hunting/surging rhythmic idle 07es350, 180k mi
 

Hello all,

I have a hunting/surging/rhythmic idle. Once off of cold start, the idle will drop to about 500rpm, then surge up to about 1100rpm, then back down and repeat in a cyclic/rhythmic fashion.

So far to troubleshoot, i have performed the following:

1. measured fuel pressure
   • stayed around 48psi while at idle and when revving up and also while idle issue present (seems to be within specs)
2. performed a smoke test
   • no smoke escaped, but replaced upper/lower intake gaskets, and TB gasket anyways
3. replaced PCV valve
   • ($6 part, why not)
4. removed vacuum lines and capped the intake manifold (brake booster/evap/PCV, etc.)
   • idle still surging
5. looked for codes or misfire counts using techstream
   • no misfire counts or codes
6. ran o2 sensor test using techstream
   • passed
7. replaced fuel filter and sock just to be safe
   • no change
8. observed fuel trims
   • LTFT = +10%, both banks at idle
9. looked for valve cover leaks
   • none present from what i could see
10. replaced injectors with "remanufactured injectors" hoping mine were just dirty
    • -found injector seals were hard as a rock, but replacment made no difference
    • 3 of them didn't even work 😤, so much for being "flow tested and cleaned" thanks Ebay seller
    • at this point 3 of the "cleaned" injectors and 3 of the original injectors are installed

Another thing that i notice is that at times, the engine will make a nice, strong intake induction sound under acceleration. Other times, it will feel weak, lack acceleration, and sound different, almost as if it's running lean.
-it is totally possible this issue is unrelated though

I would appreciate any help/suggestions. Will gladly report any data from techstream that I can, although i'm not sure if the data logging function works.

My only thought at this point is that:
-it is possible that the injectors aren't still 100% flowing as they should
-maybe the fuel pump is just weak and isn't always keeping up under acceleration. I'm also not sure if fuel pumps actually fail in this manner.

A couple of other things come to mind:
- bad / dirty MAF
- sticky throttle body

I assume you checked the air filter.

Where's the PCV on this engine and how hard is it to change?

when you say fuel trims, is that the same thing as Lamda? sounds like the computer is doing this, based on some input its receiving. did you test your 02 sensors hot? ya, I'd keep hunting on the fuel trim issue, Lamda, air/fuel mixture and see if that leads to something. The MAF is a good idea too. can you set idle to say 1000 RPM and it holds it? or 1500, etc? or does it get squirrely even then? also, one other thing, there are a lot of smart guys over on Toyota Nation if you cant find help here.

BTW - took my BMW injectors to a pro to have them cleaned and tested, they essentially soak them in ultra sonic bath for 4 hours, then flow test them. those ultra sonic baths not that expensive, of course the one they have is probably explosion proof.. not sure what solution they use to do this. sounds like your "new" injectors are sketchy. they also make really cheap plastic adapter that you hook onto the ijnector and some crc fluid and spray the injector while its held open with 12 volts for a second

-MAF seems to be within spec at idle, according to the Toyota documentation i found for the 2GRFE. I cleaned it as well.
-cleaned the TB but didn't notice any change
-air filter is clean

I also checked to see if the throttle body closed and open position parameters were in line with what the Toyota documentation showed, and they were. Only thing I can think of is that it is worn out in the idle area...but i don't seem to have any throttle-tip in issues.

PCV is located on the front valve cover at the top. it took me all of about 2 minutes to change out, super easy. Requires a 19mm socket, IIRC.

Good thoughts.

I did test my O2 sensors hot.
Holding RPMs is not an issue. 1000, 1500, no problem. Acceleration/throttle tip in feels smooth too.

I will definitely check out Toyota Nation, thanks for suggesting it!

I do have the adapter and an injector testor ($30 amazon buy). I was going to use this to perform a test. You essentially prime the injectors with the fuel pump, hook up the tester and pulse for a given interval. The drop in fuel pressure should be some given value (around 5psi?), and should be the same between all injectors. However, to do this, you have to remove the upper intake plenum.......so I figured at that point i might as well have them professionally cleaned and flow tested to put numbers to it and have confidence in the performance of the injectors.