Lazer Z with Kohler Command Pro 26 EFI

[Grizzly1200]

Evening all. New to the forum. Working on an 06 lazer z with the EFI CH26s Kohler engine. This mower is taking years off my life and graying my hair at a rapid rate. Machine will run fine Cold, but as soon as it warms up it starts to cough, sputter, stall, and essentially fall flat on its face. Initial codes were 22 and 31. Here’s what I’ve done.

Replaced Throttle Position sensor. Tried multiple ways of “resetting or learning ecu”.
Checked fuel pressure - good steady 36 psi
Replaced ignition coils and plugs
Replaced crankshaft position sensor
Checked/ unplugged oxygen sensor

All to no avail. No change at all. Same codes. Same symptoms. I have no idea where to go from here. It’s not like parts are easy to come by. Contemplating trying to do a carb swap but that comes with its own challenges.

Any insight would be awesome. Thanks!

 

[Auto Doc's]

I recommend you download the Kohler manual for you engine if possible. Some of the manuals for the fuel injection system have been restricted to dealer only, but hopefully that will be changing soon under the right to repair legislation

 

[Tiger Small Engine]

Evening all. New to the forum. Working on an 06 lazer z with the EFI CH26s Kohler engine. This mower is taking years off my life and graying my hair at a rapid rate. Machine will run fine Cold, but as soon as it warms up it starts to cough, sputter, stall, and essentially fall flat on its face. Initial codes were 22 and 31. Here’s what I’ve done.

Replaced Throttle Position sensor. Tried multiple ways of “resetting or learning ecu”.
Checked fuel pressure - good steady 36 psi
Replaced ignition coils and plugs
Replaced crankshaft position sensor
Checked/ unplugged oxygen sensor

All to no avail. No change at all. Same codes. Same symptoms. I have no idea where to go from here. It’s not like parts are easy to come by. Contemplating trying to do a carb swap but that comes with its own challenges.

Any insight would be awesome. Thanks!

You have thrown enough parts and sensors at it. Take it to a dealer and get it fixed. Good effort do doubt!

 

[ILENGINE]

Here is code 22 and 31 diagnostics

And looks like fuel pressure is suppose to be 39 psi +/- 3 psi so your 36 is just on the edge. And would check all engine and chassis grounds. A loose or corroded ground between the engine and ECU can cause all kinds of strange sensor readings.

 

[Auto Doc's]

Here is code 22 and 31 diagnostics

View attachment 74095View attachment 74096And looks like fuel pressure is suppose to be 39 psi +/- 3 psi so your 36 is just on the edge. And would check all engine and chassis grounds. A loose or corroded ground between the engine and ECU can cause all kinds of strange sensor readings.

This reads like many of the automotive diagnostic code flow charts that I have worked with for years. Many of the fuel injected ATVs and side by side vehicles are similar except they of refer you to use their manufacturers specified specialty scanners.

 

[ILENGINE]

This reads like many of the automotive diagnostic code flow charts that I have worked with for years. Many of the fuel injected ATVs and side by side vehicles are similar except they of refer you to use their manufacturers specified specialty scanners.

So does Kohler/Rehlko, Honda, Briggs, MTD, Kawasaki

 

[Grizzly1200]

After extensively taking apart every connector, cleaning, etc. here’s what I’m left with:

Felt the ground had a lot of resistance (14-15ohms). Cleaned ground now resistance down to .2. No change.

Tested throttle position sensor. Passed test. Replaced it anyway with another Bosch sensor. Passes test again. Still unchanged. Initialized many times per service manual recommendations. No change.

The mower now runs worse than it ever has. Code 31 is gone, but I now have codes 22 and 23. Code 23 is for faulty ecu/ unable to read ecu data history. I’m not sure how the tps can still be throwing a fault if it passes every test and shows good voltage.

One caviat, the mower does have multiple bad oil leaks, and all grounds, connectors, ecu itself, etc were saturated with either oil or residue. Everything has since been cleaned.

In reference to tigers comment, I’d love to get it to the dealer. But all local dealers refuse to look at it due to its age, stating they no longer have the ability to plug in their diagnostic suite. I have the service manual and am a small engine mechanic myself, however on Atv’s and Powersports, not lawnmowers. I’m in uncharted territory.

 

[slomo]

Felt the ground had a lot of resistance (14-15ohms). Cleaned ground now resistance down to .2. No change.

Okay that was huge. Nice work on cleaning it up.

Just remember circuits need LOAD TESTED. Meaning the full amperage on THAT circuit THEN test it for a voltage drop.

If you read 15 Ohms at rest, that will be way higher under load. Probably a pretty fat voltage drop going on.

I'd call Kroller and buy a shop service manual for it.

 

[slomo]

Make sure, every connection, the pins are all TIGHT and CLEAN. Ohm out across each connector till you find the offender. Wire to wire across the connector.

Take your hand and fondle each wiring harness looking for bare copper, rubbing and so on.

Battery fully charged.........

Would also buy some Tesa Tape once you got her running and seal up all the harnesses.

 

[Tiger Small Engine]

After extensively taking apart every connector, cleaning, etc. here’s what I’m left with:

Felt the ground had a lot of resistance (14-15ohms). Cleaned ground now resistance down to .2. No change.

Tested throttle position sensor. Passed test. Replaced it anyway with another Bosch sensor. Passes test again. Still unchanged. Initialized many times per service manual recommendations. No change.

The mower now runs worse than it ever has. Code 31 is gone, but I now have codes 22 and 23. Code 23 is for faulty ecu/ unable to read ecu data history. I’m not sure how the tps can still be throwing a fault if it passes every test and shows good voltage.

One caviat, the mower does have multiple bad oil leaks, and all grounds, connectors, ecu itself, etc were saturated with either oil or residue. Everything has since been cleaned.

In reference to tigers comment, I’d love to get it to the dealer. But all local dealers refuse to look at it due to its age, stating they no longer have the ability to plug in their diagnostic suite. I have the service manual and am a small engine mechanic myself, however on Atv’s and Powersports, not lawnmowers. I’m in uncharted territory.

So you have the service manual, and are familiar with EFI, and are a small engine mechanic, just more on ATVs etc. You should be able to figure this out if you stay with it on fixing it. I have limited experience with EFI and codes and have problems with my Ferris. Has only run about 10 hours in 4 years because of electrical problems. Wish I could fix it.