P0300 code multiple cylinder misfire

Tiny
GARYPVANSICKLE
  • MEMBER
  • 2002 NISSAN XTERRA
  • 3.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 165,000 MILES
I installed an engine I bought off JDM Auto.
Everything fit perfect but had to use injector rack off old engine because of orientation of fuel Line.

Got P0300 very quickly.
Engine lacks power - severely!
3/4 Gas Peddle to get up a small hill.

Replaced distributor, plug wires, spark plugs
Crankshaft position sensor, ground wires, fuel filter.


Took to Nissan
Gas pressure very good - they could not figure it out.
No vacuum leaks I think.
They check 3 injectors which were okay - the 3 easily accessible.
Rest are under Upper Intake they did not check.

Unbolted one exhaust manifold in case a catalytic converter clogged - no increase in power but very noticeable misfire.

Thinking of unbolting opposite exhaust manifold and see if that side misfires.

Googled everything and tried almost everything.

Any ideas or suggestions?
Wednesday, October 16th, 2019 AT 4:38 PM

11 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,462 POSTS
Welcome to 2CarPros. Is the new engine the exact same as the original? Year, make, model, displacement? What year is it? What parts did you use off the old engine other than the injector rack?
There can be very small internal changes to an engine between years and even models where they won't interchange easily if at all. Have seen things like coils that looked the same but were different in wiring, sensors that were reading different. The worst was a Jeep where the engines were almost identical but they changed the directions for the cam and crank sensor triggers without putting it into service information. OOPs.
What was the issue with the old engine?

P0300 can be multiple things, but as you're not sure I would check for vacuum leaks first, The easy way would be to use some starting fluid and spray it around the intake and see if you get a sudden rpm change.
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Wednesday, October 16th, 2019 AT 5:17 PM
Tiny
GARYPVANSICKLE
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  • 9 POSTS
Well, I got the engine from JDM auto, when it arrived 2 parts were reversed on side on engine, alternator and power steering pump, just had to move brackets to opposite side and it all fit perfectly, wire harness fit perfectly, I would assume engine was either a year older or a year newer than this 2002.
So I used alternator and power steering pump off old motor.
Old engine had cracked block - very milky oil.

Started backfiring a bit tonight but I was really giving it a lot of pedal.
Literally a gutless engine.
If I floor it you hear the usual sound, hard to describe, but literally nothing happens.
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Wednesday, October 16th, 2019 AT 7:49 PM
Tiny
GARYPVANSICKLE
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  • 9 POSTS
Starter fluid?
Where upper intake meets lower intake?
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Wednesday, October 16th, 2019 AT 7:58 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,462 POSTS
Running the information shows the 2001 though 2004 engines share the same long block so hopefully that isn't the issue. Starter fluid basically everywhere but into the main air intake. You are hunting for a vacuum leak so pretty much anything could be the problem. You might want to run a compression test as well if this was a used engine. May have run okay or might have been beaten pretty good before you got it.
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Thursday, October 17th, 2019 AT 1:09 AM
Tiny
GARYPVANSICKLE
  • MEMBER
  • 9 POSTS
Found no vacuum leak with starter fluid, I did recall pulling the distributor once while swapping engines and timing was off, have it perfectly timed now, runs better, but still a lot of power missing, no more backfires.
Think all I can do is pull all the front of engine off and see if timing belt has slipped.
At 1,500 RPM's very noticeable misfire, check engine light was flashing once.

Interestingly once I had distributor in correct (prior to timing) I got the code P0031 Cylinder 1 misfire - no codes right now.

Appreciate your input very very much.

The call this P0030 on Xterra "The Code From Hell"
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Thursday, October 17th, 2019 AT 4:44 PM
Tiny
STEVE W.
  • MECHANIC
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P0300 is a pain. That is because there are so many things that can cause it and unless you can test the systems that might be the cause it gets "interesting" quick. Timing could cause power loss but usually you would get a code if it was far enough off to really cause problems. Maybe drop both exhausts and see if you get any power back. One side could be plugged enough that it's choking it out. Also check to see if the EGR is stuck open.
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Thursday, October 17th, 2019 AT 4:59 PM
Tiny
GARYPVANSICKLE
  • MEMBER
  • 9 POSTS
I have not dropped the left side exhaust yet. When I dropped the right it is very easy to hear the misfire but did not have it timed then
Now, when I ordered the engine they said "No Fluids in It" so I stuck 5 quarts of oil in it - it had oil - blew tons of smoke. Do you think oil could have gotten into one of the converters?
Will check EGR Valve tomorrow
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Thursday, October 17th, 2019 AT 7:51 PM
Tiny
STEVE W.
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Yeah it could have dumped oil in the exhaust easily. Enough to plug it if the old engine was dumping coolant in the blowby before it was pulled.
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Thursday, October 17th, 2019 AT 9:13 PM
Tiny
GARYPVANSICKLE
  • MEMBER
  • 9 POSTS
I had no luck removing the exhaust. There was no noticeable increase in power, so I drove into the two O2 sensors and one had a voltage between 0.1 and 0.8 volts and the other was 0.03 to 0.05 volts.
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Friday, October 18th, 2019 AT 12:31 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,602 POSTS
If I can jump in here. lets check the compression to see if the camshaft timing is correct. Here is a guide to help us:

https://www.2carpros.com/articles/how-to-test-engine-compression

Please run down this guide and report back.
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Sunday, October 20th, 2019 AT 1:28 PM
Tiny
STEVE W.
  • MECHANIC
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Which O2 voltages are those? Pre-cat and post-cat or side to side?
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Sunday, October 20th, 2019 AT 3:26 PM

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