Engine Breaking Up At 3000 RPM

W

Westlow

New Member
#1
#1
Hi everyone,

I need a little guidance on an issue I am having with my 2000 corolla.

Issue : engine misfire at 3000 RPM
Issue does not throw a code when it is happening.
Codes I was able to pull when the light came on the first time it happened are: P1300, P1315 and P0171

I have the freeze frame data for the p0171 fault that I have attached.

Completed repairs: cleaned the MAS, replaced spark plugs, cleaned air filter, added Lucis fuel injector cleaner, moved coils to see if the fault would follow the coil.

So far no luck, i have a feeling it may be an injector or the fuel pump. I also have LT and ST fuel trim readings I will post.
 

Attachments

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Donabed Kopoian

Donabed Kopoian

6 Speed Master
#2
#2
The attachment didn't show up.

That is really odd to get a engine stuck lean code with a misfire (usually you run rich on a misfire).

Check the wiring for the ignition coils and the fuel injectors. Might have a short occurring somewhere from frayed insulation. That is the only thing that comes to my mind.
 
W

Westlow

New Member
#3
#3
I updated the image attachment, it might not be a misfire but its def. a miss only after 3000 RPM's I will check the wires and update with my findings. if there are any readings that are needed let me know and I will post them. I will also work on fuel pressure readings
 

Attachments

Donabed Kopoian

Donabed Kopoian

6 Speed Master
#4
#4
Definitely not a fuel pump. Those either work or completely fail. As far as the injector, it is possible, but the spike in the fuel trim followed by a dip doesn't suggest a mis-fire, as you would have a rich spike and no lean spike. I'm hoping it isn't a PCM issue, but if you don't find issues with the wiring, it may be the PCM.

What it looked like happened was that the spark plug failed to fire, and immediately after the fuel injector failed to fire.

One more thing ... how do the battery connections look? I know that corrosion on the cables at the posts can have weird electrical gremlins surface.
 
little rebel

little rebel

New Member
#6
#6
The last time a corolla of mine had these symptoms, it turned out to be dirty fuel injectors, this happened on 2 different cars shortly after I bought them used. Probably poor maintenance by prev owner. Believe it or not all I did was put in a can of injector cleaner and it fixed it.
 
W

Westlow

New Member
#7
#7
Ok, an update on the issue. Cleaned battery terminals, no change, checked wires to the ignition coils all look ok, checked connections to fuel injectors and wires all seem ok. My next step is to try a new ignition coil and move it from cylinder 1 - 4 to see if it makes a change. Still have a half tank left with the fuel injector cleaner in, and will run one more through after that. Still have no CEL and no change in symptoms. Also did not find any vacuum leaks.

My next step after this will be to check fuel pressure and remove and inspect the injectors.
 
Scott O'Kashan

Scott O'Kashan

Super Moderator
#9
#9
My next step is to try a new ignition coil and move it from cylinder 1 - 4 to see if it makes a change.
Click to expand...
Don't replace parts. That gets very expensive and ends up with a trash can full of perfectly good parts.

Diagnose.

Use an ohm meter to test the ignition coils.

Have you removed the spark plugs yet to visually inspect them?
 
Donabed Kopoian

Donabed Kopoian

6 Speed Master
#10
#10
He replaced the spark plugs already. Using a multimeter on the coils would be good, but he said that he already shuffled the ones he had around with no change.

I suppose the next step would be to check the condition of the fuel injectors. Other than that I am out of ideas. Very odd.
 
Scott O'Kashan

Scott O'Kashan

Super Moderator
#11
#11
Randomly replacing parts has so many drawbacks and can exacerbate the original problem, making resolving the problem even harder.

The spark plugs are not so much the issue as what the spark plugs look like. If a spark plug is misfiring it will appear different than the other spark plugs and could provide major clues as to what is really going on. Just randomly replacing spark plugs does nothing but vacuum the wallet dry and fill up the trash can with good parts.

Did the original poster even properly gap the spark plugs? Were the spark plugs correctly torqued down so they didn't break?

Visually inspecting the spark plugs can pinpoint which cylinder(s) are misfiring and why. There could be a burned valve, or a malfunctioning fuel injector, etc.
 
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W

Westlow

New Member
#13
#13
I installed Bosch platinum spark plugs, I am also not throwing parts at the car I was going to use a known working new ignition coil to eliminate a bad coil. Worst case it is not a coil and I take it back. If the Lucis fuel injector cleaner fails to work I will try chevron techron.
 
Scott O'Kashan

Scott O'Kashan

Super Moderator
#16
#16
Do you still have the spark plugs? Compare them to this chart. Which picture do they look like? http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp?mode=nml

You never mentioned how many miles are on this car?

When did this problem start to occur? Were you just driving along and then suddenly it happened?

What preceded this problem occurring? Did you install new spark plugs and then the problem appeared?

I think you'll have much better results with NGK spark plugs in a Japanese engine than you will with German Bosch spark plugs.

What gap did you set the spark plugs at?

I recommend leaving the fuel injectors alone. They are almost certainly not the problem. No need to introduce a new variable that could confuse the issue and make things worse.

The last time you filled up the gas tank, did you use a station you haven't used before? It's possible the fuel was contaminated with water. Try using a different station and no, you don't need or want Premium gas. A waste of money.
 
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Donabed Kopoian

Donabed Kopoian

6 Speed Master
#19
#19
Scott, look at the image on post #3. That looks like a PCM compensating for a bum fuel injector that sleeps on occasion. It is probably falsely triggering the ignition circuit failure codes.

Given that there are no codes for fuel injector failures, the PCM is triggering a misfire code.

I have had shot wiring on the coolant temperature sensor circuit trigger a "Lack of HO2S Switch: Sensor Stuck Lean" Code. Why? When the wires would short in a rain storm, the engine got tricked into limp home mode, and threw that code because injectors shut down in limp home mode.
 
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W

Westlow

New Member
#22
#22
Update:

Second run of Fuel injector cleaner - No change as of yet
Spark plugs were torqued to 13 ft. lbs.
Compared to the images the plugs were wearing normally.
Fuel was from the same station i always use.
* I will check the wires on the coolant temperature sensor circuit for shorts.
* i have started to notice that an exhaust leak is getting louder. I see nothing broken, dented or rusted through but i did notice that the joint between the down pipe and the cat is loose. could this be caused by a bad reading from the O2 Sensor.

I'm sorry i forgot to mention that the car has 226,435 miles on it.

The problem appeared one day a month and a half age while driving to work. No changes were made to the car prior to the issue.

* Still no CEL but i will scan to see if any pending faults are in the system.
 
Scott O'Kashan

Scott O'Kashan

Super Moderator
#23
#23
What gap did you set the spark plugs at? Spark plugs that have not been set to the proper gap can cause exactly the symptoms you have described.

I recommend leaving the fuel injectors alone. They are almost certainly not the problem. No need to introduce a new variable that could confuse the issue and make things worse.

All spark plugs always need gapping.

 
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W

Westlow

New Member
#24
#24
The gap on all 4 plugs were the same but I do not remember the measurement. The gap was preset from Bosch, also from the old plugs to the new plugs the problem did not change.
 
Scott O'Kashan

Scott O'Kashan

Super Moderator
#25
#25
When spark plugs are shipped they are bounced around a lot and the gap changes.

If you didn't set the gap on the old spark plugs or the news ones either, that could be a problem.
 
Scott O'Kashan

Scott O'Kashan

Super Moderator
#26
#26
Did you remove the spark plugs and set the gap to Toyota recommendations? Incorrectly gapped spark plugs can cause exactly the symptoms you have described.
 
W

Westlow

New Member
#28
#28
Ok sorry for the delay, I have been a little busy lately,

Update:

Spark plug gap was good

First started the vehicle after removing the bolts to the coils and the misfire happened at 4000 rpm

Set vehicle rpm to point of misfire and removed coils one by one to see if I could notice a change from one to another, same result on all cylinders.

Disconnected MAS and ran vehicle misfire was at 2700 rpm

Today I will be replacing a rusted exhaust clamp that is not holding the exhaust together to stop an exhaust leak.

CEL is on so I will have the codes posted soon
 
W

Westlow

New Member
#32
#32
Would anyone happen to know where I can get a pin out of the PCM so I can test the wires from the PCM to the ignition coils. I tested a new coil in each cylinder today and fixed the exhaust leak and still have the issue. I'm starting to think a damaged wire or PCM but I want to test the wire harness before replacing the PCM.
 
Scott O'Kashan

Scott O'Kashan

Super Moderator
#38
#38
jackbower6864 said:
try changing your air filter it might not be getting enough air
Click to expand...
Holding up the air filter to a strong light, if we can see light through the filtration media this means the air filter isn't plugged and is in okay shape. With the cotton gauze type of air filter though they tend to show unobstructed light getting through the, "filtration media", which can allow engine wearing dirt to enter the engine.
 
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