Hello guys,
I got one minor issue with my GSX Im unable to solve. When riding at low speeds, typically through the city, the engine surges a little, instead of running at constant speed. When the throttle is opened slightly, the response is not completely smooth. This makes riding at low load very unpleasant. Also I noticed the idle is not smooth as it should be. I can hear silent popping inside the exhaust when idling.
What I already did about this is following. Disassembled and cleaned throttle bodies. Inspected and adjusted TPS and STPS. Removed PAIR system completely using good quality kit to plug all the places needed. Air filter replaced. TB synchro using home made vacuum tube filled with oil. Then synced again using Carbtune. Nothing helped to cure this.
Removing PAIR system reduced this issue somewhat, but not completely.
One thing Ive noticed while doing TB sync. When engine is running with intake pressure sensor disconnected, it idles perfectly smooth and throttle response is much better. Didnt try to ride bike like that, but maybe I should. Swapping this sensor with the one fitted into airbox didnt bring any change, so I think the sensor itself is not faulty.
Thats about all I tried already.
Anyone got any suggestions what to try next? Thanks in advance for any ideas folks.
Replace the vacuum pipes that go to that MAP sensor & also make sure you've sealed the unneeded connection to the PAIRs system from No3 throttle body. The vacuum pipes spilt with age as they go brittle & cause exactly what you're seeing. I believe they are 3.2mm internal diameter & you need about 80cm to do the lot.
Hooli thank you for reply. Will look for new tubes.
Im just washing the bike and noticed something strange. My no.3 header pipe is broken completely down where it connects to collector.
I didnt expect this, because the whole exhaust looks pretty well preserved. Also the exhaust sounds ok, not telling about any leak.
This probably cannot cause the issue with surging, but its certainly one more problem to solve. :facepalm:
I think the collectors are known to rot, only from what I've seen on here though as mine came to me with a full Akra.
If the issue is not the failed header or vac lines, then I would suspect the TPS and / or STPS sensors themselves. They can wear out internally. Try www.webike Japan, sensors are cheaper there than anywhere else and they're genuine oem suzuki.
I recently replaced both my tps and stps bike runs a lot smoother at low speeds.
Yes the header pipes are probably all rotten inside. Wile trying to disconnect no3 pipe from collector, I can see the inner tube still holds, its just outer one separated. Thats why I could not hear exhaust leak. Ive already ordered stainless pipes and collector from Ebay, so thats an easy fix.
Erik I think the same about TPS, its my main suspect. I wanted to inspect both TPS using analog ohm meter to see, if its changing resistance gradually up and down without skipping. But I didnt have opportunity to do so, yet.
When you check the TPS, also check between the resistance over a full sweep between the power & earth wires (I forget which colours but the workshop manual tells you). That test isn't in the manual but it's how two I've replaced have failed. The resistance shouldn't change, but I was getting the same results as the sensor test in the manual gave. I believe the sensor tracks get dirty & short internally, which causes it to fail that way.
Also ignore the high reading the manual gives, most of us find we don't get near it but the bikes run fine. It's the lower one that matters more.