Engine check light on

Tiny
JAMES CHINULA
  • MEMBER
  • 1993 TOYOTA COROLLA
  • 1.6L
  • 4 CYL
  • 2WD
  • MANUAL
  • 300,000 MILES
The car starts but after I travel and stop for more than ten minutes it fails to start. Even if I push start it that time it will not start. It will only start after an hour or two after a very strong push start. If I step on the gas consistently the rev count goes up and down on its own then normalizes after some three minutes.
I have done the OBD1 check it gave me code 14 Ignition signal. Code 2 airflow meter signal and code 4 engine coolant temperature signal. I do not know what to do after that.
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Thursday, May 4th, 2017 AT 3:14 AM

3 Replies

Tiny
CARADIODOC
  • EXPERT
Code 14 means the engine computer is losing the signal from the sensor that tells it when to fire the injectors and ignition coil. On your engine, that sensor is the pick-up assembly inside the distributor. Those often fail by becoming heat-sensitive, then they work again after they cool down for about an hour.

We will address the other codes once the stalling issue is resolved. Unfortunately fault codes on 1995 and older vehicles are not very descriptive. They just tell us which circuit to look at, but not why.
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Thursday, May 4th, 2017 AT 3:35 AM
Tiny
JAMES CHINULA
  • MEMBER
This was very helpful, that is what is happening with my car. Which part is the pick up assembly? Can it be replaced? Is it becoming heat sensitive because the engine is overheating?
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Thursday, May 4th, 2017 AT 4:28 AM
Tiny
CARADIODOC
  • EXPERT
Not due to engine overheating. The pick-up assembly, or in other cars, the crankshaft position sensor and camshaft position sensor, are full of electronic circuitry. Heat is the deadly enemy of electronics, regardless if it's your home audio amplifier, your tv, or the power circuits in automotive computers. Cars, with their vibration, heat, moisture, and dust, are the worst possible environment to plant electronics and expect it to survive, yet the insane engineers seem to be unable to do what we did for 100 years without incorporating numerous unnecessary, complicated, and unreliable computers. You drive a '93 model. I drive a '94 model so I don't have to worry about all the useless toys they've added on.

Well, ... To get back to my wondrous story, electronic components, mainly transistors and integrated circuits, are easily destroyed from heat, so the modules and assemblies have some means of getting rid of it. Usually that means bolting susceptible parts to a block of aluminum to suck the heat away. The problem is the parts are sitting in an area that is going to get hot under normal conditions. It's just a matter of time before a transistor fails. The thing is, a transistor is basically good, meaning working, or bad, meaning shorted or not working, but they can gradually bounce between those conditions for a while before the failure becomes permanent. That's what I mean by "heat-sensitive". When a transistor reaches a temperature at which it becomes shorted internally, that entire circuit or part stops working. It is very common for that part to cool down within about a half hour to an hour to the point the short goes away and it works again. Due to the placement of some of those parts near the front of the engine, they might remain cool enough from natural air flow to keep working while you're driving, but the most common complaint is you stop briefly, as in when stopping for gas, and when you come back, the engine won't start. The cause is called "hot soak". That is when there's no air flow, and the heat from the stopped engine gradually migrates up to the sensor and causes it to fail.

Computers can become heat-sensitive too, but 99 percent of the time it's a sensor that happens to, and it is most likely to happen to the sensors that tell the Engine Computer when to fire the injectors and ignition coil. Without signals from those cam and crank sensors, or in your case the distributor pick-up assembly, the computer won't fire the spark plugs and the injectors won't spray in fuel, ... And you have a crank / no-start condition.

I only checked one source, and they did not show a listing for your pick-up assembly. The only way to repair a failing sensor is to replace the distributor. That is usually because replacing the pick-up assembly can be a very tedious and time-consuming job, and you still have to pull the distributor off the engine. It's a faster and more reliable repair to install a rebuilt distributor that was professionally rebuilt, and has a warranty.
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Thursday, May 4th, 2017 AT 6:13 PM

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