ECM test
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Intermediate
Joined: Jan 2010
Posts: 25
Likes: 0
From: Canada
OK, it's 1am and i'm in the garage with the laptop fiddling with a harley...Good times....Anyway I chacked the voltage accross the plugs for the AIT sensor and the CHT sensor both are at 4.4v. So, where is the A/D converter? and how do I check that?
thanks
Also, does anybody tell me where to find a good wiring diagram?
thanks
Also, does anybody tell me where to find a good wiring diagram?
Road Warrior
Joined: Mar 2008
Posts: 1,691
Likes: 3
Hum, that's with the sensor disconnected? It should be closer to 5V than that. 32F would be 4.6V and 50F would be 4.3V corresponding to 9750 and 5970 ohms through the sensor. It seems if that was with the sensor connected then the sensor is bad unless you're storing the bike in the refigerator. The sensor reading 40F would be a good reason for the ECM to be reporting 40F. If that's with the sensor disconnected then there's your problem. You either have a short on the light green/yellow wire or the ECM is bad.
PS: The values are for the IAT. The values for the ET are similar but differant.
PS: The values are for the IAT. The values for the ET are similar but differant.
Last edited by LilBudyWizer; Jul 24, 2010 at 01:46 AM.
Road Warrior
Joined: Mar 2008
Posts: 1,691
Likes: 3
Oh yes, worth noting, an ohmmeter supplies power for measuring resistance and as such you do not connect it to anything powered or your ohmmeter may go boom. Also there is no seperate A/D converter, it's internal to the ECM. It's just speculation as to how it works internally and there are no user servicable parts in an ECM so it doesn't really matter.
Road Warrior
Joined: Mar 2008
Posts: 1,691
Likes: 3
I have no idea what an IST is. Reflashing won't fix the problem. Recalibration might get it to run better with the problem. If you have a SEST, the bike is transportation rather than recreation and you can't afford to fix the problem right now then that might get you by for a few weeks.
PS: Re-reading you have a PC. If the ECM thinks the intake temp is 40F then it thinks it's getting about 15% more air than it is and adding 15% more fuel than it should. So you're likely running rich. Leaning out the requested fueling to get more reasonable fueling despite a bad sensor is a bandaid fix, but better riding the bike with an apparent problems.
PS: Re-reading you have a PC. If the ECM thinks the intake temp is 40F then it thinks it's getting about 15% more air than it is and adding 15% more fuel than it should. So you're likely running rich. Leaning out the requested fueling to get more reasonable fueling despite a bad sensor is a bandaid fix, but better riding the bike with an apparent problems.
Last edited by LilBudyWizer; Jul 25, 2010 at 02:43 PM.
Stage II
Joined: Jul 2010
Posts: 2
Likes: 0
Having similar issues with an 08 Ultra. Today I took off and it was 96 deg out. The first 20 min was fine no issues at all. I headed down the freeway and at 2800 RPM and 75 MPH is started cutting out. Stopped for a soda and it would barley take off from a stop with out popping and studdering which did not happen when I first started. Got back to the house and headed out again taking off fine and started skipping and studdering at 2000 to 2500 rpm and on the freeway it was running fine. Everytime I shut it off and start again it is acting up at a different throttle position and rpm. Any Ideas?
Road Warrior
Joined: Mar 2008
Posts: 1,691
Likes: 3
Sounds a lot like water in the gas to me. Fuel filter, fuel pump, pressure regulator, injectors. The starting point for that would be a pressure test. Just because it's easier I would check the spark plugs first though it sounds like a fueling problem. If there's a brown, glassy buildup on those that can melt and short out the spark plugs.
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Thread Starter
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Intermediate
Joined: Jan 2010
Posts: 25
Likes: 0
From: Canada
Finally!!!!!!!!!
OK I finally got it running.. well almost ...The verdict was a bad ecm. but there was more ... The ecm I wrecked had a stage 1 flash and so I had to decide if I was going to put the stage 1 on the new ecm or start from scratch and re-dyno.. I chose to re-dyno just incase this ever happened again.. The problem is it doesn't run as smooth. Does anyone know if there is any timing changes on a stage 1 download????
It really sucked not having a ride for most of the summer buy I'm looking for some good fall rides.
thanks in advance
It really sucked not having a ride for most of the summer buy I'm looking for some good fall rides.
thanks in advance
Stage I
Joined: May 2020
Posts: 1
Likes: 0
From: Hampshire
First of all, why do you believe it is not healthy? It is very rare for an ECM to actually be the issue. Most of the time there is something else wrong when the bike is not running properly. For instance, bad spark plug wires, bad gas, holes in the gas line, exhaust leaks... I could go on and on, but I am sure you get my drift.
I know that this doesn't answer your question - the only thing I can think of is if you have a SERT or SEPST or TTS you could re-upload your calibration. If that worked then it is functioning as expected. Think of it like this, the ECM is like your computer. If you can start Windows (if the bike starts), then it is likely not the computer (not the ECM).
I know that this doesn't answer your question - the only thing I can think of is if you have a SERT or SEPST or TTS you could re-upload your calibration. If that worked then it is functioning as expected. Think of it like this, the ECM is like your computer. If you can start Windows (if the bike starts), then it is likely not the computer (not the ECM).
I DO NOT agree with this statement anymore as ECM's are very *sensitive* modules and only as good as the components used inside to manufacture them. The software side is straight forward. But alot more ECM's are failing especially on Harleys bikes that approximately 4-7 years old... its almost as if its date stamped for when it fails ffs.