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roy, import/domestic specialest
Category: Toyota
Satisfied Customers: 1934
Experience:  ASE master tech for 40 years
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Celica: I have a 2001 Toyota Celica 1.8L engine. It is misfiring

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I have a 2001 Toyota Celica 1.8L engine. It is misfiring and running rough however it idles fine it is under load that I have issue, however it goes in and out when you drive, meaning it bucks then clears up then does it again irradicly. I am getting a p0300 and p0301. I have changed the COP on number one. Checked compression 200 PSI each, checked OHMs on each injector as well as primary and secondary on Each COP. All readings are good, used a NOID light to ensure pulse for injector. I am not at a standstill as I do not know where to go from here.
Submitted: 1 year ago.
Category: Toyota
Expert:  roy replied 1 year ago.

good morning my name is XXXXX XXXXX I will assist you.

 

Did you change the plugs???? It may be as simple as a plug breaking down under a load.

 

Roy

Customer: replied 1 year ago.

Yes I have changed all plugs and ensured that the gap was correct at .044


 

Expert:  roy replied 1 year ago.

ok, good. remember when a computer sets a missfire code, it is not always exact on the missfire cylinder. it may be another cylinder. the computer gets its info from the O2 sensor and guesstimates the cylinder. I always recommend replacing all the coils when you have a 300 random and an exact one. It acts like it is guessing the cylinder number.

 

Roy

Customer: replied 1 year ago.

that is not the answer as I have checked Spark on each COP as well as Primary and secondary resistance and that all comes out ok. So the real question is where to go next and changing all COP is not the answer here. I moved the COP around from 1-4 as well and it still comes up as misfire in 1.

Expert:  roy replied 1 year ago.

ok, if all the ignition parts are good, then I would suspect an injector. even though you checked the ohms and they tested well, it may be partially clogged form dirt on the pindle. did you try moving them around??

 

Roy

Customer: replied 1 year ago.

no I have not moved them however I did test them for resistance as well as a NOID light to ensure that they are firing. All of that came back ok. So I did not want to go through moving them without ensuring that I have tested everything that may be of issue without that. I did have an odd thing with COP 1 the Spark jumped through the side of the wire and jumped to my thumb. This is why I moved 1 to 4 as I was concerned that perhaps I had carbon tracks that I did not see however it did the same thing with the new COP as well as with the one from cylinder 4 when I moved it to 1. Is there some type of wiring issue that could cause this and I am loosing Spark on an irradiate basis

Expert:  roy replied 1 year ago.

no wiring issue but the boot on the coil may be leaking spark. it will ground out before hitting the plug.

 

when you verified the dead cylinder, did you remove the coil connector to verify it is number 1 missing??

 

Roy

Customer: replied 1 year ago.

I did not remove the Coil connector however I removed the connector on the injector and it was acting the same and that really shuts down that cylinder. Keep in mind as I said it idled ok however as soon as I give it some gas it starts missing. So that is why I am trying to really find out did I miss something. what else is there to check. the issue really shows itself under load more then Idle. So steps wise what am I missing is the real question. What are the chances that it is a clogged injector and would I still get good resistance or would that start to fail the injector and change the reading. The ohms resistance on all 4 injectors was almost exact. I felt like it needed to be spark, compression, fuel, air. I did not get any MAF issues on the computer however perhaps there is a test I could do to ensure I have Air flow to cylinder or something else I am not thinking of. Additionally I did check Ground on number 4 wire on COP connector by piercing and ensuring with key on I was getting the 12 volts and I was on all for so it is not a grounding issue I could find.... so again is there something else there I could look at.


 

Expert:  roy replied 1 year ago.

ok, if you are getting 12 volts on the ground side then it is not grounded. if it were grounded it would read 0 volts.

 

you have good compression, new plugs, switched coils, I doubt it is a vacuum leak. the injector solenoids can read good but fuel may not be passing through the injector when commanded.

the only other thing I can think of is a mechanical issue with valve spring or cam issue in the motor.

 

Roy

Customer: replied 1 year ago.

OK so my question is if was mechanical issue wouldn't that show up with the compression test? If it is was a vacuum leak what would be the most likely place where vacuum was leaking and not completing its connection correctly. Any culprit I should be looking at. Additionally is there any testing on the MAF that I should be looking to do?

Expert:  roy replied 1 year ago.

MAF is not the issue. will not cause a missfire on 1 cylinder. it would be a different issue and would code.

 

as far as mechanical, crnaking compression can be good but running compression may be different with the valve train working much harder under the load of engine running. to be sure, do a running compression in all 4 cylinders, testing one at a time,

 

vacuum leaks are common where the intake manifold meets the head. spray some carb cleaner around the area to see if the idle changes.

 

Roy

Customer: replied 1 year ago.

OK Roy you gave me some Ideas, I will do a compression test while running, I will spray the intake around the head, and I will move the injector to determine if it is clogged. I appreciate the assistance, I am very frustrated with this issue. with the exception of the listed next steps is there anything else you think I should be looking at or testing beyond that. Could it be the computer misfiring on that cylinder or something very odd like that.

Expert:  roy replied 1 year ago.

I would not suspect a computer issue.

 

Do the other tests and lets see where it takes us??

 

Roy

Customer: replied 1 year ago.

Roy is it ok that I leave this open until I finish these tests. you have been very helpful I just don't want to have to start all over again with another person.

Expert:  roy replied 1 year ago.

you can rate me and keep on communicating with me anytime. I am on weekends and evenings

 

Roy

roy, import/domestic specialest
Category: Toyota
Satisfied Customers: 1934
Experience: ASE master tech for 40 years
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