Car question

[glatt]

Originally Posted by tw

For example, an EGR valve must open and adjust position during normal mode. Same EGR valve must be completely closed during idle. Same EGR valve acts completely different in the two operation modes. EGR valve could be leaking (defect during idle mode). But performs as a completely different device (100% functional during normal mode). IOW the same part has two completely different operation modes.

Your EGR tests said the EGR valve in both operation modes was OK.

When I checked the EGR valve, I could open and close it by sucking on the hose that goes to the diaphragm, but I couldn't see inside the valve to see if it was sealing properly when it slapped shut. Maybe there's a little grit keeping it from closing. I sprayed A LOT of carb cleaner in there so I think it's clean, but I can't know for sure. I suppose I could have tried somehow blowing through the exhaust channel to see if it was blocked. Even after cleaning, there's no way I'd want to press my lips against that surface.

[tw]

Originally Posted by glatt

When I checked the EGR valve, I could open and close it by sucking on the hose that goes to the diaphragm, but I couldn't see inside the valve to see if it was sealing properly when it slapped shut.

That's why you kiss the ERG valve and just blow (or suck). Didn't they make a movie about that?

[glatt]

I have another car question. Yay!

This one is about a 2001 Toyota Camry.

We bought this car used about a year ago, and so don't know its history or what "normal" is for it. No idea if all proper maintenance had been performed because maintenance records are incomplete, but the car has fairly low miles (65k) still and it appears to be in pretty good shape.

Sometimes when driving on a highway at steady speed, I would notice a very very slight fluctuation in engine power. Kind of like a stuttering. But so minor, that I thought it might perhaps be my imagination. Except I was sure it was actually there. This has been going on for the past 3-4 months very intermittently. We buy brand name gas. This stuttering was not a big deal, because is was barely noticeable, and others in the car didn't even notice it.

Last weekend, after driving on highways for about 2 hours on our way to the beach, we got to a surface street and had to stop for a light. When it was time to go again, the car wouldn't move. And the check engine light was on! After a moment of panic, I realized the car had stalled, but I hadn't heard the engine stop because the radio was so loud. The check engine and a couple other lights were on, but went off when I restarted the car. It started fine. We continued on our way.

We had about 15 more miles to travel to our hotel, and the car was sputtering intermittently the entire way. It stalled two more times, in spite of my efforts shifting into neutral and giving it some gas as we stopped at lights. The last time it stalled, it started back up again and behaved perfectly normally for the last mile or so to the hotel.

Driving it the next few days at the beach, it behaved perfectly normally.

On the 3 hour drive back home, it behaved perfectly normally.

I tinkered with it in the driveway at home and it behaved perfectly normally the entire time.

the clues:
-There is no check engine light on, and no diagnostic codes. I assume this means the spark plugs are firing, because I think the computer would report no spark.

-It behaved a lot like a lawn mower running out of gas. Except the tank was 3/4 full when it stalled.

-The repair manual says that when you turn the ignition key to the "on" position, you should hear the fuel pump whirring for about two seconds, and then it will turn off. When I turn the key to the "on" position, the fuel pump does not run. The fuel pump doesn't begin running until I turn it to "start."

-I checked the fuses and relays that the manual said I should check, and they appear to be fine. One relay check was only a partial check though, but I swapped it with an identical relay for the horn and the horn still worked and the pump still didn't.

-I pulled out the back seat and checked the voltage at the connector to the gas pump when the key was turned to "on." It had battery voltage at one conductor and 5 volts at another. The manual didn't say what it should have.

-I saw a creepy little spider crawling around on top of the gas tank when I opened the hatch under the back seat to look at the fuel pump connector. How long had that guy been there?


So do I just go ahead and replace the fuel pump? They cost like $200 for the part, and there's also some whirlygig contraption next to them that controls them and I don't know what they cost, but they look expensive and complicated.

I also noticed that there is no little metal flap on the gas tank opening on this car. Every other car I've had has one of those little flaps under the gas cap. Could that flap have fallen into the tank and blocked something? Or didn't this car have one?

[Gravdigr]

Originally Posted by glatt

...Could that flap have fallen into the tank and blocked something? Or didn't this car have one?

Possible. Next time it does this, slam on the brakes good and hard, if that's the problem, it should clear up, for a while.

I'd start a fuel pump/fuel filter replacement fund, anyway.

Also, you might go to an Autozone, and have them check your ignition coil(s). My local Autozone does this for free. They might can tell you what those voltages you spoke of at the tank are supposed to read, too.

Also, too, FWIW Momdigr's LeSabre did not show a 'check engine' or 'something's f'ed up' light with a dead miss/no fire at the plug.

[tw]

Originally Posted by glatt

-I pulled out the back seat and checked the voltage at the connector to the gas pump when the key was turned to "on." It had battery voltage at one conductor and 5 volts at another. The manual didn't say what it should have.

Voltage to the pump typically should be 12 volts. No reason to put an expensive 12 volt to 5 volt regulator on pump power. So why is it only 5 volts?

I saw this once on another car. One transistor would not properly conduct in rare cases when it got warm. So the car would not start until that transistor cooled. Then works fine. Later I heard of a service bulletin for this problem.

That is but one example. Many reasons could explain this. But only 5 volts on what should be 12 volts is enough to concentrate on that symptom. To go further or say more requires electrical diagrams. Generally $40 from the only company that sells these books (Amazon apparently is not permitted to compete.)

All cars start same. When a switch is first placed on, then the fuel pump operates for a few seconds. You must be in a quiet area to hear it. In your case, it probably works most of the time but maybe does not work when something is too warm or has some other environmental change after long operation.

Moving on to other symptoms. For your problem to create a check engine light, you may have to aggravate the problem on multiple and consecutive restarts. For example, after each restart and when the engine is hot, floor it. Find some place (ie steep hill) to do this so that the engine demands full fuel. You may not feel a problem. But the check engine computer does. If you restart the engine only once without doing this, then you must repeat this test all over again.

A check engine light for this particular fault only lights when the same problem has been seen at least two or more times consecutively (after each restart). This problem would only be seen by a check engine light when the pump is taxed (full flow). If you restart the engine once and do not tax that pump, then the check engine light zeros its counter.

[xoxoxoBruce]

It had battery voltage at one conductor and 5 volts at another.

!2 volts to power the pump, 5 volts to operate the gage, ground to chassis.

[glatt]

Makes sense.

The pump not running for two seconds when the ignition key is turned to "on" is an actual observed problem. But I don't know if it's the same problem that caused the car to stall. If I track down the pump running problem and fix it, I have to wonder if that will also keep it from stalling.

I think I may need to research the ignition switch and test that next. I wonder if a problem with the switch is causing the pump to not run for those two seconds.

Meanwhile, the car runs fine on errands around town.

[xoxoxoBruce]

The couple of seconds of pump action is to bring the fuel pressure up to the range the fuel injection needs, before it even bothers to turn the engine. If it thinks it has pressure it won't start the pump.

[tw]

Originally Posted by xoxoxoBruce

If it thinks it has pressure it won't start the pump.

Depends. Only some vehicles monitor pump pressure. Often a two second (on some longer) pump action is only by a time delay relay or something equivalent. Without those schematics, nobody can say anything more.

If problems exist as suspected, then the 'floor it with each restart' test is essential so that the check engine system (light) can report what is defective and intermittent.

I don't see lots of other important facts such as amount of gas in the tank, engine temperature, battery voltages (ie lights changing intensity, a check of all battery cables for a loose connection, etc)

Of course you can call into Car Talk on NPR every Saturday and Sunday. They may even sell you a voodoo doll on the shameless commerce division of Cartalk.com to keep away evil spirits. That sometimes works.

[glatt]

When it stalled, the tank was at 3/4, and the engine was hot from driving two hours. The battery terminals are clean, and look tight, but I didn't try to move them or tighten them more. That's another thing to double check. I don't remember the battery voltage. A little under 12 volts, I think, but the engine was turned off then. The voltage would probably be higher with the alternator running.

This car's computer does not report fuel pressure. I tried checking it with my CarChip pro data logger but there was nothing to record. It has no dashboard fuel pressure gauge either. I wish it did.

I'm going to take another look at it this weekend when I get some time. Meanwhile, it's driving normally.

[tw]

Originally Posted by glatt

I don't remember the battery voltage. A little under 12 volts, I think, but the engine was turned off then. The voltage would probably be higher with the alternator running.

Voltage must be above 13 volts when running; over 12 volts when engine is not. CarChip can report this voltage.

However that voltage would not explain your problems. A loose battery connector would explain problems. Better mechanics always disconnect the battery when doing work. Sometimes attach the cable but forget to tighten it. So high temperatures longer (ie 2 hours) means the connection is not as firm.

[glatt]

Wouldn't the radio have cut out if the battery cable was loose? And it stalled at a traffic light while the car was perfectly still. Doesn't matter. It's an easy thing to double check.

[Gravdigr]

I wouldn't associate any of that with your problem(s).

I'd focus on the fuel system.

Just sayin'.

**********************

Remember the seventies? If your car didn't work right, it was a fuel/air/fire issue.

Nowadays, if it don't go, it could literally be one, or more, of 75-100 different things.

[BigV]

it is still about fuel/air/fire, as long as we're talking about internal combustion engines.

...

however...

when the fire is sent, when the fuel is sent, how much fuel is sent, the control of the air (via variable valve timing), those kinds of things are MUCH MORE strictly controlled, and affected by MANY, MANY MORE factors that didn't used to be considered. Those factors are evaluated by VASTLY MORE sensors, and that means lots and lots and lots more points of failure.

[Gravdigr]

Yeah there's about twelve dozen electronic fuck-ups that can leave ya hoofin.