[Hughesy1961]

Yes I added one sensor at a time with the last being the distributor trigger from the coil through the above circuit.

[Hughesy1961]

The car is now running after I purchased a "Universal Distributor Adapter" and I have had it on the road doing auto tuning. It is running very well. Thanks for all your help!

One question I have is the car has a manual gearbox and I am finding that for higher rpm gear changes I need to be very precise with the throttle to get a smooth change as the rpm drops very quickly. I believe that the Holley Sniper has a "ramp down" setting to help smooth out gear changes. Is this possible with Speeduino?

[jonbill]

what does they Holley Sniper "ramp down" feature do?

[Hughesy1961]

I was told about this feature. Quick search brings up the Sniper Manual - search IAC rampdown. chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://static.summitracing.com/global/ ... 512_hh.pdf

[Hughesy1961]

This video explains it fairly well https://www.youtube.com/watch?v=4d7PWbc559U

[PSIG]

Please do NOT assume IAC changes are the best fix for these symptoms. There are useful alternative solutions. This is the age-old IAC control issue. Do a search for "dashpot" function. The problem is simple with simple control, that the IAC when above idle is always trying to pull the rpm down to target idle. When throttle is closed above idle, the IAC is also closed (trying to pull rpm to idle), and so the decel is harsh. Also, when decelerating to idle, the IAC is closed until it hits target Idle, and then acts surprised that it has to try to reverse to raising rpm from a closed position. <play circus music>

Simplest is to hold current or set IAC value if throttle increases, effectively halting closed-loop control until rpm returns to the target area. Holley calls this “hold” or “freeze” position. More involved is to open the IAC on throttle-up to a set value that will allow decel to be less harsh, and allow rpm to be settled from above idle rpm to idle without overshoot and recovery required. Holley calls this "Ramp Start" position and combines with "Ramp Decay" to settle rpm to idle (increasing PID control in the seconds following the Ramp Start position elevated rpm). We call that "dashpot" function. Now, stop thinking about that and look at it a different way.

As many of us instead use Idle Timing Control or idle timing troughs/walls, effects with both functions operating would be a good idea. In-fact and for now, using open-loop IAC control, with Idle Timing Control or table troughs for rpm stabilization is a more effective way to approach it. Idle-Up can still be useful with these schemes for AC and similar add-on loads. Using rapid timing instead of slow IAC control is also one reason little has been done on the IAC control, as it isn't necessary (or even good) for most uses, while also avoiding the IAC issues above.

Holley is only one example with their own terminology and functional concepts. We already have some of those from previous discussions, and ideas on how to create those functions in the code we use. I would suggest starting there (where we left-off) if looking to proceed, but you will have to establish that advanced IAC control is better than other methods. There are many requests for functions used in other systems, without looking at how we do it now, or other ways it could be done. Just because another system uses it in a certain way, does not mean that is the best or even a good way to do it with this system.

[Hughesy1961]

Thanks for your detailed explanation.

I do not have an IAC fitted and I don't yet fully understand what you are telling me above. I would therefore be open to your suggestions/instructions for what I need to buy/do to improve the drive-ability for my set up

[Hughesy1961]

The car was running much better today. After your comments I checked the IAC settings and it was set to "on/off" type rather than "none". Whether that caused the better gear changes I don't know but at the moment I think it is back to how it was when using carbs.

[Hughesy1961]

Hi my car has been running well the last few months however recently it has developed surging at idle when hot and has been running for about 10 minutes. It appears to be running great up to that point and gradually gets worse. If you recall I am using a fuel only set up and using the original twin Stromberg carbs as throttle bodies. I have an electronic distributor with a low impedance coil. I have rebuilt the carbs thinking there maybe an air leak but that has made no difference. I believe that it is either fuel or electrical, ie, possibly the coil breaking down when hot.

I have attached the current tune together with a log file recorded at idle with a little accelerator pedal towards the end. Looking for suggestions!

[LPG2CV]

I can't suggest why it would of just started happening!

It's difficult to know what rpm you want it to idle at because of the surge. You have quite a lot of advance at idle though.
If you were to have less advance at idle, and open the throttle stop a little to bring the idle rpm back up. And then add advance to the area in the columb in front of the idle range (500 rpm columb), that would add the advance back in as the rpm dipped.

I'ts going back into cranking and then ase. I suspect this is a usb cable rattling around in a port causing resets. Try a different port.