2007 Toyota Corolla engine vibration, low milage

  • 1 POST
  • 1.8L
  • 4 CYL
  • FWD
  • 9 MILES

Dear Sir.
I scan my car by using ELM 327 blue tooth device andfound the data which I will describe below
ECT -;203 F
IAT -;122 F
Throttle position -;12.15% [steady in idle]
maf air flow rate -;2.25, 2.79 g/s [variable]
engine rpm -; 6.68, 7.20 [variable]
calculated engine load value -; 18.82, 20.39% [variable]
timing advance -; 6.5, 11.5 [235-278 m/s]variable
bank 1 sensor 1 v -; 0.02, 0.89 [207 to 325 m/s]variable
bank 1, sensor 1 % -; -3.09 to -6.19
fuel system status -; closed loop using o2 sensor for fuel mix
short term fuel trim -; -2.89 to -7.02 % [235 - 278 m/s] variable for idle speed
long term fuel trim -; -20.3% [235-278 m/s] steady for idle speed
moniter dtc status. -; Error MIL:off spark ignition

kindly go through it. Which part is faulty. How to fix
thank you

Do you
have the same problem?
Sunday, January 11th, 2015 AT 1:40 AM

1 Reply

  • 29,782 POSTS

You can't identify a defective part this way. The place to start is by having the diagnostic fault codes read and recorded. An engine vibration is usually due to a misfire, and some fault codes will identify which cylinder is responsible. The first suspect would be spark plugs that need to be replaced.

When you have a misfire due to a spark plug issue, unburned fuel and air will go into the exhaust system where the oxygen sensor will detect the unburned oxygen and the Engine Computer will interpret that as a too-lean condition. In response, the computer adds fuel, but it adds it to all the cylinders. The exception could be that since a misfire has been detected, the computer may be altering the fuel metering calculations as a result, because this number:

long term fuel trim -; -20.3%

is the opposite of what would be expected. Minus 20 percent normally means the computer is commanding 20 percent less fuel than what is considered normal. 20 percent is a REAL lot. Normal readings are around plus or minus two or three percent.

The fuel mixture is supposed to switch between too rich and too lean about two times per second. That is needed to make the catalytic converter work properly. It is likely the exhaust is never going into a lean condition because of all that unburned fuel from the misfiring cylinder, and that's why the computer is continually trying to reduce the amount of fuel. No matter how much it cuts back on fuel, the exhaust will never go into a lean condition, so the computer keeps reducing the fuel more and more without success.

Rather than trying to interpret these numbers in a useful way, approach an engine misfire like you would on any engine. Start with the basics first, like spark plugs, then ignition coils.

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Sunday, January 11th, 2015 AT 2:28 AM

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