Strange car problem

[timosyy]

Recently (sometime in the last week), my car started having this problem where occasionally, when stopped at a light/stop sign/middle of traffic (basically, when its in drive, & running, but at a full stop), the engine will sort of shudder & die, and all the warning lights pop up on the dash. It sort of feels... like a stall, for lack of a better word, except its an automatic and its at a stop. When this happens, I throw it in Park & turn the car off, turn it back on again. Sometimes it takes a long time for it to start, and this leads to some aggravated drivers behind me . Sometimes it just doesn't start at all (thankfully, the two times this has happened were in areas with no traffic where we could push the car out of the way), and we basically have to just keep trying at random intervals until it starts again.

I've noticed this "stalling" happens more frequently when the car is low (~1/8 to 1/4 tank) on gas & stopped on a slight incline, but this has happened on pretty level areas as well.

I brought it to the mechanic but the only thing they could think of was to replace the spark plug wires (something like that?), which didn't fix it (happened 4-5 times two days later). Does anandtech have any ideas?

To clarify, what happens is - engine shudders slightly & dies, warning lights pop on (its akin to if you turned the car "on" but didn't start the engine). Turning car off & starting it again (when it actually starts) puts it all back to normal, no warning lights, etc.

Thoughts? It worries me because I drive this car a lot and I need it to be reliable, and right now it's anything but.

 

[nismotigerwvu]

Try cleaning your airflow sensor...a year/make/model would help a lot in determining what type of sensor you have and the best way to go about cleaning it.

 

[SpeedEng66]

if you have a check engine light goto autozone and they will give you the codes

but it does sound like a map sensor

 

[timosyy]

1999 toyota camry

 

[Vetterin]

Originally posted by: timosyy
Recently (sometime in the last week), my car started having this problem .......

I've noticed this "stalling" happens more frequently when the car is low (~1/8 to 1/4 tank) on gas & stopped on a slight incline, but this has happened on pretty level areas as well.

I'm a little confused by your post. Did this just start "in the last week" or whenever "the car is low on gas"?
If if just happened after your last gas fill up it would be do to water in the gas and a can of heat gas additive should fix you problem. If it happens everytime the gas is low I would check for a fuel pump getting ready to crap out or a clogged fuel filter.
You're mechanic actually said spark plug wires????
FWIW, all your dash warning lights will come on when the engine quits, just the same way they come on when you turn the key to acc. No biggy!

 

[urname7698]

Well the low fuel in the tank makes me think a problem with fuel delivery or the fuel itself. I'd throw some gas treatment in there in case you have water/bad gas. Have you replaced the plugs/etc recently? Did you replace the spark plug wires? Is the idle low all the time? Check the basics: Air filter, fuel filter, fuel pump, etc.. How many miles on the car as well?

 

[exdeath]

Not familiar with that year Camry, is there any kind if idle air control system (IAC valve)?

Edit: looks like there is and the IAC valve and throttle getting gunked up and causing stalling seems like a common problem.

If you want to check yourself, it should be a small device (with wires if electronically controlled) on it on the intake plenum right behind the throttle body, or integrated into the throttle body itself (not to be confused with the throttle position sensor which is axially aligned at one end of the throttle shaft).

Those things are pretty sensitive if the engine is MAF meter based, as it pulls in idle air that isn't metered by the MAF and the computer relies on the exact specifications and calibration of the IAC to pull in specific known amounts of un-metered air.

 

[ViviTheMage]

does the CEL (check engine light) flicker when it starts to do this?

could be coils, could be plugs, could be a bad ground on your coil wires...or something worse...

not sure about camry's though...

 

[timosyy]

136k miles on the car.

What're the symptoms of problems with some of the things mentioned in this thread? The car runs absolutely normally otherwise, and it never dies when its actually moving (thankfully?), only when I'm stopped at a light/stop sign/whatever ... which means a lot of rolling stops, extreme nervousness at lights, and a deathly fear of traffic.

does the CEL (check engine light) flicker when it starts to do this?

No, simply turns on like every other warning light on my dash.

I'm a little confused by your post. Did this just start "in the last week" or whenever "the car is low on gas"?

Midway through last week was the first time it happened. I just filled the car with a full tank of gas yesterday after it happened 3 times on the last 1/8th tank of gas or so, thinking that might have something to do with it. Happened again today though on the commute back /sigh

IAC valve seems interesting. Friend (who isn't a mechanic and doesn't know the inside of a car by any means) also suggested fuel pump because something similar had happened to his car once.

 

[LTC8K6]

Shift to neutral when you need to stop and see if it idles okay.

 

[timosyy]

I'll do that tomorrow (today).

 

[DaedalCipher]

My girlfriend had the exact same problem as you, and despite what Vetterin says about plug wires, that could definitely be it. We got hers replaced (bought them ourselves and did it- it's easy, and the dealership wanted 220 for the job. Wires and everything were like 35 bucks), and it fixed the problem.

That's one of the first things i would check. Next in line for me would be the fuel pump or fuel filter. i do agree with Vetterin that a crappy pump or clogged filter could be making it happen.

What LTC8K6 says about shifting to neutral- my guess is it might run a little smoother, but ultimately die. If you want, you can always just shift to neutral at a light and keep it idling a little higher until you figure out the problem- shouldn't hurt the car a bit.

Oh yeah- if you know someone with an OBDII sensor, borrow it and hook it up. It is a handheld sensor about the size of a twenty-ounce bottle that plugs into your car just under the steering wheel (looks a lot like a computer monitor jack), then you turn the key to the "on" position. Press the "check codes" button on the OBDII and then see what comes up. Dealer or anyone else is just gonna do the exact same thing and then charge you 75 bucks, no matter what. I work at a ford dealership, so I know.

So- check spark plugs and spark plug wires. Then, fuel pump and fuel filter.

If it still does it, check out the O2 sensor. This is a little sensor that tells your car if the gas mixture is too rich or too lean. My family has owned nothing but toyota corollas and camerys, and our experience has been that the O2 sensor craps out around 200k, which is the only problem we've ever really had with toyotas except the timing belt. So check that out if nothing else works.

Good luck. Come back and le tus know what fixed it, will ya?

 

[timosyy]

Yeah, still died with car in neutral at a light this morning.

Plug wires were replaced, last week, so thats not it... brought it back to the mechanics, added in the notes to take a look at the IAC valve, fuel pump, etc. We'll see what happens

 

[timosyy]

Arg...

Repair shop said IAC was all gummed up so that was probably it, paid to replace it (worth it imo if it fixes the problem), drive it out today and have the exact same problems (engine dies when at a stop in Drive or Reverse (found this out when I was waiting to back out of a spot), sometimes has trouble starting from when car is off as well).

Frustrating.

 

[natto fire]

Wow, some bad advice in this thread. Really doubting it is a bad airflow sensor and you can't really "clean" a MAP sensor. The IACV is more likely, but it was your description of when it usually occurs that makes me think it is gasoline related. As suggested it could be bad gas, but it is more than likely a defective fuel pump, or the relay controlling it.

 

[exdeath]

Originally posted by: Captain Howdy
Wow, some bad advice in this thread. Really doubting it is a bad airflow sensor and you can't really "clean" a MAP sensor. The IACV is more likely, but it was your description of when it usually occurs that makes me think it is gasoline related. As suggested it could be bad gas, but it is more than likely a defective fuel pump, or the relay controlling it.

Yeah MAF problems would be all across the board, stalling all around, hesitation, bogging, CEL for "emissions control" reasons from too rich/lean mixture, etc.

Same with fuel pump, it would cause problems starting and running as well, not just idle. Though with new return less systems and variable fuel pumps could cause a similar problem where it's fine under load with a high duty cycle on the pump, to overcome a clogged filter for example, but not enough force at idle.

Same with ignition, generally it effects the entire operating range of the engine, not just idle or start.

Problem he described only at idle, and the only significant change in engine condition at idle from any other condition, is the throttle is completely closed, so it sounded like the engine was being choked completely.

Next thing I would check would be fuel pressure at idle, may be something simple like a fuel pressure regulator as well. Excess fuel pressure that isn't bled off at idle would flood the engine under low demand if it's out of the range that the computer can compensate with shorter durations. You wouldn't see this while driving as the engine demands would come up to the level that the fuel system is supplying already.

It is frustrating sometimes, esp when the part that is the most likely culprit is in fact in questionable condition when you check it out, but fixing that doesn't resolve the problem.

Also something quickly, disconnect the battery for a few minutes to reset the computer, as it may have learned, or tried to learn, to adapt and compensate for a defective control or feedback device, and if that part is replaced, it might need to re-learn and stop adapting. It's possible the idle target tables got all screwed up from the gummed up IAC and now it's trying to use those same values for a working IAC and is basically confused to hell.

Basically go after the cheap, easy to check stuff, before having to do more expensive stuff like drop a tank or pull a fuel pump.

 

[cprince]

I would replace all the fuel filters(if you have more than one) because they could be clogged up. Next, check to see if your camshaft position sensor is still good. I had a similar problem with my '95 Altima. The camshaft position sensor on the '95 Altima is placed inline with the engine, and there is only one o-ring separating the engine oil from the sensor. When oil enters the camshaft position sensor, it blocks the sensor(just a light emitting diode and a photodiode) from reading the markings on the rotor plate at low engine speed(idle) and the engine stalls because the computer does not know the position of the pistons to fire the spark plug. At high engine speed, the rotor plate is spinning fast enough to throw the oil alway from the sensor.

When the engine is off, the oil that was leaked into the camshaft position sensor slowly leaks out of the sensor and allows the sensor to work again until the engine starts.

Hope all this will help you, somehow

 

[Zenmervolt]

Sounds like a fuel pump relay.

Replace that first. It shouldn't be more than $50 and you can replace it yourself.

ZV

 

[exdeath]

What about a pump relay would cause this problem only at idle? Wouldn't it be intermittent at any time, starting, cruising, etc?

Something about flow volume and engine demands being large enough to mask momentary relay failures that are more easily noticed at low demand?

 

[Zenmervolt]

Originally posted by: exdeath
What about a pump relay would cause this problem only at idle? Wouldn't it be intermittent at any time, starting, cruising, etc?

Something about flow volume and engine demands being large enough to mask momentary relay failures that are more easily noticed at low demand?

Good point, I had missed that part and was thinking intermittent stalling only. Thanks for pointing that out.

ZV

 

[timosyy]

Mini-update...

Brought it to another mechanic, who didn't do anything big, just replacing filters, changing some airflow settings (?), etc.

From what I can tell, its still not "fixed", whatever it is. I went out for a short drive around the neighborhood and basically, as far as I can tell, the engine just idles higher. I havn't had it die at idle yet, but heres what happens: Engine idles at 1000 rpm instead of 500rpm like before. When stopped at idle, after a few seconds it'll suddenly jerk down to 100rpm and you can hear the engine about to die, then work its way back up to 1000rpm. I have no doubt that if the engine were still idling at 500rpm like before, the engine would die.

Basically, temp. fix, as far as I can tell, and still very possible for engine to die at idle (its literally nearly there as it is when it spikes down). Based on this though, any new thoughts? (rpm suddenly jerking down at idle).

Edit: Apparently it also still has problems starting up (from completely off). Couldn't get it to start just now when I wanted to take another drive around the neighborhood . If it means anything, after a couple tries I gave up and went back into the house, smelled heavily of gasoline around the front/hood area of the car (gas station smell).

 

[Zenmervolt]

Fuel delivery problem. Fuel pressure regulator or dampener is possible if you're smelling gasoline, or any number of other leaks.

ZV

 

[natto fire]

Originally posted by: Zenmervolt

Originally posted by: exdeath
What about a pump relay would cause this problem only at idle? Wouldn't it be intermittent at any time, starting, cruising, etc?

Something about flow volume and engine demands being large enough to mask momentary relay failures that are more easily noticed at low demand?

Good point, I had missed that part and was thinking intermittent stalling only. Thanks for pointing that out.

ZV

Not sure how it is on other makes, but on Hondas the main relay either works or it doesn't. First hand experience, all too much. It makes it easier to test, but it still has it's problems.

Like I said, this could be a fluke, but for any Honda I have seen, it is safe to assume that if the main relay allowed the car to start, it will continue to work. (That is not to say they don't go bad.)