P0507 - what next?

Joined
Oct 27, 2021
Messages
7
Been playing with my 2005 Nissan Frontier 2.5L (engine is QR25DE) with a 5spd transmission and 180k miles. Dealing with P0507. Idles around 1500 RPM, then when it gets good and warm (minimum 20m driving), the idle will surge from 1500 to 2000, then back to 1500, then back to 2000...

Stuff I've done so far:
1. Replaced all sparks and changed intake box air gaskets
2. Replaced PCV valve (was failed, truck has been burning oil)
3. Checked for vacuum leaks twice, none found. LTFT is close to zero all the time.
4. Cleaned throttle body front & back (it was filthy, this helped acceleration noticeably)
5. Cleaned MAF sensor
6. Left negative terminal off overnight (ECU)
7. Performed idle air relearning procedure many times

This truck doesn't have an EGR (uses VVT) nor an IAT.

What would be the top things to try next? Trying to hit low hanging fruit first. Thank you!
 
Joined
Jun 2, 2002
Messages
3,282
Location
Georgia/Retired
Sorry, I asked if you'd done the relearn but then noticed you had done it numerous times. I once had an old 1997 model Nissan hardbody and I ended up having to replace the throttle body to get it to run correctly. There's something about Nissan and cleaning the throttle body that messes things up. There might be a wax pellet in there that gets contaminated or something and once it's ruined it will never work correctly.

Just a thought.
 

sippyCUP

Thread starter
Joined
Oct 27, 2021
Messages
7
Fuel trims are really pretty good, LTFT is close to zero all the time. Sometimes goes a little lean, like 2.
 
Top