jatf

Just found these forums yesterday. What a great resource!

Yesterday on the way home My wife's '02 RX300 started misfiring. I have a codescout 2500 which says "Cylinder #2 misfire". I figured 'hey, it just crossed 100k, probably time to change the plugs.' Picked up some iridiums and put all six of them in. Same code. Swapped coils 2 & 4. Same code - #2. Changed coils with 2 & 6, same code. Can feel the injector firing, but swapped 2 & 4 anyway (careful not to lose any o-rings!). #2 doesn't look as nice as #4 around the base, but no change. Same code. Each time I change something I reset the code and it takes about 45 seconds to 2 minutes to re-display the code, and it's always code #2 misfiring.

I know I'm on the right cylinder because if I pull the injector control wire or coil wire from 4 or 6 the engine *really* bogs down, but if I pull #2 nothing happens. It's still missing, it just doesn't get any worse.

I've left the injectors swapped just because I don't want to take the rail off again, but everything else is back (except for the new plugs).

Any ideas?

code58

It would seem logical that it must be a failure in the juice to the #2 COP. If it were me, I would pull the COP on #2 cyl and install 1 of your old plugs on the COP laying where you can see the tip of the spark plug. (remember to disconnect the plug for #2 injector, you don't need to flood that cyl any more with fuel it's not burning. If it's not showing any spark, you know you have to trace it back up the line to the source to see if there is a grounded or chaffed wire or if it is actually back in the PCM. I think you've ruled out it being anything but electrical to the COP. You could do a compression test on #2 but that cyl is already washed down pretty good with all the unburned fuel so the compression may be a little low because of that. I think #2 is on the rear bank so doing a compression test is a little bit of a challenge. Probably be able to tell if it was low by just shorting across the starter with the key off and whether it rolled over evenly or not.

salimshah

Getting a code is one thing, but if possible, you should verify the problem. Cylinder misfire (actual) can be experienced by rough engine and loss of power. Without these, there is some other problem. I would suspect it is the sensor or wiring to-from-cpu.

If it was the actual misfire then you would trace the spark path or fuel.


Salim

jatf

It definitely runs rough and has loss of power. I had moved the coil to Cyl #4 and the problem didn't move with it. I'm going to go over my troubleshooting again this morning, and move the new plug from 2 to 4 to make sure I didn't get a bad one out of the box.

Cyl #2 is in the front-left, as I'm facing the engine, right? Like this:

Firewall

_______________
|--1---3---5--|
|-------------|
|--2---4---6--|
|_____________|

Front of car

--JATF

salimshah

My bad ... your picture is correct.

Incidentally when I lost #2 at 140K miles, I replaced all plugs. When I started the engine the problem moved to #4 and it ignition pack died on #4. After replacing that, every thing went to normal for me.

Salim

Nad1370

Two other possibilities:
1. Bad injector. (like you said)
2. Low to no compression on cylinder 2. (worse one)

I would do a compression test first to rule out a bad cylinder. Then replace the injector.

jatf

I wound up checking the spark against the frame and it worked fine.

Unfortunately, the compression meter does not lie. 70psi on C2, 195 on C4 & 6.

I've turned it over to my local shop. He has a scope to see if it's a broken valve, a pulled seat or worse. It happened all of a sudden so I don't think it's the rings. Well, at least I can hope, right?

Thanks for all your help. It helped me keep from going crazy chasing it down.

--JATF

jatf

If it needs new heads, are the Toyota parts a direct replacement on that engine, or would I need to get Lexus parts?

brncgreen13371

And here's your sign. Lexus parts duuh. Jokes... It's a Toyota engine brother. Lexus is no more then that L emblem. Everything else it's toyota

salimshah

The parent company is Toyota and one of its brands in Lexus. When you buy Lexus part, it most likely will be boxed in Toyota packaging. Also Toyota does not manufacture many parts and Toyota purchases them from another manufacturers (eg: Denso etc). Staying on Denso, they may sell the part to other retailers and that may or may not of the same quality as they sell to Toyota but they will not be in Toyota packaging. That opens up an opportunity of fake packaging and reboxing.

Lexus parts will most likely have a different part number than a Toyota part number of a sister model offered under Toyota badge.

Should a Lexus customer blindly cross over and purchase Toyota part from its sister model?
Let me take it a step further and ask should '98 model Lexus RX purchase 02 Lexus RX part? For generic part the answer is yes. But if it is a specific part which interfaces with certain model ecu, then NO. Provide the VIN to get the right part. [Ex: Knock sensors --- they have different part number based on manufacture date ... do not confuse it with superseded ...more on superseded part later].

My way is to buy parts from online Lexus retailer and my savings comes from DIY.

Salim
PS: Superseded parts: Based on use/quality_concerns/cost Toyota/Lexus may discontinue and substitute with another part number. I would alway urge members to call Lexus parts and get the latest part number before purchasing genuine yet discontinued part.

On lighter note: Is Lexus the same as Toyota? I jokingly say if you purchase Toyota parts, you should openly state that you drive a Toyota.