Not starting in the morning

I have a V6 2002 Tacoma that is not starting in the morning. Specifically over the last week it would crank well in the morning but no signs of starting, this occured on four different mornings. Waiting a few hours (with increased air temperatures I presume) it started easily. I also one day didn't try to start it until later in the day and it started no problem. No codes seen for me.

It is currently with a mechanic, who reproduced the issue once and mentioned it threw crank and cam position codes. I believe he mentioned he tested manually and didn't see an issue with them. The mechanic said he can try replacing the crank sensor, but isn't confident it will actually fix the issue. He also said it started fairly quickly after the initial failure, though the truck was kept inside the shop(he cautioned about catalytic converter thefts and not leaving it outside his shop overnight) vs outdoors as I do.

One other piece of possible relevant info is it has on occasion had a rough idle where it dips then returns to normal, generally in the winter but independent of engine temperature.

Anyone have any thoughts on the issue?

 

Ambient air temperature in the morning and when it starts?

When it does start does it go into a High idle?

An intermittent open circuit causing the fuel or ignition to not work.

It might be the main ECM ground on the left side of the engine.

A code does not mean just the sensor but the complete circuit..

More in depth trouble shooting is called for. Did you put a limit on the trouble shooting time?

 

After looking it up the ambient air temp is not significantly different, like 5-10 degrees F, though the sun does warm up the car itself more.

I think it goes high idle, though not sure on that. May be getting the car back today and could check then.

Will check the grounding you mention.

Yeah, the mechanic wasn't confident in the code with manual testing done showing no issue.

No, limit given. He did ask if I wanted him to try to replace crank sensor but didn't actively suggest it, and also mentioned I might instead try driving more for it to be a more consistent issue. Wondering if I should take it elsewhere. I do trust that this mechanic is very honest from my historic work with him though in those cases the problem to fix was always quite clear.

 

So when it fails to start earlier in the day, do you try several times, or give up quickly?

It's officially summer, and seems like temperatures shouldn't be a major factor.

Has it ever failed to start when warm (i.e. coming back out of a store)? Or only failed on cold starts? If only failing on cold starts, it would seem like more likely a fueling issue.

 

keep in mind the fuel pump circuit only energizes when cranking or the engine is running.

If by chance your injector has a very slight leak or the fuel drains back into the tank over night you might need to crank it 3 or 4 times to get fuel to the rail

Then no matter how long the engine sits it would still need a long crank time.

I would be looking at fuel pressure and have a scanner hooked up to the OBDII plug.

Checking fuel pressure and see if the OBDII connection is lost while cranking perhaps your mechanic has already done this.

Good luck I wish i was close enough to help.

 

>So when it fails to start earlier in the day, do you try several times, or give up quickly?
I try several times, total time i try during a morning is likely for around 10 seconds. Not so sure how long my battery will last, maybe l should try longer. Also i have tried starting it only later in the day ,(not in the morning) and it started immediately.

Given it started immediately after letting it sit till midday I though maybe not a fuel check valve issue.


Now that you ask, there was one time fairly recently it didn't start on my first quick try (say 1.5 seconds of cranking) when coming out of a store but started immediately on the second attempt. But generally not seeing it occur.

 

With a problem like this I crank 4 times for about 15 seconds each.

Is it time for a new battery as well??

 

Battery still seems fine, it cranks well, I just don't have a great way to charge it easily and try to not run it down. Unfortunately only have street parking. I did try jumping it from another running vehicle to make sure it was getting good cranking and it cranked great but no signs of firing.

 

Many times over the years I pulled batteries and carried them inside .

On those cooler nights around -50 F besides plugging the block heater in.

 

Maybe try swapping the horn and fp relay

 

Good, point. I can pull the battery to charge inside. Though in terms of temperature and keeping battery warm... the lows currently are +50F so not actually cold.

I tried swapping "pwr outlet" with "efi relay" that were the same model number, still no start. I presume EFI relay also covers fp, i didnt think I saw one labeled for that specifically

 

there is a grouping of brown wires on the D/S of the intake. These are the ground wires for the PCM an other necessary electronics. See if they are tight first then individually grab each wire and check to see if it is broken internally. These usually get bent over right where it goes into the eyelet.

 

Got car back for the weekend.

Car is going into high idle when starting (as I presume it should be).

Didn't notice any loose grounds, but I need to spend a lot more time finding where the grounds are specifically for PCM and ECM that were mentioned, it is not so obvious to me and will need to search for where these actually are. I do have a supercharger that has been installed by previous owner more than 100K miles ago, so unsure if any wiring locations have changed or harder to access.

I did have one strange thing occur today, when coming off the freeway, I want to say either light engine braking, neutral, or light throttle it seemed to shut off for like 1 second. I noticed check engine light illuminated then quickly went away(my guess is was just from engine being off for that second). I checked codes for anything pending (should have checked right after getting back from mechanic, to see if they were still pending from his testing), and sure enough had crank sensor pending fault. Which makes me think the mechanics hunch could be correct or as others are saying some grounding and/or wiring issue. Otherwise the driving and starting was normal. I have now cleared the pending codes and will monitor if they come back.

Pending Fault Log
------------------
P0335: Crankshaft Position Sensor A Circuit

Historic Fault Log
------------------
ECU reports no historic faults
Other discovered fault codes
(possibly pending, current or manufacturer specific)
----------------------------------------------------
P1335:
[Toyota] No Crankshaft Position Sensor Signal - Engine Running.

 

Slap a new cps into that Bitch.

 

i had a very similar issue the engine would quit coming off the exit ramp .

Almost like backing off the throttle caused something to open never a problem with the manual the engine just restarted.

I upgraded the main grounds and the problem never returned.

Wires corroding or breaking under the insulation is common.

Good luck

 

Turned out the decade+ urd timing calibrator that was installed by previous owner had become intermittent, after removing it issue appears gone. Might even have fixed my rough idle.