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Help with building your Speeduino, installing it, getting it to run etc.
By GhjEng
#40944
Guys,

Just dropping this topic here to help anyone else that stumbles into this...

I just spent a couple days chasing a hunting idle, checking the usual suspects:
1.) Vacuum Leak
2.) Lean fuelling
3.) Dodgy IAC
etc...

Then, after looking at a log that I took, I saw that the DFCO (deceleration fuel cut off... in the accel enrichment page) was coming on, cutting fuel,--> causing rpm to drop... then when rpm dropped enough, it would switch fuel back on, causing rpm to rise, etc... and this presented itself as a hunting idle.

This wouldn't usually have been a problem, but my intake is a bit leaky, causing a higher rpm than usual... so I was getting into the area where DFCO was active...

Image
By GhjEng
#40958
pazi88 wrote:So problem was just lack of tuning :D
:D Yeah, exactly... first tuning experience, so very silly mistakes. Just like you I’m very strong with electronics and control... have a mechanical engineering degree, worked in industrial automation, Mechatronics and robotics for 15+ years and I still make silly mistakes like this ;)

But again, thanks for all your posts, videos and work... big inspiration and a big help!
User avatar
By Guidosaur
#41030
Ahhh I remember this problem well. Took me way too long to realize what it was lmao. Gotta make sure you set the dfco point somewhere comfortable, but also safely above your highest idle point.
By ric355
#41042
Guidosaur wrote:
Thu Feb 20, 2020 1:24 am
Ahhh I remember this problem well. Took me way too long to realize what it was lmao. Gotta make sure you set the dfco point somewhere comfortable, but also safely above your highest idle point.
It should be turned off until the engine is properly tuned.
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