So I went to a local Shop and after telling the mechanic all the things I done to clear the Misfire, he asked me to turn on the car and he told me that he thinks it’s the Timing Belt. He thinks it might skip one tooth since it’s a Rubber Belt and should be replaced at 80,000
Can’t speak to your particular engine, but it’s fairly simple to verify the camshaft is properly sync’d with the crankshaft on my Corolla. It’s just a visual check of the timing marks is all, takes 15 minutes. Put the crankshaft at TDC compression stroke , then make sure the timing mark on the camshaft pulley is aligned with its mark. The only complication is you have to remove the valve cover as I recall. And make sure the TDC is the compression stroke & not the exhaust stroke of course.
As implied above, there’s likely at least one other problem besides the o2 sensor. The compression results are a little suspicious, but it’d hard to blame the 155 for the amount of problems you are having. Have you checked for a robust spark on number 1 spark plug? Is there anything unusual about this car’s history? Has it been in a flood, under water, even briefly? Was it running fine, then one day all of a sudden this misfire and generally poor engine performance started for no reason? Is there currently a difference in the misfire symptoms when the engine is cold (been sitting overnight) vs when it has reached normal operating temperature?
Shop may well be on the right track about the timing belt, but I’m guessing no, the valve timing is ok. For one thing, I doubt being one tooth off would cause such severe symptoms. Unless there’s a variable valve timing problem, but I don’t recall you posting any such codes. If it turns out the valve timing is spot on, the symptoms are consistent with not enough fuel being injected for the airflow, and its running way to lean. That will show up first as a misfire in the cylinder with the least compression, which is what you are seeing. Problems with spark timing could cause this, but that would usually show up as a diagnostic code.
Do you still get misfires if you completely disconnect that particular o2 sensor?
Well, I installed a new spark plug and that didn’t help.
No that I know. I bought the car at 140,000 and has never been in an accident. Theres no accidents records with its VIN #
Maybe. Cause here in Puerto Rico, Floods are very common. Also the it was a rainy day the day it started shaking like crazy.
It was running fine, except with the problem that started this thread. Idle was ok, but when I shift to “D” or “R”, the RPM’S began to fluctuate. That also happens right now. When is idling, RPM’S stays at 600 RPM Aprox. but when I shift to D or R, the car starts shaking like hell and wants to die and now has no power. Fuel economy has drop a lot too. So I think this is the same problem from the begining, but worse.
Same. It doesn’t matter if its cold or hot.
For one thing, I doubt being one tooth off would cause such severe symptoms…
Maybe its was one tooth off and now that is worse is two booths off xD
Yes. I tried that and the symptoms are the same. Also I want too add that I did an OnBoard Monitoring whit the OBD2 scanner while driving and while Idling and the O2 sensor pass all the Tests. Voltage was good and working properly, but as soon as the check engine light turned ON, the OBD2 Scanner showed a “Failed” mark on the OS2 sensor. So Is safe to say that the OS2 sensor is ok. Something else is triggering the fault. Also, its a new OS2 sensor… so…
You need to test for spark to verify the coil is working. When dealing with a misfire, testing for spark is usually performed before removing the fuel injectors.
Well, I tried a new spark plug and wires and that didn’t helped. What do you suggest? Test the distributor?
This just not seem to be going anywhere so I suggest it is time for a real shop to solve this.
Remove plug wire # 1 from the spark plug, insert an old spark plug into the wire, rest the base of the spark plug against something metal (not the plastic valve cover), start engine and observe the gap for spark.
Already did. They said it’s the timing belt which they think it skipped one tooth. Tomorrow the new timing belt kit will arrived through FedEx. Let’s see…
Will do. Although the OBD2 scanner showed good voltage on all spark plugs.
The spark is about 8,000 volts at idle, that is not on the scan tool.
I kinda agree. So now we’re doing timing belt in addition to everything else. I’m not a mechanic but just can’t see how the timing skipping a tooth would cause a problem on one cylinder or a fluctuating idle. I hope it won’t be off with the head next.
Well guys, here’s an update. I bought a water pump + timing belt kit that also include an idle pulley and tensioner and I did it myself following all the instructions on the service manual. Everything was installed by torque specs <3
Guess what… the problem is gone. No more misfires or Check engine lights. Car runs like new.
I want to thanks all of you for your comments and support. I hope someone else googling the same issue can resolve its car problem with this looong thread.
BTW… this was the hardest part. 120 lbs torque.
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Well I for one will admit I was a doubter. Never would have thought the was the problem, but that’s what these discussions are good for.
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Congrats. Asking a pro shop for diagnostic advice seemed to have turned the trick, good for you! The symptoms didn’t seem consistent w/ a minor skip of a cam-belt. Was the valve timing actually incorrect then? Was it off a lot? How many teeth? Any idea how it skipped like that? Problems discovered w/the tensioner or belt just plum worn out? Or were there several complicating factors?
I presume you mean tightening the crank bolt, done at the end of the job. Tricky b/c the engine rotates when you tighten it. You used the strap technique apparently. I think when I’ve done that on my Corolla I use those holes on the edge of the harmonic balancer. I fashioned a pin-tool with plywood and screws, so the ends of the screws were spaced so stuck into those holes. Then I wedged the tool against something that wouldn’t move. It was a one-time use tool, the force tended to destroy it, but one time is all I needed it for.
Yeah it rotates when you try and loosen it too. When my chain went, I actually had to block the crank from turning since the oil pan had to come off.
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Now you mention it, seem to recall like the harder problem was loosening the bolt.