Check Engine Light, misfires

CARHEADACHE2020

MEMBER
1992 TOYOTA COROLLA
4 CYL
2WD
MANUAL
200,000 MILES

Car starts fine, but after driving along for a few miles, it will start to misfire and jerk, and the Check Engine Light will flicker on and off rapidly.

After this happens for a few miles, the car will stop misfiring and jerking, Check Engine Light will be a solid color, and the car will have no problems after that.

The Check Engine Light will not be on when you start the car, again.

There are no codes to pull.

Also, the oil was changed about a month ago, and when I checked it two weeks later, it was black,

Any idea what the problem is?

Also, is there a reservoir in the engine area so I can check the level of the manual transmission fluid? If not, where do you add it?

Vehicle listed above is a DLX wagon.

3 Replies

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Hi,

If the check engine light is flashing, that is an indication of a misfire. You mentioned there are no codes. That is odd. Have you checked for codes prior to turning the key off and having the light reset? Take a look through this link and see if anything helps.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Also, if you have a live data scan tool, could you let me know the short-term fuel trims?

As far as the transmission, you will need to remove the plastic splash pan under the engine compartment. Locate the transmission. On the side of the transmission will be a check/fill bolt. I can't remember the exact size, but it may be 19mm. See pic 1 below for the location.

Remove the bolt and the fluid level should be even with the lowest threaded point of the fil/check plug.

Let me know about the drivability issues as well. Also, here is a link the explains the most common causes of a check engine light being on:

https://www.2carpros.com/articles/check-engine-light-top-ten-reasons

As far as the oil, if the oil hasn't been changed on a regular basis, sludge and dirt will build up in the engine. When you install new oil, it has a detergent in it that will start cleaning right away. That causes the oil to get dirty really fast.

Let me know what I can do to help.

Take care,

Joe

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Friday, October 15th, 2021 AT 5:57 PM

CARHEADACHE2020

MEMBER
10 POSTS

Hi,

The light will not re-set until you turn the car off. When you try and pull a code, the light just keeps flashing. The manual says that if this happens, there is nothing wrong with the car.

I just ordered a scan tool (which will make it much easier to pull a code instead of using the paperclip method) so I do not know what the short-term fuel trims are. What could be the problem with the car if short-term fuel trims were a problem?

As far as the oil, it has been changed on a regular basis, so that is not the problem. I also noted that in less than a month of changing plugs, they had carbon build-up on them.

A friend of mine said it could be something to do with a coil or a throttle position sensor.

Another friend said it could be the muffler or the catalytic converter.

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Saturday, October 16th, 2021 AT 1:54 AM

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Hi,

The fuel trims will tell me if the engine is getting too much or too little fuel. As far as a scanner, since it's an OBD1, chances are it may not provide that info.

Thinking back, I remember the light staying on solid indicated no codes. However, if the manual says blinking indicates no codes, that's what I would go with.

As far as the plugs having carbon, are they black, dry, and have soot on them? If that is the case, that is commonly caused by a rich fuel mixture.

If they are black, wet, and have oily deposits on them, that could indicate they are oil filed. That can be caused by worn piston rings or oil getting past the valve stems and seals. That could also indicate why the oil is getting dirty fast.

Let me know. Also, as far as the suggestions that were made, I could see how any of them could cause issues. However, in this case, I have a feeling it has to do with fuel pressure. You may have a regulator going bad that is working and then failing. That is a theory at this point. Hopefully, the scanner you get will help.

Let me know.

Joe

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Saturday, October 16th, 2021 AT 8:23 PM