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Ask Chris(aka-Moose) Your Own Question
Chris(aka-Moose)
Chris(aka-Moose), Nissan Technician
Category: Nissan
Satisfied Customers: 621
Experience:  16 years of experience
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I hope

Customer Question

i hope
Submitted: 2 years ago.
Category: Nissan
Customer: replied 2 years ago.
im ready for the answer. the page said the mechanic was waiting for me to pay. I paid and I am waiting
Customer: replied 2 years ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Juan Crespo replied 2 years ago.

Hi there. I just logged in and saw your posting. Unfortunately, all I can see from you at my end is:

"i hope"

"im ready for the answer. the page said the mechanic was waiting for me to pay. I paid and I am waiting"

Would you please elaborate on what it is you need our help with?

Customer: replied 2 years ago.
00 Nissan Frontier, 2.4l high idle and bad performance. Replaced plugs, wires, rotor button cap, iac, map, tps, 02 sensor and even did a smoke test. 300 miles to a tank one week, 240 the next. What's going on?
Expert:  Juan Crespo replied 2 years ago.

Thank you for that information.

Are there any trouble codes in the PCM's memory? Do you have access to a scan tool capable of reading engine data?

Customer: replied 2 years ago.
No codes. I do have an obd scanner but no codes
Customer: replied 2 years ago.
About 1/2 of the time, engine idle will hover around 1100-1200 rpm then Will slowly drop and almost bottom out at 3-400 rpm before settling at 7-800. Will goes as high as 1800rpm while stopped and clutch pushed in.
Expert:  Juan Crespo replied 2 years ago.

OK. I see that you had a smoke test done, which makes me believe there are no vacuum leaks, correct? If so, the issue might be related to valve adjustment or engine timing. Have you checked either one of those? Any possibility of you getting access to a scan tool that can show us sensor values?

Customer: replied 2 years ago.
No I haven t checked timing or valve adjustment. I would have to buy that tool to read sensor values. I do use a fluke meter, when I installed new tps. I'm tired of throwing money at the truck. Excellent condition, clean as a pin, just bad performance. To good of a truck to junk.
Customer: replied 2 years ago.
If the timing was off wouldn't it reflect In the 750-800 rpm at normal idle. It cranks up easy, no prolonged starting, and no back firing. Sitting still pressing on gas pedal u wouldn't think anything is wrong. Under load and going down road, a different story.
Expert:  Juan Crespo replied 2 years ago.

I really hate to speculate (which to me is the same as guess), but timing affects intake pressure, which affects MAP signal, which affects injector on-time, which affects O2 signals, which affect idle quality, etc., etc. Valves being misadjusted would have similar effects, so would EGR operation, restricted exhaust, and so on.

Back to the issue at hand; trying to diagnose this issue by symptom only is quite impossible. I would need to know whatever data the sensors are sending over to the computer and then see what the computer is doing in response to that data.

My advice at this point is to start with the basics; set timing and adjust valves, then measure vacuum to see if it is between 18-22"Hg at idle. If not, check exhaust for restrictions. If OK, check EGR valve operation.

Best Regards.