Has anyone played with cam angle configuration to improve idle quality.
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Has anyone played with cam angle configuration to improve idle quality.
Normally you do the opposite with VCT to make a lumpy idle, but unfortunately we can't control the cams in that way.
Hmmm, there appears to be a fair amount of control in the software, once there is a better understanding of what these controls do some trial and error may be in order.
I've done some rb tuning with the inlet cam being either "on" or "off".
Basically I would turn inlet cam "off" at idle so it would idle smoothly. Then it would turn on around 1100 rpm and switch off again at peak torque which was about 4800 rpm on my motor.
It would spool earlier and make more power in the midrange like this, opposed to having it disconnected and not switching at 1100 and 4800.
With this information one could in theory make reasonable changes to the cam maps without totally fucking it up.
Given the amount of variables in tuning a couple of cams that can move by degrees rather than on and off again, it would be difficult to get it spot on without a dyno.
I don't know if the ford cams can move enough to let the valves hit the pistons with incorrect settings?
Maybe someone else can chime in on this?
The best way to improve idle quality is to run less timing, more fuel and don't have the spark gap too small.
Edit: I found this link which might help. https://www.hpacademy.com/forum/gene...ar-adjustments
The VCT is already advanced 10 degrees at idle for improved idling. The stock cams should idle very smoothly anyway, if you have a problem with idle then you should look for the actual cause.Quote:
Originally Posted by Yortt
If you want to mask a problem the simple way is to drop idle ignition and increase idle airflow, eg what happens when your car is cold. It will use more fuel but it will be a "stronger" idle. I believe they do this to increase exhaust temps to get the cat up to temp fast and hence emissions under control.
Quote:
Originally Posted by rolls
The rough idle was caused by aftermarket engine mounts, replaced them with genuine ford, problem fixed.
In addition to changing the mounts idle ignition was dropped and the engine smoothness improved.
Increasing the idle airflow will not make a difference to the stable idle as the PCM controls the idle speed airflow and the fuel being in C/L.
With respect to the idle smoothness, standard they are good but not perfect and it should be, given the computer controls the cam timing provided it has the capacity to do so. My assumption is the ford engineers are restricted by emissions so there may be gains to be had with moving idle cam timing.
I think -10 is the most you can advance the camshaft, you could try a bigger number but the SD tables don't go past -10 either so I suspect the cam is limited there.
Have you ever tried playing with the cam retard at cruise? I've seen some people change it from 25 deg all the way up to 40deg retard at ~0.5 load to supposedly help fuel economy but I'm unsure if it kills power. I couldn't find much reading about how this works. I know some cars have an EGR which is why they retard the cams at cruise, is this true on the XR6T s?
I've never tried but I thought you could edit the dashpot settings to get more airflow at idle. I know changing the ECT dashpot tables definitely decreases airflow on cold start however unsure about normal running conditions.Quote:
Originally Posted by Yortt
The VCT Maximum Retard Limit -80 to 100 degrees so It would be interesting to play, I dont know if the software/mechanical can go too far and do some damage! Haven't played with any cam settings other than use the Fg F6 settingsQuote:
Originally Posted by rolls
My understanding of the dashpot function is as it transitions from a higher rpm to an idle rpm it makes additional air available which is decayed untill it gently settles at the commanded idle rpm
https://i.imgur.com/Vvaol29.png
I read this setting as it either uses closed loop idle OR the dashpot setting for idle.
I suspect if you changed VSS to a negative number or set "RPM error" to a large number it would never use closed loop idle and you could increase idle airflow via dashpot.
I believe on cold start it also ignores closed loop idle and only uses the dashpot feature.