dtc 171 174

jaydnjr · #1 11-08-2005, 09:28 PM

2000 ford windstar 3.8L- 50,000 miles bought used no warranty. check engine light came on today. Went to local autozone and the codes po171 and po174 came up. They told me that it was running lean in bank 1 and 2. couldn't get much info from them. So went online and noticed all the comments on replacing leaking manifold gaskets and bolts,etc. not sure if that is the problem, but the Ford dealer wanted 100.00 for a diagnostic check. Not sure if it is worth it? or is it a waste of time. or should I just replace the gaskets and bolts,etc. don't know what to do next because I have been told it could be anything from changing the spark plugs to the fuel filter and the o2 sensor along with the vacuum hoses. PLEASE HELP!!!!

DRW1000 · #2 11-08-2005, 10:26 PM

171/174 indicates a lean condition on both banks 1 and 2. A lean condition normally occurs when air enters the system after the MAF (the device that measures airflow). In other words the PCM "thinks" there is a certain volume of air and adds the appropriate amount of fuel and then the O2 sensor reads lean after combustion.

Causes include:
- MAF not reading correctly. Could be defective or dirty.
- Fuel flow problem
- Vacuum leak.
- Bad O2 sensor

I would not suspect the O2 sensor although they seem to get blamed more often than they should.
A MAF sensor theoretically can be cleaned. Fuel flow would probably affect drivability.

More than likely you have a vacuum leak. It is hard to pinpoint an intake leak but you could ensure that no hoses are loose. The infamous Isolator bolt leak is a good candidate and if you have no other drivability concerns that will probably be what Ford recommends after you pay the $100 for them to read the codes.

jaydnjr · #3 11-08-2005, 10:35 PM

to DRW1000: thank you for replying. most likely I will have to replace the bolts.

MT-2500 · #4 11-08-2005, 10:43 PM

Go threw what DRW1000 posted.

If that does not help there is a tsb no 3-16-1 aug/18
For the codes if they are stored in memory.
The deal with a new type valve cover.
A new fuel reg vacume hose .
intake gaskets.
And a PCM reflash.
Have your dealer run your vin no for tsb and recalls and PCM reflash on it.
MT-2500

jaydnjr · #5 11-08-2005, 10:52 PM

when we bought the van last year the engine light came on about a month after-we took it back to where we bought it and he said he would have to bring it back to ford to reflash the computer and we didn't have a problem until today. Is there anyway to know if he fixed the bolts and the gasket? thank you for your help.

MT-2500 · #6 11-08-2005, 11:10 PM

Hard to say. Have them check there repair records.
Did they put a reflash or campain sticker under the hood?
Does it have new or old style valve cover?
MT

jaydnjr · #7 11-08-2005, 11:36 PM

MT-2500: at the risk of sounding like an idiot-what exactly is a campain sticker and how do I know if they actually did change the valve cover- because mine has the year 1999 on it!?

DRW1000 · #8 11-09-2005, 09:46 AM

Quote:

Originally Posted by jaydnjr

MT-2500: at the risk of sounding like an idiot-what exactly is a campain sticker and how do I know if they actually did change the valve cover- because mine has the year 1999 on it!?

There is a way to determine whether the Valve cover was replaced (The position of the hole in the baffle under the oil filler but I don't have the details handy).

The valve cover replacement is supposed to be a preventative measure to prevent oil from entering the intake. I personally did not buy into that philosophy and did not bother replacing the valve cover on mine.
If you have the new valve cover then chances are the entire TSB was performed however not having the new valve cover does not necessarily mean that the bolts have not been replaced.

The rubber around the bolts deteriorates due to oil contamination and this causes the lower plenum to manifold seals to leak. The only sure way is to remove the upper plenum and check the colour of the rubber surrounding the bolts. The new design is green and the old design is black (I think but someone please verify).

This really is not that difficult to check. There are about 15 bolts and then you should be able to lift the upper plenum up enough to shine a flashlight in to see.

I will bet that if you only had 50K when you bought it that it probably was not done before.

I am fairly sure that this will be your problem but I listed some other simple things to check first. (rather than blindly stating what your problem is). This Isolator bolt/port seal issue affects a lot of Windstars and the TSB is written such that when a customer brings their Windstar into Ford and they exhibit 171/174 and have no other drivability issues than they simply perform the TSB.

MT-2500 · #9 11-09-2005, 10:15 AM

Quote:

Originally Posted by jaydnjr

MT-2500: at the risk of sounding like an idiot-what exactly is a campain sticker and how do I know if they actually did change the valve cover- because mine has the year 1999 on it!?

When the dealer peforms a tsb or recall they put a notification sticker on it saying what tsb or recall or reflash they have done.
Look underhood and on drivers door for the sticker.
And like DRW1000 says there is no way to tell for sure on the valve cover and intake gaskets except to look at it.
MT

MT-2500 · #10 11-09-2005, 11:46 AM

I only posted the tsb to help if all else failed.
Before you get into the TSB check out the things DRW1000 outlined in upper post.
Check fuel filter and fuel pressure and fuel reg. mass air flow sensor pcv valve and watch the fuel trims on a scanner or anything that can make it run lean.
Is the code stored in memory are they hard codes?
I think the tsb only refers to codes stored in memory.
MT

jaydnjr · #11 11-09-2005, 08:20 PM

called the dealership where we bought it from and he said that they reflashed it and the light came on again so we had to bring it back and they told us that they changed the gasket. not sure if it was one or both? when we push on the accelerator you can hear a whooshing sound coming from the back of the engine.

MT-2500 · #12 11-09-2005, 09:15 PM

You need to get it in and get it checked out.
Let us know how it goes
MT

jaydnjr · #13 11-11-2005, 08:49 PM

thank you to everyone for helping and giving free advice unlike the ford dealerships but anyway bringing my windstar in monday mourning for a diagnostic check will let everyone now whats happening and how muchit will cost me thanks

tateresa · #14 01-19-2006, 08:01 PM

Our check engine light went o over the weekend and we had it read- resulting codes 0174 and 0171(pending). the place we had it read turned the CE light off and it has not been back on again yet- it's been driven about 500 miles or so...should I be worried or wait until the light comes back on? There's no driveabilty issues now, nor were theree before the light went on...

dougand3 · #15 01-19-2006, 10:24 PM

Quote:

Originally Posted by tateresa

Our check engine light went o over the weekend and we had it read- resulting codes 0174 and 0171(pending). the place we had it read turned the CE light off and it has not been back on again yet- it's been driven about 500 miles or so...should I be worried or wait until the light comes back on? There's no driveabilty issues now, nor were theree before the light went on...

If the lean condition returns, it will reset the code and give the CEL. Don't worry.

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