Engine misfiring

Tiny
SATURNTECH9
  • MECHANIC
  • 30,870 POSTS
Any car can get water in the fuel or a bad tank of gas which from the symptoms sounds like that's what happened.
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
DRAGGINZFLY
  • MEMBER
  • 1 POST
When all cylinders misfire. It the air mass sensor that doesn't detect air coming in the engine cause misfire. Not enuff oxygen. It doesn't happen at all like that. Give a try to replace air filter, pcv valve need to be replaced and air mass sensor replaced and use obd2 scanner to erase code and see what happen. It wouldn't come back on
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
DIECASTER21401
  • MEMBER
  • 1 POST
  • 2000 TOYOTA SIENNA
  • 16,000 MILES
Had check engine light come on auto zone diagnosis was misfire cylinder 1 &6 and random misfire have replaced plugs wires all coil packs and #6 injector still surges and runs poor any idea
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Engine running rough or misfiring can be cause by the following:

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

1.Defective spark plugs
2.Inadequate spark/coil,defective spark plug wire.
3.Lack of compression
4.False air leakage.
5.Faulty fuel injectors.
6.Insufficient fuel pressure.
7.Contaminated fuel.
8.EGR valve that is leaking.
9.Oxygen sensors.
10.Throttle position sensor.
11.Manifold absolute pressure sensor
12.Mass Airflow Sensor
13.Idle air control valve

Note: If it doesn't apply disregard it-
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
Do a compression test and check if coils firing injectors pulsing
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
DCOLLINS1973
  • MEMBER
  • 1 POST
  • 2000 TOYOTA SIENNA
  • 6 CYL
  • 150,000 MILES
I have a 2000 Toyota Sienna XLE which is having some problems. The engine seems to be misfiring and the codes P0300 P0304 P0306

I replaced the plugs and the fuel filter so far. Should I replace the plug wires next? It seems like they will be hard to change at the back side near the firewall. Any suggestions would be helpful. Thanks
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
DANLESABRE
  • MEMBER
  • 230 POSTS
You should replace the spark plug wires when you replace the spark plugs. Do you know if the intake plentum must be removed to replace the wires by the firewall?
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
TECHROVER
  • MEMBER
  • 4 POSTS
  • 1999 TOYOTA SIENNA
  • 3.0L
  • V6
  • 2WD
  • AUTOMATIC
  • 109,000 MILES
I had the water pump, timing belt and seals replaced around 91, 00. I do regular oil changes, and have noticed some oil drops on floor over last year(though oil level is always fine).

Car was driving fine till yesterday. Today wife complained (after driving five miles) about burning smell and steering wheel was vibrating. Check engine lights came on.

I checked codes - P0300, P0302, P0305. I found the coolant tank was almost empty(some coolant at bottom). I found the engine compartment was sprayed with white salt type liquid and dried (I have photos).

I reset codes. Refilled coolant. I started the engine after refilling coolant it runs fine, but the steering wheel vibrates when engine is in "D". Also the panel light for "D" does not illuminate (P and R lights do illuminate).

Need help to figure out if it is a radiator issue or spark plug/coil issue. I also have some oil leaking from the engine that was already present due to age of the car.
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,606 POSTS
Have system pressure checked for leaks, but with the codes you have it may be a bad head gasket. and it may have sprayed coolant on to the transmission selector and causing your illumination problem.

here is a link to a pressure test video

http://youtu.be/W8kra65m15c

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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
TECHROVER
  • MEMBER
  • 4 POSTS
Thanks HMAC300. I will try to get the system pressure tested today.
Some more information. I started the car and got it to operating temperature. The codes returned (P0300, P0302, P0305). No visible leak except for a few drop of coolant dripping below radiator. The engine and steering wheel vibrates when put in gear(R/D) but not in P or N. I touched the inlet and outlet radiator hoses both are hot with car just parked in garage. Sounds like radiator issue?

I am going to do coil swap to rule our coils/wires. Will put in the fuel injector cleaner to clear nozzles.

Any other suggestions?
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
TECHROVER
  • MEMBER
  • 4 POSTS
Pressure tested using Harbor Feight Radiator Compression Tester. Radiator has a leak at top inlet pipe. Coil swapping to be done next.
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
ED-WEEZY21
  • MECHANIC
  • 248 POSTS
Just to add to this one a little, a vehicle may cause misfiring codes when its overheating. I would fix the coolant issue first before diving into the misfiring problem just in case it sorts itself out. If the coolant issue is fixed and misfire codes are still present, proceed with coil swapping to see it the misfire follows the coils. Inspect the spark plugs as well while you're in there and make sure they aren't worn down where the spark plug gap is too big. Best of luck.
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
TECHROVER
  • MEMBER
  • 4 POSTS
Thanks all for the help. After researching and getting help from posters like you, I was able to sort out the problem (hopefully.)
1. Problem#1 Busted radiator - Radiator inlet was leaking as detected using the pressure test. Replaced with new radiator. Drained/flushed/refilled coolant.
2. Problem#2 Engine Misfire cyl #2 & 5. Turned out to be bad ignition coil. It was my mistake earlier to have not labelled the coils properly when swapping. When I did the spark test - it came out clear.
3. Problem #3 Exhaust manifold(Upper catalytic converter) was turning red hot due to unburnt fuel getting there. This was due to Problem #2 and so once that was fixed, it corrected.

I learnt a lot in the process and am thankful to the community for tips. Youtube is also great help.
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
99TOYSIEN
  • MEMBER
  • 3 POSTS
  • 1999 TOYOTA SIENNA
  • 3.0L
  • V6
  • FWD
  • AUTOMATIC
  • 195,000 MILES
Misfire #1 cylender. During ideal and acceleration. Comes and goes. Might be weather related misfire less during cooler low humidity days. Temperature under 70 degrees less misfire occurrence.
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,606 POSTS
Check fuel pressure with a gauge and for vacuum leaks first then compression
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,544 POSTS
I'm glad we could help you, please use 2Carpros. Com anytime we are happy to be of assistance.
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
99TOYSIEN
  • MEMBER
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Forgot to mention Scan error codes P0300 & P0301. I know P0300 is random misfire & 301 is misfire cyl#1.
It acts more like an occasional bad connection. ("On again/off again" misfire)
If it was fuel pressure problem would it only affect one cylinder? And if it did, would it then be a injector problem?
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,606 POSTS
No it still cold be fuel pressure due to being low as well as vacuum leak. It also could be injector but check what I said first.
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)
Tiny
99TOYSIEN
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Will do, will report back, Thanks!
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Wednesday, July 29th, 2020 AT 5:45 PM (Merged)

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