Idle issue when clutch is released

[Rotax3006]

Im having a strange issue occasionally.  I have a 98.5 with a 5 speed transmission.  When I let the clutch out, the truck usually kicks the throttle up and the truck starts to move without adding fuel from the pedal. It has recently started not doing this requiring me to use the pedal to start from a stop. Its intermittent and seems to do it when the engine is cold.  The truck has RV275s and a new injection pump recently. Everything else is stock.

 

Thanks

BIll 

[dripley]

The engine shoud throttle up when letting clutch out. It is the anti stall feature in the ECM. When the engine starts dropping below idle rpm it adds fuel. The truck should tend to lunge forward some the quicker you let the clutch out. Every once in a while mine wont do it but very seldom as in once in a month or more. If yours has stopped doing completely I would think it is an ecm problem but dont know that for sure. 

[Rotax3006]

Well thats a bummer......Mine is similar to yours in that it only does it occasionally. I would say once every 2 weeks.  My earlier post may not have been clear enough on the frequency.  

 

[Mopar1973Man]

Manual transmissions all will launch without any throttle. The ECM governor will throttle up to hold the 800 RPM's. Like on my truck with such large injectors (7 x 0.010) its more likely to stall without throttle because the ECM can't react fast enough at times. With stock or near stock RV275 (Stock RV injectors for motorhomes) then they normal launching will occur.

[Rotax3006]

So if its not doing it anymore would that indicate an ECM problem?  I have 275s so it should react similar to stock.  I like the feature just noticed it occasionally not working.

 

7 hours ago, Mopar1973Man said:

Manual transmissions all will launch without any throttle. The ECM governor will throttle up to hold the 800 RPM's. Like on my truck with such large injectors (7 x 0.010) its more likely to stall without throttle because the ECM can't react fast enough at times. With stock or near stock RV275 (Stock RV injectors for motorhomes) then they normal launching will occur.

[dripley]

Me, I don't worry about it. It only happens to me very seldom.  Most likely it is just a quirk and nothing failing. If it quit all together that might be a problem. But if every thing else was working right I would keep driving it that way. This is the first stick I ever had that did this.

Edited May 14, 2020 by dripley

[Rotax3006]

Thanks for the comments.  I'm definitely going to drive it until something else in the ecm fails causing more problems.  It doenst really do it too often so i will just keep an eye on it. Might be some strange sequence of events im doing causing it. I was hoping for a quick sensor swap or something simple.