Idle Airflow config ?
05-21-2018, 09:49 PM
#101
It's Startup Flare Control - Table 12643.
Did you add airflow to Startup Airflow Initial? Set that to like 4g in the colder regions and 1.5 where it's 0 now. And then bump up the decay a little bit to get rid of the hang that comes with doing that. Now that you have the blade open enough, you can start using the IAC to actually control startup and idle.
05-22-2018, 06:04 PM
#102
Not to detour the thread, but I wanted to touch on something I read earlier in the thread.. You guys want the Throttle Blade to be CLOSED to the point where the vehicle will just idle with the IAC closed. I can understand that you don't want the IAC to be able to stall the engine, but there must be a reason the factory sets them up the way they do.. What happens if you set it so that your IAC counts are only 30 or so, with the T-blade set such that the engine will idle with the IAC closed and you get a vacuum leak? Since the IAC is already closed as far as it can be, the engine idle speed will be ABOVE where you want it to be because the IAC can't close enough to bring down, or control, the idle speed. Granted none of us would drive around with a vacuum leak but what if it happened while you were away from home and needed to limp it home? Am I losing my mind? I was driving down the road thinking about this and thought I would throw it out for public consumption.
05-22-2018, 06:11 PM
#103
I think it's a matter of semantics. The TB needs to be open enough to work with the IAC closed. The whole point of having IAC counts in the 30s is that it is nearly closed during normal operation anyway. But too often people with cammed cars, big cube motors, or aftermarket TBs, set the TBs too closed and then they have to rely on the IAC to even idle. That's how you stall a car out.
The IAC is too slow. And is garbage. The Vettes don't have an IAC. The PCM just opens the TB a little more when it needs more air. It's much faster and easier to deal with. It's one of the issues when tuning a Gen III drive by cable PCM vs anything else DBW.
The IAC is too slow. And is garbage. The Vettes don't have an IAC. The PCM just opens the TB a little more when it needs more air. It's much faster and easier to deal with. It's one of the issues when tuning a Gen III drive by cable PCM vs anything else DBW.
05-22-2018, 06:14 PM
#104
Not to detour the thread, but I wanted to touch on something I read earlier in the thread.. You guys want the Throttle Blade to be CLOSED to the point where the vehicle will just idle with the IAC closed. I can understand that you don't want the IAC to be able to stall the engine, but there must be a reason the factory sets them up the way they do.. What happens if you set it so that your IAC counts are only 30 or so, with the T-blade set such that the engine will idle with the IAC closed and you get a vacuum leak? Since the IAC is already closed as far as it can be, the engine idle speed will be ABOVE where you want it to be because the IAC can't close enough to bring down, or control, the idle speed. Granted none of us would drive around with a vacuum leak but what if it happened while you were away from home and needed to limp it home? Am I losing my mind? I was driving down the road thinking about this and thought I would throw it out for public consumption.
you have vacuum leak, you fix vacuum leak. What if the iac valve fails and stays closed? Then the car won’t run. I’d rather have a high idle than not run lol
I posted what works for my car and the handful of cars/trucks I worked on that had idle issues I had to fix. Maybe I’m doing it wrong, but I would think that because it worked so well for me, I’ve got to be on the right track. I would also think it wouldn’t be a good idea to rely on an iac motor to keep the car running also. Just my humble, but lightly experienced opinion.
05-23-2018, 10:38 AM
#105
Yeah... you're decreasing the amount of timing being retarded.
It's Startup Flare Control - Table 12643.
Did you add airflow to Startup Airflow Initial? Set that to like 4g in the colder regions and 1.5 where it's 0 now. And then bump up the decay a little bit to get rid of the hang that comes with doing that. Now that you have the blade open enough, you can start using the IAC to actually control startup and idle.
It's Startup Flare Control - Table 12643.
Did you add airflow to Startup Airflow Initial? Set that to like 4g in the colder regions and 1.5 where it's 0 now. And then bump up the decay a little bit to get rid of the hang that comes with doing that. Now that you have the blade open enough, you can start using the IAC to actually control startup and idle.
Edit: Just looked and I already added 25g to the 1500hz cell.
Question, does the PCM default to a specific Airflow or fuel table after the battery has been disconnected or the PCM unplugged? I've noticed that after I disconnect the battery and/or unplug the PCM it fires right up. Example, 1. Last year my battery died so I took it out to charge it and the car fired right up after reinstalling. 2. I disconnected the battery and PCM to do some rear frame welding and after hooking everything back up it fired perfectly. 3. Battery died over the winter so I replaced it and it fired right up. After all the initial good starts it goes into its stumbling phase. Yea weird right.
Last edited by Monte4ever; 05-23-2018 at 11:04 AM.
05-23-2018, 11:45 AM
#106
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The computer does learn. That is what your idle trims and fuel trims are. When you disconnect you clear all those trims and it goes back to the values in the tune with no corrections.
05-23-2018, 12:19 PM
#107
So, here is a very easy test. Connect the scanner and start recording BEFORE you turn the key so we can capture the cranking. Start the car cold, let it stumble, give it ten to fifteen seconds (before it catches), and then shut it off and pull a spark plug. Let's see if the plugs are wet and fuel smelling. What I also want to see is the initial starting fuel spray. During cranking, mine has a big shot of fuel going in. I want to see if yours is also doing that.
I'm also going to see what I can do with the data in the log to look at your IAC effective area in the meantime, but I don't think we should change that just yet. Edit -- nevermind, I can't because the tune is locked. Grrrrrrrrrr
05-23-2018, 01:18 PM
#108
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Still got the "remote tuning" error. Drat.
Looking forward to the log from the test tomorrow. It would be much easier in person for sure. Don't give up on this thread though. I'm REALLY curious what ends up correcting this now.
Looking forward to the log from the test tomorrow. It would be much easier in person for sure. Don't give up on this thread though. I'm REALLY curious what ends up correcting this now.
05-23-2018, 01:37 PM
#109
I haven’t been following much. Sorry. I have a short attention span. During this thread I had a starting issue with mine. Basically every time I’d start it, it would flare up and then idle down, stumble and almost die. Messing with the ve did nothing this time. So ended up making sure my tps was at zero percent during cranking. It was acting wonky. However. That didn’t have any effect either. So I added fuel in the startup and that seemed to fix it. I dunno. My advice at this point is start over. If you have a copy of your original file, open it and save a copy, rename it. Copy all your stuff over except anything that has to do with startup and idle. And start over. Make sure the car will run with the iac closed. I don’t know what else to tell you to do. Maybe you have a vacuum leak. What intake manifold do you have? Maybe the bolts on the valley cover are hitting it like mine were. I failed to read the instructions that told me to put lower profile bolts on the valley cover.
05-24-2018, 08:08 AM
#111
All I can do is laugh at myself to keep from kickin myself in the azz.
Ok, it started right up this morning after I added some fuel to the Afterstart Enrichment table, HOWEVER IDK if it was because of that or me leaving my Procharger's By Pass Valve unplugged which created a big vacuum leak SHM. Yea I know right lol. I was investigating a ticking sound (everything is ok) and had to disconnect the By Pass line to pull the valve cover and forgot to hook it back up before I started it. Oh well, I'll give it a go tomorrow.
Ok, it started right up this morning after I added some fuel to the Afterstart Enrichment table, HOWEVER IDK if it was because of that or me leaving my Procharger's By Pass Valve unplugged which created a big vacuum leak SHM. Yea I know right lol. I was investigating a ticking sound (everything is ok) and had to disconnect the By Pass line to pull the valve cover and forgot to hook it back up before I started it. Oh well, I'll give it a go tomorrow.
Last edited by Monte4ever; 05-24-2018 at 08:22 AM.
05-24-2018, 02:41 PM
#112
Well I'm somewhat convinced that it needs more air at startup. It would usually fire right up after sitting 4 or 5 hrs but this time it didn't. This morning with the extra fuel and the unhooked vacuum line it sparked right to life and fast. I tried earlier to open the blade and the voltage wouldnt zero out it would go to .79 and no lower. Ima give it another shot in a few days........ I need a break lol. Btw, adding air by way of the startup airflow tables does not help soooooooo IDK.
Last edited by Monte4ever; 05-25-2018 at 06:52 AM.
05-24-2018, 02:50 PM
#113
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Originally Posted by Monte4ever
Well I'm somewhat convinced that it needs more are at startup. It would usually fire right up after sitting 4 or 5 hrs but this time it didn't. This morning with the extra fuel and the unhooked vacuum line it sparked right to life and fast. I tried earlier to open the blade and the voltage wouldnt zero out it would go to .79 and no lower. Ima give it another shot in a few days........ I need a break lol.
Mine has a 13/64 hole near the center. Stock TB has a hole also. I can not remember if this was checked, but check the ID of your IAC port. Some aftermarket iac are smaller than stock and do not flow enough. Should be at least 3/8" ID.
That it fired up great with the extra fuel tells me it needed that too. So I would leave it in there.
05-24-2018, 06:22 PM
#114
I posted what works for my car and the handful of cars/trucks I worked on that had idle issues I had to fix. Maybe I’m doing it wrong, but I would think that because it worked so well for me, I’ve got to be on the right track. I would also think it wouldn’t be a good idea to rely on an iac motor to keep the car running also. Just my humble, but lightly experienced opinion.
05-24-2018, 06:31 PM
#115
Once you cross 0.69 to 0.76 volts, the TPS will not always rezero. And it is not always consistent. If you get to 0.69 and still need more air, then you either need to clock the tps, open bleeder more, or drill a hole in the blade.
Mine has a 13/64 hole near the center. Stock TB has a hole also. I can not remember if this was checked, but check the ID of your IAC port. Some aftermarket iac are smaller than stock and do not flow enough. Should be at least 3/8" ID.
That it fired up great with the extra fuel tells me it needed that too. So I would leave it in there.
Mine has a 13/64 hole near the center. Stock TB has a hole also. I can not remember if this was checked, but check the ID of your IAC port. Some aftermarket iac are smaller than stock and do not flow enough. Should be at least 3/8" ID.
That it fired up great with the extra fuel tells me it needed that too. So I would leave it in there.
05-25-2018, 09:41 AM
#118
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Yes, the hole behind the sensor. There was some really good work by a user named "JimmyBlue" a while back on this. I'd have to really hunt to find the post/thread, but he had an aftermarket throttle with a IAC port that was only 3/16" and it showed the airflow leveling off somewhere around 150 steps. So from 150 to 300 IAC counts, he gained zero airflow. Caused him all kinds of problems. He drilled out his IAC port to 3/8", which is close to stock (probably 10-mm is stock?) and gained back a lot of control of his idle. The Nick Williams for a while was the only aftermarket throttle that actually had a 3/8" IAC port. There was a phase where people were drilling out the fast 102 throttles to open up the IAC port.