Random flashing check engine light + what feels like a miss

[paoutdoorsman]

Ok, new issue for me with an 02 Corolla S. A few nights ago I took a 60 mile road trip. This was mostly a highway drive. About half way to my destination, the car seriously lost power, and began to shake/vibrate rather badly while in 5th gear, and the check engine light began to flash. If I left off the throttle a bit, it would ease up, but the more I pressed the throttle the worse the vibration would get. Dropping down to 4th gear and running the same speed at higher RPM's smoothed the motor out a bit, but it still felt like it had a bad miss, and the check engine light would flash for a while, then go out for a while. I made it to my destination and the car would barely idle, and still sounded like it had a miss. No check engine light or codes set at this point. After completing my business, I ran the car about a mile down the road to an Advance Auto Parts to see if I could get it resolved before the 1 hour return trip. Just as I pulled into Advance, the car did set a P0303 code (Cyl 3 misfire). I pulled all the coil packs, and the spark plugs. Cylinder # 3 plug was black, and had gunk arced across the gap. I assumed bingo, bought 4 new Iridium Denso plugs and installed them. Fired it up and it ran smooth as glass. I cleared the P0303 and headed for the highway. Unfortunately it wasn't long until it was doing the same thing. It was late at night, I had my kids with me, and I just dropped it to 4th and nursed the throttle to the position where the motor ran the smoothest. The check engine light would occaisionally flash, but it never did set any more codes.

The next day I did a lot of searching and reading on here. I disconnected the battery, pulled the new plugs and checked them all, pulled and cleaned the MAF really well (I did use brake cleaner which I now read may not have been the best). I then reconnected the battery and took it on a 5 mile test drive. It ran perfectly. Good strong power and smooth across the RPM range, smooth idle, couldn't ask for more. We ran it on 35 mile run the next morning. It sat half day at our destination, then we ran it back home - never missed a beat.

The following day, I ran the car 60 miles without issue. Stopped a store for an hour, then drove to my sisters place less than a mile away. In that 1 mile trek, while accelerating from a traffic light, the car glitched twice back to back for a split second, but then was fine. Had dinner and went to leave. 2 miles into the trek it was back to flashing check engine light, miss/vibration, and no power. Again if I nursed the throttle and accelerated very slowly, the problem was less evident. Just a little pressure on the gas pedal, or when the engine loaded pulling a hill, the problem became more pronounced. It did this the rest of the way home, and nearing the end of the trip it set a P0302 (Cyl 2 misfire).

I'm not sure where to go next with this one. I ordered a factory service manual, but it's coming snail mail from CA so it'll be late next week till I have that in my hands.

Thoughts on this one?

[paoutdoorsman]

Sorry for the long winded explanation. Just figured the more detail the better. My son reminded me that the the car did go completely back to normal for the last 5 mile miles of our last trip home.

A little more background on the car itself. It has 231K on it. It's a 5 speed manual. It is burning oil at a rate of 1 Qt 225-250 miles.

Here are 2 pics of the Autolite plugs I took out at Advance. Cyl 1 - 4, left to right - assuming cylinder 1 is next to the timing set.




Here is a pic of the coil packs in the car. Not sure if it is signifigant, but the middle two are missing the rubber seal at the top. All appear to be original Denso equipment.


And finally, here is a pic of the new Denso plugs I installed. A total of about 250-300 miles on them since being installed.

[KarlH]

OK, here are a few things for you:

- When the CEL is blinking, it means that the problem is occurring at that exact time and is something that needs to be addressed ASAP!!! (Damage may occur if it still keeps running)

- You mentioned in an earlier thread that you pulled all the fuel injector plugs.... Did you push them back all the way in and ensure they clicked?? I have seen this exact problem before when a fuel injector electrical connection plug was not all the way plugged in... The plastic on the harness was broken so it did fit in the fuel injector plug, but was not "clicked in" and tight and the vibration was causing connection issues... same blinking CEL and ironically same cylinder....PO303

If not that, check the fuel injectors and ensure that you did not disturb an O-ring and may be leaking some fuel, or that you have not inadvertently cracked a fuel injector (all the fuel injector rail bolts need to be torqued down to is around 15 ft lbs...). Have seen these get cracked by over-torque.... Cracks may be miniscule and you have to look for them.... Fuel injectors should easily twist left and right by hand....

Misfire codes on one cylinder aren't Always correct. These codes go off the input from the crankshaft position sensor and the ECU extrapolates what cylinder it thinks is the problem, they can identify a wrong cylinder, and when the ECU is really confused it can throw a PO300 code (multiple cylinder misfire)...

I would start with checking the fuel injector harness ensuring all are plugged in properly and there are no cracked wires or grounding... I would then put noid lights on the injectors and test the electrical connections to them (or you can use a multimeter...)

There are other things, but lets see how this helps...my gut tells me you have an issue with the fuel injectors properly working...

Cheers!

[paoutdoorsman]

Thanks for all the advice!

Actually my first compression test (when I disconnected the harness connectors at the injectors) was the morning after the road trip that this problem started occuring. I thought perhaps I burned a valve since it has been using oil for some time now. At any rate, none of the injector harness connector's are broken, and all seated and clicked in securely. I'll look very closely at the rest of the harness wiring tomorrow.

Noid lights would be new to me. I do have a multimeter though. Could you give me some guidance as to what/how I should test for?

[KarlH]

Originally Posted by paoutdoorsman

Thanks for all the advice!

Actually my first compression test (when I disconnected the harness connectors at the injectors) was the morning after the road trip that this problem started occuring. I thought perhaps I burned a valve since it has been using oil for some time now. At any rate, none of the injector harness connector's are broken, and all seated and clicked in securely. I'll look very closely at the rest of the harness wiring tomorrow.

Noid lights would be new to me. I do have a multimeter though. Could you give me some guidance as to what/how I should test for?

OK,

Given what you have said, and with number #3 having good compression and the condition of spark plug #3, I believe you have one of two issues....

One, there is a fuel delivery issue on #3, either the fuel injector is not getting power or only intermittently getting power... carefully inspect the wires or, perhaps the fuel injector is bad or clogged... there is also an OHMs check for fuel injectors, it should be between 13.4 to 14.2 ohms. How well a fuel injector is working can only be truly diagnosed with a lab scope reading waveforms... usually easier for a DIY guy to replace if no other issue is found. Also, fuel injectors can "stick", sometimes a light tap with a screwdriver will get them working again....This may only work for a short period or it may fix the problem......

Two, there is a spark issue with #3, you have replaced the plugs twice, but #3 is noticeably different. Check the COP and especially the wires going to the COP.... ensure this COP is getting spark by pulling it out, leaving it hooked up and put a spark plug in it.... You also can experiment with a COP from another Cylinder....

Noid lights can be picked up from harbor freight and plug into the fuel injector... When you start the car, they flash if they are getting power...

I do have a concern about how black that plug is, but since the compression on #3 was fine, I am thinking that the cylinder is just not working... A leak down may be necessary to determine if rings are bad and all that black stuff is oil fouling things up.....

Good luck....

[paoutdoorsman]

Before leaving for work this morning I took a close look at the fuel injector wiring and connectors. From what i can see, everything looks very good. The wires are only slightly exposed where the covering stops and the connector joins. Everything else is still in the factory sheathing and does not appear to have been disturbed, rubbed, pulled, stressed, or burned in any way. I also disconnected #3 (which looks nice a clean with a little dielectric grease still on the connector), and reseated it. Below are some pics of what I'm seeing.

I also wanted to say in response to one of the earlier suggestions that I'm fairly certain I do not have an injector leaking. Everything is dry around all the injectors, and I do not have any fuel odor under the hood or in the garage.

I agree that plug #3 is interesting. I have no idea how long ago my sister may have had those Autolites installed. The only set I put in was the set of Denso's a few days ago, and after only about 300 miles that plug is blacker than the other 3. Plug #4 also intriuged me a bit as it had some black caking cracking and flaking off - like it had been extra hot or something.

If the injector on cyl 3 were to fail open when this thing does glitch, would it be dumping excess fuel into the cylinder, and in turn cause that cause the plug to be black?

I switched the COP's on cylinders 2 and 3 this morning as a test. I drove the car on my morning commute to work - about 8 miles in 10 degrees, and it didn't miss a beat. It had full power and ran smooth as silk.

[KarlH]

Intermittent problems are a pain to diagnose... If you cannot find any logical explanation through visual inspections when it is running properly, you are stuck..... Techs have to give back cars on occasion and have to say to the owner that they are just not getting the problem the owner complains of....

There may be an issue with that injector sticking on occasion, or a wiring issue.... That would be where I would look next.... Until then, keep on driving....

Good luck....

[lexusman]

time for a new engine

[paoutdoorsman]

Originally Posted by lexusman

time for a new engine

I'm fairly convinced at this point that this is not a mechanical issue with the engine, and would remain even if the engine were replaced. It comes and goes like someone flipped a switch. I believe it has to be electrical, either with fuel or spark.

Ran it about 30 miles total today in 3 independent trips and it didn't miss a beat.

When the symptoms do occur, it does seem to be load based. Trying to pull 5th gear, or when going up an incline, the issue is much more prevalent.

I'm in a holding pattern at this point, waiting to see if problem resurfaces. Though they all looked really good, I did clean the battery terminals, the COP grounds at the side of the head, and the engine to the body ground, and reconnected all with a little dielectric grease.

[KeMBro2012]

On the right side of engine there are two sets of brown wires (see here: http://cdn.2carpros.com/automotive_p...m_sensor_1.jpg ). Those are grounding leads for the COPs; unscrew them and make sure they're clean (mine were dark brown, I polished them to a shiny golden brass), apply a small amount of dielectric grease, then screw them down securely (not *TIGHT* since you don't want to strip the holes out -- just tight enough that they're secure). I had a similar problem with my 2000 and that was the fix.

[lexusman]

i base my thoughts on ur previous thread and now looking at the condition of ur plugs..not the misfire issue..sorry if i wasnt clear