16197427 idle issues - motor idles high when rolling forward

**g_chaps** · 02-14-2017

When I set up this bin I used the same spark table in both idle and off idle so even if it switches over it should still use the same values. I run a york air compressor for airing up my tires on the trail so I increased the values on the AC idle table to help air up quicker. That would be awesome if you would compare my BIN to yours, I will send you a pm.

Fast355, I tried running a couple auto bins, I think they were BJYL and BJYM, but i kept getting really weird spark advance numbers. It would idle at the right part of the spark table but as soon as i revved the motor and let the rpm fall back down to idle the values would max out at some ridiculous number like 3000 degrees of advance, which isn't good. I'm not running a knock sensor so I think when I swapped over from 7747 to 7427 the knock sensor wiring might be different than what the new computer wants. I bypassed the knock sensor in the 7747 by giving it 5 volts and never had an issue. I think the 7427 is looking for a different voltage range for the knock sensor to show everything is okay.

What's really weird is the first time I tried the $0E BMHK it never had any spark issues, so I just disabled all the knock sensor and spark retard limits.

**JeepsAndGuns** · 02-19-2017

I would recommend ditching BMHK and going to a $0D bin as well. I started out with BMHK and I chased around various issues for a long long time before I switched over. I ended up using BJYM, which is a 5.7L auto bin, and just changed the spark and fuel to match what I was using. I have made many changes to it, but in the end it was way better than BMHK. I would recommend starting anew. I'm sure you could do a little searching on this site for my name and BMHK and find some of my troubles.
I am running mine on a AMC 401 with a manual trans.

**g_chaps** · 02-20-2017

JeepsandGuns, funny enough I actually read through a couple of your threads but by the time I found them I had already put a bunch of time into the BMHK BIN. After I read your threads I tried changing to $0D BJYM but I had some weird issues I couldn't figure out. I ended up going back to BMHK.
I've been exchanging emails with myburb and we tried tracking down the issues with little luck. We're gonna try starting with another $0E BIN and see what happens. The BIN were trying out is BDCH

**notime2d8** · 02-20-2017

I fixed my idle issues with a new timing chain....mines was stretched a good bit. I couldn't tell with the carb I had. The other issue I had was exhaust leaks. I had one by the O2 sensor and one a little after. These made my setup run richer too and had it constantly with big swings in fueling going from way rich to lean.

**JeepsAndGuns** · 02-26-2017

Originally Posted by g_chaps

I tried changing to $0D BJYM but I had some weird issues I couldn't figure out.

What issues were you having?

**g_chaps** · 03-06-2017

Sorry for the delayed response, I was out of town for awhile.

The truck seemed to idle okay with the $0D BIN but as soon as you would hit the throttle it would fall on its face and the spark advance would jump all over the place. When I was watching the spark advance gauge in Tunerpro the numbers would max out to 50 degrees but if I watched the spark advance graph it would reach something like 2000 degrees of advance. It only reached 2000 degrees after you would let off the throttle and let the rpms return to 800, as soon as the rpms were steady at 800 the advance would look normal again. I switched over to $0E and never had that problem again.

**sturgillbd** · 03-06-2017

Weird spark data in tunerpro sounds like you have the wrong adx file loaded. A decent build with a cam and heads will require more AE than stock. What size injectors are you running?

**g_chaps** · 03-07-2017

Could be that I had the wrong adx file loaded. I can always give it another shot and see what happens. When I tried the BJYM BIN I tried adjusting the AE tables but it didn't do anything which lead me to believe it was spark related. I'm running the 61.2 pph injectors at 15 psi. I've tried running big block injectors, 75.5 pph, running the 61.2 pph at 30 psi, but it was too hard to control overfueling at idle.

Small update on trying out the BDCH BIN.
The idle on this BIN is sooo much smoother than the BMHK. It's the first time I've ever had a smooth closed loop idle and the BLM's sit right at 128 at 800 rpm. I noticed that the BIN asks for a slightly richer commanded AFR at idle than the other BIN, its 13.9 instead of 14.7. As for the idling up as soon as I start moving, it still does it but it's not as extreme as the BMHK. Overall the BIN is much smoother than the BMHK. I still have to adjust my VE tables a bit because some of the values are a little off from switching over to BDCH.