Hi there!! Newbor to forum who needs help diagnosing rough idling on 97 altima. Typing on iPhone, so will keep everything short for this posting.
Stats on car:
Things replaced to try and fix rough idling/misfire:
Engine cover gasket replaced (fixed and cleared #4 cylinder misfire)
Distributor rotor,seals, and cap replaced
New spark plugs and wires after engine cover gasket repair
New alternator( this was a separate problem)
Just replaced egr valve and gasket( scraped off old gasket and carbon from egr base including 2 opening holes in base)( I was told there is no egr pipe in my car, so didn,t do that.) ( FYI, this cleared egr code)
After all this with codes cleared, 0400 code came up for about 2 weeks but now there is no codes for past couple of weeks.
Running rough at idle, chugging out of tailpipe. Worst is when in park idling, but no engine cut out so far. 500-1000 rpm is when it is bad. Barely noticeable over 2000 rpm (aka highway)
Haven,t checked knock sensor yet. Hoping to work on this today so any help would be great. Have Haynes manual. Wondering if I do have an egr pipe?? Also could it be egr temp sensor, bpt(need more info on what this is and how it works), iat temp sensor(what is difference between iat sensor and egr sensor??), tps sensor(maybe??), or exhaust system like (muffler, pipes, cat converter)(FYI had everything from behind cat converter replaced 2 years ago)
Thanks a bunch everyone and hope someone can help!!
P.S. 1997 Nissan altima SE, 4 cylinder, 2.4 liter??
I would suggest you concentrate on only the engine misfiring issue for now. A true misfire should typically be captured in the ECU diagnostics. So a diagnostic scan should had caught it. If that's not the case then try to isolate the problematic cylinder by disconnecting a spark plug at a time to see which one DOES NOT make the engine idle get worse.
is it still missfireing. if not it could be an intake leak. try spraying some carb cleaner or WD-40 tword the intake till the idel straightnss out. the knock sensor and egr temp will through codes if those were the problem.
On my '93 altima, I had a stumble on idle and stall condition. I thought for sure it was the IACV. Turned out it was (I think) a bad ground wire on the ignition control module. All I did was remove the black electrical tape on the harness connector, and the car has been fine since. I'm guessing that repositioned the bad ground to make full contact. (my best guess).
P0400 Exhaust Gas Recirculation Flow http://engine-codes.com/P0400.html
You can check the functionality of EGR -- in the tube going from BPT ( back pressure transducer ) to EGR valve and the tube going to bottom of BPT from exhaust tapping tube -- inside tube there are small restrictors -- rubber tube inside tube to control the flow of Exhaust gas to BPT and the vacuum to EGR valve -- make sure the rubber tubes are passing air -- when you blow thru them -- I found mine to be plugged with carbon !! --
That's a nice article and website. I suggest people go out and download it locally.
It had a few minor areas which could had used either further explanation or correction. But overall, it's a nice piece of diagnostics for the 1st Gen.
I still say, and don't know why, my preferred method for troubleshooting the ignition system hasn't taken ground. The quickest, best, and non-intrusive way to trouble the ignition system is by far to use an ignition timing light. If you first place the pickup on the ignition coil high voltage wire, you will easily identify a constant or random misfire. And I'm not talking about using the light strobe on the crank timing mark. I'm talking about visually checking the strobe pattern to identify ignition misfiring issues.
Also keep in mind that an ignition misfire doesn't always lead to a bad ignition component. You can have something like a single cylinder run extremely lean or rich where the spark plug won't even fire at all.
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