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.

 

"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

 

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

 

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

 

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.

 

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 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 ...

 

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

 

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

 

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?

 

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

 

UPDATE:



Replaced all the wires with the NGK's recommended in a post previous to this one. Then, asked The Wife to go get 93 octane and throw some injector cleaner in it. Before all this, I took'er for a ride, and sure enough, it was skipping. I put the wires in (10 minutes or so, nice and easy), then took'er for another ride, and it ran like a champ.

We did have a dramatic change in temp here in New England (85F today), perhaps that aggravated what ever was sick with wire #4, or maybe some bump in the road caused some internal breakage to affect performance.

At any rate, it "seems" fixed for now.

Thanks all for the replies.

 

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.

 

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

What is the "wasted spark ignition"?

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

 

Glad it's fixed.

The 93 octane will not help anything. If the engine is not pinging, there is no advantage to higher octane fuels. Most major petroleum manufacturers use the same additive package in all their grades of gas, according to Consumer Reports. The higher octane fuels have an additional additive to raise the flash point of the gas. That's the temperature at which the fuel ignites. It's not needed for most engines.

The injector cleaner may help a bit, especially if the injectors haven't been cleaned for while.

Mike

 

Here we go again: P304.

Motor hesitates/misfires only on low RPM, i.e., below 2000RPM, and only sometimes
Once RPMs are up, it is fine.

-I did put in the NGK wires a while ago.
-I pulled them all out, check resistance, 5, 5, 4, 3 in order of wire length longest to shortest. Is this what is expected?
-Inspected for cracks, etc. Nada
-I checked plug #4, looks fine, these at NGK's also

I am going to try a bottle of SeaFoam in the gas next fill up.

I have yet to do the fuel filter... that'll be on my list also.

ANything else before I take the big plunge on the 1, 4 coil ?
Also, suggestions for coils?

 

just my 2 cents. make sure the EGR system is operating correctly, because the EGR pipe from the valve is connected to the head very close to cylinder #4 ... and if it happens that the EGR valve stays stuck at idle feeding exhaust to it when it's not supposed to, then the combustion on closest cylinder would surely suffer, likely resulting in some misfire on it as the ECU would keep adjusting AFR based on total cylinders performance (or rather the o2 levels in exhaust stream). it cannot compensate for each cylinder individually, it's either all or none.

I think you can switch ignition modules around and see if problem moves to a different cylinder (or pair of them), if it doesn't then the issue is not related to ignition modules.

you wireset resistance is very good, batter than new OEM, that's the power of NGK

pull the spark plugs out and check how they look, especially compare against the one from cylinder #4 and see how it looks like when compared to others, could give you a hint.

 

Hi all. P304 just will not go away. Engine misfires during low RPM then is fine once above 2000 RPM or so. it is totally reproducible, just find a gear (it is a 5-speed) where RPMs will be 1000-2000, put it to the floor, and misfire city.

Here is what I have done:

- Seafoamed the engine about 1000 miles ago.

- switched coil packs, removed battery neg wire for 2-3 mins, plugged back in. Took it for a ride, same deal, misfire at low RPM. I was hoping it would say P303 but it has P304 pending now after this exercise. Does not seem to be coil-pack related.

- checked OHM on #4 wire again : 3 ohms. This is good, right?

- checked plug condition on #4 versus #3. They look the same. I switched them and will test drive in a few. Wires and plugs are NGK. plug replacement was not that long ago. there are a nice, consistent, white'ish color, no erosion on the electrode

- I used a timing light at idle to try to see if i could catch it in the act, i.e., is it a spark issue or something else. the timing light showed some fairly odd behavior:
#1, #2 - it seemed to flash at 2x the rate #3 and #4.
Not sure if this is 'by design' or not - #1 and #2 both happen to be the LEFT port of the ignition pack
but, it was consistent in both the fast-flashing case and slow-flashing case, i wasn't missing any sparks, at least as far as i could tell.


what do you guys suggest next?

I gotta get through inspection with this PoS this month. 2001 Camry has been a check engine light from hell of a car... worse toyota I ever owned in this regard... my '94 corolla went 201K with zero check eng light issues.

 

Well, well, well...
As I said in the last reply, I swapped #3 and #4 spark plugs, put wire #4 back in to the car, and now the issue appears to have gone away. Could it be my NGKs are sacked out and ready to be replaced? I'll have to let The Wife drive the car for the week and see what happens. She does a TON of stop and go drives, all local driving, etc. though we do take it on the highway often....

thoughts?

 

OK, I have reread this entire thread and can only think of 3 things that I can now suggest.

1. Did you ever check the gap on all these plugs? Too large of a gap can make it difficult for the plug to fire under some circumstances

2. Try switching the 2 coils with each other. See if the misfire switches to plug 2 or 3. That will tell you it's a problem with that coil now firing plugs 2 and 3. If it remains on cylinder 4, you know it's not the coil.

3. I'm surprised you haven't seen a P0420 code with all this misfiring. That P0420 code would mean the cat converter has been destroyed by all the pure gasoline being sent through it, if this is indeed an ignition system misfire. What I'm thinking is that the injector is not spraying fuel in to that cylinder. It could be an injector problem or a clogged fuel filter. In my mind that's the only thing that could cause a misfire code for an extended period of time without destroying the cat converter. I would try a good fuel injection cleaner like Chevron and see if that helps.

Mike

 

OK, I have reread this entire thread and can only think of 3 things that I can now suggest.

2. Try switching the 2 coils with each other. See if the misfire switches to plug 2 or 3. That will tell you it's a problem with that coil now firing plugs 2 and 3. If it remains on cylinder 4, you know it's not the coil.

Mike

I did (2) already and the misfire did not follow the coil. I think I have convince myself the coil is not the issue.

As for (1) - checking the gap. I have not tried that. I can do that. .044 i think is the gap for the 2001 2.2L federal?

I did see P420 once... but, not since reset and the car has been on 4-5 short trips since.

 

I'm sorry if it's been asked already, but has the EGR system been checked yet?

it happens that it's supposed to get activated around 2,500rpm so would not affect idle and it doesn't matter when driving under load, but if it is indeed stuck "open mode" then it would affect idle and surely can cause misfire on cylinder 4 (that's where the EGR pipe connects to the head).

 

Is there a procedure somewhere to check this on the 2001 Camry?
I can try it out...

 

I can't win with this P304 crap... it is back and the engine is skipping again a low RPMs, i.e., between 1000 - 2200RPM or so, then it clears out. Check Eng light isn't on yet, but it is coming...

I will get a new set of plugs, they are cheap enough to try out.

I still need a pointer to the procedure to check the EGR valve.
Anyone have that pretty please?

 

This DIY is on the V6, but they're nearly identical as far as the EGR systems go.
http://www.toyotanation.com/forum/1...-1992-1996-1997-2001/357502-diy-1mz-egr-code-p0401-p0402-diagnostic-repair.html

 

sea foam should also be added to the air intake line for full cleanse. i do it every 15-20k just to get max performance. lots of stuff ends up smoking out, not sure if its the additive or carbon deposits. wont fix the p0304, but will help once you fix that.

i had to replace several of the parts listed in the EGR when i pulled those 04xx codes. it was the EGR-VSV and the vacuum control both needed swapped out. aguy at toyota said the vacuum is usually the first out of the system, followed by VSV. those two fixed the CEL.

ONLY BUY OEM TOYOTA PARTS. this is an important system for your engine. dont skimp.

 

I cannot figure it out

Hi all,
P304 / P303 is being totally elusive. The observed behavior is misfire from 1000 RPM to about 2500 RPM. Once above 2500 RPM or so, it runs fine, no misfiring I can detect.

here is the long list of things I have done to try to diagnose/fix this issue. I am at a loss for next steps, any additional things to consider, please let me know, as I think I'm gonna have to go to the Stealership next. Boo!

1. Checked ignition wires. The OHM'ed out ok, resistance, 5, 5, 4, 3 in order of wire length longest to shortest. To double make sure, I snaked wire #4 from my father's 2001 Camry, put it in there, same behavior.

2. Replaced the plugs. Double checked the gap, they are set to what is recommended by the book.

3. Swapped ignition coils. The code did not follow the ignition coil swap. If it was a bad coil, I would have expected it to follow.

4. Seafoamed the engine.

5. Removed the EGR and checked to ensure the pipe is completely clear and not blocked. It was clear, no blockage. I also checked the port where it connects to the engine in back of cylinder #4, that was clear also.

6. Tested the EGR. I put my finger against the EGR valve, used a vacuum pump, and sure enough, the valve opened and closed as expected with vacuum (open) and closed with no vacuum. The EGR valve opened at around 2 in/Hg of vacuum pressure. Also verified EGR is not leaking, it was able to hold the vacuum pressure.

7. Hooked my vacuum pump up to EGR vacuum port at top of EGR valve, and whilst the engine was idling, I pumped vacuum to about 5 in/Hg , engine started running real rough, eventually stalled. This verifies the EGR valve is indeed working and the passage is not plugged (which was also confirmed when I removed the EGR valve/pipe from the engine in step (5).

8. Measured EGR valve pressure during a road test - I tee'd in a vacuum gauge and put a long piece of hose so I could have it with me in the passenger compartment. During normal driving/lite throttle activity, I measured about 3 or so in/Hg, which, from step (6) is sufficient to open it (noted it would open at 2 in/Hg of vacuum). I am declaring the EGR healthy.

9. Verified correct behavior of the VSV (vacuum switching valve). I took the "Q" vacuum hose from the vacuum modulator and connected it to my vacuum pump, then disconnected the host at the EGR and put another vacuum gauge there. I pumped vacuum up to 5 in/Hg and the vacuum gauge connected to the EGR hose matched the pressure exactly. Then, I energized the VSV by turning on the ignore of the car and the vacuum measured at the EGR hose dropped to zero as expected. I'm declaring the VSV "healthy"

10. I spliced ports P and Q on the vacuum modulator, started the engine, and put my finger gently against the diaphragm in the EGR. Observed the EGR valve opening around 2000-2500 RPM.... this would indicate back pressure to be ok.

11. Checked Ports P and R off the manifold. P showed gradual increase from 0 in/Hg at idle to about 20 in/Hg at 3000 RPM. Port R also behaved as desired - goose the throttle, it showed instant positive vacuum. Slow increase in throttle showed little vacuum until higher RPM.

The only thing in the thread mentioned I have not done yet is the fuel filter. I can do this, but have a hard time seeing why it would cause misfire on 2 cylinder reliably at 1000 - 2500 RPM and have no misfire above 3000 RPM.

Outside of this, what next guys? I am at a loss... this has been a total pain.

thanks!!
camry_jc

 

A few things I haven't seen recommended or in your notes of times checked:

1. Cylinder compression pressures (after engine has been warmed up)
2. Swapping fuel injectors (good for possible bad, such as #4 cylinder with #1 cylinder, to see if the intermittent problem becomes cylinders #1 & #3).

It is possible you have poor compression on 2 of the 4 cylinders, or your have fuel injector issues which the fuel injector cleaner did not resolve. Because cylinders #1 & #2 never seem to be causing an issue, I don't think your ignition or mechanical timing are off, but it would be worth checking at least your ignition timing by the method indicated on the sticker under the hood just to make absolutely sure (this would be a 3rd check to make on this engine).

 

One more piece of CRITICAL (hopefully?) data:

The mis-fire issue DOES NOT appear to occur when the engine is cold. So, if I let the engine sit over night, start it up, and try to reproduce the problem, it doesn't happen. As soon as the engine is warm, boom! misfire city at 1000 to about 2500 RPM.

Based on this, I am not convinced it is anything to do with compression or dirty injectors. I am going to measure the compression now, however, and will report results.

I am starting to think this is ignition related.

Question for the crew is: what is different between cold and warm?
And, why would it not misfire when cold?

The hunt continues!

 

This is a good piece of information.

If you have an OBD scanner, based on your new CRITICAL data, I would suggest you clear all codes with the engine off, then leave it sit overnight. Then run the engine until you get your check engine light on. Then put your OBD scanner on it, read the codes and collect the freeze frame data. It would be very interesting to see what your LTFT (long-term fuel trim) and STFT (short-term fuel trim) values are. You may have something going on with your O2 sensors whent he ECU switches from open-loop control (when engine is cold) to closed-loop control (when the engine approaches normal operating temperature). Still could be injector related, but if you find swapping injectors to be more trouble than what the diagnosis is worth, this data could still tell us a lot on what is going on.

Below is a good evaluation of what LTFT & STFT values can tell you:

When the numbers are negative, the computer is subtracting fuel to compensate for a rich mixture. The most likely reason is a dripping injector. This will drive the other cylinders extremely lean, almost to the border-line of misfiring. The result is that on quick acceleration from a dead stop, the engine may hesitate, stumble and stall. A leaky injector will be less detrimental at higher speed (2000 RPM & higher), since the number of drips is only 30% of what it would be at idle. To prove this, increase speed to 2000 RPM or higher and observe the short term percentage number dropping toward zero.

When the numbers are positive, the computer is adding fuel to compensate for a lean condition, like a restricted injector or a vacuum leak.​

 

This is a good piece of information.
Then put your OBD scanner on it, read the codes and collect the freeze frame data. It would be very interesting to see what your LTFT (long-term fuel trim) and STFT (short-term fuel trim) values are.

I do not think my fairly primative ODBII reader can get freeze data, so I don't think I can get this.
I'll check it.