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Post by neilf on Apr 8, 2020 16:59:30 GMT
Loosening and re-tightening the STV actuator seemed to clear the fault, as the secondary valves moved with the throttle. I let the engine warm up and blipped the throttle until the engine reached approx 10K rpm, at which point the valves stuck open! Without a functioning multimeter (one of the probe cables broke on the cheap one that I have and I don't have a soldering iron at home to fix it), I can't check the voltage or resistance of either the STV actuator or the STP sensor respectively. However, my Haynes manual states that when you turn on the ignition, the vales should first close from fully open, then open again to about 95%. When I turn mine on, the secondary valves are already in the closed position, then open to 95%. When I start the engine, the valves then close before moving when I open the throttle.
I checked the STVA and STPS connectors and pins and I can't see any corrosion. I also checked the connections on the ECU for good measure.
The FI light is no longer on and, when I short the pins on the test connector, the dash returns a C00 code, i.e. No Fault.
I'm not confident that this has cured the issue, as my gut is telling me that the STV actuator is faulty. But without a functioning DMM, it'll be difficult to diagnose. Is the STV actuator assembly supposed to rattle when when you shake it?
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Post by Diego the toe clipper on Apr 8, 2020 19:29:46 GMT
Some pics would help Neil...
Did you you remove the black actuator box from the end of the throttle bodies by undoing the "tamper-proof" bolts with the domed heads?
With this off and in your hand, it would rattle a bit, yes. The actuating motor spins a small gear which turns a quarter circle segment of a much larger diameter which would be loose when not engaged on the valve shaft.
Anyway, mechanical failures of the actuator are extremely rare, and being picked up by the FI system, even rarer, so I would discount that.
If you've got it back on properly, firstly we'll done because that's the hard bit, and why Suzuki don't think we can be trusted to remove it in the first place, and secondly, if the valves cycle when the fuel pump primes, there's likely no issue (currently) .
You don't want to be testing resistance / voltage in the position sensor. Even Suzuki have got the standard values wrong in the official service manual. Waste of time, they either work or they don't. If you really suspect a fault with the STV position sensor, swap it with the throttle position sensor, same part.
If the fault has cleared, I'd do two things.
1) Next time you start if from cold, look really carefully at the opposite end of the throttle bodies where the STV shaft comes through to actuate the cold idle mechanical cam (where the idle screw is visible under the tank). Make sure that is engaging properly and that when the valves settle back to 95% open, the cold start idle cam is totally free. This guarantees correct reassembly mechanically speaking.
2) Ride it. Make sure you get to WOT a good few times and that it still pulls as hard as you remember. If the FI code doesn't come back that's it.
But I'll put hard cash on it returning soon!
If you want a moody copy of the official Suzuki manual let me know and I'll sort you out!
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Post by neilf on May 3, 2020 10:36:18 GMT
The fault did re-appear the next time I tried starting the GSX-R.
Giving the connector a wiggle during warm-up cleared the fault and then it came back. I've cabled tied the connector in place so that it can't move and so far the fault hasn't returned. I checked the cold idle cam and it engaged properly during warm-up, then was free when up to temperature.
I still haven't had a chance to ride the GSX-R yet because of the UK travel restrictions; as soon as these are lifted, or if I have to go into work for any reason, I'll take the bike and go the long way round.
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Post by Diego the toe clipper on May 4, 2020 7:22:46 GMT
The fault did re-appear the next time I tried starting the GSX-R. Giving the connector a wiggle during warm-up cleared the fault and then it came back. I've cabled tied the connector in place so that it can't move and so far the fault hasn't returned. I checked the cold idle cam and it engaged properly during warm-up, then was free when up to temperature. I still haven't had a chance to ride the GSX-R yet because of the UK travel restrictions; as soon as these are lifted, or if I have to go into work for any reason, I'll take the bike and go the long way round. The connector of the STV actuator is comprised of four male spade connectors soldered onto a very small PCB. Over time, the copper tracks on the PCB suffer from the vibrations / heat / tension of whatever and crack, causing a break in continuity on the PCB itself. The connector block is disproportionately large and heavy compared to the PCB it is soldered to. When you wiggle / move the connecter, what you are doing is introducing a slight bending force on the PCB which causes the copper tracks to connect through physical contact. But I'm sorry to say that it is very unlikely to be a permanent repair. You need to get inside the STVA and repair those copper tracks. Edit: Found a picture.  The first time I did mine, I just re-soldered the 4 points of connection at the right side on the picture, and dragged a thin line of solder up the copper tracks. That worked for about a month, but then it came back. So then I took some fine insulated solid copper wire, cut it and bent four lengths into the shape of the four tracks and soldered them in place, substituting the PCB tracks with wire connections. That has been going good on mine for a couple of years now. |
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Post by neilf on May 5, 2020 11:34:57 GMT
Cheers Clipper, I'll look into that. I've repaired PCBs using the the latter process that you described in the past, so fixing the actuator PCBA doesn't cause me any worries. I've wanted to buy a decent soldering iron station for ages, so this will be an excellent excuse.
My only concern is removing the actuator cover as it's held in place by tamper proof screws (or was it rivets? I'll have to have another look). Did you replace these with threaded screws and nuts?
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Post by Diego the toe clipper on May 5, 2020 11:50:43 GMT
Cheers Clipper, I'll look into that. I've repaired PCBs using the the latter process that you described in the past, so fixing the actuator PCBA doesn't cause me any worries. I've wanted to buy a decent soldering iron station for ages, so this will be an excellent excuse. My only concern is removing the actuator cover as it's held in place by tamper proof screws (or was it rivets? I'll have to have another look). Did you replace these with threaded screws and nuts? I did indeed. It's quite tricky to get the old rivets out without damaging the plastic casing, but I sealed mine with black thermo-glue after bolting it together and it is fine. Even looks tidy much to my pleasant surprise! |
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Post by neilf on May 5, 2020 12:07:03 GMT
Is there a gasket/seal between the actuators base and cover?
I suspect that when the engine was replaced last year, my mechanic may not have routed the wiring loom correctly and put a strain on the PCB header/loom connector... or the PCB needed to be thicker when it was designed.
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Post by Diego the toe clipper on May 5, 2020 12:57:37 GMT
Is there a gasket/seal between the actuators base and cover? I suspect that when the engine was replaced last year, my mechanic may not have routed the wiring loom correctly and put a strain on the PCB header/loom connector... or the PCB needed to be thicker when it was designed. No, no gaskets anywhere in this process. I wouldn't blame anyone other than Suzuki for this fault honestly. Thousands of these have failed before any mechanic has done any major work. Top tip though: Mark the position of everything with Tipp-ex as you take it apart, the STV shaft, the socket for the shaft in the actuator, the cogs inside... I didn't, and I spent weeks getting it all aligned again when I put it back together. This is probably why Suzuki will only sell one to you already bolted to the throttle bodies with tamper proof bolts, and for 900€ plus VAT! I did ask Suzuki how much to do an authorized repair, and the reckoned around 1400€. |
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Post by neilf on May 21, 2020 11:09:00 GMT
I've purchased a new soldering station and a Dremel kit (my wife likes to do glass engraving, plus some tinned copper wire and leaded solder (the latter should cope with vibrations better than lead-free). I've found the following high temperature silicone adhesive in place of using thermo-glue; www.amazon.co.uk/TEMPERATURE-SILICONE-ADHESIVE-SEALANT-RESISTANT/dp/B006C62M6Q/ref=asc_df_B006C62M6Q/I'm also going to hold the STVA enclosure using locknuts; what size screws did you use Clipper? My guess is M3. |
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Post by Diego the toe clipper on May 25, 2020 9:41:35 GMT
I've purchased a new soldering station and a Dremel kit (my wife likes to do glass engraving, plus some tinned copper wire and leaded solder (the latter should cope with vibrations better than lead-free). I've found the following high temperature silicone adhesive in place of using thermo-glue; www.amazon.co.uk/TEMPERATURE-SILICONE-ADHESIVE-SEALANT-RESISTANT/dp/B006C62M6Q/ref=asc_df_B006C62M6Q/I'm also going to hold the STVA enclosure using locknuts; what size screws did you use Clipper? My guess is M3. M4 with nylock nuts I think Neil. I've got some left over so I'll take a closer look or measure one later. |
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Post by neilf on May 25, 2020 11:01:21 GMT
Nice one Clipper. Edging closer to getting this thing sorted.
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Post by Diego the toe clipper on May 27, 2020 18:43:41 GMT
Just checked, definitely M4.
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Post by neilf on May 27, 2020 22:01:18 GMT
Thanks Clipper. I'll get some on order; cheers for your help.
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Post by neilf on Jun 13, 2020 13:13:29 GMT
Clipper. How the f**k do you get the motor out of the housing recess? I've got this horrible feeling that you're going to say, "Turn it over and cut the top off the housing, the bit that says Mikuni, then push the motor/PCB/connector assembly out."
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Post by neilf on Jun 13, 2020 13:55:48 GMT
Sorted; it was just really tight in the housing. Did you cut tracks which run from the connector pins to the pads where the cool wires fix to the PCB, or just form the wire and solder in place?
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