4-tec horrible idle after first start clears when warm

[spicymemelord1]

Hey everyone, I have a 2003 Gtx 4-tec 155 that idles poorly almost seems like it's misfiring however if I give it a bit of throttle it clears right up. So far I have replaced the spark plugs and reset the tps 0 setting however that hasn't made any difference. I have also scanned for codes on the Candoo and nothing comes up. I use the ski for about 2-4 hours every weekend and run and non-ethanol 91. I think the injectors may need cleaned but it runs fine at speed so let me know what you guys think.

 

[mkov608]

Sounds like it's starving for air at idle. When you're at idle, the engine gets air from a port just in front of the closed throttle plate (item 5 in the picture below); the air passes through the idle by-pass valve; the idle by-pass valve is controlled by the ECM/ECU. I suspect your ski runs well off idle because the engine is getting air with the throttle plate open, but there is a problem with the idle bypass valve or there is a clog or restriction in the throttle body between item 5 and item 6. Dirty throttle body can cause problems as well, so make sure the throttle body is clean.

Remove the intake duct from the throttle body; and start you ski (don't forget the water). Put your finger over the idle bypass duct inside the throttle body (item 5). Does it make any difference? If there is no difference when port 5 is plugged or unplugged, you have either a faulty idle bypass valve (item 6), or the passage inside the throttle body is clogged or restricted, or the throttle body is so dirty that the idle by pass valve is at its max open position and it can't open anymore.

 

[spicymemelord1]

Thanks for the info. I will inspect the throttle body and test the idle bypass this weekend. I have heard faulty idle bypass is not uncommon on these machines.