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Post Info TOPIC: Three blown ECUs !?


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Three blown ECUs !?


I am a year into this problem and way too many dollars. Very long story and extensive troubleshooting but have not found the problem or way to prevent this. All three times my third cylinder from sprocket side wont run at low RPMs (temp gun shows 300F on header where as all others are 600) but then wakes up partially but still goes in and out at higher RPMs. It gets fuel and air just no spark. Swap over another ignition circuit and it works fine and problem follows this 3rd cylinder circuit. Replace ECU and it runs fine for a short period of days to to weeks. Ignition wiring to ECU has been tested andcurrent monitored when running and nothing obviously work or suspicious.Ignition coil replaced and injectors cleaned/rebuilt as they were very clogged but still killing ECU after this. It runs perfect when firing on all four and even hard to tell I have a problem when this cylinder is misbehaving until it goes completly out.

Any ideas? It looks like only other component tied into the ignition circuit is the fuel pump relay and fuel pump but dont seem to be having any fuel issues.

Any inside info to what might easily kill the FETs that operate these I assume or perhaps a way to put something inline with the wiring to prevent a spike from taking out this circuit? Does it in any way make sense or perhaps a clue to the problem thats it always the third cylinder that goes bad first(I will say if leave it like this a long time the second cylinder then starts to go bad too)?

Any chance my ECU is actually not dead and just had some bad values forced to it that could be cleared?

FYI, I am using a Power Commander, GiPRo Speed Heeler, and GiPro w/ATRE so my only plan of action now is to put the fourth ECU in without these connected and see if I get lucky but unsure if those could easily kill the ECU if defective.

So ready to be done with this ... any help greatly appreciated.



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'07 Hayabusa engine in a Polaris RZR


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Have you tried putting the damaged ecu into another vehicle and see if its realy damaged ?

only thing i can think of that may cause premature failure would be too little resistance in the circuit , are you running std coils or aftermarket

Flashing the ecu would replace the PC and tre


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Dont know if I will come accross anyone will to test the ECU in their ride but hopefully will.

Coils are stock.

I might be overthinking this too much but my mechanic also seems to agree that might be caused by the fuel pump I am using which is aftermarket as I use a fuel cell rather than stock gas tank. Unfortunetly the person that originally built this went with only a three gallon tank and its a circle track type where it is not gravity fed and thus pump has to pull the fuel out which I understand most pumps dont like to do. On top of that with the fuel tank so small and an off road environment the fuel is sloshing around a lot. I added fuel cell foam and three pickups in the tank but suspect the pump might still be getting starved. The end result from both these situations is even though it is a low 5.4 amp draw pump (I am not sure yet what stock pump is) I assume when starved it might pull alot more and could even be getting hot which probably further decreases its efficiency. The fuel pump is on stock fuel pump relay are inline with the ignition and injectors. Sound likely? Maybe just put another relay between the pump and the stock relay since it feeds the ignition/injectors?

I also came across an interesting post that said if fuel pump is not under a constant load the relay only outputs 2V to the injectors. I know when I flip the ignition on my setup the fuel pump kicks in but then it shuts off. So perhaps this makes sense since it seems the cylinder wakes back up once on the gas but all evidence is still that its not really happy and eventually goes out completely. low voltage equals high current so maybe it is just a slow death of the FETs.

In terms of why the #3 cylinder and then #2 cylinder go out this might have something to with the timing. Looking in Service Manual it mentions a different timing map for the #2 and #3 cylinder vs. #1 and #4. My mechanic also said these cylinderers is only hit twice in a cylcle where as the other two are hit once at low RPMs so any problem might be much worse for these two cylinders ECU channel. I am not 100% sure what he was really trying to tell me LOL as this is a learning process for me ... I think he was mentioning pulse width too ... just beyond me.

Any further input greatly appreciated to understand likely elctric causes frying the ECU.

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'07 Hayabusa engine in a Polaris RZR


Senior Member

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Remove PC and all that junk, you can do it in stock ECU.
I would guess that is what messes up your ignition, using ignition module also?
Seen many bikes with shop tuned PCs that when removed bike runns better stock, and no missfires wich happens alot on bikes i have tested with PCs.

I would try stock fuel pump first also, to see if it works stock or if problem lies in stock parts.

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Yeah, will get rid of the PC but its just strange as every time it has been fried have had it back on the dyno after replacing to get custom map/verify running great with adjusted by the PC just fine. So, its not that the PC is showing any signs of being defective but there still is the chance its doing something weird at some point taking out the ECU.

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'07 Hayabusa engine in a Polaris RZR


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On one test bike with same junk as you had mounted, it would cut of every now and then, totally sporadic in high rpms.
Not fun when on country road with good angle through a corner in 260km/h hehe, so that it makes some interference is no doubt in my opinion.

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