Rough idle

This section is dedicated to discussion of DTA engine control units such as the DTA E48 EXP, P8 Pro, DTA S40, S60, S80, and S100, as well as all things ECU related.

Rough idle

Postby iceman_n » Wed Jun 19, 2019 5:08 pm

i have notice in some engines not all of them that when the engine is cold and the weather also cold lets say 10 degrees water 5 degrees air temp, the engine fires up and runs but in some cases it runs rough, the same engine with warmer weather it runs fine...

i am pretty sure that cold intake runners make gasoline droplets and thats why it runs rough like old days with carburattors that they used heat from exhaust manifold, can i do something to fix it because the same engine but with the OEM ecu works fine...any ideas ?
iceman_n
 
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Re: Rough idle

Postby stevieturbo » Thu Jun 20, 2019 11:58 am

Tune it better ?

Often they run better when cold because they'll be a little richer.

But without knowing what you're doing with tuning or the build when cold vs when hot....hard to advise how to correct it.
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Re: Rough idle

Postby Rob Stevens » Thu Jun 20, 2019 12:59 pm

Need to know more about your set up.
I use idle by ignition and works very well even sub zero starts.
If your hot idle is Bob on, use a knobs box to fine tune the warm up enrichment as it moves through the turns table
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Re: Rough idle

Postby iceman_n » Fri Jun 21, 2019 3:44 am

its very good tuned at least at idle, i use advance for idle too...i did not explain it very well, idle is stable...engine sounds rough when its really cold that why i am pretty sure that gasoline droplets on cold intake runners has something to do also the very light bottom end make things worse, its 12kg lighter than stock...thanks both of you
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Re: Rough idle

Postby katana » Sat Jun 22, 2019 4:49 am

A light flywheel / clutch is never going to idle as smoothly as a heavy one - period. If the gas speed is low enough to allow condensation on the inlet runners i'd increase the 'cold' idle speed just like the 'old skool' choke mechanism with carbs - this can then decay against ET back to normal idle at running temps?
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Re: Rough idle

Postby iceman_n » Sat Jun 22, 2019 4:40 pm

i am glad hearing that because the only thing i found to make it better is to have 1200rpm cold idle and when water temp goes over 60 drop it at 1000rpm, below 1000rpm its really bumpy even engine is hot...it has not aggressive cams at all, it has a fast road cam with 221 degrees at 1mm lift...so the bumpy effect is from the very light bottom end
iceman_n
 
Posts: 120
Joined: Mon Jan 16, 2012 1:39 pm
ECU Model: S40 Pro
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Re: Rough idle

Postby Rob Stevens » Sun Jun 23, 2019 3:33 am

But you said it is fine on the OEM ecu
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Re: Rough idle

Postby iceman_n » Sun Jun 23, 2019 5:21 am

yes thats true...but then i remember that the oem ecu has the oem crankshaft and flywheel that is 12kg more in weight that the ones that is installed now on the engine...so i have not try the the oem ecu with 12kg less rotating mass
iceman_n
 
Posts: 120
Joined: Mon Jan 16, 2012 1:39 pm
ECU Model: S40 Pro
Firmware Version: 58

Re: Rough idle

Postby katana » Sun Jun 23, 2019 6:38 am

Also the idle timing could be a little too advanced so building more cylinder pressure than the light flywheel can compensate for?
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Re: Rough idle

Postby iceman_n » Sun Jun 23, 2019 10:43 am

the problem is not the stable idle, the problem is that the engine sounds running rough on really cold weather at start up, something that is not happening on warm weather, thats why i believe that gasoline droplets on cold intake runners make that rough engine sound as it stops sounds like that when the engine becomes hotter...and yes more advance timing and more rpm at cold start up help a lot...

also something i notice 20ms injector start pulse are a lot on hot weather but fine for cold weather..it could be very helpful the ability to have more settings on start pulse via degrees (cold/hot)
iceman_n
 
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