Car question

[Gravdigr]

Originally Posted by Clodfobble

I dunno, I'm pulling stuff out of my ass here.

Congratulations, you are now as qualified as most professional mechanics.

[tw]

Originally Posted by glatt

I think now I just drive it around for a while and see if it stalls again. It seems to go a month or two between stalls.

So what was Car Chip monitoring? And what did Car Chip record with the stall?

[glatt]

The thing that jumped out to me with the data from this "stall" was that the voltage was fluctuating a little bit on this trip in a way that it doesn't normally. Almost like the alternator is flaking out on me.

Here is the data from the trip when it *almost* stalled. At the point of the green arrow, I was stuck behind some slow cars, and felt the engine stumble. Because I was still moving, I didn't want to shift into neutral and give it gas, but I also couldn't give it gas without rear ending the car in front of me. It almost stalled, and in fact the oil light even came on because the engine was going so slowly the oil pump wasn't pumping hard enough. A couple other lights came on too, but they all went out a moment later. When we came to a light and stopped a couple blocks later, I shifted into neutral and gave it some gas throughout the red light. I repeated this behavior for the next couple minutes of the trip.

[glatt]

And this is the voltage. In other trips, the voltage remains steady at around 14 volts, but on this trip, it was fluctuating. You would expect it to drop a lot when the RPMs went down to 200 or so, but it was dropping even before then.

[glatt]

Just for comparison's sake, this was a trip in the car the previous day, and the voltage then.



So what could cause intermittent voltage changes? If the alternator intermittently craps out, what's causing that? I don't hear any belts slipping and squealing, so I doubt it's that.

[Gravdigr]

Voltage regulator? Alternator diode(s)?

[glatt]

I don't know much about alternators. I'll need to read up. Assuming the alternator is the problem.

[tw]

Originally Posted by glatt

And this is the voltage. In other trips, the voltage remains steady at around 14 volts, but on this trip, it was fluctuating.

Voltage in that last attachment (18 Feb) is ideal voltage for all vehicle electronics. Ideal voltage is typically anything from 12.6 to 14. Apparently voltage is a little higher (maybe 14.5) on 18 Feb implying the battery required more recharging current. Which is the alternator working just fine.

On 19 Feb, the first thing that concerns me is the idle dropping to less than 750 RPM. That should not happen. At 750 RPM and lower, the alternator really does not output much current. In fact an alternator often outputs near zero current if RPMs are well less than 800. (BTW, maximum output current starts at maybe 1500 RPMs which means racing an engine any faster does not recharge a battery any faster).

A sudden marked voltage drop on 19 Feb could be a drop much lower than the graph indicates. But that typically would not cause problems as long as voltage remains above 9 volts. Battery (without alternator) should provide enough power. However, is there any reason why neither alternator nor battery maintains above 9 volts? One possible reason is an intermittent ignition key switch. Or an intermittent relay that should but does not hold battery connected.

500 RPMs is a defect. During those 500 RPM periods, was the engine not surging or stumbling? Fact that the engine idled at 500 RPMs is itself an engine defect even if the engine did not stumble. A perfect example of viewing a 100% defect even though the engine appears to be working just fine (not stumbling).

So an interesting question. Is low voltage somehow causing the engine to idle below 800? Or is idle below 800 causes a significantly lower voltage? An example of trying to solve a closed loop system.

[glatt]

I had ordered an LED light array meant to go in your car's trunk instead of the little wimpy incandescent light bulb that came with the car originally. It uses less electricity than the old incandescent and is much much brighter. Pretty cool, actually. Only $4 on Ebay.



Installation was easy. You just take out the old light bulb (quickly before it has a chance to heat up and burn your fingers.)



And then put the appropriately shaped light bulb adapter into the socket. Connect the light array, peel off the adhesive backing and stick it to the underside of the trunk. The light output is pretty impressive.



So bright, and uses less power.

But I was too smart for my own good. Apparently the Camry has a circuit board in the back that checks the resistance of the light bulb circuits, and if they go outside certain parameters, it turns on a warning light in your dashboard that your tail light is out. The resistance is so low on these LEDs that the circuit board thinks there is a problem. I'm getting a warning light on the dashboard.

[Gravdigr]

Originally Posted by glatt

...I'm getting a warning light on the dashboard.

[xoxoxoBruce]

With the trunk closed, and the light off, the Camry is concerned the bulb may be bad? WTF?

[glatt]

I think it has a memory. I popped the trunk with the engine running the other day, and the light came on shortly after.

I dunno. I checked all the tail lights and blinkers and reverse lights and they all work. And this warning light came on shortly after I installed the LEDs, so I think that has to be it.

[BigV]

And when you put the old bulb back in, what happens?

[glatt]

I don't know yet.

[glatt]

We just took two cars to a band performance and I followed the Camry. Turns out one of the five brake lights is out. Don't know how I missed that last night.

So it wasn't my LEDs!