2005 DF140 Starting/Idling Issue

[Yooper2]

Need some help on my 2005 DF140. It has run perfectly since new until last weekend. When up on plane, I backed off throttle to idle and motor cut out and died. It would then not start. It would fire every time but would not start and run. I was able to manually open the throttle just a touch and then motor would start. When I let go of the throttle plate motor would either die or idle very rough. I was able to salvage the weekend by turning the Throttle Close Sensor in by 1.5 turns which seemed to force the throttle open slightly. Motor then ran for the next 2 days but would not start well when cold and idled at 1000 RPMs giving an alarm. Motor ran great at higher RPM's all weekend.

Back in my shop, I returned the throttle close sensor back to original setting and motor would not start unless manually holding throttle open slightly. Once started it would idle but not well. I tuned air bleed screw to increase idle RPM's over 1200 then backed it back idle RPM back down to 675. Motor would stay running but when keyed off, it would not restart and only fire.

I am thinking about taking IAC motor off and cleaning it as my next step. Any help or advice would be greatly appreciated.

[STxFishing]

Hi Yooper,

Are you getting any trouble codes, either audible or ck eng light flashing?. it will be a series of beeps or flashes depending on gauges. I don't think the IAC motor is cleanable, it's normally carbon build up in the air passage that chokes off the air. I would remove it and take a look at the intake where it mounts for build up.

Spencer

[Yooper2]

I do not have Suzuki instruments but have audible buzzer. Single beep every 3 seconds which goes away once idle is turned down under 1000 RPM. No other codes when starting or running.

[STxFishing]

That would tend to lead me to think IAC itself is ok. I would check intake air passage at IAC for carbon buildup.

[Yooper2]

Thanks for the feedback. I will try to pull the IAC out tonight and check out the carbon buildup and motor itself and report back.

[redlowrey]

When you adjusted the idle by the closed throttle switch it should have brought the check engine light on when you went over 1000rpm. Check and make sure it is working properly, It should be zero volts at closed throttle and five volts throttle open. When you adjusted the idle at 650 rpm was it smooth. The closed throttle switch plays an important role on rapid deceleration, the iac will bypass more air and the timing will advance to stop the engine from stalling.

[Yooper2]

Redlowery-You are correct. When I adjusted the closed throttle sensor, it would alarm out when idling over 1000 RPM's. I do not have lights but it would beep one time every 3 seconds. When I adjusted the RPM's back down, it would not idle smooth. It also would not start unless I manually held the throttle linkage open slightly. I am travelling for the next few days but hope to investigate more closely this weekend. IF there are any other suggestions or things to look at, please post them up here and I will report back with my findings after Saturday.

Thanks in advance-

[Yooper2]

Does anyone know the part number for the CTP switch by itself. I searched the exploded view parts diagrams and do not see the CTP switch listed unless it is in an assembly with something else.

[Yooper2]

Just wanted to follow up on this issue. After cleaning out IAC hoses and passageways, checking the CTP switch for functionality, the same problem persisted. I ended up changing out the IAC valve and it has cured the issue. The motor now starts like a champ even when cold and when decelerate off full throttle to idle, there is no stalling. Thanks for all the help!

[FishingFool]

Just wanted to follow up on this issue. After cleaning out IAC hoses and passageways, checking the CTP switch for functionality, the same problem persisted. I ended up changing out the IAC valve and it has cured the issue. The motor now starts like a champ even when cold and when decelerate off full throttle to idle, there is no stalling. Thanks for all the help!

Curious where you ended up buying the IAC valve and how much? I have a 2002 DF140. Was any programming needed with the new valve or does the engine automatically calibrate itself?

[Yooper2]

Purchased aftermarket from Rockauto. The Suzuki p/n cross referenced to an aftermarket Airtex brand. Paid right around $200 but it was exact fit and solved the problem. It looks like with more investigating I could have found an alternative aftermarket for quite a bit cheaper. The motor started right away after install but I did have to reset the idle...Most likely because I had messed with idle speed and CTP switch while trouble shooting the old one.