Engine misfire?

Its a random misfire code. It means you could have more than 1 cylinder that isn't firing. This can damage your catalytic converters, and give you horrible gas millage and performance. I don't know why the mechanic said to not worry about it. Conman causes could be an ignition problem, spark plugs, spark plug wires, multiple things that would cause this. How is it running, as far as acceleration/performance?

This guide will help us

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Sean

I'm sorry-the car runs great and very smooth, acceleration is great as well as overall performance-no hesitation or kick, and starts right up-that's why he said "don't worry about it now,(maybe to save her money) but if any sign of performance problems, running, or hard starting bring it in. I do plan to diagnose the issue soon starting this weekend, it looks as if I have to go over it very thoroughly. I heard injectors are a big problem on this Toyota model.

If you don't notice any performance issues, then it should be fine to drive until you start to diagnosis the problem. It could be the injectors but it also could be 100 other things. Let me know when you start to diagnosis it and we should be able to figure it out.

Sean

It sounds and feels like it's misfiring on one cylinder at idle speed and up through about 3.5 RPMs. At higher RPMs the problem is undetectable. But the whole car shudders with hesitation during acceleration until higher speeds are reached.

I've changed all of the spark plugs (got fancy new iridium ones), and that didn't help the problem. But I noticed that the ignition coil tubes were covered in oil and the spark plug heads were in oil. So I changed the valve-cover gasket, but that didn't fix the problem. Also, one of the coil tubes is slightly cracked at top part that holds on a rubber gasket.

I tried to isolate the problem, but whenever I disconnected a spark plug wire the engine would just die. So it seems to be an intermittent misfire.

There is no real fuel filter on this car, the whole fuel pump assembly has to be changed, although there is a little strainer that can be replaced. I haven't tried toying with that yet. I don't think it's the fuel pump, but I have no idea.

The air filter is clean. The radiator fluid is good. Transmission is fine. Pieces of plastic are breaking all over the place, and the ceiling foam is falling apart, but otherwise it's been a great car. I can't figure out this problem.

I think that is everything.

Any suggestions?

Hello,

This sounds like a low cylinder compression issue lets remove the plugs and follow this guide.

https://www.2carpros.com/articles/how-to-test-engine-compression

this guide can help as well

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Please run down this guide and report back

Cheers

Thank you for this post I had the same problem and # 3 cylinder has down to 90 pounds it had a burnt valve cost me $980.00 of a valve job runs great!

I recently did a lot of work to it, I changed the exhaust catalytic converter and, all new coil packs, spark plus, fuel injectors ,valve cover gasket, mass air flow sensor. I got on a freeway and code p0420 came up and then I got on freeway again to come home and when I got off freeway car was running really rough and codes came up p0300 and p0303. I changed the exhaust and catalytic converter because it was defective. I changed the O2 sensors, and changed spark plugs also gasped them too .044. I swapped #3 coil pack with #1 coil and everything was okay. I recently got on freeway again and when I got of the rough idle was back and so was the two codes p0300 and p0303, when I am around town the car is fine, but when I get on freeway and car is at a high rev it does this.
Your help is greatly appreciated thank you very much.

When misfiring occurs, it is usually caused by plug coils, spark plugs or injectors. You have already replaced all of them but sometimes new components do fail and since the plug coil has been swapped with another cylinder, that should rule it out as the cause.
Try swapping the sparks plugs. If that still fails, then you would need to remove the fuel injectors and swap that too. check and ensure the fuel is clean and not clogged.

While you are there, have the compression tested as well. Leaking valves can cause misfiring as well but minor leaks cannot be detected via a compression test.

I took the connection off of every fuel injector and there was a change in engine every time.

For an engine that running correctly, this is expected. Your problem is intermittent misfiring which would not show when engine is not misfiring.

I first would like to say this website has been very helpful-I ran the freeze frame data on my scanner and realized the coolant temp did not change-after the car was fully warmed up and upon a complete overnight cold start-which I think indicates a non-functioning coolant temp sensor. I have one on order, however the CEL is on, and could this be a strong possibility that the misfire is caused by this?

Thanks for all your help with diagnosis/answers

I don't know why you would be looking at freeze frame data for something like that. That is just a frozen point in time and you don't know if the engine was actually hot at that time or not. You need to just look at raw data both before starting the engine and after. Before starting the CTS and the IAT temps should match. Once started the CTS should start rising raster than the IAT.

my mistake that was from another diagnosis of a different car not related to this question asked, can a coolant sensor cause a CEL to com on and indicate that it is a random misfire?

A faulty CTS may or may not put a check engine light on. The CTS has a direct effect on fuel mixture so if it was to read too high the result would be too lean a mixrture which would lead to misfires but that a reach. Not real likely at all.

Thanks

I was decently low on oil, getting close to dot on bottom but wasn't there yet. Could the low oil cause the misfire or is spark, compression or fuel to blame? I've had zero issues before this. Car's at 160,000 miles. Checked using OBD 2 scanner.

Hello,

Well it could be any of the latter three, but I would recommend starting with spark, specifically doing a tune up. In the diagrams down below I have included the recommended spark plugs for your vehicle including the proper gap. Change the spark plugs and get back to us with what you find out, please.

this guide should help us

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Thanks,
Alex
2CarPros

Hey Alex, thanks for the response. So, i'm guessing the car being low on oil couldn't have played a factor in the cylinder misfiring. I don't know much about engines I just like to work on my own cars. Is there any way having low oil caused the cylinder to "seize"? Just want to make sure its worth trying sparks, coils and etc. The oil might have been lower then I mentioned because the car was parked on a slope.

Cheers, Kake

Hello,

If the vehicle was low enough on oil to seize the motor, it would seize the entire motor, not just one cylinder. Ignition problems are around 75% of all individual cylinder misfire problems, so chance are this will fix the problem.

Thanks,
Alex
2CarPros

Hey Alex, changed the spark plug. Problem still persists. Check Engine light went off. I ran the car for a few seconds. Car vibrates and exhaust sounds like it cuts off like before. The shop I got plugs from didn't have coils otherwise I would have done those too. Should I try coils or fuel injector cleaner next.

Appreciate the help.

The code says I have a misfire #3 cylinder. I have replaced the spark plugs and the coil on #3, and have tried fuel injector cleaner. The engine light (yellow) still remains on as well. The light then will blink when driving.

Check compression on #3 cylinder.

Hello again,

I would suggest new coils. Only then can you rule out ignition as the problem and move on to fuel.

Thanks,
Alex
2CarPros

on my '88, misfire was caused by oil leaking down the distributor shaft into the distributor cap, insulating the lowest tower (forget which cylinder). Obviously, changing plug wires didn't help. Eventually, since the leak was non-fixable (only have to buy new diz for $400) I drilled a hole in the cap so the oil could drain. No more misfire, but oil all over the trans.

Hey Alex, changed the coil and voila she was running alright. Thanks for your help!

Check and test injector no.3

Hello again,

Okay, great. Here is a guide on misfires below if you should have this happen again.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Thanks,
Alex
2CarPros

2001 Toyota corolla le, 183000miles, this car misfires on #4, I have switched sparkplugs, and coilpack and it didn't change the misfire, I swapped injectors and it didn't stop misfire on #4, I cleaned tb and maf sensor and didn't stop the misfire on #4, the only thing I haven't tried is compression yest. I just got car so not much info on past drive ability. It misfire whether idling or under load but mostly under a load. It throws the code for #4 misfire. Could you think of any thing else it could be

I recommend you do a compression check on no.4 cylinder, if okay could be its wiring or computer problem

Forgot to add I checked the injector wires and the do have voltage raging from .3-.5 vdc running, and coil/plug wire has good speak also

Try squirting a VERY small amount of oil into the cylinder and running it. If the problem goes away, you most likely have bad rings.

As the other tech mentioned, perform a compression test. I will add that you should perform both wet and dry tests. Do the test right after pulling the plugs. Do all 4 cylinders. The swing should be no more than 15 PSI from high to low (some would say 5-10 PSI high to low). Then do the test after squirting a very small amount of oil in the cylinder. Typically, you want to see around 150 PSI. If the compression is low and the wet test doesn't improve it, then most likely you have a bad valve. At the mileage you have, this is what I think is the issue.

If a vehicle that has rings going out (whatever that means) and no compression on cylinder 3 but good compression on the others could I still run it for a while as long as I keep oil in it? Seems like it might last a while, especially for short trips (50 miles or less).

More Details/History:
My 2000 Corolla has been increasingly eating oil for 18 months. In the last 6 months there were Fault codes thrown: Misfire on 3 (first), Random Misfire, Catalytic Converter fault of some kind. First time I replaced the plug for #3 no "check engine" light for a few months. Check Engine recently started flashing indicating ongoing misfires. Has some stuttering, mostly at low rpms. Recently changed plugs but made little or no difference. Mechanic checked it today and found cylinder 3 has no compression, the other cylinders have good compression. I drove the vehicle back home from far away recently (450 miles). I have free towing for 100 miles. Would prefer to drive it until it dies then tow it home to my barn (store for parts, I have another similar corolla) or junk it.

Bad rings will not cause "no compression." Are you sure it is at 0?

Also, running on 3 cylinders is going to cause other problems. You will be dumping raw fuel into the exhaust system which will destroy the catalytic converter, cause the O2 sensors to send bad readings to the computer to lean the system... Can you drive it? I guess you could, but other issues will come up and the vehicle could stall in a bad situation or other things...

Thanks for your responses. The mechanic said bad rings would cause loss of compression eventually since the rings hold some compression for the cylinder.

As far as still driving the vehicle; What I have heard is that the catalytic converter will cause back pressure to build up and eventually blow a head gasket or something like that. But it could take a while. One person suggest I could remove the catalytic converter and go "straight pipe" as he put it. Not sure what all teh implications are of doing that.

Do you know?

Thanks Again.

I can't tell you to do that. It's against federal laws. As for the rings, you could remove them and still have compression. It would just be lower. I think you had a valve stuck open.

I have a 2000 corolla, 129,000 miles, automatic transmision. 1.6L 4-banger. I bought the car at about 75,000 miles and in rainy weather, I heard a noise which sounded like an air leak somewhere under the hood. But, about 1,000 miles ago, I started noticing a vibration when I got up to about 40 mph. It feels kind of like a one of my tires is out of balance. So I got them rotated and balanced, which was due anyway. The vibration didn't go away. Then I noticed that the frequency of the vibration variated whithin each gear, but ONLY when I was moving. While idling, I can rev the engine and there is no vibration. I figured it was a spark problem and changed all the spark plugs, but still no luck. Last night I bought a new spark plug coil and replaced each coil one at a time. Each test showed no improvement. If it's not sparking, I'm afraid I might be burning up my cat. Could it be an injector is bad? or compression? or what?

Thanks

Got any OBD code/s-get scan and comeback with the code.

Could also be a transmissiion problem/Halfshaft Joints

Might be a half shaft like Ras says. Might also want to check to make sure the staeering parts, wheel bearings have no play as well. The higher speed vibrations are more apt to be steering/ suspension/drivetrain than performance.

I'm sure its not an wheel problem because if I'm driving down the road and the vibrations are really bad, I can put the car neutral and the vibration goes away completely. I reengage and the vibration comes back. I've had transmission problems before and it doesn't feel like that at all. It MUST be one of three problems. 1. Compression, which is fine. 2. Ignition, which I have eliminated the problem of a bad spark plugs and coils or 3. Fuel injection, I have a fuel injector on the way and im going to perform the same test on that as I did with the plug coil. I just need some more input.