2011 CRF450r won't idle -any suggestion

Adobe-Al · Dec 21, 2017

2011 CRF450 won't idle and the the high idle knob does nothing(turn it or pulling out) when I pull it out I can hear air be pulled in to the engine. Swapped tanks with another bike and had no effect.

Checked TPS, changed plug, no flashing codes, clean air filter. Runs perfect until you let off the gas then idles down and quits. It seems to be worse after it has warmed up.

RACINSTATION · Dec 21, 2017

Tight intake valves will cause low idle. TPS adjustment will also aid this cause, but you said that was checked.

Adobe-Al · Dec 21, 2017

RACINSTATION said:
Tight intake valves will cause low idle. TPS adjustment will also aid this cause, but you said that was checked.

Sorry forgot, I check the valves and they are good. Bought a PR2, seemed to improve it for a day then back to the same old problem.

RACINSTATION · Dec 21, 2017

What were your intake valves set at?

What was your idle voltage on the TPS?

Adobe-Al · Jan 30, 2018

Ok, I'm about ready to light this POS Honda on fire. The bike is at the dealership. Here is what we have tried so far- valves perfect .006, TPS voltage perfect, throttle body cleaned perfect, swapped 3 ECU's runs great for a while then same old problem won't idle. Swapped tanks with a good running bike same problem. Has perfect fuel pressure when it dies, cleaned injector. Dies when hooked to a 12 volt source. I'm pulling my hair out and so is the shop. Any suggestions? All grounds checked, changed capacitor, changed oil. Will idle when cold, but dies when warm. The idle knob pulled out has zero effect when warmed up.

s.back · Jan 30, 2018

If your able to look at pids i would look at the coolant temp sensor and intake air temp sensor. When the bike is cold those two sensors should be close to the same. Make sure the temp sensor goes up to temp. Have seen those sensor cause similar problems when they dont work right. Also make sure you dont have some sort of vacuum leak.

J&L Snowhawk · Jan 30, 2018

Obviously making sure oil is not gas contaminated

Adobe-Al · Jan 31, 2018

s.back said:
If your able to look at pids i would look at the coolant temp sensor and intake air temp sensor. When the bike is cold those two sensors should be close to the same. Make sure the temp sensor goes up to temp. Have seen those sensor cause similar problems when they dont work right. Also make sure you dont have some sort of vacuum leak.

Thanks, the temps seem to be working correctly on the diagnostic tool. Think a malfunctioning MAP sensor? not a complete failure just misreading? It throws no codes.
The oil was the first thing I changed. I bought the bike thinking it would be an easy fix. I did replace the kill switch.(maybe a defective one)

Adobe-Al · Feb 2, 2018

Update: might of found the problem, low voltage to the map sensor and TPS at idle. The stator has correct AC voltage, so it seems like I might have a rectifier/regulator problem. Not sure how it could fail and over regulate voltage(to low of voltage). Maybe someone can explain how and if that is possible.

s.back · Feb 2, 2018

Adobe-Al said:
Update: might of found the problem, low voltage to the map sensor and TPS at idle. The stator has correct AC voltage, so it seems like I might have a rectifier/regulator problem. Not sure how it could fail and over regulate voltage(to low of voltage). Maybe someone can explain how and if that is possible.

Make sure your on the right wire. Most of those are just a 5 volt reference.

Adobe-Al · Feb 2, 2018

s.back said:
Make sure your on the right wire. Most of those are just a 5 volt reference.

Thanks,
Correct, I watched it drop to 3.4 volts at sensors. And the idle got all rough and then flamed out. I just assumed that the rectifier would fail and burn stuff up? I hate electrical problems!

s.back · Feb 2, 2018

Check voltage going into ecu should be battery voltage and then the ecu steps it down to 5 volts. I would check those wires coming out of ecu. If you hold 5 volts then you may have a connection issue. Check all connectors for corrosion.

MBKMTRS · Feb 3, 2018

Fe570s need new or cleaned injectors when they won't idle.

harooch · Feb 5, 2018

its your wiring harness

I had a 2010 crf450r Honda. I had the exact same problem after snowbiking on it for 3 years. I replaced everything: stator, flywheel, rectifier, condenser, plug, fuel pump, fuel injector, kill switch, etc. etc. etc. Turns out it was just my wiring harness was corroded. It would run and fire and work with gas, but would not idle. All the water/snow from riding, and salt on the highway from transporting just wreaked havoc on the wiring harness. So, my guess is there is a 95% chance it is that. Good luck.

Adobe-Al · Feb 6, 2018

harooch said:
I had a 2010 crf450r Honda. I had the exact same problem after snowbiking on it for 3 years. I replaced everything: stator, flywheel, rectifier, condenser, plug, fuel pump, fuel injector, kill switch, etc. etc. etc. Turns out it was just my wiring harness was corroded. It would run and fire and work with gas, but would not idle. All the water/snow from riding, and salt on the highway from transporting just wreaked havoc on the wiring harness. So, my guess is there is a 95% chance it is that. Good luck.

Thanks, did you replace the wiring harness or repair it?. The voltage drop is seems to be in or after the rectifier. Not sure how big a job the wiring harness replacement is.

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2011 CRF450r won't idle -any suggestion

Adobe-Al

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