1227165 ECU Questions

American Delco GM ECUs and PCMs, ALDL, OBD 1.5.
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Re: 1227165 ECU Questions

Postby pman92 » Sat Jul 28, 2018 7:34 am

You really want the 100kpa VE table column to peak around 90. Make sure you get steady state measurements when adjusting it.

The AE, there will also be a coolant temp multiplier. I think it starts off pretty low (something like 0.15 at operating temp). If you bump that up you can bring the rpm multiplier down from near the 2.55 max
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Re: 1227165 ECU Questions

Postby delcowizzid » Sat Jul 28, 2018 7:59 am

Your low pulsewidth add-on table for the injectors is at 0 everywhere will make the ve table need more down low .I still don't know how it's gone from going good to now needing a shitload of a/e added wasn't it too much a/e when you first started
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Re: 1227165 ECU Questions

Postby K1ng0011 » Sat Jul 28, 2018 8:45 am

Yah I dont know why I need such a high amount of AE either. At least I know that AE is working at this point though. I could not feel any changes in acceleration until I hit the 2.0 threshold in the AE. Right now I have been driving it around and tuning through the day. So far my highest VE is around 85 at 100kpa. I found a thread that mentioned Transient - AE Gain Vs Delta manifold fuel can help AE issues. The only issue with driving it around right now is that at 20kpa from about 1500RPM to 2600RPM when I let of the throttle it goes dead lean 19AFR. The engine sounds like it is backfiring not very loud but its a problem. I think there is something related to the deceleration in the bin causing the engine to shut off fuel to the engine. Its weird my first set of injectors were 19lb. I was rich all over and had to set them to 24lb to lean it out. Then that is when my tune was pretty good. Now I have 22lb injectors and they are to lean and I have to decrease the injectors size in the .bin to 20lb to richen things up and bring down the VE. Everything points to some issue I just dont know what it is I have troubleshooted everything I can think over over the last few weeks. Attached is my current bin with my latest log. You can see when I let off the throttle it goes straight to 19AFR above 1500 rpm.
Attachments
350TPI Manual Trans 12p v112-work in progress 7-27-2018.bin
(32 KiB) Downloaded 29 times
2018-07-27_13.36.41.xdl
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Re: 1227165 ECU Questions

Postby delcowizzid » Sat Jul 28, 2018 9:02 am

Decel fuel cut or decel enleanment
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Re: 1227165 ECU Questions

Postby K1ng0011 » Sun Jul 29, 2018 9:06 am

I had to do a little bit of reading to understand these two functions. Since tuning 12P I have not had to use either of these functions. The way I understand it is basically DFCO is deceleration fuel cut-off. When certain parameters are met rpm, tps, etc the engine cuts all fuel when you let off the throttle and are coasting. This is a fuel saving feature when you get below a certain rpm the computer starts to inject fuel again. So when I am cruising down the road and I let off the throttle it cuts all fuel to the engine until I reach under 1700RPM. That is about when I see my wideband go back to normal AFR. So when I see it go dead lean 19AFR when coasting this is just a normal feature of 12P. I also read about deceleration enleanment. From what I understand when you have AE injecting extra fuel into your intake the fuel can condense in your manifold on the walls of your intake. When you suddenly let off the throttle the high intake vacuum can suck that extra fuel into your intake causing a rich condition. Decel enleanment takes account of that extra fuel manifold fuel to make it so your not running rich for that moment. I just wonder what the popping noise is. Since DFCO is putting no fuel into the engine there should be popping noises from the exhaust. Might have a header leak or something loose hitting something when I decel maybe.

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Re: 1227165 ECU Questions

Postby kojab » Sun Jul 29, 2018 10:31 am

Leaky injectors can cause popping in the exhaust during decel. Look at your injector pulse width, making sure its at zero when commanded by the PCM.

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Re: 1227165 ECU Questions

Postby pman92 » Sun Jul 29, 2018 10:53 am

Do the popping noises happen when it starts to exit DFCO as it starts to inject fuel again?
What exhaust system do you have?

There should be settings related to exiting out of DFCO. Not just RPM, but it won't start full injection but rather gradually add fuel back in with a decay rate
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Re: 1227165 ECU Questions

Postby K1ng0011 » Sun Jul 29, 2018 2:18 pm

With my previous set of injectors I had some backfiring going on one of the last things I had not tuned out before. It was loud too it actually would scare me when it would do it sometimes. :lol: This is not loud this is pretty quite. It sounds like a little muffled pop or maybe ticking its pretty quiet compared to the engine running. When I do hear it though it is when I am not touching the pedal at all. The moment that I touch the pedal I never hear a thing. After reading out DFCO I feel like it may not be actual backfiring but possibly something else. My car is a 1972 camaro. Not a nice restored one. It is one that someone never took care of so it makes its fair share of creeks and other noises. Or maybe it could leaky header gasket or something. It has a set of long tube headers and 2.5 inch exhaust with a set of mufflers. Pretty ordinary exhaust nothing special.

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Re: 1227165 ECU Questions

Postby oldn64 » Mon Jul 30, 2018 9:25 am

K1ng0011 wrote:With my previous set of injectors I had some backfiring going on one of the last things I had not tuned out before. It was loud too it actually would scare me when it would do it sometimes. :lol: This is not loud this is pretty quite. It sounds like a little muffled pop or maybe ticking its pretty quiet compared to the engine running. When I do hear it though it is when I am not touching the pedal at all. The moment that I touch the pedal I never hear a thing. After reading out DFCO I feel like it may not be actual backfiring but possibly something else. My car is a 1972 camaro. Not a nice restored one. It is one that someone never took care of so it makes its fair share of creeks and other noises. Or maybe it could leaky header gasket or something. It has a set of long tube headers and 2.5 inch exhaust with a set of mufflers. Pretty ordinary exhaust nothing special.


Exhaust leaks can be simple enough to find. Does it only happen when hot or with cold as well? Dependant on access running your fingers around near where the flanges are will allow you to feel the exhaust gasses escaping. (no do not touch the metal all you are feeling for is air currents) On tight vehicles where it is hard to get hand access I have used soapy water before but this will not work too well if the car is hot as the water turns to steam quickly and stops the view of what is truly going on. The other aspect is based on the thermodynamics of the cast manifolds etc you have a high chance to crack them. Much better if the issue happens cold as you will have a visual aid, but most exhaust leaks (in there initial stages) will only leak when hot.

If you do find a manifold leak then I would pull the manifold and use a product call maniseal. I am not sure you have it in the states but this product is amazing for sealing small imperfections in exhaust headers and flanges. I have used it many time to resolve problematic exhausts that alot of others have not been able to pick.

Keep us up to date.

The other thing to do is see if it is motor related or elsewhere in the car it to turn the engine off during this period and listen. I have had unis that sound like slight detonation occurring before which showed up like your symptoms under load it was fine under decel it occurred. Drove both myself and a mate mad before we found it.

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Re: 1227165 ECU Questions

Postby K1ng0011 » Mon Jul 30, 2018 9:49 am

I think in this case a picture is all I need to explain the issues I have been having. It turns out that both my header flang gaskets are destroyed. What surprises me is that at least one of the header gaskets was good a few months ago. I had to install the wideband o2 sensor in my exhaust for this setup to work. I had one of my headers out then. I obviously would have noticed the gasket being destroyed. So some point between my wideband install and now the header gasket got blown out. The gasket that is missing was not attached to my header flanges to it was blown out when I was driving at some point. Maybe the backfiring I had before had something to do with it or maybe I just have horrible luck. All I did today was put in a new set of header gaskets where it meets the block and flange gaskets. After I did that I started it up. It idles fine. However the moment I pressed the throttle it went to 10AFR. Which got me thinking I wondering if this fixed my AE issue. I set the AE all the way down to .31 at 800RPM. Went back out and tested it. I am now getting about 12AFR. My best guess is a massive exhaust leak messing up my wideband O2 readings. I just drove it around about ten minutes before writing this forum post. Driveability with forced open loop on has improved a lot with no real changes to the bin other than AE. I have to go through the process of tuning it again with the new injectors and the exhaust leak fixed but in the next day or two I will be posting as I get things dialed in. Thank you delcowizzid for sticking with me all this time and giving suggestions and all others on this thread. My moral has got a pretty big boost because of this.

Bad Header Gaskets.jpg

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