Warm start issues

VALGLAD1

MEMBER
2016 TOYOTA RAV4
2.5L
4 CYL
4WD
AUTOMATIC
32,000 MILES

I bought my vehicle listed above LE model brand new.

After about a year, I started having a warm start issues. I stopped fueling my car at the particular station where gas seemed to be slightly cheaper right after that. I talked to the dealer and he said, it's vapor lock and it's normal.

The reason it's normal, he said, because there were no codes. Usually, after 20-30 minutes it cranks and cranks and sometimes never starts, but always starts on the second try.

I noticed it starts a lot better (but still not perfectly) in a better grade of fuel, i.E. 89. Or when I pour a bottle of HEET.

So my guess it might have something to do with ethanol. The dealer suggested to turn a key to the accessory mode and wait. That didn't help. Nor does a slight press on the gas pedal.

Cold start works just fine.

What could this potentially be?

Thank you.

5 Replies

94 TRANSAM

MECHANIC
680 POSTS

Hello My name is Rich.

First your guy at the dealer is. Well I am not going to say it but vapor locking is not normal under any conditions and can in fact be a safety hazard. Vapor locking happens when a fuel line is too close to an extreme heat source and the fuel boils inside the line thus turning it to vapor which in turn can drastically increase fuel line pressures. This condition should not be ignored or played down.

However, unless there was some damage or the vehicle was assembled wrong at the factory there is little chance it is vapor locking as it is both a reliability and safety issue they take great care to keep fuel lines from heat when designed.

Unless the above has happened it is more likely you have a coil, module or sensor that is going bad and when it gets hot the internal resistance goes up and it malfunctions.

Would you like to troubleshoot this yourself or have a friend help you with my guidance or are you just looking for what it could be?

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Sunday, November 10th, 2019 AT 10:04 PM

JACOBANDNICKOLAS

MECHANIC
109,874 POSTS

HI:

I agree with the aforementioned response. Vapor lock is not normal and on today's vehicles is extremely unlikely.

As mentioned, I too suspect is it a sensor issue, specifically the crankshaft position sensor. When they start going bad, heat has an adverse affect on them. They can cause stalling or a no start condition.

Interestingly, under certain conditions, they will not set a diagnostic trouble code. That may explain why the shop isn't seeing one and placing blame on vapor lock.

Do me a favor. Take a look through this link and see if what it describes mirrors what you experience.

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

Let us know,

Joe

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Sunday, November 10th, 2019 AT 10:31 PM

VALGLAD1

MEMBER
3 POSTS

Thank you very much both Joe and Rich.

I have an OBD2 scanner and once in a while I do check for potential problems. I took a car this morning for a ride and let it cool for about half an hour.
Usually, this is when warm start problems happen. Hot start is fine but from about 20 minutes after the last drive and up to 3-3.5 hours, the car is hard to start.

The section measuring sensors doesn't show any sensor failing the test. None! Nor does the scanner indicate any other problems; misfires, temps, etc.

I followed the crankshaft sensor link and, although I can't say for sure it doesn't look exactly like my problem. The car's never stalled. When it runs it runs just fine, nor does it vibrate at any point, at least I can't feel it.

The only issue is these damn warm starts. Initially, I did fuel up at the same station for abut a year, year and half. Then for some reason, I switched to a couple of different stations. That's when these issues started. I wonder if my ECU has something to do with it?

Thank you,
Val

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Monday, November 11th, 2019 AT 12:13 PM

VALGLAD1

MEMBER
3 POSTS

To Rich: Yes, if possible, I would like to troubleshoot this problem. It's driving me nuts.

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Monday, November 11th, 2019 AT 3:38 PM

94 TRANSAM

MECHANIC
680 POSTS

Okay then, off we go!

First it is no surprise this happens after a drive when the car sits. When you drive you have airflow in the engine compartment which cools things. When you stop the heat sits in there and saturates everything.

The fact that I believe this may be a thermal issue makes thing harder because you will only get bad readings when it is hot.

Also this could be anything from bad plug wires to any of the sensors, modules or coil.

This may sound crazy but Id like you to run it until it is good and hot, IE until it wont start. Then pop the hood and get a garden hose and spray each sensor 1 at a time for 60 seconds then try to start it. If it doesn't start go to the next one and so on. If it does start, drive it again and get it hot until it wont start again and repeat the last thing you sprayed. This is because it may cool down on its own while you are doing this so you need to confirm it was the hose that did it.

Please let me know if you need locations for all or any of these.

Coil
Ignition module
Crank sensor
Cam position sensor
ECU if its under the hood
Plug wires

Spray them in that order.

Rich