P0301 and Stumble: 98 ZX2 | Ford Escort Owners Association (FEOA)

P0301 and Stumble: 98 ZX2

Discussion in 'ZX2 1998-2004 2.0L DOHC' started by timturner, Sep 29, 2007.

  1. timturner

    timturner Guest

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    The stumble occurs at idle once the engine has reached temperature, and about 2,000 RPM on acceleration. The P0301 code comes up.

    I changed the plugs and pulled the fuse for the A/C. The plugs were worn (300,000 km on them) but all four looked in good shape. It ran like a top for a week then the problem came back when I put the A/C fuse back in. I pulled the A/C fuse again and the problem persisted. I’ve no idea if powering the A/C circuit had anything to do with the stumble or was a coincidence.

    I recently replaced the Relay Control Module because the clutch relay had burnt.

    Does anyone have any troubleshooting ideas?

    I appreciate that some people may have opinions about spark plug brands, but I’m hoping to avoid that discussion here.

    Thanks

    Tim
  2. timturner

    timturner Guest

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    I think I’ve eliminated a couple more possibilities but still have the misfire on cyl 1.

    The vacuum seems fine at 19-20 in.

    I also swapped the 1 and 2 injectors and the misfire stayed on 1.

    Does anyone have any other ideas to narrow it down?
  3. RonS

    RonS Guest

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    I didn't see you write about this but did you check plug wires?
  4. timturner

    timturner Guest

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    Thanks for the reply RonS.

    Not yet but I’ll try that next.
  5. timturner

    timturner Guest

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    It occurred to me after swapping the injectors that there wasn’t much pressure when I relieved the fuel rail. I put a gauge on and it only measured 12 psi. My misfiring cylinder 1 was at the far end of the manifold and the pressure was supposed to be 55-85 psi so I rationalized I'd found the problem. Of course the first thing to do is change the fuel filter – it’s only $10 anyways. After installing the new filter (an awkward job) I measured the pressure again and it was still 12 psi. I picked up the old filter and blew through it without much resistance (mmm, tastes like Tequila). I jammed the air compressor into the gauge and it measured – 12 psi. It turns out the $7 fuel pressure gauge I’d picked up pinned at 12 psi. I guess my only fuel problem was a cheap gauge.

    In the meantime I checked the VCT, IAT, MAF and coolant sensors, PCV valve and various and sundry wires and connectors. The stumble only got worse. I put a spark tester on the wires and watched a bright blue spark snap flawlessly for at least 5 minutes.

    I picked up new wires (the old ones had 300,000 km on them so I figured a good maintenance schedule was to change them out anyways). I decided to pull the new plugs and have a look at them. 2, 3 and 4 looked new if just a little blued. However, when I pulled the cylinder 1 plug oil ran out of it. The plug was fouled!

    At this point I did a compression test. All four cylinders were almost identical. They squeezed 120 psi on the first press and 185-190 psi after 5 or 6 compression strokes. That reassured me somewhat.

    I cleaned the fouled plug and put it in cyl 2 and installed the new wires. Took the car out on the highway for about a 50 km run it ran like a top. I pulled the cyl 1 plug again and it was clean and blue. I realize 50 km wasn’t much of a test, and I won’t consider myself out of the woods until the car’s ran well for a couple weeks.

    What fouled the plug though? I have a bit of a confession that I hope might explain the oil. About 40 days ago I did an oil change and put in some 0w30 synthetic that I run in the winter. The car got hot and I realized my mistake and changed the oil again the next day. I screwed up again and grabbed my van’s oil and put in 10w30. The ZX2 didn’t like that either. After a couple of weeks I read that Ford was now recommending 5w20 for the ZX2 for better mileage so I thought I’d try that. Well, after seeing that oil in cyl 1 I changed the oil again today and put 5w30 back in.

    I should also mention that the timing belt broke earlier this summer. It happened at idle and there didn’t seem to be any damage and the car ran great for a month after the failure. I don’t want my problem to be valve damage so I may be in a bit of denial.

    Does anyone think the thinner oil might have caused my oil infiltration problem? Are there any theories as so how I’m getting oil into cylinder 1 only and still have good compression (and a smooth running engine when the plug’s firing)?

    Thanks for any ideas.
  6. digitalvehicle

    digitalvehicle Guest

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    Does anyone think the thinner oil might have caused my oil infiltration problem? Are there any theories as so how I’m getting oil into cylinder 1 only and still have good compression (and a smooth running engine when the plug’s firing)?

    Bad rings? The extra oil would help seal the rings. But you would be seeeing some smoke from the tailpipe. You know i've had the same prob on my EGT, I pulled a plug and it was all oily. come to find out it was a valve cover gasket that leaked the oil, when I pulled the plug it just covered the plug end to make it look like the cylinder was full of oil.
  7. boostedzx2

    boostedzx2 Guest

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    Yes sir , specially on the zx2 valve cover gaskets are known to leak. You can fix this by taking the valve cover off , cleaning everything up nice and using some rtv along with the gasket. You should see the oil on top of the plugs though if it's leaking from the gasket.

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