So I now this topic has been covered a lot. I have spent many hours researching and testing. I could use some more advice.

1998 3.4 4runner LTD 222,000 kms automatic 4x4

I get pending and faults, check engine light comes on. P0300, P0302, & P0305. Misfire in cylinders 2 & 5. These codes happen all the time and have for 3 weeks. Once and only once did I get a pending misfire in cylinder 1. The truck is running extremely lean. An average reading would be 14.7-1, mine is at 28.38-1. I get no other codes. The codes come on at idle and under load.

Replaced with OEM Toyota parts
Spark plugs
Wires
Coil Packs
Injector #2 (had bad resistance)
Engine Coolant Temp Sensor (had bad resistance)
Alternator
Batteries
All Ground and Positive wires
Air filter
Fuel filter
Timing Belt (20,000 kms ago)
Waterpump (20,000 kms ago)
I have had recent and regular maintenance done following the Toyota schedule.

Tested and is okay
Mass Air Flow Sensor
Injectors
Intake Leak
Vacuum Leak
Vacuum Lines
Coil packs swapped around
Crankshaft Timing Pulley Bolt
Injector cleaner through a full tank of gas
Cleaned MAF
When it misfires, I can barely feel it. The truck runs pretty good now, it shifts better and is much more responsive. Under load I can feel a very little lack of power. It is still throwing the same codes. It constantly does it. Anyone else have some advice?

 

Compression Test

1 - 170
2 - 155
3 - 160
4 - 155
5 - 160
6 - 165

 

I see you checked the crank bolt, but did you check the key way on the pulley itself? And if thats good then I would try a new crank sensor.

 

I haven't taken the timing belt cover off yet. That will be my next step. I don't understand the term key way? No mention of key way in FSM. What do you mean by key way?

 

I was able to google it and get some info.

Thanks,

 

2 & 5 are on the same coil pack (anytime the difference is three = same coil pack) so I would insist on spark issue. Try swapping plugs and ohm out wire. A bad plug or wire can mess up both as the spark voltage goes from coil through odd plug to engine to even plug ground, then up through plug and down wire to return to coil. Any open along that path will mess up both. Shorts will only mess up one.

I know you swapped the parts, but bad out of the box does happen for plugs, coils and wires.. Swapping with a known good coil or plug will rule this out. Ohming out the new wire will take care of that. 2 & 5 is just too glaring to not insist on the spark issue. Also check the wire to the igniter.

I would also do this to check the igniter and confirm spark issue in general(from FSM, p IG-1)

I know it runs fine most of the time but maybe you can see if spark is weak compared to another pair.

 

How tight were the spark plugs installed? I'd do a visual spark plug test at night and see if the spark for 2&5 is as strong as for the other plugs.

Also check the wire connections to both the injector and the coil. If the copper is on the way out due to oxidation or the like, then that may be your problem.

 

Have you checked valve clearances? At 220k km, its over-due

 

Swap the suspect coil with one of the other ones and see if the misfire follows it.

 

Yes the spark plugs have been tested and swapped around. No difference. I have inspected and checked all wire connections. They were all in good shape.

 

I myself haven't checked. Is there an easy way of doing this without ripping open the engine? Does Toyota do this for regular maintenance? If so it has been done.

 

read my original post, thanks for the advice, but I have done that already.

 

Try putting 93oct gas in it and see if it is any better.

 

I usually run 91 oct gas. The last two tanks I ran 93, no difference.

Thanks

 

Odd, if the issue doesn't follow the coil and it is always in those cylinders then the issue must be prior to the coil getting the signal. Wiring issue would be the first place to start looking. Make sure it is getting the correct voltage and there are no shorts ect.

If that checks out then it is possible it is an issue with the ECU/ECU connector.

 

Hello I have almost the same problem on my 98 4Runner, did you check the PCV valve, it was not listed above. Do you have oil in the intake system, or PCV valve & hose. Not sure if it means any thing I have that symptom, and it was leaking oil from valve covers. With mine I get miscellaneous random misfires, but my check engine light goes away sometimes as well. Not trying to hijack here but thought I would throw that out, you probably already checked it you were pretty thorough. I am going to try cleaning the intake with Sea Foam.
Like TA said check the wiring, while doing that check the insulation on the wires also make sure it is not brittle. It could be as simple as unplugging the ECU letting sit out a minute then plugging it back in. Do you know about the procedure to clear the codes from the Readiness Monitor in TSB EG003-02 using the drive patterns procedure? I have a copy of the TSB in PDF form, I do not remember where I downloaded it from, but it is not hard to find. Wish you luck in solving your malfunction.

Hey TA I have a couple quotes for you.

"I believe that the right of the citizen to keep and bear arms must not be infringed if liberty in America is to survive." - Ronald Reagan

“Never trust a government that doesn't trust its own citizens with guns.” - Benjamin Franklin

 

Love it^!

 

No oil in the plenum or intake chamber. I did check the PCV valve today and is moves fine, no oil or anything. I only have a few things left to check. I have checked the wires briefly I didn't strip them out and fully test, but nothing is brittle and they all look good. Not too sure on the readiness monitor. I will look into that

Thanks!

 

When you guys say ECU, what exactly do you mean? I see a 4WD Control ECU and a Shift Lock Control ECU. Do you mean ECM (engine control module)? or is there something I am missing. I am by far not the expert, but am becoming one fast

 

Well, everyone calls the ECU something different, ECM, EFI, ECU ect ect. ECU 99% of the time without some other clarifier means the main ECU that runs the engine.