I have an 07 Camry with 190k miles. It runs and drives very well however sometimes after driving for an hour it will not want to restart. The issue only happens when I try to restart the engine after being off for only a short time. When this happens it will turn over just fine and all other electronics work fine as well. I first took it to an independent mechanic who couldn't find any issues and reset the modules at no charge, the issue went away for several months but then came back. I then took it to a Toyota dealership twice and after $680 in repairs in the last month the issue has come back again. Any ideas?
Take it back to Toyota. Their work should be under warranty if it's the exact same issue. If they find it is caused by something else, the misdiagnosis is their responsibility and should credit money you spent from the previous visits.
All the work that was done was for things that needed fixed, valve cover gasket, crank shaft sensors. ignition coil plugs, and they did something to clear out the carbon in the throttle body. If none of those things have gone bad I'm not likely to see any credit even if it doesn't fix the initial issue.
Clean the fuel injectors.
That's what you get when you go to a dealer, you get screwed.
"No Starts" when hot are often an electrical problem. Electrical components are "heat sensitive" when they're failing.
In your case there's several components that could be acting up.
So 1st, get used to listening for the fuel pump to run for a few seconds when you turn the key to the ON position.
On your 1st Cold Start when this isn't an issue, turn the key to ON and listen for the fuel pump running for a few seconds. If you can't hear it, pull the gas cap off and have someone else turn the key to ON and listen at the gas fill neck.
Now that you know the "subtle" sound of it running, go back into the car, turn an ear towards the back seat and turn the key to ON again. You should be able to hear the fuel pump run from the driver's seat. (when you turn the key to ON the fuel pump will only run for a few seconds to prime the fuel rail for the injectors. Once the RPMs go over 400 or so, the computer will turn the fuel pump to ON). The reason I'm not suggesting hooking up a fuel gauge to the fuel rail is because I don't think you have a Schrader Valve on your fuel rail and it's a little bit of a pain to do that.
So on the next "No Start When Hot", listen for the fuel pump. Do you hear it? If you don't then you may suspect a faulty main relay, a faulty fuel pump relay, or a failing fuel pump. (at least you'll have a path to follow to figure this out)
But what if you hear the fuel pump running during a "No Start When Hot"?
I'd still bet on something electrical. You replaced the crank sensor but if that were acting up I'd expect the engine to just die while running.
I think you have COP coils on that '07 Camry and if one were failing and acting up because of heat, again it wouldn't be just an issue during a "Hot Engine Restart". It would be misfiring while running.
So that leaves a couple of "usual suspects". One would be a faulty ECT (Engine Coolant Temperature) Sensor.
If the computer doesn't know the engine is at operating temperature, it could be "flooding" the engine with too much fuel during a "hot start".
Any cheap scanner (Live Data Mode) will show you what temperature the ECT sensor is telling the computer. If it's saying 90 degrees and you know the engine is hot, probably over 200 degrees from just being turned off 5 minutes ago, that's probably your culprit.
The other guy is the Camshaft Position Sensor. The Cam sensor tells the computer where the camshaft is in relation to the crankshaft.
It needs to know this for Ignition and Fuel Injector timing.
