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Discussion Starter · #1 ·
I finally have my Frontier on the road after new head gaskets, timing chains, cats and myriad other small parts. I had an issue with the plenum (cracked) so I replaced it. I took it to the dealer to have that diagnosed because it wouldn't idle down and I couldn't find the vacuum leak. While it was there they put it on their analyzer and set up the timing and idle rpms. Ever since then, when it's warm and it sits still at a light or in traffic, the idle will drop to about 575 and the motor will idle rough. In addition, the oil gauge arrow will drop to the lowest allowable point, almost right on the white line indicating minimally acceptable pressure. My reading here tells me the idle should be bumped up to about 750, not 650 that the dealer set it at. The technician there refuses to up the RPM's claiming 650 plus or minus 50 is the correct parameters. My research indicates that the 05, 06 and 07 4.0's could have the rpm at idle changed without issues and 750 is not out of line. I've also read that there are apps out there that would allow me (Car Gauge Pro), using an ELM 327 or STN blue tooth device, to connect my phone or computer and make that change. I have also read that the Android phone can pair but the app is not compatable with the iphone. MSS3Y is someone who seems to have done this procedure and I'd like to talk with him, or anyone else that can help me find a way to change those idle rpm's. I have an iphone and a laptop, bluetooth enabled running microsoft 10. Can anyone help me find an app or a way to set those RPM's up a little without the dealer?
 

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I have an 06 and have had problems in getting the idle down from 800 rpm to 650 rpm. Nothing I could do but let the computer go through the idle air relearn protocol. I do not know of any legal way to change the idle rpm. You can of course buy a TUNE which will allow you to change many operating parameters.
 

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A scantool or a tuner can adjust the base idle setting and even the ignition timing advance. I can do it with both my Superchips Flashpaq tuner and my Autel MaxiCheck MX808 scan tool on my 06 and 08 Pathfinders. The oil gauge dropping to the lowest line can be an indication of another problem. VQ35 and VQ40 Nissan engines that show low oil pressure at idle often have this due to a failed gasket on the rear timing cover oil gallery cover. The oil leaks past the gasket and back into the crankcase. Unfortunately, to replace this gasket, you have to remove the front timing cover. Here's a YouTube vid showing it on an Infiniti VQ35DE, but the same thing occurs on the VQ40DE, as well.

 

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Discussion Starter · #5 ·
A scantool or a tuner can adjust the base idle setting and even the ignition timing advance. I can do it with both my Superchips Flashpaq tuner and my Autel MaxiCheck MX808 scan tool on my 06 and 08 Pathfinders. The oil gauge dropping to the lowest line can be an indication of another problem. VQ35 and VQ40 Nissan engines that show low oil pressure at idle often have this due to a failed gasket on the rear timing cover oil gallery cover. The oil leaks past the gasket and back into the crankcase. Unfortunately, to replace this gasket, you have to remove the front timing cover. Here's a YouTube vid showing it on an Infiniti VQ35DE, but the same thing occurs on the VQ40DE, as well.

I already replaced those gaskets because after it was all together, the oil pressure went to nothing at idle. However, I believe I found my problem this time. The connection to the #2 coil was loose. After I connected it fully, everything seems to be working as it should, finally. It's been a long road for me to get this engine back. I've never been involved in this sophisticated a motor and I believe I had the front timing cover off at least 4 times. But it seems to be running well, finally. So now I look for another Nissan that needs a timing chain or even head gaskets. I believe I could do one over a week end. Nothing creats ability better than experience. I'm 68 and much more at home with 60, 70 and 80 vintage motors. Thanks for the replies to everyone.
 

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Thanks CT - I'm currently looking at tuners.
Gopedal...have you looked at the Nissan DataScan II program??? It looks like it works with VQ40DE motors.
If you're local to the LA / SoCal area, could you use a helper pulling a motor, replacing a timing chain or repairing a head gasket? Be a great learning experience watching / helping someone working on a VQ40DE motor. :):):)
 

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Discussion Starter · #7 ·
Nice thought and thanks for the vote of confidence. I’m on the east coast, PA. However, there are some great U-tube videos of most all of it. Actually, the challenge was fun. I sold the truck to a friend who desperately needed a vehicle for what I had in it. I’d love to try another one. Best to all.
 
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