will not start when hot?

Hi,

Based on the description, it sounds like a possible issue with the crankshaft position sensor. When they begin to fail, they are adversely affected by heat. Once they cool, they work again.

Do me a favor. Take a look through this link and let me know if it seems to mirror what you are experiencing:

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

Also, when it refuses to start, check to see if there is an ignition spark to the spark plugs.

Here is a link that explains how that is done:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

Let me know what you find or if you have other questions.

Take care,

joe

I have seen engine coolant sensors heat soak and short out to cause this issue, to be sure let's disconnect the sensor when it won't start to see if anything changes. Here is the location. Check out the images (below). Please let us know what happens.

Replaced crank position sensor, car runs much better, still would not start when hot. Replaced coolant sensor, now starts when hot but sluggish.

Sorry, I spoke too early. Still will not crank when hot. Code says coolant sensor output high, and cylinder 3 misfire.

Hi,

There is a good chance we have a short to power between the sensor and the ECM/PCM. If it is a P0118 code, that indicates there is an excessive amount of voltage coming from the ECT sensor to the PCM

Did you try what Ken suggested above as far as disconnecting the sensor to see if there is a change?

Also, disconnect the ECT sensor and with the key in the run position, check for a 5v power signal. The connector should have two pins. One is power and the other is a signal wire. Therefore, one connector pin will show nothing and the other should have 5v to it. Check that so we can confirm there is nothing is shorting from the power supply. Note: You are checking the connector on the wiring harness side.

If that checks good (approx 5v), then we will need to check return voltage at the ECM which is a little bit more involved, but still not hard. Additionally, inspect the connector pin to make sure nothing is allowing the two pins to touch.

Let me know what you find and let me know if the code you are getting is a P0118.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

One last thought. LOL If your scanner can provide live data, before starting the engine in the morning (engine cold), check what the ECT signal is indicating and let us know what you find.

Take care,

Joe

code is p0118.

voltage coming to sensor is 4.6 volts.

Hi,

Were you able to check the voltage between the sensor and PCM? (Signal voltage) If that is 4.6v, we may have a short to power.

Let me know.

Joe

with the ignition on, voltage coming to sensor is 4.6v.

I need to know the signal voltage back to the PCM. If it is 4.6v, that is too high.

Let me know.

Joe

Have not had chance to check voltage return yet. Trying to work on the car while driving car. Only car available. Getting code for o2 sensor out of range sensor 1 bank 1. Is this the up-flow or down-flow sensor?

When you say it will not crank, do you mean the engine will not turn over (starter)? or the engine is cranking but not running?

Please go over this video:

https://www.youtube.com/watch?v=lXLJbuAZ4CE&pp=0gcJCb8Ag7Wk3p_U


Please go over this guide and get back to us.

engine turns over but will not crank (run) when hot. Sometimes I can disconnect the engine coolant sensor, and it will crank sometimes not but, wait a few minutes and it will run. What I really need to know right now is which o2 sensor is bad. I cannot remember the code, but it says sensor 1 bank 1.

I have seen the fuel pump get weak and stop working when hot. Have you done a fuel pressure test?