Check engine indicating misfires, but no misfires (1 Viewer)

[Allagash19]

Hi everyone, I'm new to this forum, but not new to the land cruiser. I have a 2000 land cruiser that's been in my family since it was new, and I've been driving it for about 5 years now. It has about 130,000 miles. Recent service includes a new cat about four months ago, as well as a new speed sensor around the same time. Also, I had a new muffler put on last week, as my old one was rusted through.

I recently had my muffler replaced on my 2000 LC, and about a week afterwards, I noticed my check engine light, VSC Off and VSC TRAC lights on while driving. The engine didn't really feel rough at all. The shop pulled the codes and the codes indicated misfires on three cylinders. Even though the mechanic didn't actually see evidence of misfiring, they suggested I replace the coils for those three cylinders. I told them to go ahead and do it. The cost was $479. As soon as I picked the car up from that shop, the check engine light was still on! The guy told me it hadn't been on when it was in the garage, and cleared the codes. Sure enough, later that evening, the lights came on again (check engine always comes on with VSC TRAC and VSC OFF), so I planned to take it back to that shop this morning. When I was driving it to the shop, the check engine light actually started flashing, which I understand is an indication of a hard misfire. Problem is, I just don't feel any misfiring, although maybe I just don't know what that feels like. Even if there was misfiring, the cylinders that are showing misfires on the codes were just replaced! That same shop is looking at it now, but at this point I feel like I deserve a refund. The fact that the light was flashing this morning means to me that the vehicle is actually in worse shape than it was when I brought it to that shop. There are a few things I would appreciate feedback on:
1) Has anyone experienced this type of problem before? - Codes indicating misfires but no other indication of misfiring.
2) Has anyone had to go through the experience of convincing a mechanic that they deserve a refund or partial refund?
3) According to another mechanic, the cause could be a speed sensor (shown in the codes as malfunctioning) indicating a wheel slip and then causing the engine to misfire. Anyone experienced this?

I'm really stuck here. To make matters worse, I'm a college student a bit strapped financially (but I'm still going to pay to fix this one way or another), and the nearest dealer is about a half hour away. If there really is a hard misfire going on, I probably shouldn't be driving a half hour to the dealer, and of course want to avoid towing. Because I'm in a town that's not my hometown (my college town), I can't go to my usual repair shop, where I know the manager, and I've been going to different shops because I don't quite know who to trust yet. Feedback of any kind would be greatly appreciated. Thanks!

 

[TXLX100]

Sounds like you have a lot going on with your vehicle. Couple of questions,
Why was the catalytic converter replaced 4 months ago? Did you replace it with an OEM part? Seems like low miles for a cat to fail unless there was some unaddressed issues with O2 sensors and/or misfiring (bad plug, injector, cat, coil pack).

A flashing CEL indicates there is a serious failure or malfunction. As far as a refund goes, if they in fact misdiagnosed it, I would think they owe you something. But proving that and getting the shop to participate may prove difficult, esp if it's an independent. That's why sometimes it's better to let dealers tackle difficult issues, as their resources are greater and more willing to stand behind their work.

 

[Allagash19]

Sounds like you have a lot going on with your vehicle. Couple of questions,
Why was the catalytic converter replaced 4 months ago? Did you replace it with an OEM part? Seems like low miles for a cat to fail unless there was some unaddressed issues with O2 sensors and/or misfiring (bad plug, injector, cat, coil pack).

A flashing CEL indicates there is a serious failure or malfunction. As far as a refund goes, if they in fact misdiagnosed it, I would think they owe you something. But proving that and getting the shop to participate may prove difficult, esp if it's an independent. That's why sometimes it's better to let dealers tackle difficult issues, as their resources are greater and more willing to stand behind their work.

I am fairly sure that the cat is an OEM part. In any case, the cat does have a pretty good warranty. I haven't nearly hit the mileage of that warranty. Honestly I can't quite remember what my mileage is, but it might be closer to 150,000. Is that still low mileage for a replacement cat?

Anyway, as far as the coils go, the shop called me and said they think replacing the coils would fix it, but weren't completely sure. They essentially said the options were to replace the coils or they didn't know what else to do. I, knowing much less than the mechanic, of course, said they should go ahead and replace them. In hindsight, the fact that they didn't see real evidence of misfiring but suggested replacement anyway, seems a bit sketchy. They also called me in the middle of the job to recommend replacing every spark plug since they looked "rough." I said no to that.

I think the shop will just tell me that they warned me that the coils may not really be the solution, but I do feel like I was cheated out of almost $500. This is probably a solvable problem, but the issue comes down to whether I'll be able to get the vehicle to the dealer.

 

[Sandroad]

Most of us have also had the frustrating experience of trial and error repair work. The shop you used should have known it would be extremely unusual to have 3 coil packs fail at once. On this forum, others have reported a noticeable difference in performance with a mis-firing engine from even one bad coil pack. I wonder the shop read the code(s) correctly and got the right diagnosis for the Toyota code(s). There is a complete list of Toyota codes posted in the FAQs in the stickies at the beginning of this forum.

 

[Allagash19]

Most of us have also had the frustrating experience of trial and error repair work. The shop you used should have known it would be extremely unusual to have 3 coil packs fail at once. On this forum, others have reported a noticeable difference in performance with a mis-firing engine from even one bad coil pack. I wonder the shop read the code(s) correctly and got the right diagnosis for the Toyota code(s). There is a complete list of Toyota codes posted in the FAQs in the stickies at the beginning of this forum.

They did read the codes, P1310, P1320 and P1340, which indicated, according to this key (http://www.toyotanation.com/forum/135-corolla-lounge/148676-obd-ii-trouble-codes-full-list.html), igniter circuit faults on Bank 3, Bank 5 and Bank 8, respectively. I don't know what exact words their key used. It seems to me that they just assumed the coil replacements would fix the problem, and didn't really think about it. This is especially suspicious because, as I just learned from you telling me, it is pretty obvious when there are misfires. Even if I couldn't tell, shouldn't the mechanic have been able to determine that there were no actual misfires and therefore no reason to replace the ignition coils. I really think I was scammed here. I think the mechanic had no idea what to do, and wanted to get some profit out of this so he threw that suggestion at me - replacing the coils. Otherwise, he would have given me a free diagnosis and without giving me a solution, he wouldn't have made any money.

 

[TXLX100]

^I'm not a technician, but 3 misfire codes tells me that further diagnosing is probably in order. Throwing parts at it of course isn't the best way to fix it. The way it should work is, they ask you for diag $ upfront, use that time as needed to figure out the issue and then communicate with you if they need more time or give you the bad news that it will require fixing problem A, then moving on to problem B, etc. A good tech will know when it needs to be sent to a dealer.

Misfires can be caused be several different failures. If at all possible, get your vehicle to a dealer and on a Toyota scan tool so the issue can be properly diagnosed. They will be able to check the vehicle's monitors in detail, not just retrieve codes.

 

[Allagash19]

Thanks for the feedback. I am definitely going to be asking the repair shop for a refund, and take further action if I do not get one. I forgot to mention, after the coils were replaced (they were replaced yesterday), I drove the car this morning to go back to the shop since the check engine light was on, and this time it actually started flashing, which I know is a sign of a more severe problem than a steady light. So, the shop may have actually made the car somehow worse than it was!