I have a consistent misfire on cylinder 2, Ztech 2.0L dohc. I have replaced the spark plugs, coil pack, tested the compression and wires, switched injector from cylinder 2 to cylinder 3 and the misfire is still on cylinder 2. This started about 3 weeks ago and hasn’t been driven since. Maf sensor is clean, all hoses are connected. Is there anything else that it could be? The only other thing that I can think of is the computer, but I don’t know for sure. I’d rather not have to spend that amount of money if it could be something else.
Sooo are you outside the USA? We didn’t get DOHC Ztechs in our awful version.
How do you know the misfire is on #2? Not sure what diagnostic system you have on-board.
What were the compression readings? Was #2 low, wet or dry?
How did you test those wires?? Depending on when and if they were ever replaced, I’d just get new ones to eliminate any possibility - or at least swap #2 with another of similar length and see what happens.
If the ECU is original, it may very well be bad. The ECU is VERY old for electronics!
I’m in the U.S. I have an obd2 reader, and the same exact code comes up every time for cylinder 2. The compression readings were just above 60 psi, and the wires have been changed within the last year or so. We have a tester for the wiring, and it sparked the same as the others. The spark plug was completely dry on cylinder 2 so we replaced all of them just in case. The ecu is original, so that could very well be it, but it happened gradually. It was running fine, and then started running a little rough probably about 5-6 months ago. 3 or so weeks ago it died while I was driving back from filling the gas tank, of course. It started back up just fine, but there was another loss of power before I got home. Since we made the changes, it hasn’t died in test starts. We’ve left it running for a couple of minutes to recheck to see if the same code gets thrown and it does it every time.
Perform a leak-down test on cylinder 2.
Tester
What would I need to do to test that?
Compressed air and one of these.
Tester
OK, first off, OBD2 didn’t arrive on US cars until 1995 on some and 1996 on the rest. Second, the Escort did not offer a DOHC 2.0 engine in 1992. So what year is it, really?
Third, 60 psi compression is about 100 psi low. If I saw that in a compression test, I’d pull the engine and tear it apart 'cause it is a goner.
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Oh, that would be easy for me to get ahold of. I’ll try that.
Wow, my bad, it’s a 99. I have no idea why I put 92.
So how many miles on this engine? And did your compression test only show 60 psi, or are you referring to fuel pressure?
It has just under 160,000 miles on it, and I just asked the person who did the compression test and they said it was just over 90, about 92, on all cylinders. I thought they said 60 before, but apparently not. What should compression be at?
90 psi is still very low. Not exactly sure what your engine should be but over 120 psi. Yours is 30 psi low. Uniformly low, but really low.
A leakdown test, as @Tester suggested, would likely show more than a 20% loss which means the engine is worn out.
Could it be the head gasket, or would I need an engine swap if that’s the case?
Here’s what a leak-down test will reveal for that cylinder.
Tester
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Also, why would it only be throwing the p0302 if they are all leaking air?
Not a head gasket because of uniform compression readings. 160,000 miles worth of wear.
The “leaking” is past the huge gaps that are now in your piston rings from wear and the lack of valve seal at the valve seat, also from wear.
The misfire on #2 is that #2 has just reached the threshold of misfire. The others are soon to follow.
A 20 year old car is generally not worth the expense of a re-manufactured engine.
Too bad I truly can’t afford a different car at the moment.
Thank you for the help, I appreciate it.
I will have to check that too.
Thank you for the help.
With compression test values of only 90 PSI I would say that the test was invalid, the compression test wasn’t performed correctly. If the compression was that low you would have had problems long ago, if one cylinder drops below about 130 PSI you can get a fault/check engine light.
Check for power and ground to the cylinder # 2 fuel injector, preferably with a noid light. Also you can listen to each injector “click” with a stethoscope to see if it is operating.
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