Ford EEC4 timing and idle control question

olddog · #1 (**permalink**) 03-18-2010, 07:54 PM

I have observed that when the engine was reved up and returning to an idle, that the timing drops back to the base setting (10*), as it settles to normal idle.

I don't know if I read this or assumed as much, but I thought this is basically to duplicate what ported vacuum did on the old vacuum advance distributors, which was done to reduce emissions by keeping the combustion chamber hot.

Now I had someone claim that the EEC4 uses timing to control the idle speed. I thought that is what the IAC does, I said. The reply, it uses both. The timing has a much faster response. Then he said in my case the idle is set up to 900 rpm and the ECU is trying to control at 600 or so. So the IAC is staying closed and cannot get the rpm down to setpoint. Then it pulls all the advance out to try to get idle rpm down to setpoint.

Ok the argument sounds logical. I have read a fair amount on the EEC4, and I have not heard anyone else mention timing is part of the idle rpm control strategy.

Can anyone tell me if this is true or false?

DonC · #2 (**permalink**) 03-20-2010, 08:30 AM

After everything else was set properly I noticed that my idle was up around 1100 rpm. Also noticed that I was at 31* btdc at idle. Corrected the timing down to 12* btdc at idle and it brought me down to ~860 which is where I wanted to be for right now.
I used the functions Idle-Spark vs ECT and Idle-Spark vs RPM to get it down where I wanted it at idle and reset to all in by about 1800 rpm.
For starters I reset the "base idle" buy unplugging the SPOUT connector and the IAC (also called ISC for Idle Speed Controller) and mechanically set the idle to the point where the engine would just barely run without and input by me via the idle stop screw. Ended up around 650 rpm. Plugged everything back in and started making adjustments in the system to get the idle where I wanted it. By setting this base idle it insures that the system is controlling the idle
DonC

olddog · #3 (**permalink**) 03-20-2010, 04:05 PM

Quote:

Originally Posted by olddog

I have observed that when the engine was reved up and returning to an idle, that the timing drops back to the base setting (10*), as it settles to normal idle.

I need to amend that statement. It does not drop all the way to base. I do not recall exactly where it drops to (looking at it last year), but it is above base, as when you disconnect the SPOUT the timing drops to base, which drops the idle some more. From memory when you drop the throttle and as the engine is slowing to an idle, the timing is up in the high 20 something and just before reaching idle, the timing suddenly and sharply drops bellow 20. I'm thinking somewhere around 15 or 16. When it makes that drop it goes dead steady and does not move regardles of what else goes on, until you move the throttle. As soon as you bump the throttle, the timing jumps up into the 20's.

olddog · #4 (**permalink**) 03-20-2010, 04:07 PM

Don,

Are you using the TWEECER?

If I remembered that right and you are, how happy are you with that system?

DonC · #5 (**permalink**) 03-21-2010, 09:04 AM

Yes I'm using a TWEECER and am satisfied with the system. More importantly I'm using Binary Editor and EEC Analyzer from Clint Garrity for software to adjust and analyze the system. The software that comes with the TWEECER is a very basic program that has far less capacity for tuning than BE and EECA. BE and EECA also have a quite extensive online support forum at:
http://eectuning.org/forums/viewforum.php?f=7
One caveat is that "if I knew then what I know now" I probably would have gone with a Moates Quarter Horse unit instead of the TWEECER. The QH allows more parameters to be data logged in BE and EECA and allows for "Tune on the Fly" adjustments. The QH also has a couple of features that the TWEECER does not. On the flip side the TWEECER is a plug and play unit whereas the QH needs to be installed in the EEC internally. The internal installation is about a 15 minute job if you have the screw driver bits necessary to open up the EEC (I do so it isn't a problem other than having to dismount the EEC to install the QH).
Regardless of which system is used I can't praise highly enough the BE and EECA programs for tuning. They cost about $80.00 for the two of them and have easily payed for themselves many times over in ease of use.
To your original question, it sounds like the EEC is doing what it's programmed to do. In my opinion the only thing you might want to change is the slope of the advance to slow it down a bit but not necessarily a whole bunch. You could also lower the idle timing by a couple of degrees which will probably drop the idle rpm slightly.
DonC

philminotti · #6 (**permalink**) 03-22-2010, 11:43 AM

Don, you have a PM.

olddog · #7 (**permalink**) 03-23-2010, 07:10 PM

The reason for my initial question was that a dyno tuner, that I was interviewing for the job, claimed an EEC4 uses both timing and IAC to control the idle. Well that seemed wrong to me and counter to everything I have read. So either this guy knows more than everyone else, or he is not the guy I was looking for.

I managed to find a copy of ford documentation on the program code that runs in the EEC4. I can find nothing about timing being changed to control the idle speed. That is strictly a function of the IAC.

UPDATE:
Oh no I am flat wrong! I did find in the ford manual where they do indeed use timing to help control idle speed. Sounds like this guy knows more than many people, including me.

DonC · #8 (**permalink**) 03-23-2010, 11:26 PM

If you want to check the effect that timing has on idle speed try the following.
Configure the engine to get base idle. Do this by starting with an engine that's at full operating temperature then disconnecting the SPOUT and the IAC (Also called the ISC). Mechanically adjust the throttle stop screw to just barely keeping the engine running and set the timing to whatever is recommended for the engine (usually around 10 to 12*). After setting the timing readjust the throttle stop screw if necessary. You may have to repeat the sequence of throttle stop and timing a couple of times until everything is where it's supposed to be.
Once you have the above set turn the distributor to advance the timing above your target point. Up to a certain point you'll see engine speed increase with additional timing. Retard the timing below your target and the engine speed will decrease.
Reset everything back to the base idle setting and plug the ISC/IAC back in. You should notice an increase in rpm as the ISC/IAC adds bypass air around the throttle butterflies.
Plug the SPOUT back in and you may or may not see an additional change in rpm depending on where the program has the timing set.
DonC