Took this car for scheduled maintenance, tuneup on 12/19. AFTER the tuneup, it started shaking when in idle or going slowly. Took it back 1/5, they confirmed it was misfiring, checked a computer code, replaced one of the coils. ($120 – they SAID they were only charging me for the part, tho that looks to me like the price for a set of 4 on the internet.) The misfiring went away but returned, worse than ever, last week (early Feb).
I read somewhere that replacing coils for misfiring can be just treating the symptom, not the cause. What should I do now?
What engine?
How many miles?
Has the maintenance been kept up to date?
The price was fair. Over the internet you’re paying for only the part. In the shop you’re paying for their expertise, use of their tools, their administrative costs, and use of their bay as well as the part. $120 actually sounds like the “minimum charge” that most shops use. They have to get something fair to tie up their assets for an hour.
Replacing the coil is not just treating the symptoms. Coils fail from age and exposure to underhood temperatures. There’s a lengthy technical explanation involving differences in the coefficient of thermal expansion of the copper wire and the varnish-like polyimide-amide coating on the wires and the loss of elasticity of the coating…oh, never mind. Coils just fail without the failure having been induced by some other factor. It happens. However, they have a fairly consistant lifespan, and if one failed the others may begin to fail one by one.
If it were my vehicle, I’d just change the rest of them, throw in some new plugs, and I’d bet it’d run great for years to come. Unless, of course, it’s burning oil and fouling plugs or something like that.
Everything mountainbike said about the coils is right on.
You said that you took it for a “tune up” but the term tune up refers to nothing in particular. Did this tune up work include new spark plugs? If so then, I’d wonder about what kind of plugs went in. Not all plugs are the same and some cars just don’t get along with certain types & even brands of spark plugs. If the plugs are new, find out the brand and type & report.
Thank you very much to both of you for your responses. It’s an LE, 4 cylinder, 85,000 miles. I did neglect the maintenance for way too long, about 2 years, 15K miles, before last December. I don’t think it’s burning oil though.
The work in December did include replacing the spark plugs. The shop’s writeup about this says “In-Line4-including fuel injection cleaning and throtle body cleaning and adjustment”.
I’ll see if I can find out the brand and type tomorrow.
I might also mention the check engine light has been on for months. In Dec. they said it was a problem with the evaporation system but it wasn’t something that needed fixing right then. (I had a bunch of other things that came to $700, so I wasn’t eager to fix anything that wasn’t a real problem.) Just mentioning this in case there’s any possible relation to misfiring or it really should be fixed.
Now that you mention it, you should find out exactly what error codes were stored in the computer. Its likely that the evap system code is still there, but there would have been codes related to the misfiring. The codes look like “P1234.” Find out what codes are there & report. If there’s no record of them on the invoice or at the shop many auto parts stores will read them for free.
If one coil went bad, the other 3 likely aren’t far behind. Some of the coils sold on the internet are junk and some are good. No way to really tell. Go to a NAPA or other good parts store and get their prices. Get 3 new coils from wherever and put them in. On a 4 cylinder it should be a straightforward easy job. Since the plugs have been misfiring, I’d put new ones in with the new coils. Use the plugs recommended in the owners manual, Denso or NKG of the correct number.
I’m just seeing UncleTurbo’s comment now, but following up on yesterday’s comments: I went to the shop this morning. The mechanic there told me they use nothing but OEM parts; he was not more specific than that. He also checked the code and said the problem is the same coil that they replaced before, number 4. I went to a parts store and got the code: P0304, cylinder 4 misfire. (Also P0440, evaporative emission system; I got a new gas cap on the recommendation of the parts store employee.)
The mechanic said they would replace the coil in number 4 again for me tomorrow.
You should have the compression checked on cylinder #4. Low compression will lead to a misfire. If the 2nd new coil doesn’t resolve the problem; then weak compression or a defective fuel injector are next items to check out.
I just fixed my #3 cylinder misfire on my 1996 camry. It ended up being the fuel injector. It checked good using an ohm meter, but it was not working all the time. good luck. I switched injector to another cylinder and the problem followed to that cylinder. I had taken my car to the dealer and they told me my coil was bad, but I told them I had switched coils, then they told me it was my coil connector. The bottom line is they did not know either.
The shop replaced the coil yesterday, and the shaking has gone away. I hope that lasts. I did ask about the compression; the mechanic did not say they checked it, but he said that if that were the cause, I would notice the problem at all speeds, not just at idle or low speed.
Anyway, I second 1looselugnut’s comment. Thanks again to all who have commented. Your advice and suggestions have been very helpful!
Thanks, and I’m glad the problem is solved. It’s funny, every time I get in my car I expect it to shake too because I can’t believe I actually fixed it. Go Camry!!!