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Question about Idle Learn

#1 · August 11, 2018, 2:38 pm

Quote from Todd on August 11, 2018, 2:38 pm
Hi All,

I have a question I was hoping that you experts can help me out with. I've been playing around with my GoEFI 8 for several months now, and have everything running perfectly on the street. Also, warm idle is perfect and both hot and cold starts are perfect. My last remaining issue was a bit of rough idle while cold.

I believe that IAC screw is good -- IAC Steps are 8 or 9 at warm idle just before the fans come on. I have idle AFR set to 14.3 -- much lower and I get a gas smell in my garage and much higher and I get lean eye burning.

I've played around with the fuel cranking settings for weeks, and it seemed like the following ended up being best:

Prime Fuel Mult: 150; Crank Open TPS: 17.0; Prime Shot Delay: 1.5; Prime Crank Revs: 4; Crank IAC Mult: 0.0; Crank Fuel 20F: 0; Crank Fuel 65F: -15.5; Crank Fuel 170F: -40.6; Afterstart 20F: -30.5; Afterstart 65F: -30.5; Afterstart 170F: -30.5; Warmup 20F: -50.8; Warmup 65F: -50.8

This seemed to be the best I could get, although it's a bit frustrating because it takes so long to play with these numbers since the issue is at cold idle. I get one shot in the morning before work and one shot at night. After that, the engine is warm and it takes all day/night to cool.

Anyway, I was still having rough idle with those numbers until the engine got to around 150F. Kind of on a whim, I decided to try raising the Idle Learn Max from 16.0 (which I think is default) up to 100.0. To my surprise, my cold idle pretty quickly started getting better, and I noticed that the Idle Learn 65F went way up from the 16.0 it had maxed out at before and seems to have settled at 92.3. Cold idle actually seems good now.

So, my question is really whether there is any downside to having the Idle Learn 65F so high? My gut tells me that this is a bandaid non-optimal situation, otherwise why would the default Idle Learn Max be so low (i.e., 16.0)? Or is the 92.3 Idle Learn 65F an OK number? Should I be making further adjustments to try to bring the Idle Learn number down from 92.3? If so, what should I adjust?

Or maybe I should adjust Idle Learn Max even higher than 100 just in case the Idle Learn 65F wants to go even higher than the 92.3 that it's currently at if conditions change? Looks like you can go as high as 205 for Idle Lean Max if you want to. Again, I don't understand why default Idle Learn Max would be so low if it's OK to make it very high.

Any thoughts would be greatly appreciated! And please feel free to let me know if you need any info about my setup. I wasn't sure how much info was necessary, since my question is really more of a general one about Idle Learn settings.

Thanks in advance.

Todd

Hi All,

I have a question I was hoping that you experts can help me out with. I've been playing around with my GoEFI 8 for several months now, and have everything running perfectly on the street. Also, warm idle is perfect and both hot and cold starts are perfect. My last remaining issue was a bit of rough idle while cold.

I believe that IAC screw is good -- IAC Steps are 8 or 9 at warm idle just before the fans come on. I have idle AFR set to 14.3 -- much lower and I get a gas smell in my garage and much higher and I get lean eye burning.

I've played around with the fuel cranking settings for weeks, and it seemed like the following ended up being best:

Prime Fuel Mult: 150; Crank Open TPS: 17.0; Prime Shot Delay: 1.5; Prime Crank Revs: 4; Crank IAC Mult: 0.0; Crank Fuel 20F: 0; Crank Fuel 65F: -15.5; Crank Fuel 170F: -40.6; Afterstart 20F: -30.5; Afterstart 65F: -30.5; Afterstart 170F: -30.5; Warmup 20F: -50.8; Warmup 65F: -50.8

This seemed to be the best I could get, although it's a bit frustrating because it takes so long to play with these numbers since the issue is at cold idle. I get one shot in the morning before work and one shot at night. After that, the engine is warm and it takes all day/night to cool.

Anyway, I was still having rough idle with those numbers until the engine got to around 150F. Kind of on a whim, I decided to try raising the Idle Learn Max from 16.0 (which I think is default) up to 100.0. To my surprise, my cold idle pretty quickly started getting better, and I noticed that the Idle Learn 65F went way up from the 16.0 it had maxed out at before and seems to have settled at 92.3. Cold idle actually seems good now.

So, my question is really whether there is any downside to having the Idle Learn 65F so high? My gut tells me that this is a bandaid non-optimal situation, otherwise why would the default Idle Learn Max be so low (i.e., 16.0)? Or is the 92.3 Idle Learn 65F an OK number? Should I be making further adjustments to try to bring the Idle Learn number down from 92.3? If so, what should I adjust?

Or maybe I should adjust Idle Learn Max even higher than 100 just in case the Idle Learn 65F wants to go even higher than the 92.3 that it's currently at if conditions change? Looks like you can go as high as 205 for Idle Lean Max if you want to. Again, I don't understand why default Idle Learn Max would be so low if it's OK to make it very high.

Any thoughts would be greatly appreciated! And please feel free to let me know if you need any info about my setup. I wasn't sure how much info was necessary, since my question is really more of a general one about Idle Learn settings.

Thanks in advance.

Todd

#2 · August 11, 2018, 3:23 pm

Experts??????😂😂😂😂

Thanks for the vote of confidence. As I have said before, Crank and Accel are the two areas where you must fine tune. It can be frustrating and time consuming. Every engine is different. My c10 has a 600hp running on e85. In the Texas heat, it can be a real bitch. I keep a can of starting fluid on hand.

I don't know how radical your engine is, but here is a suggestion. Many have moved away fr9m the 5-10 iac step rule. 10-15 steps are common and 15-20 steps on radical builds. I would try moving your steps up by backing your idle screw off slightly. This will give your IAC more control of your cold idle conditions.

#3 · August 11, 2018, 5:27 pm

Thanks, Austin, that was a mighty quick response. Well, you guys SOUND like experts anyway! 🙂

The engine is a 572 BBC, but definitely not radical. Cam is Comp Cams. (01-424-8) 540/560 lift; 242/248 duration; 110 lobe sep.

I'll try your suggestion and back off the idle screw a bit to try to get IAC steps somewhere in the 15-16 neighborhood tonight. Obviously, I'll have to let it warm up for that, so I won't get to see what effect the change has on cold idle until tomorrow. I'll let you know how I make out.

Thanks again.

Todd

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#4 · August 11, 2018, 7:30 pm

This site was started by me. Wanted to take the static out of the Social Media groups. It is my hope, and some have, that more of guy's can get involved helping others. This forum builds off of everybodies issues and fixes. Thanks for your post and compliments.

#5 · August 19, 2018, 9:58 pm

Hey Austin,

So, I tried your suggestion and upped the IAC steps to the 15-16 neighborhood. I really didn't notice any change in anything, but I appreciate the suggestion. I've been playing around with the Cranking Fuel menu, and everything seems perfect. Starts cold or hot instantaneously and then idle picks right up smoothly. And idle is nice and smooth from cold to hot now. These are the numbers I landed on:

Prime Fuel Mult: 150; Crank Open TPS: 17.0; Prime Shot Delay: 1.5; Prime Crank Revs: 4; Crank IAC Mult: 0.0; Crank Fuel 20F: 0; Crank Fuel 65F: -15.6; Crank Fuel 170F: -40.6; Afterstart 20F: -30.5; Afterstart 65F: -30.5; Afterstart 170F: -20.3; Warmup 20F: -70.8; Warmup 65F: -70.8.

I also upped the Idle Learn Max to 125. The Idle Learn 65F usually lands somewhere between 90-110.

For the life of me, I have no idea how to get the Idle Learn 65F lower than that, but I figure there's no reason to drive myself nuts chasing a number on the handheld when the car is performing perfectly. If anyone happens to know how to get the Idle Learn 65F number down or if there's any downside to that number being so high, please let me know. Otherwise, I'm just gonna enjoy how nice it's been starting and idling! 🙂

Thanks again!

Todd

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#6 · August 29, 2018, 2:19 pm

Hey good afternoon all. I wanted to add 2 questions here in relation to idle issues that I am having on my Fitech 400 attached to my 1967 Firebird with a GM 327 motor. I have only had the system up and running for about 100 miles since installed, so maybe not enough time to learn. But I figured I would throw out my issue.

Issue #1...Currently when I am accelerating and then letting off quickly when coming to a stop the idle drops down to below 300 Rpm’s and then slowly recovers to the initial setting of 790-815 rpms at idle. Sometime the engine actually stalls when I let off quickly.

Issue #2...sometimes when rev’ing the motor when starting out (I have a 4spd) at low RPM when driving in say a parking lot or traffic the motor isles up to say 1500-1800 rpms but stays there for 3 to 5 secs and slowly settles down even when I have my foot off the pedal.

Neither of these issues existed at first but after 100 miles or so it has started to happen frequently?

any ideas? I haven’t attempted any tweaking on the system yet. Wanted to hear what people think.

Thanks...

#7 · August 29, 2018, 6:19 pm

I would need to see a datalog to help. Can we start with a 30 second idle log at operating temp? Cam specs? Fuel Pressure and system? Cam setting?

#8 · August 29, 2018, 8:37 pm

I will see what I can pull together tomorrow for info

Thank you

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Question about Idle Learn