Kohler efi 29hp surging issue

[6536jim]

Hello
I am having a problem with my exmark x series with the kohler efi 29 hp model ecv 749-3014.
After a few minutes warming up the engine at mid range and full throttle surges. It's worse at
mid throttle then full with a load. I have no codes present. I have done the ecu reset procedure
The idle improved but no change in the surge. The plugs seem to show the engine is running
on the lean side. I recently installed a long block but the issue was present with the old engine.
Any help would be appreciated. thanks

[Luffydog]

Seen some brand new ones do the same thing until you full throttle and apply the pto. Can't also rule out the o2 sensor or the throttle position sensor or the pos. If you have software check voltage

[KE4AVB]

Haven't work on one these so I just looking through the service manual. Most EFI system that I have work on all need to go through a learning phase.

Sounds like you're working with the ECV system and not the Bosch system. When you reset the ECU you did go through the TPS learn procedure too didn't you?

[Luffydog]

most of time the ecu is what people do but the rest is where your talking about is setting the idle screw at over 1500rpm after the ecu reset.. tps learn procedure..

[KE4AVB]

most of time the ecu is what people do but the rest is where your talking about is setting the idle screw at over 1500rpm after the ecu reset.. tps learn procedure..

The reason I mention this as I was reading that a mis-calibrated TPS can the engine to run on the lean side which the OP seems to think might be happening. But this lean condition can be for by testing the O2 sensor output which I do first as it might save some time.

[Luffydog]

yes that was what I was saying in the first post I made except I put the wrong letters tps yes. sometimes has a low voltage reading for the cause of the 02 to send a wrong reading causing either or rich or lean that I have seen.. hmmm maybe I did mean (pos) hahaha kidding crankshaft senor as well as throttle will cause such readings. the soft is ok but really only good for the elctro and wiring part if anything else its back to basics..