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Discussion Starter #1
Does anybody reliable still flash settings for an S or take a deposit to send me their Yosh box?

After ringing out the harness and megging the sensor, I've found the cause of my too-rich mixture is my IAT is only getting a 2.65V signal. Next troubleshooting step is to replace the ECU but I need to zeroize the new one and then dial it in.
 

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To rich at idle, or too rich across the RPM band?

Is the clutch switch bypassed?

I do have a Yosh Box I can loan out for a deposit, but save yourself some money by confirming the source of the problem before you go that route..
 

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If the clutch switch has been bypassed just by shorting the switch wires then your engine will always run on the rich choke map as the yellow/green ECU indicator wire connection is always earthed telling it it's about to have the engine started or stationary.

The same wire needs to be earthed to allow the starter solenoid to work. So if you permanently earth those switch wires you need to cut the wire to the ECU so it stays off the rich choke map and resumes to the normal map.
 
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Discussion Starter #5
No clutch bypass and the TPS / TB sync was done within the last 500 miles. I fixed the cold map issue by moving the coolant temp sensor to the thermostat back in 2003. This is a new-build engine I finished last Nov and it has run spectacularly for its first 2000 miles. It developed an intermittent cold start problem in June and I noticed by jacket reeked of unburnt fuel so I pulled the plugs. Sooted up and powdery so I ran through the IAP, AP, and IAT where I found the temp sensor supply voltage signal was OOT. The thermocouple tested OK per the manual's temp/Ohm schedule and the wiring back to the ECM had minimal resistance with no shorts. To my mind that leaves a faulty ECM, which almost made it to 145000 miles so not too bad.

Thuddds, I'll take you up soon on the Yosh box so I can make sure I'm starting from zero. Before I risk eBay electronics, anybody got a good -02F41? Probably no time soon but I'll to de-pot my old ECM and see how badly I can muck up flashing replacement chips.

Ain't she lovely?
20181202_092917.jpg 20181202_093541.jpg
 

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I had the 2.65 voltage on the 5volt wire until I put the stand up. I would check that switch and diodes before swapping the ecu.
 

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Discussion Starter #8
I checked the side-stand interlock circuitry and found my 2-wire GPS (bike is a 97 with 97 harness but TLR engine) did not have continuity in neutral. Neutral light works just fine and the side-stand/clutch switch/gear position work as designed (no start with kickstand down and in gear etc.). Pulled the clutch and polished the shift drum contacts on the GPS but no change in continuity at the connector end so either an internal wire break in the pigtail or the sensor itself is dead. I haven't heard of a GPS dying yet, but anybody else? Guess it's time for a TRE since I don't feel like pulling the water pump to change out the GPS.
 

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Discussion Starter #10
I agree, which is why I started with the IAT as the enrichment culprit instead of gear selection. But after several cleaning and R&R attempts I could not get continuity between blue/pink and I still have a functioning neutral lamp. I haven’t figured out what combination of failures could cause it, but nonetheless...
 

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Few things...

I highly doubt it is the ECU. HIGHLY DOUBT.

Go through and look at all connection points on vacuum. These hoses get cracked and are old. Snip like 1mm off anything suspect. Also snip like 1mm of the HT lead at the plug. Could be a bad connection.

Brainless on the planet has a Yosh box rip off, but I have used it and it works...

I have a 97S too...

I went -5,+5,+5 and 11'oclock.

Runs like a champ.
 

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Discussion Starter #13
TunaGlove, you're right I misread the manual. I'll go back into the GPS.
rxf610 - vacuum lines will be re-re-checked, may just replace. I started there but I'll do it again.
With a full exhaust, +4mm overbore, and right about 13:1 CR I was running the same map settings as you and could float the tire in third. After riding it for 18 years I still love this engine.
 

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Discussion Starter #15
No change on the IAT voltage with the kickstand either up or down, but the interlock functions clearly work. The diode test shows around .61V up and open when down and the fuel pump cuts off as it should. I've ordered another kickstand switch just to have a spare to test. Vacuum lines and connections all good, btw.
I believe the coolant temp is the major contributor to the fuel map and the IAT is a trim for the ECU, and my coolant holds rock solid at 190F when I'm getting the overly rich running. I'll throw in some new plugs and redo the TB sync/TPS just for fun.
 
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