P0300 and P0304 on 2001 Camry with 4-cyl

[camry_jc]

Hi, I have a 2001 Camry, 4 cyl, 5-speed manual that is throwing P0300 and P0304. I replaced the 1-4 coil pack with an OEM part and the code is still being thrown. There are 89,000 miles on the car.

Now, at idle, it SEEMS to be fine, i.e., it idles perfectly smooth. and, if i slowly depress the throttle and bring the RPMs up to 2000, 3000, 4000 is SEEMS to be fine.

To prove this to myself, i yanked the Cyl#4 wire, started the motor up, and sure enough, you could tell it was misfiring... it is all lumpy.

Putting the #4 wire back in, i restarted, and all is smooth. When I bring the idle up by hitting the throttle hard (rather than slowly), i can hear / feel the misfire.

I checked the wires, they look fine. I do not see any burn/meltedness to it, the connectors look shiny, etc.

I am starting to think this is not an ignition problem, but rather a fuel delivery issue. I would think if it was the fuel filter, I would be getting P0300 - P0304 inclusive. Seems to be sticking on cyl #4 as the issue.

What do you suggest for next steps? I am pondering the injectors, tried searching the forum for a "how-to" on this but could not find one.

thanks
-jc


Based on this, I am thinking it is not an ignii

[abew330]

you try cleaning the injectors? ive used bg 44k to clean... its a bit expensive but i do notice a difference. i believe you can try seafoam as well

what about changing the fuel filter? usually inexpensive $4-8 at local parts store

might not help the misfire but always a good idea to clean up the TB.. a can of cleaner also found at local parts store $3-4

may not help but also try clean up the connections / plugs to coils / injectors (electronic cleaner)

[camry_jc]

Originally Posted by abew330

you try cleaning the injectors? ive used bg 44k to clean... its a bit expensive but i do notice a difference. i believe you can try seafoam as well

what about changing the fuel filter? usually inexpensive $4-8 at local parts store

might not help the misfire but always a good idea to clean up the TB.. a can of cleaner also found at local parts store $3-4

may not help but also try clean up the connections / plugs to coils / injectors (electronic cleaner)

No, have not done either yet. Can anyone point me to the procedure on how to remove the injectors? I have been searching around the 'net with no luck.

[Mike Gerber]

"I checked the wires, they look fine."

Looks can be deceiving. Although it can be that fuel injector, missing under load like you are describing is more often caused by faulty ignition system components. Have you checked that number 4 spark plug wire for resistance with a digital volt/ohmeter? I wouldn't be surprised if you can't get a reading, showing an internal break in that wire. Have you pulled that number 4 spark plug and checked it's condition? I would think of those components first, before moving on to the injector.

Mike

[camry_jc]

Regarding Mike's questions:

Have you checked that number 4 spark plug wire for resistance with a digital volt/ohmeter? I wouldn't be surprised if you can't get a reading, showing an internal break in that wire.

Ok, just did this test with my ohmeter set at 2000k:

#1 wire: 10
#2 wire: 8
#3 wire: 10
#4 wire: 5

What is expected? Is there more demand on the integrity of the wire as the power is increased? I would think it is all about RPMs and given that I can rev it with little throttle and it appears ok, the spark is being delivered. Thoughts?

Have you pulled that number 4 spark plug and checked it's condition?


Yes, pulled all 4 plugs, they look consistent. They are NGKs and I replaced them not long ago.

Thanks.
-jc

[abew330]

^^^^^^^^^^^^^^^^^^^^^^^
im not sure on I-4 but the 1mz resistance suppose to be at 13

[91MR2quickNA]

Remember, the 2000+ 5SFE is wasted spark just like the 1997-2001 1MZ, so when cylinder 1 is firing just after TDC in the intake stroke, cylinder 4 is also firing in its exhaust stroke (albeit with less energy).

What I'm getting at is the increased wear on the ignition components. You say you changed the coils. Good. Now its time to change out those wires. Go OEM or nothing. The resistance is low on cylinder 4's wire.

[fenixus]

I would definitely try new fuel filter and wires. just, i'm perhaps anal about this but i would go with OEM fuel filter (23300-79545 at $26 shipped from toyotapartsoutlet.com) only and NGK wires only (

TE58

TE58

at $27 shipped from amazon).

I heard bad opinions about fram/champion fuel filters. they do not last in good condition as long as OEM.
also stay away from bosch products for this model, it's a quality catastrophe.

Also in Advance Auto Parts you can get Chevron Techron concentrate in buy 1 get 1 deal (tried 2 of them so far and it makes the difference). they also sell Sea Foam treatment (now on sale @ $6.99) which further smoothed out my ride and made top of cylinder head really nice (checked today).
how is your air filter ?

though i didn't have any misfire codes, just trying to figure out why my ride uses +14% up to +25% on long term fuel trim at idle. after all it seems i've got partially clogged injectors. was thinking about BG 44K but this is expensive ...

[camry_jc]

UPDATE:

So, turns out, my old man has an '01 Camry, same engine, automatic. So, this morning, I go and snake wire #4 from his car, throw it in my Camry, and viola, the problem is solved - no more misfire. I say to myself, "Yeah! Wire set needed". I drive back to my old man's house, put MY #4 wire in his car, fire it up, and his engine runs fine! Ok, so here were are:

- bad #4 wire in my dad's car
- good #4 wire in my car
- both run mint!

Now, I swap'em, but before that, I measure the resistance. Both wires weight in at 5 ohms. Ok, Put the good back in my dad's car and the bad back in my car. They STILL both run fine.

So, now I can't explain what made things 'better'. A good night's sleep in the laneway perhaps? I am thinking next steps of:

- get some injector cleaner in the gas tank @ next fill up
- use 93 oct gas for a tank
- replace fuel filter
- replace the wires

then, see how it goes.

for now, it seems alright, but I must say, I am uncomfortable at not getting down to root cause for failure here.

-jc

[Mike Gerber]

You may still have a poor connection on that #4 wire, or it may still have a break internal to that wire. Moving things around a bit can cause that break to make contact again. If the problem returns, I would try to replace just that wire as a test. I don't know if they still do (and I'm not a strong proponent of using afterrmarket) but places like NAPA used to sell individual wires. Some Toyota dealers sell individual wires.

Mike

[camry_jc]

Originally Posted by Mike Gerber

You may still have a poor connection on that #4 wire, or it may still have a break internal to that wire. Moving things around a bit can cause that break to make contact again. If the problem returns, I would try to replace just that wire as a test. I don't know if they still do (and I'm not a strong proponent of using afterrmarket) but places like NAPA used to sell individual wires. Some Toyota dealers sell individual wires.

Mike

I ordered wires from the reference provided in an earlier reply. Once those are in, I'll install and then continue monitoring the situation.

Thanks all for the replies, suggestions, etc.

-jc

[camry_jc]

Alright, this is getting strange. Wife drives car Monday, says it is running great. Then, today, she reports it starting to act up again. Same behavior. I have not taken it for a ride yet to confirm, but now I am at a loss at an explanation why it suddenly regressed. On the positive side, I did get the new wire set and will put'em in and see if there is an improvement. Outside of that, anyone have any explanation/ideas as to why it would suddenly improve, only to regress in a few days?

[fenixus]

i think a broken spark plug wire can do that, it would also react to heavy humid weather i think (did for me with another car). however on a different one it was a dying engine

[93celicaconv]

Just curious on this one, if the 2001 5S-FE uses the wasted spark ignition system (I don't have a 5S-FE that new), and a single ignition spark pulse is delivered to both #1 & #4 wires at the same time, and according to what I know about electricity, the circuit with the least resistance will get a majority (if not all) of the pulse energy.

Wires #1 & #4 are on the same ignition circuit. Wire #4 has half the resistance of wire #1 (per post 5). It would seem logical to me that an imbalance of resistance between these two wires of that degree would cause cylinder #4 to fire much more easily than cylinder #1. So I'm wondering if cylinder #1 is misfiring because of the low resistance from wire #1?

It would have been interesting to have checked the resistance of wire #4 that temporarily came from the donor car. And I wonder why wire #4 is so low in resistance compared to the other 3 (unless wire #4 is actually where it should be, and the other 3 have become worn with age and use - which is the reason one should not change a single spark plug wire in a wasted spark system, as maybe wire #4 was once replaced by itself and is the reason its reistance is low compared tothe rest).

Regarding the question of spark getting all the way across the gap of a spark plug, physics tells us electricity flows across a gap far easier in a vacuum than in our normal atmosphere. That also means, in a car engine, it is easier to get a spark to jump a gap on a spark plug when there is less pressure in the cylinder at the time the ignition pulses a spark. When an engine is accelerating, the throttle plate opens, manifold vacuum drops, so each cylinder gets more air, and with more are, the pressure in the cylinder during the compression stroke is higher. That is why an ignition system that is borderline on getting spark to jump the gap of a spark plug may be OK when the engine idles or is steady running at a fast speed, but it may miss when under load.

[camry_jc]

Originally Posted by 93celicaconv

Just curious on this one, if the 2001 5S-FE uses the wasted spark ignition system

What is the "wasted spark ignition"?

Originally Posted by 93celicaconv

Wires #1 & #4 are on the same ignition circuit. Wire #4 has half the resistance of wire #1 (per post 5). It would seem logical to me that an imbalance of resistance between these two wires of that degree would cause cylinder #4 to fire much more easily than cylinder #1. So I'm wondering if cylinder #1 is misfiring because of the low resistance from wire #1?

It would have been interesting to have checked the resistance of wire #4 that temporarily came from the donor car.

Interesting. The code was definitely P0304, which suggest the computer detected the misfire on Cyl #4. I did measure the resistance of the #4 wire from the donor car - it was 6 ohm versus 5 ohm for the "bad" one.

-jc