Toyota RAV4 Forums banner
Cancel
Create thread New Garage Forums

2000 misfiring-Codes 300/304/171 acting strange

Jump to Latest
1 - 17 of 17 Posts
E

evlelephant

· Registered
Joined
·
10 Posts
Discussion starter · #1 · (Edited)
Silver 2000 167,000 miles (named Ravi) Timing belt/water pump/alternator replaced at 92,000, OEM battery replaced in last 10,000 miles. Oil Changed Regularly, Coolant changed and levels are proper.
I have an intermittent problem.


CEL Came on, then starteding flashing and Ravi threw codes P0171/P0300/P0301/P0304-I parked it and I did the following

New NGK OEM Spark Plugs (4)
New OEM Plug Wires
New OEM Ignition Coils (2)
Fuel Injector Cleaner

Checked all hoses for vacuum leaks- found none
Fuel Cap checked- no leak

Codes were cleared and she drove perfectly (better than before-better acceleration/mpg/smoother/quieter) for 2 weeks. Then flashing CEL and she threw codes P0300/P0301/P0304. Parked it, bought an OBDII reader and started it up, all codes were gone. Drove it for 1 week and today, flashing CEL and codes P0300/P0301/P0304 again. After checking codes, turned it off, restarted and it ran fine again and CEL went out. Not sure what direction to go.
Help, I can't trust Ravi right now!

Code Legend:
P0171 System too lean bank 1
P0300 Random Misfire detected
P0301 Cylinder 1 Misfire detected
P0304 Cylinder 4 Misfire detected
 
#2 ·
-- No. 1 and No. 4 cylinders fire off the same ignition coil pack (the one that is forward-most in the engine bay). I wonder if one cylinder's misfiring can affect the other's, via the coil pack. Certainly especially check the connections to the coil pack. Is there an intermittent ground somewhere?

-- Did the old spark plugs have oil on them? Is there any oil in the spark plug tubes themselves? For a DIY on replacing the spark plug tube seals, see demoder's excellent instructions at https://www.rav4world.com/forums/85...6729-diy-replace-valve-cover-gasket-reseal-spark-plug-tubes-stop-oil-plugs.html

-- What fuel injector cleaner did you use? A bunch of Rav4.1 owners swear by Lucas Upper Cylinder Lubrication and Injector Cleaner. See
at https://www.rav4world.com/forums/94...fications/75984-i-ve-seen-too-many-fuel-injector-problems-suggestion-lucas.html . See also:

-- Have you double checked for secure electrical connections to all involved parts?

-- I would be concerned that the head gasket blew. Does the engine oil show any signs of having coolant in it? Is the coolant level steady or has it been going down?

-- After any maintenance involving a CEL, I suggest resetting the engine computer, by pulling the EFI fuse in the engine bay fuse box on the driver's side for a minute (with the engine off), then re-installing.

-- I bet you saw that many people swap fuel injectors to see if the problem follows the injector. I see that removing the injectors is not an easy chore, though.
 
Discussion starter · #4 ·
Update-

I did what Elle_Rav4 suggested. Checked all electrical connections. Oil is good, no milkshake. Coolant levels are steady. Used Lucas injector cleaner.



I tapped out and took it to a shop, they diagnosed faulty IAC and Bank 1 Oxygen sensor.

Replaced IAC and Oxygen Sensor with OEM parts.

Drove great for week and a half and went thru a full tank of gas.,Gas Mileage went from 25mpg to 29 mpg! I thought I had it licked...



Today it threw the same codes as before.
UPDATE-edit it just added code P0171 again.
CEL flashing
P0171 System too lean bank 1
P0300 Random Misfire detected
P0301 Cylinder 1 Misfire detected
P0304 Cylinder 4 Misfire detected
 
#5 ·
My next steps would be:

-- Remove the new plugs and check for oil on the electrodes especially cylinders 1 and 4. The oil would be from a failed spark plug tube seal. There is a good DIY here at Rav4world on how to replace these seals.

-- Get the compression on each cylinder checked.

-- Check that fuel pressure from the fuel pump is sufficient. You'll have to buy a fuel pressure gage et cetera. I think fuel pumps fail "soft." As they are deteriorating, they are especially prone to failure when the fuel tank is low. When the fuel tank is low, the fuel pump is not fully immersed and is not being cooled as well by gasoline. I think a fuel pump near the end of its life is more likely to fail long after the engine is warmed-up and when the fuel tank is low. The fuel pressure regulator (in the fuel tank) may also be failing.

-- Swap injectors and see if the problem follows the injector. You can buy four refurbished injectors on eBay for under $75 and install them. Since the Rav drove fine for about 10 days, I am wondering if the injector cleaner did its magic for awhile but then the injectors acted up again, due to... ?

-- Look for vacuum leaks.

-- Check the egr system (simulating a vacuum leak).

-- Else I am wondering if the engine valves are not sealing, due to worn springs or the valve seats being worn et cetera. But if this were the problem, I do not think 10 days would go by with no problems.

I still wonder if there is a connection between both cylinders 1 and 4 misfiring and there both being powered by the same ignition coil pack (the forward-most coil pack).
 
Discussion starter · #6 ·
Elle_Rav4
Thank you for your response.

Replacing #2 oxygen sensor- it's showing Fail on my OBDII tester.

Just finished removing and checking the spark plugs. no oil as far as I can tell. they are a little sooty and #1 & #4 were a bit darker. Would they still be wet? As they were dry.

checked the spark plug tubes for oil, all good.

Don't have a way to check compression yet- hopefully will get tool today.

fuel tank is full. little over 3/4 of a tank. Need tool to check fuel pump, hopefully I can get it at the same time as above.

checked for vacuum leaks-none so far.

Will check Egr now-
I wondered the same thing about the coil pack- i got a new pack and tested it, same issues. It appears my new coil packs are good.

Injector/CKP/CMP is where I'm leaning, but not sure.
 
Discussion starter · #7 ·
checked the EGR, unplugged the line, no change. Ran the same with EGR hooked up as without. Strange? Or did I do something wrong....
At this point I have cleared the codes and it's running very rough. No flashing CEL.
 
#8 ·
For now, I would cross off the spark plugs and an oil leak in the spark plug tubes as being the problem

Are you getting a CEL code for the oxygen sensor? And do you mean your OBD2 tester is showing the aft oxygen sensor (near the catalytic converter) is not working right? Which O2 sensor was replaced?

If either oxygen sensor is not working right (or is not properly plugged into its harness), then I bet this is the cause of the latest issue (rough running). Why this suddenly arose is the question. Is unburned fuel going out the exhaust and fouling one or both oxygen sensors?

Make sure the oxygen sensor that was replaced is properly plugged in. I was messing with my Rav's O2 sensor a few months ago and accidentally left it less than fully plugged in, giving poor engine running. It finally came completely unplugged and threw a code, whence I found the connector unfastened.

Here are some clues on checking the fuel injectors: https://www.rav4world.com/forums/85...com/forums/85-4-1-faults-fixes/276065-1998-rav4-bad-functioning-when-hot-3.html . As I check the archives, I am liking more and more the theory that the fuel injectors are toast. Scotty Kilmer on fuel injector replacement:
Re-check your connectors to the EGR as well.

The CMP and CKP sensors are on my mind a bit too. But if either is failing, then they should throw their own code at some point.
 
Discussion starter · #9 ·
No CEL for oxygen sensor, when I test the Oxygen sensors thru my reader it tells me the aft sensor (near catalytic converter) is not working.

I replaced the first O2 sensor- for California it's an Air Ratio Sensor. Double checked the connections to 02 and everything else I could reach. all good.


user Daniel0005 ( i would post the link to the thread but I'm too new) had the same codes 0171/0300/0301/0304 and it turned out to be Injector #1 .

I tested mine with the mechanics scope like Daniel did and found they were all clicking but I've not ohm tested them or taken them off to check yet. It's a bit of a job.


Fuel injectors are what I thought to begin with, however the shop I took it to said the fuel trim and other info did not lead them to believe it was injectors. I replaced what they recommended ( Air Ratio Sensor and Idle Air Valve) but I'm having the same issues, so maybe I can't trust their opinion.



I tested the TPS the Scotty Kilmer way, the result was hard to differentiate. There was a difference but couldn't tell which way, good or bad.

Checked the intake manifold gasket like Scotty said as well (sprayed cleaner to see if it revved) no luck.

I am going to remove and clean the EGR valve, it won't hurt and decide if I'm pulling injectors.
 
#10 ·
..that combination of codes is very specific .... if someone else has had exactly the same issue..with exactly the same codes ...then I would be concentrating on following their lead and replacing whatever they replaced to fix it ..ie injector no.1
Of course .... if you need to replace one ..then doing all 4 would be a wise move ...
 
Discussion starter · #11 ·
gpfleming thank you for your response.

I am going that direction at the moment, I checked them with a mechanics stethoscope and confirmed all 4 are ticking and they all sound the same and fairly strong. That doesn't rule out them being dirty/clogged but it doesn't make me want to jump into them just yet. I'm on a budget and it's getting very tight at this point, not to mention time constraints.
 
#13 ·
-- Common Problems That Trigger P0301 (and P0302 et cetera), from https://repairpal.com/obd-ii-code-p0301:
Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable)
Incorrect ignition timing
Vacuum leak(s)
Low or weak fuel pressure
Improperly functioning EGR system
Defective Mass Air Flow Sensor
Defective Crankshaft and/or Camshaft Sensor
Defective Throttle Position Sensor
Mechanical engine problems (i.e.—low compression, leaking head gasket(s), or valve problems
[Engine coolant temperature sensor, from many sites. Its resistance is easy to check, and it is known to cause problems on Rav4.1's]

Common Misdiagnoses
Fuel Injectors [but many do find that the injectors are the problems]
Oxygen Sensor(s)
Powertrain/Drivetrain problems

-- A person with a 1997 Rav4 (distributor version) reported getting codes P0300 to P0301-P0304 (all cylinders misfiring). He found that the bolt holding the crank position (CKP) sensor had come loose. See https://www.rav4world.com/forums/83...eral/214993-pinging-poor-running-sluggish-p0300-p0301-p0304-issue-resolved.html . Unfortunately you have to do a mini-timing belt job to access the CKP sensor and check its bolt. Certainly also check that the bolt holding the cam position sensor is secure. Of course, it makes sense that a loose CKP sensor would cause a misfire at all cylinders. But could it cause a misfire on only two cylinders? I think not. Still, it might be worth checking these sensors.
 
#14 ·
Being that cylinder 1 and 4 are involved and you state that you have new coils...
Click to expand...
A couple of off-the-wall ideas:

The new coil is actually bad? (Not uncommon with electrical parts)

Ground wire, from the firewall to the back of the engine, is bad. If so, replace it and search the site for how to add an extra ground / earth strap.
 
#15 ·
good call on that rear ground strap .... esp. if you have an unusual 'electrical' fault .. which is intermittant. and you have already replaced the suspected bits ..ie. that coil.

Defo worth checking/cleaning up/replacing that ground strap.

you could also swap the coils over ... see what happens to the fault codes .... if the codes change to cyls. 2 & 3 ..bingo.
 
#16 ·
No guarantees that the following will not break anything. Try at your own risk.

Per gpfleming's post, to do a "swap" of the two ignition coil packs:
(a) leave both ignition coil packs where they are. Unbolt nothing.
(b) swap the two coil packs' electrical connectors. Hopefully Toyota did not make the connectors different shapes. If Toyota did make the electrical connectors different, then the following will not work.
(c) take the cylinder 1 ignition cable and insert it into the aft ignition coil pack, front end
(d) take the cylinder 4 ignition cable and insert it into the aft ignition coil pack, rear end
(e) take the cylinder 2 ignition cable and insert it into the fwd ignition coil pack, front end
(f) take the cylinder 3 ignition cable and insert it into the fwd ignition coil pack, rear end.
(g) start engine. Let idle. If all seems well, take for test drive. Read any codes that occur. Report back.

Notes:
With everything connected normally --

-- the firing order is 1-3-4-2

-- the far-most passenger side cylinder is number 1.

-- the forward coil pack, front post fires cylinder 1. The rear post fires cylinder 4.

-- the aft coil pack, front post fires cylinder 2. The rear post fires cylinder 3.

-- numbers are stamped on the ignition coil packs showing which side of each coil fires which cylinder.

-- the coil packs have two different part numbers (90919-02218 and 90919-02217). Their mounting bolts might not be located in the same position. Their advertised prices are around $10 apart at online Toyota parts sites. It seems like they would operate the same, but I cannot say for sure.
 
Discussion starter · #17 ·
FIXED!!!!!!!!!!!!!

Thank you to everyone who responded with advice and suggestions for poor ol' Ravi.

Recap:
CEL Came on, then starting flashing and Ravi threw codes P0171/P0300/P0301/P0304. Looked for the MAP, found this vehicle has a MAF, no MAP. Repeat, no MAP on 2000 Rav 4's.
Replaced these parts (for no reason, insert sad face)-coils,spark plugs, plug wires, primary and secondary 02 sensors, IAC (oof on this one). bunch of vacuum hoses (they were fine, just got wrecked when I removed them).
Did the usual diagnosis on TPS, TCS, EGR, cleaned every fuel or electrical part like PCV, etc. checked injectors with a scope, with Ohm Meter, Checked grounds, looked into adding ground wires, basically every, single suggestion this forum gave me. Each replaced part and inspection yielded a better running Ravi but did not fix the issue. Codes would return.

Final Results:
It turned out to be bad injectors (#1 and #3 but I might have damaged #3 during removal). I chose to replace all 4 due to them being so cheap and I'd already spent a ton of money so why not.

How I came to this conclusion (why I should have trusted my gut and prior experience first!!!!):
User Daniel0005 had the same codes 0171/0300/0301/0304 and it turned out to be Injector #1.
Upon further research (hundreds of hours scouring the interwebs for any mention of this set of codes) I found that Bad injectors on this particular engine family is common. What happens is they will intermittently reduce gas flow when they reach certain temps, thus the intermittent problem and why my local shop ruled them out. I used my OBDII to trak the fuel trims until I was positive an injector or 2 was intermittently fuxing up.

TLDR:
CODES P0171/P0300/P0301/P0304, RESULTED IN REPLACING INJECTORS AND THE PROBLEM IS RESOLVED.
 
1 - 17 of 17 Posts
About this Discussion
16 Replies
5 Participants
Last post:
evlelephant
Toyota RAV4 Forums
posts
1.1M
members
174K
Since
2004
Rav 4 World is the internet's largest Toyota Rav4 SUV and EV online forum community. Discuss towing, modifications, and more.
Full Forum Listing
Explore Our Forums
4.3 General 4.3 Mechanical 4.5 RAV4 Hybrid (except Prime) 4.5 RAV4 Prime 4.3 Exterior