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peterpete190, Auto Technician
Category: Nissan
Satisfied Customers: 26630
Experience:  Over 17 years diagnosing and repairing vehicles.
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Pathfinder: After replacing the head gaskets on an 01 pathfinder,

Customer Question

After replacing the head gaskets on an 01 pathfinder, I have misfires on cyl #1&3. I have verified that all of the timing marks line up. I have checked the injectors, swapped coils and plugs, checked compression(205psi and 215psi), installed vacuum guage on manifold(17.5 and steady), verified that when commanded with a scanner, the timing actuator is working, as the rpm's change when the command is sent. The vehicle did not have this issue prior to taking it apart, it would overheat while driving, and there was air entering the cooling system up to an hour after starting the vehicle. All chains, guides, tensioners, water pump, spark plugs are new. Heads were sent to be milled and pressure tested(they said the valve were fine). I still have this misfire issue, and I am stumped! Any ideas?
Submitted: 1 year ago.
Category: Nissan
Expert:  peterpete190 replied 1 year ago.
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
If you have only checked the signal to the fuel injectors I would have the injectors themselves tested to see if you can locate one or both atomizing incorrectly.I have seen this occur and cause this issue here.
If this was already checked and found o.k. let me know.
Thanks Pete
Customer: replied 1 year ago.
I have lifter all 6 injectors out of the intake while still connected to the fuel rail, had a helper spin the engine, and visually watched all 6 injectors spray fuel.
Expert:  peterpete190 replied 1 year ago.
Is one coil or coil boot longer then the rest on this engine?
Customer: replied 1 year ago.
The coil for cylinder #1 is different than the other five, but the difference is where the connector plugs in. All of the coil boots are the same length. I swapped #3 coil with #2 coil, the misfire did not move.
Expert:  peterpete190 replied 1 year ago.
Can you do a running compression test?
This is done with one spark plug removed at a time and the compression gauge threaded into the spark plug hole then the engine run.The compression should be about half of the normal compression and all cylinders will be even.You will have to burp the gauge when it reaches its highest compression reading.If one shows lower compression then the rest this can indicate a valve issue.
Thanks Pete
Customer: replied 1 year ago.
I can do that, however, it will take some time as I currently have the front timing cover off. Taking the advise of our local Nissan dealership, I took it back off to verify that all of the timing marks lined up, which they do (verified by 4 people). Although you do not here any strange noises when it is running, is it possible that a lifter(s) got damaged in the process? I did not remove them, but I don't know about the machine shop. Thinking along the lines of a valve issue, it would have to be that it is not opening all the way, because if it's not sealing, that would show when checking manifold vacuum, right?
Expert:  peterpete190 replied 1 year ago.
The vacuum test would usually show this but there is a chance that a valve isn't opening properly due to lifter failure and a running compression test will help point this out in some cases.With it having spark and fuel and timing is correct I suspect a mechanical fault with a valve or lifter issue.
Thanks Pete
Customer: replied 1 year ago.
Ok, I've done a running compression test on the 4 cylinders that can be accessed without removing the plenum. All of them are in the 100 - 115psi range. 3 of the cylinders are on bank 1, with the 4th cylinder tested being on bank 2.
Expert:  peterpete190 replied 1 year ago.
O.k.,this is a tough one for my to answer myself from here.I will have to open your question up for others here to see if anyone else can assist further on this.I hope you can get this resolved with ease.
Thanks Pete