Ignition coil repair

Happy 4th of July to all!

First post here folks. This seemed like the logical location given the circumstances. Some background:

2005 Prius with 85K miles (my girlfriends car) she developed a bad "shudder"/misfire the other day when, during a rainstorm, a car passed her and covered the Prius in a wave of water. Approx 10 minutes later she called saying it's "shuddering". It was towed to the dealer and they confirmed that it was #4 misfire and suggested that she have the coil & plug (along with various filters...) replace and sealant for the cowl performed. I told her about the TSB & she politely declined the dealer offer and asked that they do the repair as a goodwill gesture. In the end, Toyota & her 3rd party warranty company both declined. She was most displeased, actually furious, but I said "Hey, no problem...I'll do it"!

I've lurked on the board for awhile picking up useful tidbits, but now I'm stuck.

-I pulled the cowl (to seal up thoroughly after replacing coil) and pulled the #4 coil off of the plug & started the car to test: no spark arc
-Removed old plug (just some mild staining, no heavy rust)
-Installed new plug and new #4 coil, then started car
-Still misfiring
-Pulled #4 coil off of plug while running, no spark arc
-Reinstalled new #4 coil and pulled #3 coil to test and started car, very obvious spark arc from #3, 2, & 1.
-Replaced all 4 plugs and noticed plugs #1 & 2 were both quite rusty
-Also noticed quite a bit of rust sediment on #1 coil, but again, it worked fine
-Pulled new #4 coil and and unplugged from harness, I notice there isn't a nice audible "click" when I reconnect. I even tried plugging other coils into the #4 harness, but no click sound. Plugged the new #4 back into same harness & am now getting spark, but still #4 misfire/running rough.
-I hooked up my Dashhawk scanner and pulled the codes for the CEL
I got a total of 4 stored: random misfire, #1, #3, & #4 misfire. I cleared these and am still getting a repeated #4 misfire code

I'm stumped! Am I missing something? The wires going to the # 4 coil look good, but to be sure I traced them through the wiring loom and even used a spray bottle with some water to "mist" them while the engine was running to see if I could locate a short. No dice. Now I'm at my wits end, faulty coil & plugs were replaced, but still a misfire on #4. Again, no problems whatsoever & the car worked perfectly fine until this incident.

Folks I need some sage advice to save face here with the girlfriend, get the car running properly, & prevent yet another dealer visit. Help!

 

The first piece of advice for your girlfriend is to let her know that a TSB is not a recall notice or an extended warranty. The TSB shows what warranty is applicable (if any). The fact that a TSB exists does not mean that she is entitled to a free repair regardless of vehicle age and odometer reading. If she persists in holding that belief, that is the equivalent of "pounding sand" and she'll continue to be frustrated when working with the Toyota dealership.

Maybe her third party warranty company should have taken care of the issue. In general I think it is a waste of money to buy a third party warranty.

You mentioned that the #4 connector body does not make a clicking sound. You need to figure out why. Maybe the root cause is a bad connector so that the pins in the spark igniter head are not engaging with the connector and therefore the igniter is not receiving 12v power or the ignition signal.

Insert the spark igniter into the connector and then insert a spark plug into the spark igniter so that you can see the spark plug tip. Run a ground wire from the spark plug shell to ground. Start the engine and see if there's a spark (be cautious of the high voltage on the exposed center conductor). If no spark, you have to work on the connector until you see a reliable spark.

Since the car has logged 85K miles and you have misfiring on three cylinders, take the opportunity now to replace all spark plugs with the correct NGK or Denso iridium plug as specified in the owner's manual. This will cost ~$10-$12 per plug at the dealer. Do not buy some cheap plug from your local discount auto parts store.

No plug should have rust or other residue on the ceramic tail. All spark igniters should be in good condition and none should have rusty residue or any other imperfections on the plastic body. Replace any igniter that does not appear to be in perfect condition. Good luck.

 

Sir,
Thank you for the advice. Response to your suggestions and comments below

Hmmm, not sure why that bit of Toyota-education disclaimer was felt to be needed, but OK...
We are both aware of the difference i.e. TSB vs. recall. Hence, my mention of the dealership being asked to perform the work as a goodwill gesture. Sense of "entitle"-ment? No. Rather, asking Toyota to man-up and repair an issue that should not be an issue. She purchased the car new. She only recalls being under a wave of water once, just prior to the engine beginning to misfire. By your account if this occurred when she drove it off of the lot with say...2 miles on the odo, Toyota should fix because...well, it's their fault in the design/build out the door as a new car, but if you don't get under that wave-o-water until after warranty, well tough.
That Sir, is not "pounding sand" (although in my region, it's referred to as pounding salt, but I digress) but instead, I think, good customer service. I believe I neglected to mention that the car has been serviced exclusively at Toyota service facilities since new, and yes, after warranty as well. A goodwill gesture to a loyal customer is not an unreasonable request.

I agree 3rd party warranties are sometimes a waste of money. This was however, her choice.

After closer inspection of the new ignitor vs. the old, it appears that the protruding plasic "tip" that is designed to lock it into the connector (and is responsible for the audible "click" when inserted) is less pronounced than the design of the old one (perhaps 0.5mm difference). However, the new ignitor does in fact lock into the connecter. Not sure why, but when I plugged in other ignitors to #4 connector, they did not originally click. However after repeated tests of the # 4 connecter she's clicking well. I'm no longer inclined to believe this the root cause.

When I used the above test there appears to be ample spark. Granted, my experience with Atkinson cycle ICE (Prius type) vs Otto cycle ICE is limited. But, a comparison of the ignitors on the other cylinders, when pulled and tested individually as you recommended for #4 appears to yield similar results.

As mentioned in my 1st post, these were all replaced.

Correct, none should have rust, yet they did. From reading other posts, I gather other forum members have also discovered this. Is it a result of water leaking due to insufficient cowl trim seal? Seems likely to me.

Again, thanks for your assistance. I guess another flatbed, to another dealer is the next step

 

Very interesting. Since you've verified that spark is good in cyl 4, then the other usual reason for misfire would be a bad fuel injector. Do you feel like removing and inspecting the injector (which requires removing the valve cover first, so that the fuel rail can be removed?) If not, I agree that dealer service would be warranted.