Contour Enthusiasts Group Archives Forums General Troubleshooting I've tried EVERYTHING...

Okay, the symptoms are: surging idle (which disappears temporarily any time the computer's memory is wiped), most pronounced when halfway warmed up; occasional CEL, with code 0171 "too lean", that appears when climbing or accelerating; significant loss of power, and mild loss of mileage.

Here is what I have already tried:
- look for vacuum leak
- injector cleaner in tank
- fuel filter
- cleaned MAF (soaked with brake cleaner)
- remove CTA and put stock intake back on (for smog inspection)
- restore CTA, double-checking for non-airtight joints
- look harder for vacuum leak
- replace PCV valve (the old one looked perfectly good)
- check EGR valve
- check all PCV and EGR plumbing as thoroughly as possible
- more gas tank injector cleaner
- (getting desperate now) replace oxygen sensors
- pull out fuel rail, inspect and watch it squirt into open air... no sign of any clogging

An inspection of the spark plugs does not show the pale color associated with a long term lean condition. If anything the color is on the dark side, though overall the plugs look healthy.

I don't know what to think, except maybe there's still a vacuum leak. That would explain the idle trouble. But how could a leak explain the lack of power with throttle >50%? It would have to be huge.

The only thing I can think of to try now is to get a hand vacuum pump and try pumping out various vacuum circuits and see what holds air. There are four vacuum hoses attached to the manifold. There is also the EGR pipe. The other possible points for vacuum leakage are the manifold's gaskets...

Or maybe there could be leakage down in the crankshaft chamber, letting in air (or exhaust) through the PCV. My god... maybe the piston rings are leaking... hot exhaust blowing back into the intake manifold... no, that would get tons of oil into the PCV, right? There was no oil to speak of in there.

I guess another possibility is that the EGR is open too much of the time? But again, I can only see how that would affect idle, not running at high throttle.

Or maybe the MAF needs replacing. But if it's not dirty and not broken, how could it go wrong?

See my responce here.

My previous recommendation.

By the way mine CEL for P0171 has been gone for 4 months and the car has driven a little over 4000 miles.

Just got through with the symptoms you mentioned...tuned out to be the MAF which was replaced under Emissions Warranty.

One question: does your car die with the a/c on at idle? That was a symptom that slowly became more pronounced (and aggravating) as time went by.

Regards, Art

So it's possible that the MAF can be contaminated with silicone? There has actually been some silicone spray around my air filter... not enough, apparently, to poison the oxygen sensors... Would brake cleaner fail to remove silicone? What does remove silicone? Acetic acid?

I haven't noticed trouble with the AC, but then I only run it about twice a year. The last time I used it was a few weeks ago and it didn't cause any stall.

I was going to voltmeter the MAF as my next step anyway...

The MAF is Contaminated with Silicone from the Factory. It's not removeable and repeted cleaning will only limp it by. The car gets just a little out of line from build up and throws the code.

My MAF from FPO was only 50 bucks.

Hm. My MAF was fine up through last summer, so I don't think it's a factory problem.

What is FPO? Are they online? The best price I've seen is $89 from fordpartsonline.com. Kragen and Autozone want $101 for remanufactured crap!

If I have to buy a new MAF, maybe I should get a larger diameter one. Do you know anything about what is or is not a workable replacement? Would a duratec MAF work? Those cost like 50% more...

Possible FPO = Ford Parts Online

I had a P171 and it was the MAF. BTW - Ford Parts Online's MAF (at least for an 98 2.0L) is remanufactured. It is a genuine Ford part, the rep said they don't make new ones anymore. You'll also get charged a $70 "core charge" till you ship back the old one.

Sometimes you can not clean a MAF. Try disconnecting it seeing if you get your power back. If so, it is the MAF.

It was my MAF, sure enough. Had black crud on it, despite having been cleaned this spring. I hope I don't have to clean it every three months...

Gaah. If I need a new one I might as well spend $200 for a 70mm Pro-Flo, maybe.

But maybe "remanufactured" is actually perfectly good -- probably means they replace the electronics and use the same metal body. The metal doesn't wear out, so I see no reason not to reuse it.

You should not be building up crud on the MAF unless unfiltered air is getting into the airstream. Oxidation on the element is understandable, however, since it is a heated element. Check for leaks.

-Lance