Engine tach is vibrating

Tiny
SARGIS36
  • 2009 TOYOTA COROLLA
  • 12,500 MILES

Dear specialists
Toyota Corolla LE 1.8 VVTi 2009
How can I know, whether is broken down the MAF Mass Air Flow Sensor : or works badly, I am doubting that it doesn’t work normally
During the free working engine the tachometer dart doesn’t keep straight, it vibrates. When I drive and (for example I stop under red light) I keep beak and the tachometer dart always falls down and vibrates, and it seems that soon will close, shut the engine. And one time has been such a kind of thing, during the driving accusingly the engine was shut, and I couldn’t start… after 3 hours I tried and the engine started. The last winter was the problem, in Summer it wasn’t so, in summer was Ok… but now is cold weather and again became so. Maybe that problem is not connected with MAF? Or maybe it’s exactly MAF problem?

Thank you so much

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Wednesday, November 9th, 2011 AT 12:13 PM

14 Replies

Tiny
DRCRANKNWRENCH
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The first and best thing to do is to have the trouble codes pulled. Any Advance or Auto Zone parts sotre will do this for free.
In the mean time check the large vacuum line that runs from the brake booster to the intake for leaks.
Also, performa this quick test to check the brake booster for basic working function;

With the car off, pump the brake until the pedal is firm.
Then with your foot on the pedal, start the car. The pedal should drop down slowly with the weight of your foot upon it.
If it does not there is a vacuum leak or a problem with the brake booster.

Do these checks, get the codes pulled and come back to us.

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Wednesday, November 9th, 2011 AT 3:08 PM
Tiny
SARGIS36
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Thank you,

Here we did diagnostic, and it showed the problem code is P0171

Then I forget to say ( if is dark ) when I turn on the car lights, the tachometer dart little goes up and keeps so straight, like I would like to be it, and it doesn t vibrates or falls down, and immediately quite reverse when I turn off the lights

About the vacuum, I will try it, still I didn t approach the car.

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Thursday, November 10th, 2011 AT 8:10 AM
Tiny
DRCRANKNWRENCH
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The trouble code, Po171, translates to, "Sytem Too Lean".
This makes me think there is a vacuum leak.
I would check the brake booster and booster vacuum line as the symptoms you describe indicate a large leak and it seems to be associated with using the brakes.
Let me know how it goes when you get a chance to look at the car and test the booster.
Listen for a sucking or whistling sound underneath the hood when you look for a leak.

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Thursday, November 10th, 2011 AT 1:27 PM
Tiny
SARGIS36
  • MEMBER

I checked the vacuum system, like you explained the way, and it worked exactly finely. By our computer for P0171 codes = is written 1. Lean mix (I think this supposed about fuel) 2. Oxygen regulator 3. Air regulator.

But it's so very strange when I drive the engine force is too much strong, when I push the gaz pedal the car runs swiftly

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Thursday, November 10th, 2011 AT 2:41 PM
Tiny
SARGIS36
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But I think if the problem were connected with the vacuum system, in that case the car wouldn t have so strong force, or wouldn t work the breaks so normally. Within a day sometimes the problem NEARLY disappear, sometimes appears. I am mostly inclined about some sensor (regulator ) is broken down.

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Thursday, November 10th, 2011 AT 3:16 PM
Tiny
DRCRANKNWRENCH
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I think the next step might be to check the fuel pressure with a manual gauge. Most Advance auto and Auto Zone stores laon them out with a deposit. There is a test port on the fuel rail. The specification for fuel pressure is 44-50 PSI at idle. Also look at the vacuum line going to the fuel pressure regulator, this is on the fuel rail at the end between fuel rail and return fuel line with a vacuum hose diaphragm on top, and see if removing the vacuum hose changes the pressure or engine idle.

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Thursday, November 10th, 2011 AT 4:41 PM
Tiny
SARGIS36
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Thank you very much, I think the cars problem is very probable connected with this last version, you said. In these days I will be engaged in that, and later I will keep informed you.

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Thursday, November 10th, 2011 AT 5:20 PM
Tiny
DRCRANKNWRENCH
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Sounds like a plan. I will await the results and we can go from there.

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Thursday, November 10th, 2011 AT 10:25 PM
Tiny
SARGIS36
  • MEMBER

Hi my friend

I didn t forget you, just all these time I was partly engaged in that problem . And eventually finally we found the problem.

As a mutter of fact: in front of the engine there is "plastic intake manifold" yes? And a little part of that plastic intake manifold was cracked and because of that small crack the engine was working so badly, and tachometer dart was vibrating. We glued it with its same plastic material and now is Ok, no vibrating tachometer, and the Check lamp is off. In any case thank you so much for advising me.

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Thursday, December 1st, 2011 AT 12:58 PM
Tiny
DRCRANKNWRENCH
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You are very welcome. That is great news! I am very glad you did not go out and spend any money having it fixed, you did it yourself.
That is great.
Take care and come back to us in the future if you ever need help again.

Dr. C

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Friday, December 2nd, 2011 AT 4:50 AM
Tiny
SARGIS36
  • MEMBER

Thank you so much, it was pleasant to see your willingness to help me in future.
I didn t know that, that small crack was playing so important role for engine working. So after MAF when air goes into the engine, between them was air leaking place on that mastic intake manifold.

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Friday, December 2nd, 2011 AT 7:58 AM
Tiny
DRCRANKNWRENCH
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Yes, come back anytime, that is what we are here for. Our whole team of Techs are very eager to help others. Our boss and the owner created something really good here.

So, the car was getting more air than the MAF was thinking it was getting. It made the air/fuel ratio too lean and the engine ran bad because of that and the loss of vacuum affected other parts that needed the vacuum to perform correctly.

Diagnosis is hard and you should give yourself a pat on the back for finding the leak. Not everyone has mechanical inclination to be able to find things that are not right.

I am very glad your car is running well and I hope you have a good feeling of pride in yourself for finding the leak and fixing it.

Take care.

Dr. C

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Friday, December 2nd, 2011 AT 11:56 PM
Tiny
SARGIS36
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Oh it seems my cars problems are endless. On the dashboard (digital) shows there is 10 mile to drive according to fuel in tank, then I refueling, the dart rises up, but as digitally it shows again 10 mile, and after about an hour or more driving it only just itself shows the expected normal digits. Why it s so? How can be rectified it?

Thank you

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Sunday, December 4th, 2011 AT 9:37 AM
Tiny
DRCRANKNWRENCH
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This being a new issue needs to generally be posted as a new question, but don't worry about that now.
There is a device called a thermistor, which sensens the low fuel level, usually gives you 25 miles of gas left, and sends a voltage signal to the low fuel light. It may have failed as the signal is getting the but not correctly. For now depend on the fuel gauge which uses a float and a different circuit.
If you can re=post the question about the thermistor. In the mean time I will try to find the wiring diagram to show you the circuit. You will have to remove the tank to replace this part.
You actually won't get much more information out of a re-post, so don't bother. The circuit wires run parrallel to the fuel pump wires to the gas tank. The thermistor will be the stand alone wire that grounds out close to its location. So, it will have only one wire in most cases.

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Tuesday, December 6th, 2011 AT 10:52 PM

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