She drives a 2010 Subaru Forester. Its got 140k on it. She is regular as clock work with maintenance work. Sometimes it cranks and crank but just won't turn over. It will start again a few minutes later. Seems to happen with quick stops. To work and back its never happened. Here's the strange part. When she does get it started after a problem the check engine light is on solid. The traction control light comes on solid, and the cruise light comes on blinking. Got my multimeter the first time we got it home after. Battery tested 12.5 resting. 14.5 under load. My OBD2 reading comes up with no codes. The idiot lights were off during the first test. Consulted dealership recommended new battery. Did so and didn't solve the problem. Took it to dealership had them check for loose connections. Did it again. Took it to my guy they thought replacing the belts my solve it. They couldn't get any codes to come up either. Nope. Guy on youtube suggests replacing key fob battery. Nope.

Any suggestions?

Are the spark plugs original?

Weak start can be weak spark. That can be several things, but spark plugs are a great place to start diagnosing horizontally opposed engines.

Also, that engine in that year is one of the one known for busting head gaskets. Any fluids in the wrong place? Sweet smelling oil? Again...condition of the spark plugs can help with that diagnosis also.

Can you make the sound for us? When you try to crank it… Can you imitate the noise?

kindly,
the tappet brothers

Bad ground, probably from the engine to the chassis.

On my Toyota when I get the check engine light and a flashing traction light with a solid warning my computer logs a code which I can read with a scan tool. Usually I get the evap code because I forgot to put my gas cap back on again. I wouldn't be surprised if you have a code stored. It sounds like a sensor is failing but from this side of the internet it's hard to tell. Like the OBGYN says, I'd have to look at it.....

Shot in the dark, your wheel speed sensors or bad ABS Module.

But a bad ground makes even more sense. Any blown fuses?

Strangest thing I encountered similar to this issue occurred back in the 1980's. A friend was driving an old Dodge station wagon he picked up cheap.

He'd stop to pick me up and we'd go out to start the car but when he turned the key - nothing. No cranking, no clicks, etc. Wait 15-20 minutes and it would start with no problem.

After many occurrences, we accidentally stumbled upon the problem trying to figure out the issue. There was a white/translucent connector on a ribbon cable under the dash. The male side of the connector had round connectors while the female side had split rings. We noticed that one of those connections inside the connectors had blackened the connector just above it.

We figured the connection was arcing and heating up the split ring enough to lose contact. When cool, the ring contracted enough to make the connection again.

He took it to his mechanic who fixed it and he never had another issue starting the car.

The 2.5L engines of that ear had a known ground issue in the harness coming out of the firewall to the engine. The crimp where the spark plug ground separates into 4 leads to the individual cylinders oxidizes and is intermittent. Sort of like a cold solder joint. You have to unwrap the harness and find the crimp and then solder it up. But, this would tend to throw random misfire codes.

Anytime you have an active code, the cruise control and traction control are disabled. Guess it's an incentive to go get it fixed instead of applying black electrical tape to the light.

Fuel pressure? Bad check valve not keeping pressure in the line?

My wife's Flex has a similar issue with extended cranking before starting. Too intermittent to diagnose easily.

If it runs and idles fine, it doesn't sound like spark plugs to me. It wouldn't hurt to do plugs, wires and spark plug tube seals if they're original though.

Has the fuel pump or fuel filter been replaced?

You mentioned belts, which are easy to check yourself. The timing belt inspection cover has three 10mm bolts you need to remove and you'll need a 22mm socket with a long ratchet to turn the crank.

I'd also check the resistance on the VVL switches. I had one go out at 40k miles on my 2010.

Hopefully you can pull some codes the next time your CEL comes on.

quote:

Originally posted by SIGnified:
Can you make the sound for us? When you try to crank it… Can you imitate the noise?

kindly,
the tappet brothers

I laughed at this. I remember that radio show. Those guys were a hoot and a half. Other questions fuses. I don't know. Plugs I think they've been replaced. No leaks that I'm aware of. Fuel pump/filter I don't think they've been replaced since we've owned it. I'm trying to run down where this motor ground is located. Timing belt was replaced at 110k. Made sure of that because of the motor type. If that sucker goes it bends the rods I think. What's the chance that the onboard computer is crapping out? That happened on my Mom's car many years ago.

quote:

Originally posted by goose5:
If that sucker goes it bends the rods I think.

It can bend a valve. You'll know you messed up the valvetrain when it cranks fast and there's no compression. I'm still leaning towards a fuel issue but it's hard to diagnose over the internet.

If I were you, I'd try to replicate the problem with a short test drive before it leaves her stranded.

Intermittent failure of the crank sensor or the crank sensor circuit in the ECM?

One tip-off at least that I have seen in the past with GM cars that while it would crank but not fire the tell tale was that the in dash Tachometer needle would not move but once it fired the needle would move.

And those failures were usually triggered when the engine was at normal operations temperatures.

At least the way GM’s worked the crank sensor going “open” circuit, it acted like the ignition switch was turned off. At least with the way those failed it would never throw a trouble code as the ECM would “think” the ignition was shut off intentionally.

What is the age of the current battery?

I kid you not, my sister in NC is on her 4th factory battery with her 2018 Subaru. Her mechanical skills are zero, bought some extended warranty.

Not the same as your problem, but I’d still evaluate the condition of the battery & age.

I wonder if its the ignition switch.
Sounds very similar to my Hondas problem a couple weeks back.

Did anyone replace the timing belt and idler pulley at 105k?

Could be an intermittent fuel pump.
My Ranger did this.

Some of the symptoms your wife’s car has are mentioned in this article about ignition switches (worn contacts)going bad. Happened to my son’s Toyota awhile back. Check it out…

https://www.aa1car.com/library/ignition_switch.htm

quote:

Originally posted by MRBTX:
Some of the symptoms your wife’s car has are mentioned in this article about ignition switches (worn contacts)going bad. Happened to my son’s Toyota awhile back. Check it out…

https://www.aa1car.com/library/ignition_switch.htm

It's a Ford, but this did not resolve the problem on our Flex.

quote:

Originally posted by Oz_Shadow:
Did anyone replace the timing belt and idler pulley at 105k?

OP said it was replaced