P0300 on one side of the engine

Tiny
APPLEUP
  • MEMBER
  • 1995 TOYOTA CAMRY
  • 3.0L
  • V6
  • FWD
  • AUTOMATIC
  • 270,000 MILES
Hello! For the past couple months I have had a check engine light with codes P0300, P0302, P0304, P0306, and P0171. So the whole front of the engine is randomly misfiring and I am stumped. I have replaced the plugs, coils, vacuum lines, egr valve(which was also throwing a code), run sea foam, and probably another thing I am forgetting. It also takes a bit to start. If I let it crank for a while, it will start, but starts before then if I open the throttle. I tried a trick and turned the key to "on" to let the pump build up pressure and it had no effect. I do not want to keep throwing parts at it and hoping for the best, so I would appreciate it if I could get some help to diagnose the cause. Thank you.
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Tuesday, March 28th, 2017 AT 10:57 PM

9 Replies

Tiny
HMAC300
  • EXPERT
There are many things that cause misfires basic problem, injectors, vacuum etc. but check your fuel pressure it may be low because of the one code you have 171 which means lean and takes a while to start. auto parts rent gauge you may need an adapter as well to check it if no fuel rail connection.see link.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
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Wednesday, March 29th, 2017 AT 6:39 AM
Tiny
APPLEUP
  • MEMBER
Just finished testing the pressure and when iturned the key to "on" nothing happened. Engine started and slowly rose to 35 psi at idle. When I snapped the throttle it jumped to about 40-44. When I removed the vacuum hose from the regulator it went up to around 48. And it fails the leakdown test, as it took the time to shut off the engine and write this (5 minutes) to drop down to 15 psi and falling.
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Thursday, March 30th, 2017 AT 1:26 PM
Tiny
HMAC300
  • EXPERT
Pressure should be 38-44 psii minimum and should hold 21 psi after 5 minutes this can be a pump, filter, leaking injector, or regulator from what you are having from your readings put a pump in it. Seems more like the problem. Also change filter when you do this.
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Thursday, March 30th, 2017 AT 3:38 PM
Tiny
APPLEUP
  • MEMBER
I changed the filter before doing the tests. I have a feeling it could be the injector, because wouldn't the pump affect the other 3 cylinders?
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Thursday, March 30th, 2017 AT 5:56 PM
Tiny
HMAC300
  • EXPERT
Not necessarily you can do what you want bu ti really think it's apump/regulator problem
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Friday, March 31st, 2017 AT 6:42 AM
Tiny
APPLEUP
  • MEMBER
Probably should have been the first thing to check, but I did find gas coming out of the vacuum line on the regulator. Going to replace it later today and ill let you know how it runs.
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Monday, April 3rd, 2017 AT 2:07 PM
Tiny
HMAC300
  • EXPERT
Ya shouldn't have any there, if yo want check injector for resistance should be in the 11-17 ohm range.
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Monday, April 3rd, 2017 AT 3:01 PM
Tiny
APPLEUP
  • MEMBER
I tested the injectors and they were around 15 ohms. I put the new regulator on and it runs great. No rough idle, starts up immediately, and all the dtc tests are compete and still no light. Now I can take it to emissions and be done with that for another 2 years. Still haven't done a pressure test yet as I haven't found time, but I think it's back up to spec.
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Tuesday, April 4th, 2017 AT 12:34 PM
Tiny
HMAC300
  • EXPERT
If you replaced the regulator and it's ok then you solved it thanks for using 2carpros
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Tuesday, April 4th, 2017 AT 3:18 PM

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