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severe break-up above 5,000 RPM


quazi-moto

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My '02 LeMans had been running real well for a while, but the other day it started acting up in the higher RPM range. I thought that a possible culprit might be bad fuel so I ran some Sea-Foam through it and ran through a few tanks of fresh gas, but its still exhibiting the problem. I have also toasted a few relays (GEI & Omron) and its always the one on the injector circuit. I can only surmise that this relay is being overloaded for some odd reason. I'm wondering if I should replace the injectors now or what? I can't leave my goose running like this. I can barely overtake cars now. I might try pulling out the My15M ECU and put the stock ECU back in just to see if there is any difference. Any advice or info would be greatly appreciated.

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My '02 LeMans had been running real well for a while, but the other day it started acting up in the higher RPM range. I thought that a possible culprit might be bad fuel so I ran some Sea-Foam through it and ran through a few tanks of fresh gas, but its still exhibiting the problem. I have also toasted a few relays (GEI & Omron) and its always the one on the injector circuit. I can only surmise that this relay is being overloaded for some odd reason. I'm wondering if I should replace the injectors now or what? I can't leave my goose running like this. I can barely overtake cars now. I might try pulling out the My15M ECU and put the stock ECU back in just to see if there is any difference. Any advice or info would be greatly appreciated.

 

Well, the swap may be a quick method of isolating where the trouble lies [ecu vs. wiring harness/injectors] so it can't hurt to try it. You're already beyond my limited capabilities, so I'll just shut up now! :D

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Bad connection or ground, especially at ECU???

Clogged fuel filter(s) or pinched fuel line???( I have mentioned this possibility many times, but nobody on the forum has ever attributed the fuel filter to a reduction in fuel flow, blown fuses, blown relays, or under-charged system)

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Open air box?...sucked the insulator down off the bottom of the fuel tank, cutting off your air at rpm? k

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stormsedge,

I do have a Ferraci lidless air filter so you might be onto something there. I'm going to pull the tank off and have a look.

 

dlaing,

I just had the fuel filter replaced so I'd have to guess that its something else.

 

Cliff,

I've had your unit for a while now and you did the map for me after we had exchanged several e-mails. It ran like a champ for a long time with the My15M. I swapped the stock ECU in today and went out for a shakedown run (in between the rain drops) and the bike is still breaking up on the top end. My gas mileage has been terrible and when my friends are behind me they tell me that my exhaust is stinky. I've already fried 3 or 4 relays and its always the one on the injector circuit. Each time a relay has failed its always been hot when I removed it. Not hot enough to burn flesh, but pretty darn warm to the touch. This is why I suspect that there's an overload on that particular circuit. I'm still running open loop also.

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You might want to pull that fuse and measure the current through it when the fuel pump is running. Should only be about 5A plus o2 heater if you have one.

Whats your battery voltage? If it is dropping due to regulator malfunction it may cause the pump to draw more current.

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stormsedge,

I do have a Ferraci lidless air filter so you might be onto something there. I'm going to pull the tank off and have a look.

 

dlaing,

I just had the fuel filter replaced so I'd have to guess that its something else.

 

Cliff,

I've had your unit for a while now and you did the map for me after we had exchanged several e-mails. It ran like a champ for a long time with the My15M. I swapped the stock ECU in today and went out for a shakedown run (in between the rain drops) and the bike is still breaking up on the top end. My gas mileage has been terrible and when my friends are behind me they tell me that my exhaust is stinky. I've already fried 3 or 4 relays and its always the one on the injector circuit. Each time a relay has failed its always been hot when I removed it. Not hot enough to burn flesh, but pretty darn warm to the touch. This is why I suspect that there's an overload on that particular circuit. I'm still running open loop also.

Could be a temp sensor issue (it would be running rich if the ECU thinks the engine is cold)?

As you have a MY15m maybe you could hook it up to a laptop and see what the temp reading is in the tuning software ?

I know it doesn't explain the fuse but it could be worth a look.

 

Dave

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Could be a temp sensor issue (it would be running rich if the ECU thinks the engine is cold)?

As you have a MY15m maybe you could hook it up to a laptop and see what the temp reading is in the tuning software ?

I know it doesn't explain the fuse but it could be worth a look.

 

Dave

 

Or you just switch off the sensors (dip switch 2 ON ? - RTFM).

But I bet you'll come up with a damaged wire harness, once you'll have looked for that. Probably between relais and injectors.

At low loads they're on only for milliseconds, producing only very short shortages, nevertheless enough to fugg up the ECU. At higher loads the fuse finally sees enough energy to pop and make an end to all that.

 

Everything else makes no sense to me. It's an interesting question how the ECU will react on such a massive and regular noise.

 

Hubert

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I could also attach the Optimiser to check the feedback from the sensors. I'll start with the basics first. Battery voltage, sensors, TPS voltage throughout the operating range, air filter, etc. I'm going to pull the plugs too and see if there's any noticeable difference between the two. It might even be a faulty connection somewhere. I've gotten caught in the rain a few times over the past couple of weeks.

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I swapped the stock ECU in today and went out for a shakedown run (in between the rain drops) and the bike is still breaking up on the top end. My gas mileage has been terrible and when my friends are behind me they tell me that my exhaust is stinky. I've already fried 3 or 4 relays and its always the one on the injector circuit. Each time a relay has failed its always been hot when I removed it. Not hot enough to burn flesh, but pretty darn warm to the touch. This is why I suspect that there's an overload on that particular circuit. I'm still running open loop also.

 

Bad coil? If your exhaust is stinky and mileage is poor, it's still getting fuel, but not firing. So much fuel it's too rich to fire? Hard to believe at the top end where you describe the trouble as occurring. I say something's wrong w/ the ignition for the troubles you describe, but then I'm not remotely an expert!

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I pulled the plugs last night and the right side plug was completely black and sooty. The left side plug looked a little better, but darker and blacker than usual. Its definitely running rich. I checked a few other things like battery voltage and the amperage at the fuse for the fuel pump. I didn't check the TPS yet. I'm going to attach either my laptop or the Optimiser and check for feedback from the various sensors. I'm also going to pull the fuel tank off. Its kinda weird how it runs pretty normal up to about 4,000 RPM, but beyond 5,000 it has no balls whatsoever.

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My money is still on a blank piece of the wire harness, although a defect or just dirty phase sensor could also be the problem.

 

Anyway, you've posted the most interesting problem since quite a while now ( I'm not sure whether this helps you a little bit at least ;) )

 

Hubert

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