# Check Engine Light-Ford Focus ZX3 2003



## wilecoyote (Aug 17, 2009)

I have a Ford Focus ZX3 2003 with a 2.3 liter engine. My check engine light came on, so I put my scanner on it and pull up a code P0171. I erased it and drove around with the scanner plug in and had a hard code of P0171 and a soft code of P2195. Can anyone help me trouble shoot these codes? I've put a vacuum gauge on with no vacuum leaks. I changed the fuel filter. I've cleaned the MAF sensor. The scanner shows the O2 sensor checks ok, MAF sensor ok. I don't have the values of the sensors to check them out. Any help troubleshooting these codes would be appreciated.


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## Wrench97 (May 10, 2008)

That motor has 2 O2 sensors upstream and downstream, sensor 1 is the upstream in the exhaust manifold in the front of the engine, did you check both sensors with the scan tool?

Does the P0171 code come up right away or only after a long highway speed drive?


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## wilecoyote (Aug 17, 2009)

The code states, system two lean bank 1. I think that would be the upstream O2. The exhaust is in back next to the firewall. The scanner shows both O2's ok. The code does not show up right away. When I come to a stop I usually put the car in neutral (manual transmission) and coast to a stop, the RPM's stay high (1800 to 1500) then drop to 1000 for about 3 to 5 seconds then drops again to 750. Then when I accelerate, it feels like the engine is starving for fuel, bogs down, hesitates, then the CEL comes on. This does not happen all the time.


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## Wrench97 (May 10, 2008)

That sounds like a vaccum leak or Idle bypass valve sticking. Do you get a hissing sound when stepping on the brakes?


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## wilecoyote (Aug 17, 2009)

From inside the car, when I brake, I here no hissing. I've check the air tube between the MAF sensor and the throttle body, and no cracks or leaks I can see or here.


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## Wrench97 (May 10, 2008)

The vacuum leak would be after the throttle body between the throttle body and the cylinder head, or any vacuum operated device that would allow an air leak that's why the idle stays up/drops slowly. I think that has a plastic upper intake manifold which tend to leak after awhile spray with soapy water and listen for changes in idle speed, the other possibilities are the MAF sometimes *tapping* with a screwdriver handle will duplicate the issue, or a dirty Idle air control valve which would have to be removed and inspected.


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## wilecoyote (Aug 17, 2009)

I connected a vacuum gauge to the intake and got 18.5 lbs of steady vacuum. So if the MAF sensor is bad, tapping on it with a screwdriver should create the problem. I haven't check the Idle air control valve. Wouldn't the scanner have values for each of those components?


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## Wrench97 (May 10, 2008)

MAF's can be troublesome, I've seen them before that did not show a code but have a rough idle and clear when tapped, or run the engine lean and when tapped go to rich.


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## wilecoyote (Aug 17, 2009)

So, should I have the scanner plugged in to see if there is a voltage change, or just tap on it and see if the code comes back?


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## Wrench97 (May 10, 2008)

Tad and see it the idle changes if not it's probably ok.


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## wilecoyote (Aug 17, 2009)

I tapped on the MAF sensor and the idle did not change. I cleared the codes and drove around for about 20 minutes with the scanner (Actron CP9180) and came up with some new codes. P0300 random/multiple cylinder misfire detected, P0301 cylinder 1 misfire detected, P0304 cylinder 4 misfire detected, P0316 misfire detected 1st 1000 Revs, P2195 O2 sensor stuck lean 1/1. These codes are Pending codes (soft codes) CEL did not come on.


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## Wrench97 (May 10, 2008)

All can be caused by either a vacuum leak or clogged injectors not delivering enough fuel.
Either too much air or not enough fuel.


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## wilecoyote (Aug 17, 2009)

So, being that I connected a vacuum gauge to the intake and did not detect a leak, the problem are my injectors. How should I go about cleaning the injectors?


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## Wrench97 (May 10, 2008)

The vacuum gauge test will only mean there is not a large leak.
There are injector cleaning kits but that would be done by a shop.they're to costly for DIY use. Some shops can also test the injectors. Keep in mind they range in price from $25 to $80 depending on what discount and where you get them so a lot of shops are no longer spending large amounts on test equipment. 
Another thing I was thinking is to test the fuel pressure low pressure will cause lean conditions.


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## wilecoyote (Aug 17, 2009)

If I'm checking for a vacuum leak, am I listening for a leak or looking for a leak? I've checked the vacuum hoses and could not see any cracks or disconnect hoses, pcv hose looks good. When the engine is running it idles fine with no shaking, every so often it will miss fire. No hissing that I can here while the engine is running.


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## Wrench97 (May 10, 2008)

I also use a squirt bottle of water, with the fuel injected systems unlike a carb, the idle is actually controlled by bypassing air around the throttle body so a small leak will not cause a rough idle the idle air control valve will not open as far and the cylinders get the same amount of air, since the fuel is sprayed at the intake valve past the leak the cylinder still gets fuel and air just not the amount the ECM/PCM is commanding. When opening the throttle body you get the TPS and MAF sensors measuring data but the leak causes air to get in the system around the MAF thus not measured.


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## wilecoyote (Aug 17, 2009)

So where do I squirt the water and what am I looking or listening for?


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## Wrench97 (May 10, 2008)

At any connection after the MAF including the intake manifold to cylinder head, if it's a split or 2 piece manifold don't over look that gasket area, also check the rubber grommet in the breather hose to intake pipe connection.


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## wilecoyote (Aug 17, 2009)

I'll check it tomorrow morning. Thanks.


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## wilecoyote (Aug 17, 2009)

This morning I started my car and let it warm up for about 3-5 minutes. Before I started to use the squirt bottle, I noticed it started to idle rough . I had to step on the accelerator to keep it from dying. After the engine evened out, I used the bottle and squirt water in all the places you had mentioned and I did not notice a change in the idle or noticed the water being sucked into any crevice or joint. Do you have any idea what's going on?


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## Wrench97 (May 10, 2008)

No it's tough without having the ability to hear and touch it, but I would check the fuel pressure make sure it's 20-25 psi.


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## wilecoyote (Aug 17, 2009)

I'll have to go out and get a fuel pressure gauge. I might have to wait until the 1st unless I can find a inexpensive one.


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## wilecoyote (Aug 17, 2009)

I found a friend with a fuel pressure gauge. Fuel pressure is normal. He had a pressurized can of cleaner that hooked up to the fuel rail. pulled the fuse to the fuel pump, started the engine and ran it until the engine died. The car runs great now and so far no codes.

Thank you for your time and knowledge, it is much appreciated.
Chris


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## Wrench97 (May 10, 2008)

Good to hear you solved the problem.


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