99 Windstar Engine Codes 171 & 174

Anyone have any experience with these codes and a fix that will work? My van, bought it used, has had the "Check Engine" light come on twice in the last six weeks. The first time was code 174 and the second time was 171 &

174. The 174 indicates a lean mixture and the 171 something similar (I forgot exactly what it is). The previous owner had the problem and Ford 'fixed' it under the warranty. He had the problem later and once again Ford 'fixed' it. His most recent probelm was around 42,000 miles and mine is at 65,000. I have his dealer maintenance records.

I will make an effort at searching for vacuum leaks and will replace the PVC valve and possibly the fuel filter. Any help with fixing this thing for good will be appreciated.

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Thanks for the tip.

It?s a common defect built in by Ford. The plastic intake manifold is secured to the lower manifold with eight isolator bolts with rubber collars. The left hand valve cover (toward front of engine compartment) has a hole in the pvc baffle which allows copious amounts of oil to be sucked into the manifold. The rubber in the isolator bolts reacts to the oil and softens. This allows air to get pulled into the manifold around the bolts and makes the engine run lean. A redesigned valve cover, isolator bolts, and manifold gaskets will run you about $150 at your local Ford dealer. If you let the dealer do the work, they will charge around $750 to $900 to fix the systemic defect. Earnhardt Ford of Tempe wanted to charge me $1400 to do mine. I found a webpage with detailed pictures and step-by-step instructions. I was able to do the work in around 4 hours and saved $1250 over Earnhardt?s bill. The 171 and 174 codes have since cleared and I can face emissions testing in four months with confidence now.

The website for the repair instructions (and TSB) is

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