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Peter Bagley
Peter Bagley, Toyota mastertech
Category: Nissan
Satisfied Customers: 822
Experience:  master tech at Toyota dealer
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Currently trying to find the source of a misfire... random,

Customer Question

currently trying to find the source of a misfire...
JA: Okay, I'll connect you to the mechanic to go over that information regarding your Nissan. Before I do, is there anything else you want him to know?
Customer: random, seldom misfire at first at idle. slowly got more common. last night a constant misfire developed. can was running lean at WOT. changed plugs earlier today. ground strap on one of them was damaged. as if cylinder overheated. This is a nitrous car, made only one pass last night. Now there is still a misfire under load and at idle. LTFT is 103/104
Submitted: 3 months ago.
Category: Nissan
Expert:  Peter Bagley replied 3 months ago.

Hello andwelciome to just answe, my name is ***** ***** to help. I read your notes and the first thing I would do is a compression check to make sure all cylinders are mechanically ok.

Customer: replied 3 months ago.
thats my thinking also, i will tomorrow as my guage is at work. can you offer any general idea why my fuel trim would be 103?? also the idea of mechanical failure is doubtful simply because this has occured before, but not as severe.
Customer: replied 3 months ago.
i almost want to point it towards a failing fuel pump or clogged injectors
Expert:  Peter Bagley replied 3 months ago.

Just start with the basics , that could be a vacuum leak possible intake. you can try spraying carb cleaner or throttle body ckeaner around the intake and watch if the tach jumps around.

Expert:  Peter Bagley replied 3 months ago.

I assume if it is nitrous you probably have a performance ECU and can't get a trouble code?

Customer: replied 3 months ago.
its factory ecu. only code is has is p0300 which isnt very helpful. tried the carb cleaner trick with no luck. ill just perform my usual routine at work tomorrow. im actually a mechanic in training. was just hoping i could get a answer on here that i hadn't thought of. prolly shouldn't have spent the money here. its ok. thanks anway
Expert:  Peter Bagley replied 3 months ago.

that code is just a generic misfire code you may have to put a scanner on it to show cylinder balance and also read live data especially for that oxy sensor as it may be faulty and trying to adjust the fuel trim wrongly. Code readers are good to a point but can be tricked and don't give you all the perimeters to see what is happening to all the inputs where a scanner will. Is there anything else I can do for you or questions I can answer? Not only am I a master tech but have built my own drag cars as well.

Customer: replied 3 months ago.
as i remember, the 02's were reading .6-.8 ish when i glanced at my scan tool. I also have a standalone wide band gauge, when you feel the misfires at idle, it goes lean. into the 15/16's A/F ratio range, i think i wont honestly be able to proceed until i perform a compression test and fuel pressure test at work tomorrow. I will let you know the results when i have them. hopefully there is no mechanical failure.
Expert:  Peter Bagley replied 3 months ago.

yes me too and yes let me know so I can further assist you.

Customer: replied 3 months ago.
Thanks. Appreciate it
Expert:  Peter Bagley replied 3 months ago.

n/p

Customer: replied 3 months ago.
Finally got it down to a p0301. Tested and replaced the coil & it's perfect now
Expert:  Peter Bagley replied 3 months ago.

se if it was on a scanner the live data would have pick that out , tools make the difference and experience reading them as well. Good for you and good luck. If you need help ot advice in the future remember us.