2003 Toyota Corolla Toyota is missfiring after Plug replace

Tiny
BAZSPAZ
  • MEMBER
  • 2003 TOYOTA COROLLA
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
I used a Acron CP1980 Scranner and got codes P0300 P3001 and P0302 Which
are multiple and misfires in cylinders 1 and 2. The car runs fine untill it warms up then it misfires. The spark plugs were just replaced. It ran fine after they were replaced but this problem started shortly after.
Could this be the Fuel pump located in the tank.
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Wednesday, January 20th, 2010 AT 4:42 PM

5 Replies

Tiny
MMPRINCE4000
  • EXPERT
You would have to perform a fuel pressure test to rule out/in fuel as problem.

Could also be a weak coil.
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Thursday, January 21st, 2010 AT 9:34 AM
Tiny
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Isn't there a fuel sensor that should give you a ODB II code on your reader if the problem were fuel related. Like low pressure from the fuel pump or injectors malfunctioning. There is a fuel sensor reading on my Acutron 1980. It just sais Fuel Sensor OK. I think the problem is with one of the 1ZZ-FE coils that sit over the spark plugs. Is there a way to test them using a ohm meter. For say one with a colapsing coil.
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Tuesday, January 26th, 2010 AT 3:59 PM
Tiny
MMPRINCE4000
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Another way to check fuel is to spray starting fluid in TB. If it runs a few seconds, then a fuel problem, if not then ignition.

You can measure primary and secondary resistance with an Ohm meter for coils, frankly not a very accurate procedure.

Shops can test actual coil output in voltage.

You can also switch coils and if miss follows coil, then coil is bad.

Fuel pressure is not monitored by PCM, would probably be a good idea, but cost to monitor would be a factor.
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Wednesday, January 27th, 2010 AT 6:53 AM
Tiny
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Thanks for the info on the fuel testing what's the TB.
I think I fixed the problem but don't understand why.
When I purchased the $3 NGK's they said to gap at.44 So I opened them up.10 from there factory setting and installed them and shortly after I had the problems with the car. To repair the car I pulled them and went to.38 gap and the problems almost gone. I bet if I go to the original.35 there will be no problem. Now its great though. I also pulled the springs apart inside the Coil housing so they would make better contact. These plugs being platnum I don't think they should have been gapped at all but the auto parts store said they had to be. I think the.44 would be for standard large electrode plugs.
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Thursday, January 28th, 2010 AT 11:12 AM
Tiny
MMPRINCE4000
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TB = Throttle Body

Gapping is directly related to coil output in voltage. The more voltage the more gap (generally). Compression is also a factor or devices that effect cylinder pressure, like a turbo. High cylinder pressures would require less gap.
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Friday, January 29th, 2010 AT 5:11 AM

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