My first time posting so here we go! My girlfriends corolla had an ignition coil code, it’s a 2009 and we ordered a set of 4 for like $50 from parts galaxy or something. Anyways I installed the coils and cleared the code and that seemed to solve the problem of stuttering and stalling, so here we are about 10,000 miles later and the stuttering is back, no check engine light. I’m wondering if the fact that they were very cheap coils has an impact on the performance. A lot of these coils online don’t have a listed brand name. Is it reasonable to think these coils are just cheap and crummy and I need to buy a quality brand coil? Or could this be something different. The vehicle is stuttering, hasn’t stalled yet and there is no check engine light. Your responses are much appreciated!! Thank you!
It is certainly possible the “cheap” coils have gone bad.
Another thought I had was did you change the spark plugs, too? That could be part of the issue as well.
Good luck.
Yes the plugs were done as well. I just thought I would get a check engine light if they were going bad. The set of four coils were outrageously cheap so I’m thinking it is most likely the low quality brand.
Yes, it is a reasonable suspicion.
And if that’s the case, it should store a fault code and can be verified by any shop with a scope.
The lack of a fault code (CEL) makes me suspect it’s something that might not trigger one, like perhaps a fuel pump problem, or even a plugged converter. Or even a problem with the variable valve timing system. Knowing the year and mileage of the vehicle might help.
It could also be something as simple as a spark plug. When was the last time they were changed?
He did change them:
Did you use the OEM plugs?
I changed the plugs about 1000 miles before I changed the coils.i don’t know if the plugs were OEM, got pregapped plugs from autozone. I should add that the stuttering is a lot more frequent and apparent, but no stalling or check engine light.
I also noticed that the stuttering is more apparent with unleaded gas.
Unleaded as in 87 octane? (all gas in the US has been unleaded since 1996, 92 in California). 87 octane should be what your Corolla requires anyway…It may be worth pulling the plugs and replacing them with OEM just to be on the safe side. It’s a very cheap thing to check, and it could fix the problem. It’s also easier to do than swapping a coil 
I have a 2007 Corolla with about 270K miles on it. For the last year or so, my car felt like it was gasping for air whenever I stopped at a light - it might be called stuttering. When I put the car in neutral at a stop light, the gasping goes away. My brother thought it might be my gas pump but it turns out it was a bad gasket (way cheaper to fix). And because I waited so long to have it looked at, the bad gasket started leaking out oil. He changed out the Valve Cover Gasket and the Intake Manifold Gasket - unsure which one was the actual culprit in letting oil leak out - and now the gasping is completely gone!
I looked up your manual online. You didn’t mention if you had the 1.9 L or the 2.4 L, but the 1.9 L uses Denso SC20HR11. The 2.4 L uses either Denso SC20HR11 or NGK IFR6A11. Gap is 0.043 inches or 1.1 mm.
If you got plugs from Autozone they probably were not OEM, I am pretty sure Toyota uses Denzo and none of the McParts stores in my area stocked them. I got them from the dealer at a reasonable price. OEM plugs in a Toyota will give good service and long life, off brand not so much. Try putting new plugs in and see if that helps
Its a 1.8l. I’ll try switching out the plugs first with new OEM plugs and see if that helps. I appreciate the ideas and I’ll be sure to post the results!
Its a 2009 corolla 1.8liter with 110,000 miles by the way
Toyota’s OEM plugs are Denso and NGK.
Places like Autozone does carry NGK, plugs, but it’s really for show only. Their main plug which they all seem to push is Autolite. Went there a couple times for NGK plugs for my wifes 96 Honda and then again for her 07 Lexus (same engine as the Camry). Both times I went they told me they didn’t stock those plugs but I could pre-order them. Let me get this straight - you don’t stock NGK or Denso plugs for the two most popular cars sold in the US?
My GF has an '07 Honda Fit. Our local shop replaced all 4 coils and within about 18 months one of the new ones failed. The mechanic said it is not that unusual. So, I would recommend the highest quality coils available to anyone doing a fix based on my limited experience.
Not true on this vehicle, you must remove the coil access the spark plugs, because the coil pack (looks like a carrot) attaches directly to the plug.
Agree about replacing the plugs, and should be with Denso or NGK. With no codes, I’m not convinced this is the
Replaced my plugs for the first time at ~186k after getting 2 misfire codes within a week. Rock Auto support(ed/s?) Car Talk and their prices and support have won new as a regular customer.
Good to know, I’ve never swapped a coil on a Corolla.
Exactly, I’m left with no codes. I might have to pay a mechanic trouble shoot it
I’d be looking for a vacuum leak next. It’s plenty old enough to have hoses and other things rot, which could let in air and mess with Air/Fuel ratio.
I don’t think it’s been mentioned, is this happening when you’re just idling at a stop and/or are you have issues while accelerating/running at a certain speed?
The issue is when im Idling, deceleration, coasting. No problem accelerating