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Rough idling, codes: P0300, P0301, P0302, P0303 and P0304

Tiny
SPYNTRAK
  • MEMBER
  • 2001 TOYOTA CAMRY
  • 2.4L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 254,065 MILES
Hi there, I am currently working on my sister in law's car it is the LE model. We exchanged the transmission with a identical Camry, I added Toyota ATF IV transmission fluid, added coolant, made sure all wire harnesses are connected, all sensors connected. When I first turned the car on it started having pretty rough idle, check engine light came on and gave me codes: P0300, p0301, p0302, p0303 and p0304. I checked all vacuum hoses okay, checked MAF sensor, okay. Replaced spark plugs, checked volts on the ignition coils, checked and cleaned fuel injectors, also checked the connectors. I changed the camshaft sensor. When I start the car it gives a 2,500 close to 3,000 rpm's then drops to maybe 600 or 500 rpm's then it vibrates/shakes like if it is going to shut off and sometimes it does. What can it be?
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Wednesday, September 19th, 2018 AT 11:41 PM

30 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
These are all misfire codes. I am wondering if you got all the computer grounds are connected. Did it run okay before you began? Do you have the air intake tube connected to the throttle body? Please let us know.

Cheers, Ken
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Friday, September 21st, 2018 AT 11:38 AM
Tiny
SPYNTRAK
  • MEMBER
  • 36 POSTS
Yes, I double checked my computer grounds, and also I do have my intake tube connected and as far as it running okay I was told it did run okay and it idled okay too. I did not actually run the car myself (due to transmission not working) but I did have on idle and it did not sound or shake the way it is doing it now. I also forgot to mention on her flex pipe it had a small hole so I removed it and replaced it with a AutoZone flex pipe. Could that maybe be causing the rough idling?
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Saturday, September 22nd, 2018 AT 11:42 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Only if the pipe is leaking, it will bring in fresh air which will fool the computer causing it to run rough. Also the IAC motor on these engine gets dirty causing the unit not to work also I have seen one of the two igniters (coils) go out and finally there is a map sensor that is very sensitive which go out as well. Here is a guide to help you clean the IAC:

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

and

https://www.2carpros.com/articles/throttle-actuator-service

Check out the diagrams (below). Please let us know what happens.

Cheers, Ken
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Monday, September 24th, 2018 AT 10:53 AM
Tiny
SPYNTRAK
  • MEMBER
  • 36 POSTS
Okay, so I cleaned the throttle bore, and now it stopped shaking/vibrating. So now when I turn on the car it gives a strong idle at 3,000 rpm's and then drops to 2,000 rpm's after three minutes or so it drops to 1,100 rpm's and stays there.
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Monday, September 24th, 2018 AT 1:07 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
This can be normal as the computer relearns. I would drive it for about fifty miles to see what happens. This guide can help as well:

https://www.2carpros.com/articles/engine-idles-too-high

Let us know.

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Tuesday, September 25th, 2018 AT 9:23 AM
Tiny
SPYNTRAK
  • MEMBER
  • 36 POSTS
Thank you ken everything worked out great.
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Monday, October 15th, 2018 AT 7:51 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,643 POSTS
Good to hear, please use 2CarPros anytime we are here to help.

Cheers, Ken
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Tuesday, October 16th, 2018 AT 10:32 AM
Tiny
APPLEUP
  • MEMBER
  • 11 POSTS
  • 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, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
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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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
APPLEUP
  • MEMBER
  • 11 POSTS
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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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
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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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
APPLEUP
  • MEMBER
  • 11 POSTS
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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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Not necessarily you can do what you want bu ti really think it's apump/regulator problem
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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
APPLEUP
  • MEMBER
  • 11 POSTS
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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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
TERENCE IGNACIO
  • MEMBER
  • 1 POST
  • 1996 TOYOTA CAMRY
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 155,555 MILES
These codes have been coming on on my honeys car and I am at a loss to locate the problem. The shop has replaced 2 colis with no results. I have replaced the jumper coil leads and plugs with Denso oem units. Same same. It may be the igniter but I am not sure as to how it can be checked? It could possibly be the computer? Any suggestions prior to me going to the dealer. They charge $125 to do the Diagnostics and if it might be the igniter I could replace it first and see whats up. I may be able to get a used one from a wreacking yard for that year to do a test. The connectors are clean and dry. It sure is strange since cylinders 2, 4 & 6 have no missfires. The coils feed 2 cyls each. I really appreciate any suggestions that may help. I have a code reader and a digita vom in case I need to look for a bad ground or something.
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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Here are the tests to perform, check in your email.
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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
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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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
APPLEUP
  • MEMBER
  • 11 POSTS
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, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
If you replaced the regulator and it's ok then you solved it thanks for using 2carpros
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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)
Tiny
MIKE412
  • MEMBER
  • 3 POSTS
  • 1996 TOYOTA CAMRY
Electrical problem
1996 Toyota Camry 6 cyl Front Wheel Drive Automatic 315k miles

Hi, I have a high mileage camry that has been in our family since new. All the regular maintenence has been done and we use mobil1 synthetic oil. The car has been stumbling a bit, mostly uphill or under hard acceleration, and it gives us code po305. I know this means a misfire on #5 cylinder, and I have replaced the plugs and wires at inspection about 2 months ago, as well as the cat converter. Tried swapping out the coil for #5 with a new one, but didn't solve problem. Never had any problems with car before, but could this be a sign that the tranny is giving up? I do have it flushed every 75k or so, but it is the original drivetrain. Please help as i'd like to try and get 2 more years out of her while I finish college. Thanks!
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Tuesday, October 16th, 2018 AT 10:33 AM (Merged)

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