to my mechanic, read the codes(again 171/174) and he found a leak on an elbow . Not sure exactly what it was connected to but here is a brief discription.

If you are looking from the front, it is a vacuum hose connected next to the IAC(to the left). When it warmed up the hole opend thus letting air into the system.

Hope this helps those out there with similar problems. Also the mechanic said that the chances of getting two O2 sensors going at the same time are very slim , but could happen.

Glad to hear your found the problem. Vacuum leaks seem to be the most difficult to find. Fortunately the parts for your repair should be a relatively small expense.

Thanks for posting the solution.

One way my mechanic said to find vacuum leaks was to take a torch , turn it on(don't light it) and if there is a leak , the vacuum will suck in the gas and you should hear the engine idle slightly different. Usually the RPM ramp up due to the increase in gas.Can also do the same with carb cleaner. Just follow all the lines and anything connected to the vacuum.Worked on my fix!!

Can also do the same with carb cleaner.

Ford warns against using carb cleaner to check for vacuum leaks, I believe it was due to IMRC failures.

Ford warns against using carb cleaner to check for vacuum leaks, I believe it was due to IMRC failures.

I didn't know this!! Maybe that was the reason why the mechanic suggested using a torch!! What effect could this have on the engine and sensors??

Look in internet about Ford TBS-03-16-1, it is a gasket failure. on all windstar 99-2003.

Look in internet about Ford TBS-03-16-1, it is a gasket failure. on all windstar 99-2003.

He's got a 96 so it doesn't apply. Glad to hear you got it solved, I seem to remember you posting about this in the past.

He's got a 96 so it doesn't apply. Glad to hear you got it solved, I seem to remember you posting about this in the past.

I did post this just before XMAS, tried several things but the problem didn't get fixed.I had just swiched mechanics about mid Jan, and this mechanic reallys knows his stuff. He actually is a GM mechanic, but he does work out of his garage at home in his spare time.Really cheap and he will actually let you watch him while he is working, explaining his reasoning to his troubleshooting. I heard him by word of mouth.I guess word of mouth is the best advertising cause he now has one new client. If we all could be this lucky!!

Forgot to mention in the last post. If it is something he thinks I can do on my own, he will tell me how to do it so I can save some $$$$

If I am correct, the "elbow" is the vaccum line that goes from the top of the intake manifold....back to the PCV valve. I had mine develop a leak also.
The PCV valve on the '96 is on the back valve cover.
I really like simple, cheap fixes. Much cheaper than the 4 oxygen sensors that some mechanics would have replaced.....and not solved the problem.

There are also a lot of vaccum connections on the back side of the upper intake manifold.

Check Engine...P171/P174

I had this problem for awhile now and I finally found the resolve to it. I had changed the fuel filter,plugs,wires but no improvement. I replaced the battery(knowing it was bad) hoping that due to the low charge it was causing the PCM to fail, but no improvement. Then the idling started getting rough and stalling constantly. Took it to my mechanic, read the codes(again 171/174) and he found a leak on an elbow . Not sure exactly what it was connected to but here is a brief discription.

If you are looking from the front, it is a vacuum hose connected next to the IAC(to the left). When it warmed up the hole opend thus letting air into the system.

Hope this helps those out there with similar problems. Also the mechanic said that the chances of getting two O2 sensors going at the same time are very slim , but could happen.
I found my code 171/174 issue....I suggest everyone look for the same thing before going into big $$$$
mine was the linkage for the IMRC ....plastic clip broke and it came off.
300+ miles on the van and NO CODES!
look on the left side as facing the motor....you'll see 2 linkage rods.