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Hard start on hot (heat soak) engine

Old 03-04-2013, 11:53 PM
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Default Hard start on hot (heat soak) engine

2005 LE - 2AZ-FE 2.4 L with 203k mi

I don't know if it's in fact a "heat soak" problem, but it sure looks like it. It's my wife's car, so I don't remember how it behaved before, but it seems different now. About 3-4 month ago the driver started complaining of hard starts. I went to check, it sure starts like a charm on cold or immediately after it is shut down. Giving it a bit of time to cool (or accumulate the heat under the hood, depending on how you look at it, it has a very hard time starting. Cranking for a prolonged period of time and finally starts but reluctantly.
Does this model have a radiator fan timer/switch that keeps the fan running after the engine is shut off until the coolant is cooled to a certain temperature?
I know I have it on my Volvos, and remember having it on Hondas, but can't recall hear it run on this Camry.
If in fact it does have something like this, please let me know where to find it.

Last edited by mikmik; 03-05-2013 at 09:52 AM.
Old 03-05-2013, 10:14 AM
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The car does not have fans that operate if the ign switch is off.

The throttle on this engine is electric. The computer controls the throttle position which controls idle speed.

The computer uses an engine coolant temp sensor (ECT) to now when the engine is cold and as result adjust fuel flow via the injectors and throttle position.

Might check the ECT sensor.

When the engine finally does start reluctantly is there any smoke coming out the exhaust? Perhaps a indication of an over rich condition caused by a leaky injector, etc.
Old 03-05-2013, 11:43 AM
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Thank you toyomoho,

There is no visible smoke from the tail pipe when restarting warm, only a bit hazy smoke when cold. But again, it starts right up cold.
Is there an "easy" way to check the ect on this car, or need to replace it?
One piece of information i forgot to mention, of course...
When i started suspecting the heat soak, I left the hood open a couple of times to see if letting the heat escape easely would help the restarting problem and it did. I tried insulating the fuel lines under the hood and it did absolutely nothing, at least nothing positive.

Old 03-05-2013, 03:42 PM
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Your thinking vapor lock? Might be bad fuel or fuel adjusted for a different time of year.

You can check the ECT with an ohm meter. Has two wires, might be colored green/yellow and brown.

At 68F 2.32 - 2.52K ohms
At 176F 0.31 - 0.326K ohm

The temp vrs ohm reading graph is more or less linear.

Location is drivers side of engine. You can check readings engine cold and hot with sensor on engine. The ECT is monitored by the computer and would generate a code if the problem occurred on a consistent basis.

Might pick up a few cans of cold spray. After a hot soak no start condition, spray electrical items such as MAF, TPS, crank and cam sensor, coils, etc. This would be a quick and dirty attempt at locating a failing part.

Something more formal would be to hook up an ODBII real time scanner and take note of what is happening engine cold and hot plus look for pending codes. Pending codes are set when an item fails a self test once. It typically takes failing twice for the check light to come on.

If your checking the ECT ohm reading also check that of the crank and cam sensor.

Cam sensor reading
Cold 835-1400 ohm Cold is temp sensor body temp of 14F - 122F
Hot 1060-1645 ohm Hot is 122F - 212F. Also check after engine has heat soaked.

Crank sensor
Cold 985-1600F Ditto above
Hot 1265-1890F Ditto above
Old 03-06-2013, 11:25 AM
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Thank you very much!

This helps tremendously. I will try checking all the mentioned sensors and see what they say. I had codes come up before but they all were misfire related and now somewhat, used coils work better than crappy ebay
My reader is not that elaborate to give me all the snap data, at least I can't see it.
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