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Rich fuel/air mixture

Tiny
MARIOC68
  • MEMBER
  • 1996 TOYOTA COROLLA
  • 250,000 MILES
Hello,
I inspected the spark plugs and noticed that all are with the electrodes of dry black color, only one is black and wet.
What steps should I take to identify the problem?
Sunday, February 11th, 2018 AT 3:51 AM

14 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hello,

The first thing you should do is take a compression test. Here is a guide to help us get started. It sounds like you will have low compression from the cylinder with the wet black plug.

https://www.2carpros.com/articles/how-to-test-engine-compression

Please let us know what you find. We are interested to see what it is.

Cheers, Ken
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Monday, February 12th, 2018 AT 10:51 AM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
I must perform the compression test by pressing the acceleration pedal thoroughly or not? That does not indicate the reference guide, however I have heard it somewhere.
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Monday, February 12th, 2018 AT 11:24 AM
Tiny
KEN L
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No you do not need to open the throttle to take a compression test.
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Tuesday, February 13th, 2018 AT 11:53 AM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
Okay, I will perform the test.
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Tuesday, February 13th, 2018 AT 12:05 PM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
Hi.
These are my results.
In cylinder number three I have the lowest reading so I added a little oil and with this went up.
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Tuesday, February 13th, 2018 AT 2:22 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Compression is not the problem I am starting to lean toward a bad fuel injector. I would remove them to do a manual test.

Here is a guide

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Please let us know what happens.

Cheers, Ken
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Wednesday, February 14th, 2018 AT 9:59 AM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
Check the injectors according to the guide. They seem to be working normally. However, perform a pressure test on the injection system, the results are: Pressure w / vacuum 38 to 40 psi (nominal, according to manual 33 to 38 psi); without vacuum 48 psi (nominal, according to manual, around 42 psi). In addition, after turning off the engine, the pressure gradually falls to zero in less than 1 minute, this should be maintained at least 1.5 kg / cm2 after 5 minutes. I tried to throttle the return hose but it still does not maintain the indicated pressure.
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Wednesday, February 14th, 2018 AT 4:19 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
The fuel pressure is not the problem. I am starting to elan toward a broken oil control piston ring. How does the engine seem to run?
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Wednesday, February 14th, 2018 AT 8:18 PM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
It feels heavy to start in the morning, like it was rich.
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Thursday, February 15th, 2018 AT 3:49 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Can you remove the spark plugs and shine a flashlight down into the holes to see the tops of the pistons? This will tell us for sure you might need to rotate the engine a little to see each piston top let me know how each of them looks.
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Thursday, February 15th, 2018 AT 10:48 AM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
Hi. I checked the operation of the TPS sensor. First I determined the connector terminals with the cables coming from ECU. One gave voltage 5.0, another zero voltage (ground) and the other voltage 4.1 (signal). Then, connect the voltmeter's pins to the terrestrial and signal terminals (connector inserted to TPS and ignition ON) to see the voltage variations by gradually opening the accelerator. Posion closed, zero voltage, just opened and rose suddenly to 4.1 and remained there until fully open position. I think something is wrong with the TPS, it is assumed that the increase is gradual, however I barely pressed the accelerator and went to 4.1 V.
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Friday, February 16th, 2018 AT 4:38 AM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
Also check the oxygen sensor signal (from a single cable), with the engine hot and running. Reads me 0.93 or stable 0.92.
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Friday, February 16th, 2018 AT 7:48 AM
Tiny
MARIOC68
  • MEMBER
  • 120 POSTS
I checked the calibration of the valves.
The manual states: Intake 0.15-0.25mm. (I have a single valve out of range, 0.13mm)
Exhaust 0.31-0.41mm (I have all below the minimum with values from 0.20mm to 0.28mm).
That can explain the excessive consumption of oil and fuel?
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Friday, March 2nd, 2018 AT 5:29 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Sorry for the work but I need to see the color of the spark plugs can you remove them and shoot a picture of them keep them in their respective holes. Still leaning toward a broken piston oil control ring. I would replace the TPS the reading look off to me.
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Saturday, March 3rd, 2018 AT 1:17 PM

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