Setting idle speed on GUFC strategy--should be simple?

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F350Brian
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Setting idle speed on GUFC strategy--should be simple?

Post by F350Brian » Tue Jul 03, 2018 2:25 pm

I have been reading this site and it has been a treasure trove of info for me getting up to speed with the Tweecer I just installed on my truck. Since I am new here, guess I should share some background. Vehicle is an 89 F350 4x4 that came with the EFI 460 engine and ZF 5-speed manual transmission. The engine is now 528 cubic inches and converted to MAF with a C3W1 ECU. Engine also has a mild roller cam in it, roller rockers, CJ size SS valves, headers, and a C&L 76mm MAF sensor, green tube, 42 lb injectors. My wife and I use this truck to pull our car trailer to shows with some classic cars we have, as well as pulling our 27' camper to the mountains for vacations.
Things are running well and I am now familiar with how Tweecer works and it is functioning well on my laptop. I worked for Cummins for 13 years in engine performance development, so datalinks and calibration editing software are not new to me.
The issue I am having now is how to set the idle speed. The truck works better with the idle speed around 800. I can set the "idle speed in gear" parameter and "idle speed in neutral" parameter both to 800 rpm and the truck idles at 800 rpm until I engage the clutch, then it goes back to the default 672 that is in the C3W1 cal. Disengage the clutch out and it goes right back to 800 rpm. The "idle speed in neutral" parameter seems to have no affect regardless of where I set it and the "idle speed in gear" parameter only affects the idle speed with the clutch disengaged.
What do I need to do to get change the idle speed with the clutch pedal pressed in? I have tried transmission strategies 0, 1, and 2, and all do the same thing.

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Paulie
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Re: Setting idle speed on GUFC strategy--should be simple?

Post by Paulie » Tue Jul 03, 2018 2:45 pm

C3W1 is the GUF1 strategy
1990 Mustang 5.0, HCI, Vortech S-trim, FRPP 42# inj., PMAS MH95, A9L, Moates Quarterhorse, BE/EA, Innovate LC-1.

F350Brian
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Re: Setting idle speed on GUFC strategy--should be simple?

Post by F350Brian » Tue Jul 03, 2018 2:51 pm

The "What Strategy does my EEC follow?" thread in the FAQ section of this forum lists C3W1 as GUFC strategy. I also found several other places on the Web that said the same thing. Since you said that though, I looked and CalEdit does not have a choice for GUF1. Which is correct--GUFC or GUF1 ?

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Paulie
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Re: Setting idle speed on GUFC strategy--should be simple?

Post by Paulie » Tue Jul 03, 2018 3:09 pm

I use Binary Editor and it does not have a GUFC strategy. In BE C3W1 is in GUF1.
1990 Mustang 5.0, HCI, Vortech S-trim, FRPP 42# inj., PMAS MH95, A9L, Moates Quarterhorse, BE/EA, Innovate LC-1.

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skunk
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Re: Setting idle speed on GUFC strategy--should be simple?

Post by skunk » Tue Jul 03, 2018 8:25 pm

I think your ok with your strategy. I want to think GUFC is how Mike has it named. Check with him to be certain.

Either way you should be able to set your transmission into a forced neutral state. I don't recall the number associated with it. Seeing as your running a manual transmission with an automatic ECU you may need to look at how your wired up. Pushing the clutch theoretically shoud equal neutral to the ECU. I really don't have a good answer for you ....just throwing things out there.

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cgrey8
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Re: Setting idle speed on GUFC strategy--should be simple?

Post by cgrey8 » Wed Jul 04, 2018 8:56 am

I recall some threads talking about wiring differences between manual and automatic wiring harnesses. One powered a pin, another grounded the pin maybe? It's been a LONG time since I dealt with that.

Anyway, there's also a scalar to setting your transmission type. Make sure that's consistent with your setup.

But another thing that you are describing is familiar to something that happened to me when my transmission's neutral switch was going out. I could put the trans in neutral, but the EEC thought it was in gear. The EEC would only see neutral when I pushed the clutch pedal in. This actually worked out better for me in that I could add some drive-to-neutral air to the ISC to get the engine ready for me to take off when I did push the pedal in.

As for why the engine would obey one idle speed over the other, I too had that experience, and it had to do with a few different settings. First, there are multiple idle modes the engine can be in. The first is Open Loop idle, which blindly uses the ISC idle functions to calculate how much Pulse-Width to drive to the ISC to get the desired RPMs.

Once the RPMs are within a range, the EEC transfers to Closed Loop Idle. This is where it compares the actual RPM to the desired RPM and modulates the ISC to attain the desired RPM.

If things are setup right, the EEC will perpetually stay in Open Loop idle and you get what you get and those idle RPM scalars basically are completely ignored. Which ever mode you are in, setup the neutral and drive ISC functions to give you the idle you want. Note, the idle and drive mode functions were really intended for automatics where the engine is "dragged down" while in gear and thus to give the engine more air so it doesn't conk out when you put it in gear. IMO, they tend to be more in the way than they are really useful on a manual. I think Ford could've come up with a better idle management strategy for manuals than trying to reuse what they had for automatics. For example, having sensors to know what gear the trans is in AND remembering what gear it was coming from would be useful to aide in down shifts and up shifts.
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, 1.6RRs, FMS Explorer (GT40p) headers, Slot Style MAF, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, Innovate LC-1, GUFB, Moates QuarterHorse tuned using BE&EA

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