Lexus RX330 2006. 219k. Nicely maintained. I went on a 120 mile drive yesterday and about 15 from my destination in heavy traffic, I suddenly started getting P0355 codes with an obvious miss. The whole car was shaking but I made it to my destination. Once I was through with my appointment, it started right up and I headed home. It ran fine for maybe 25 miles, then started up again. I got to a rest stop, I pulled over and I shut the engine off, waited a few moments then restarted. It was fine. On the way home, it repeated this about 4-5 times. Once I did even it at a stoplight, so it wasn't turned off very long before the reset. I know this is bad for the engine and cat converter, but I pressed on.

I have very recently replaced all the sparkplugs and coils with Denso, along with the connector housings.

I guess I'll swap a couple of coils and see what happens. Any other ideas? I do have a fairly good code reader.

Thanks

 

Not Much Progress Report.

I cleared the P0355 code then swapped my # 5 and #6 coils. Drove it around town a bit, maybe 10 short trips, and it seemed to be behaving. Then yesterday I took it on a 40 mile, 60 mph, drive and all was good. It sat for a couple of hours in the rain, then when I started it I got the dreaded P0355 code again, but I couldn't detect a miss and it ran fine all the way home. This morning I pulled the connector on the #5 igniter and sprayed in some contact cleaner and cleared the code. I am also getting a C1201 code.

This is very similar to a problem I had with the #3 ignition coil pack. Scroll to the bottom to see the resolution. After I replaced the connector, I don't think I've had any more failures there. Maybe I need to do the same with #5.

 

I've said it repeatedly the ignition coil connectors should be preventative maintenance items on cars this old. Thev cost $12 on Amazon take minutes to replace (depin/repin with a small pick or tiny screwdriver no soldering). The plastic gets very brittle with age and corrosion the pins likely get compromised as well for $12 why take a chance?

 

Last year, when I replace the valve cover gaskets, I replaced all six ignition connector housings, leaving the terminal intact. I subsequently had problems with #3, so I put in a new connector pigtail assembly with aviation quality butt splices and a ratchet crimping tool. That seemed to do the trick. Maybe I'm looking at the same with #6.

 

I get what you're saying, and I agree. But, it's not the $12, it's the hours spent removing the throttle body and intake plenum that is the rub. But, if I gotta do it, I just gotta do it.

 

The front 3 obviously are very easy, two of the rear 3 may be accessible without anything being removed.

I'd also suggest spraying them with electrical contact cleaner (make sure it says "safe for plastic") I might suggest a tiny film of dialectic grease to sure good contact and it's waterproof

 

If you can reach back in there, make sure your fuel injector plugs are pushed all the way on too. 💯

 

I hope you find a fix.

 

This also happened on the #1 cylinder.

To recap:

• This seemed to start after I replaced the plastic connectors, leaving the OEM pins and wire.
• New Lexus supplied spark plugs.
• New Denso ignition coils (Rock Auto)
• This also happened on Cylinder #1.
• Intermittent
• If I shut off the engine then restarted, the misfire would often go away.
• Replaced all the ignition coil connectors, reusing the old pins.
• Sprayed connector with CRC Electronic Cleaner.

Finally, I removed the connector by cutting the whole thing off, then using aircraft quality butt splices and crimper, I spliced in a new Amazon supplied pigtail. Since I did that, about two months and 700 miles ago, it hasn't failed once.

 

I've got something similar going on with Cyl #5 very occasionally under WOT. Just before redline it'll miss and pull timing, throw a brief P0355 and sometimes a P0101 CEL which goes away when the car is restarted, staying off for weeks until it returns under another WOT moment. I too also replaced all my connector shells, but I need to do a little more digging as I may be having the same issue as SoIllSam. First I'll try testing the coil and maybe swapping 5 and 6 around, to see if it carries over to Cyl 6, if not I may go the route of splicing in a new pigtail. I'll keep everyone updated - although it may not even be a wiring issue as it takes such a specific thing to trigger it vs. happening randomly.

I also need to inspect my injectors and replace the seals as they weep ever so slightly

 

I cleaned my injectors using the makeshift cleaning adapter (bike schraeder valve) very easy to do... also replaced the seals. Regarding your connectors maybe shoot them with electrical contact cleaner and use a tiny dab of dialectic grease on each pin seeing how you're dealing with salt where you live that may help certainly couldn't hurt

 

All I can think about the root cause, maybe the new connector shells didn't force the old pins into positive contact with the Denso ignition coils, but for some reason, when using the whole pigtail connector, it did?

Totally weird.

 

Pins get dirty and/or corroded or enlarged over time, cleaning them with electrical contact cleaner then dabbing with a tiny bit of dialectric grease and squeezig the female together a bit should solve that issue. This is more common in areas that have salted roads that corrosion does nasty things even on aluminium. As Margate mentioned earlier the plastic portion also gets brittle with but age and heat cycles (which is the portion I replaced preventatively and I did bust one while changing my plugs)