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Discussion Starter #1
Hello. I'm new to the forum but I have been reading various post for a time now. Very helpful.
However i have a few problems a cannot resolve and I would be very happy for all the tips i can get.
The motor is 1az-fe (2002 car with ATM and 4x4) and was installed two years ago as a complete renewed unit.
The problems started with a p0304 code a few months ago. The code happends a bit random.
The code reader shows the misfiring on cyl 4 but also some occasionally on the others.
I tought it could be the coil and swapped it. No change. Changed the plugs and airfilter. No change.
Changed all the injectors with new ones. No change.
The motor did not use oil. There are no oil in the cooling water (or water in the oil).
I've checked compression on all cylinder - its ok. Plan to do a cylinder leakage test later if I dont find another cause for the P0304
Decided to change the oilfilter and the oil also when I was doing all this work.
I have newer had any oil pressure problems earlier. Changed the filter and filled oil. No problem so far.
Thought however it too a bit longer for the oil lamp to go out but thought is was due to the change.
Not been driving much due to the P0304 fault. Maybe 10-15 miles for testing. Also some idle.
Then I noticed that the oil lamp started to flicker and did not stop even if I reved the engine.
Thought the switch was gone and replaced it. No change. I hooked up a pressure reader and the pressure
is about 5-6 psi. the switch lights the oil lamp at approx 3 psi (stamped on the switch 0,2 bar).
When the engine is warm the lights starts to flicker and the oil pressure do not rise with higher revs.
There are no knocking sounds from the engine. Today I drained the oil. Completly fine and no metal. (the first oil I drained was also fine - black but fine)
Removed the oilfilter for inspection. Lowered the oilpan - no sludge - no metal - all looks fine. The
intake screen on the pump is fine - no sludge. Did flush with pressurized air through the oil pressure switch mounting hole
to check if it was clogged. Air flows fine down to the oil filter and out (no filter mounted). I'm going to check the
overpressure valve in the pump tomorrow. The 27 mm plug was stuck so I need to get me a breakerbar.
I going to replace the oil filter, fill with new oil. But what is going on ? Any idea ? Bad oilfilter ? Bad oil pump (motor milage after replaced approx 15000 miles) ? Anyhing else ? Oiltype (filled syntetic 5W-30) ?
I did not remove the pump because all papers I've read say You also need to remove the timing chain.... ?
This I do not understand because the pump, sprocket, chain etc are reachable from the underside ??
A lot of text - so down to two things : P0304 and next to nothing oilpressure. Ideas ??
Concerning the P0304. STFT is around 0 (-2/+2%) on both banks. LTFT is on bank 1, around -17% and bank 2, around -13%.
 

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Seems you've done a very logical and complete analysis. I have no guesses on the oil pressure and only one hint on the misfire. I recently worked on a 2003 Civic the kept showing a cylinder 2 misfire. Compression was very good and swapping coils & injectors didn't make any difference. Turned out the be clogged EGR passages in the other three cylinders causing all EGR to go the #2 making it too lean. So maybe yours is something to do with the EGR system but the Civic had 210,000 miles on it not much less like yours.
 
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My recent P0304 (2003, 1AZFE), was from a faulty ignition coil. I also had oil seeping from my valve cover gasket. Have you tested the ignition coils?
 
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My recent P0304 (2003 1AZFE) was from a faulty ignition coil. I also had oil seeping from my valve cover gasket. Have you tested the ignition coils?
From about 1/3 the way into his post:
I thought it could be the coil and swapped it. No change. Changed the plugs and air filter. No change.
 
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From about 1/3 the way into his post:
Yeah I understand that, but when mine did it, the code also threw for multiple cylinder misfires in addition to the bad coil, #3 in my case. I think it's possible he needs to check the other coils just incase. The easy way and pull to see if it doesn't stumble.
 
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The misfire might not be consistent enough to isolate at idle. With the Civic the engine ran perfect even with the code and MIL. I just had to fix the code to get thru CT emissions.
In any case IMO his low oil pressure is his dominant issue.
 
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Discussion Starter #8
Hi - Sorry for not replying - been away a few days. thansk for all input.
I bought one new coil and moved it around but the misfire stayed at #4. I will double check again.
And also check the EGR system. I also need to get this resolved due to emission testing.
I also have oil in one plug hole. I will change the seal.
I will also try to remove the nut on the overflow valve on the pump again. It seems stuck and I am afraid
of putting on too much force and break something. Its is just aluminium... any experiences on this issue ?
See that the torque is 50 Nm so it sould be possible to loosen...
Concerning the oil pressure. I've bought a new oilfilter. tried to blow air trough the old one and the new one.
It seems to flow much easier through the new one. Maybe (hopefully) it is just a question about a bad oilfilter..? i dont know until I've finished.
I wrote a bit wrong info above concerning the age of the motor. It's about 5-6 years since I changed the motor but the car has not run more than about 30-35000 km that time.
Condition of the oil and lack of metal etc in the oilpan should confirm that things are ok inside (at least with the bearings etc..).
Anyone tried to change the oilpump from the underside without removing the timing etc ? Is it possible ?
Will fill with W10-40 semi syntetic oil this time (not 5W-30 syntetic as i did last time).
Thanks so far.
 

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No it's not consistent enough. it can run on idle many 10-15-20 min or more without any misfire one day. Next day more misfires. Looks sometimes that it is more when it is mid between cold and normal temp.
Seems sometimes that when put on load it increases and sometimes not... not easy this.
 

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No it's not consistent enough. it can run on idle many 10-15-20 min or more without any misfire one day. Next day more misfires. Looks sometimes that it is more when it is mid between cold and normal temp.
Seems sometimes that when put on load it increases and sometimes not... not easy this.
Misfires are hard to diagnose when they act erratic as you describe. Before my bad coil threw an engine light (took about 2 weeks to throw a light), it acted exactly as you described which makes me think you possibly just have a weak coil elsewhere in your group of 4. I know coils are testable with multimeters, perhaps you have one at your disposal? If the Ohms are way off, you may have simply a failing coil contributing to your stumble.
 
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Discussion Starter #11
Hi

Thanks - i will ohm them all. Anyone knows the value it should be ? Do You measure between +B and ground or between IGTx and IGF ? Or any other ??
 

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Discussion Starter #13
Hi again,
Checked the oilpump over-presure valve today. Nothing wrong. Slided fine in and out. Spring was ok.
When I loosened the nut, oil came out from the suction strainer and that confirms that the nut was not leaking and that oil stayed in the pump.
If there is an internal leak I cannot tell but i doubt it. Put the oilpan in with "liquid" gasket. Now I have to wait until
the gasket is cured (I assume a day). I will pour in oil tomorrow and try. Fingers crossed ;-).
 

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Discussion Starter #14
Hi
Oil pressure resolved :)
Filled oil today with new oilfilter.
Primed the pump before starting.
Oilpressure at idle about 20 psi and when reving about 65 psi.
I suspect the filter was the cause but i dont't know. But it works.
When it comes to the misfiring, I ran the car for some time today. Now I got P300, P301 and P304 as pending codes.
Started with a P304 code. Deleted it and no new codes. But when checking i got the a.m. pending codes.
I've been looking at the curves and live data and I start to suspect the downstream oxygen sensor.
Both upstream AF sensor output a normal 3 to 3,3 V signal so they seem ok.
Bank 1 runs on a negative long time fuel trim. So do bank 2 also but not so high figures.
There are no oxygen sensor fault but if i have understood things right, shouldn't the sensor fluctuate between approx 0,4 to 0,8 V steady ??
Mine, especially the one on bank 1 seems very slow in reactions. I've included some screenshots from the reader. Anyone have any ideas ?
The sensors are high priced (aftermarket about 300 USD each) and I think it will be too expensive just to change them (hopefully just the one on bank 1) without knowing.
I've not done any leakage test yet - and as the car runs fine when completely warm I not sure if it is related to compression any more.
Are there any way to check the function of the downstream sensors ?
I can also add that when starting cold (when rpm is a bit higher) the motor runs/feels fine. When it get warmer the idle rpm go so far down that it feels as it is going to stop (and misfires also occure). When it reaches higher temp and up to normal operating temp it runs fine again with normal ide rpm.
Two examples of getting a few misfires is when I drive up a steep hill, come to the top and let go of the gas, a may few occure. Also if I drive forward, do a stop - go to reverse and back up a few meters - I also may get a few misfires. I do not notice them on the car but I see it on the live data monitoring. But as I have written above - not all the time and not everytime I do this.
Appreciate all Your help :)
(always something - while I was checking all this, all sound from the radio disapeared... guess I have to check the connections - as it has power and everything else is working :-| )
 

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Discussion Starter #15
If it has any importance; I've also checked the inspection readiness - it seems that it is only the oxygen sensor test that cannot complete.
 

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Some thoughts from my emissions saga (Nov 2016 - Feb 2017) on the 2003 Civic that might help. The car is owned (and loved) by a friend of the family who couldn't afford to replace it but would lose the use of it if I couldn't get it thru emissions.

Started with a "heater" failure on the downstream O2 sensor. Paid $25.45USD for a Denso on eBay. The cable was a little shorter than stock but reached okay.

Kept getting the P302 as a pending code followed by the CE and the random misfire code. Resetting brought it back in less than 10 miles. Checked compression, valve clearance, swapped coils, injectors, all with no change - and no charge to the owner. Thru it all the engine ran flawlessly.

With the new downstream O2 sensor I got P0420 "Catalyst System Below Threshold" I watched the waveforms on my scanner and they were similar to yours and I'd say your downstream ones are normal. I stopped the code with:

You may have a weak upstream O2 sensor but with no code for it maybe not. But if I was test replacing anything it would be that, and with a low cost eBay one.

Meantime what doesn't make sense is getting a misfire code on one cylinder, 4 on yours, 2 on the Civic. With no known way an O2 sensor that measures all four cylinders could cause that I went to the 210,000 mile old EGR system and ended up removing the intake manifold and decarbonizing the whole system guided by a youtube video.

In your case I suggest shutting off the EGR valve so there'll be no leaning of the mixture that I suspect is causing the misfire. You may get EGR codes but if the misfire codes stop you'll have a direction to pursue.
 
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Some of my experiences on random toyota diagnosis... I have seen fuel injectors only fire at or above 1000 rpm.
Possibly have a weak injector or two? I test with a waekon pulse probe tool. I have seen worn coils do funny things causing erroneous readings at o2 sensors due to the incomplete burn in cylinder. Hope this helps?
 

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Discussion Starter #18
Hi
Thanks. the RAV4.2 (gasoline 2.0) has 2 oxygen sensors and 2 AF sensors mening two catalytic converters. Bank 1 is cylinder #1 and #4. Bank 2 is cylinder #2 and #3.
There are no misfires on cyl 2 and 3 - the two that end up in bank 2. The ones that end up in bank 1 tends to misfire - especially cyl 4.
The misfire is heavy on cyl 4 with some fewer on cyl 1 when the motor is cold. When it is stabilized well warm there are fewer misfires but - not enough to set code or pending codes.
So what influences only the cylinders connected to bank 1 ? The two sensors, coils, inj nozzles, compression, wiring, ECM... Anything else ???
I will certainly check the EGR valve etc. during the weekend.

The AF sensors output a reasonable stable voltage between 3 and 3.5. Why do You think they (or the one on bank 1) may be the cause ? And why do the oxygensensor(s) state "incomplete" ?
I should have had a more advanced tester to show all the curves at the same time. Now I only can see two on a small screen... :-|
 

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Discussion Starter #19
Some of my experiences on random toyota diagnosis... I have seen fuel injectors only fire at or above 1000 rpm.
Possibly have a weak injector or two? I test with a waekon pulse probe tool. I have seen worn coils do funny things causing erroneous readings at o2 sensors due to the incomplete burn in cylinder. Hope this helps?
I've changed all 4 injectors to new ones (refurbished). It did not change anything compared to the old ones...
 

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On the Civic I found the EGR passages totally blocked on all but cyl 2. So 2 was getting all the leaning exhaust gasses causing it to misfire. Makes me wonder if your EGR valve and passages are only feeding cyl 4. (As I review guess this is a repeat of my post #2.)
 
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