2001 Toyota Solara Convertible (V6) Won't start when it's freezing

I have a 2001 Toyota Solara Convertible, V6, low mileage (92,000), and it will reliably NOT start when the temperature gets below freezing. I have tried a couple of tank fulls of injector cleaner on advice from a friend, but no success. Once the temp falls below freezing overnight, the engine cranks but never catches. Once the temp is above freezing for a few hours, it fires up fine.

Often this problem is caused by worn ignition parts. Your V6 could need new plugs, when were they last replaced? If they have more than 30K miles on them or if they are more than 4 years old the plugs could be the problem. Also your motor has 3 coils that fire 2 plugs each. One coil sits on top of the plug in the front of the motor and it has a plug wire that goes to the rear spark plug. Those 3 wires to the rear plugs need to be replaced, if they are 5 years old they are due.

Thanks Uncle Turbo. I probably should have also stated I bought the car used w/ 50k on it, did do the standard maintenance (spark plug and oil change every 3 thousand or so miles), and when I took it to a shop last year when this started they cleaned out the manifold. I am interested in the coil idea though …

Hmm, no go. Took it to my dealer this morning, and he’s trying to sell me on replacing my whole ignition computer (ECM), but at $1,100 I’m thinking no. Even if it did need it, I think I can do it myself. Anybody else have any suggestions?

It could also be that your battery isn’t quite strong enough to run both starter and fuel pump. When it gets colder, the battery’s capacity isn’t optimum. Also, it takes more juice to run a starter, with the oil being thicker when it is cold. That combined could starve the rest of the system for power while starting.
When you get in, turn the key to the position before start and back off. Do this a couple of times. You’ll hear a ‘whirr’ from the trunk area (that’s the pump priming the fuel system). Then see if it wants to start.
If it does, it could be a toss up as to the cause but you bought yourself a clue.

You could take the battery indoors overnight and put it on a trickle charger (cheap at harbor freight). If it wants to start without problems in the morning when you put your battery back in, your battery would be my first suspect.

Should that not help at all, try to narrow it down to ignition or fuel delivery:
Spray a little starting fluid into the air intake (maybe take the air filter out) and see if it acts like it wants to start. It may cough and stall or it may in fact start.
Regardless, if it behaves like it wants to start, your problem is likely fuel related.

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Between turning the crank with all it’s resistamnces such as cold oil, compression, and all the stuff it’s dragging (such as the alternator), and creating enough of a magnetic field in the coils to create a strong spark to fire a cold cylinder, a weak battery will make starting difficult. I too recommend that you get the battery and starting system checked out. Parts stores will generally do this for free.

Since it’s temp related, check the temp sensor too.

The other suggestions made here are good ones too. I’m just adding to the list of possibilities.

The problem might be with the Crankshaft Position Sensor being effected by the temperature. The crank sensor informs the computer whether or not the engine is rotating. If the signal is lost from the crank sensor the computer see’s no reason to operate the ignition and fuel systems so the engine doesn’t start.

What you might try is let a shop keep the vehicle overnight when the temperature drops below freezing. Then in the morning a scanner can be connected to the vehicle to see if there’s a crank sensor signal when trying to start the engine.

Tester

Thanks for all the suggestions. I did replace the battery last year, as well as have the intake manifold cleaned. Left the car at a shop the other night, they’re trying to tell me it’s the ECM. I’m taking it to another shop for a 2nd opinion. My question to anybody here is, if it is the ECM, can I swap that out myself? Did a little reading and googling, and since it’s a 2001 it might be as easy as ‘plug and play’ - I found one on ebay, as well as a shop in Texas that will rebuild one. From what I saw on a Camry forum, 2001 pre dates any VIN/Security lock issues.

The ECM is full of chips and printed circuit boards. These boards expand and contract with heat and it is possible one of the boards has a crack in it so that contact is intermittent somewhere in the board.

I think sending the current board to a rebuilder is a good idea. It will get tested and any thing that fails the test gets replaced. Make sure they warranty the work since it will be tested warm at room temp. If you use your current board you know it is programmed and compatible with your car.

@njcarowner61, condemning the ECM is usually only done after elliminating all other possibilities.

I’d think about getting a second opinion.