1st idle run with 1227747 ecm and modded bin.

[damanx]

Ok, I had to get out there today and verify the timing to begin with. It appears that the spark advance hack doesn't show the base timing when you are following the procedure to set the timing. In any case, the base timing is at 0 degrees.

Next up was upping the BPW in the bin from 135 to 144 and upping the IAC CL Desired idle table. I added another 50 rpm across the table.

Now, if anyone can explain to me why setting the idle rpm with the throttle stop screw and having the IAC disconnected does anything, I'd appreciate it, because it sure seems to me that the throttle adjustment and IAC count is more important while while in gear.

In other words, when I disconnected the IAC and adjusted the idle rpm to 100 below the desired rpm, I ended up having to readjust the throttle plate with the truck in gear to get IAC counts to about 15.

So, why the readjust? Am I doing something wrong?

The only thing I can think of is that once I find where this engine wants to idle, that once the idle rpm is adjusted with the IAC disconnected, that when it's reconnected and in gear, it should fall into place without any further adjustment.

[EagleMark]

Well having 8 degrees to much timing the ECM did not know about is one issue to effect idle as well as explaining the very few knock counts you had.

If you raise idle in bin the only way the ECM can raise idle is allow more air through IAC. So if you change idle RPM then you have to reset throttle blades for IAC count.

Getting good idle in these 7747 ECM is tricky, I told you how, but now your back to disconnecting IAC? This is the long way and no where near as accurate and if you follow all the write ups on how to do it? It only works properly if done at end of a drive in a manual trans... It will not be, or could be accurate in Auto Trans.

Go for a drive, come home and sit in driveway with truck in gear and see where IAC counts are? 20-30 good with stock engine, (hot built engine closer to 10), to many IAC counts? Open throttle blade 1/4 turn. TO little? Close throttle blade 1/4 turn. Put in Park and they may go down and idle RPM will not be the same.... Then forget it, because the IAC count will change a little do to ambiant temp and weather...

IAC logic in Park/Neutral is completely different then in drive. Drive has more control and tries to get to your Desired CL Idle Speed. Park/Neutral is close but had a much bigger variance, temp of engine also has a big effect, it's never as stable as in gear.

Manual trans ECM thinks it's always in gear...

[damanx]

Yeah, I'm not so sure right at the moment that the timing was off. When I swapped ECM's from the 8062 to the 7747, I know I readjusted the base timing to 0 degrees, so that 8 degrees I was seeing, I'm not sure. In any case, it is definitely at 0 degrees now.

Now, when I went back through that set up, I followed the procedure that involved the disconnecting the IAC as listed in your thread, which at the moment, I don't have a link to, but the end result seems that the best way to set idle and IAC counts is with the engine hot and in drive.

So I drove in and pulled into my parking spot and in gear, at idle, the IAC counts were running about 17-18 and the idle was smooth. Knock counts = 1. Also, the idle from cold start to operating temp was much smoother and I suspect that it has something to do with the CL Desired rpm being upped.

I do remember that with the carb, that engine liked idling about 750-800 rpm, so that is what I am going to shoot for.

[ony]

once you get it about where you want, drive it a few days, starting and getting shut off will give everthing time to program.

[damanx]

Yeah, that is what I plan on doing with it now since the knock count is down and the idle is better.

ETA: did not get the drive home log this morning as I apparently did not click on the "record" button to start the log......

but, I compared the log from the drive to work from last night to the drive to work from the night before and noticed that the blm's were ranging from 115-120 with the bpw set to 135 and that with the bpw set to 144, the blm's were averaging between 108-115.

I'm thinking that I might want to set the bpw somewhere about 139 - 140.

[EagleMark]

I'm thinking that I might want to set the bpw somewhere about 139 - 140.

Or you could do it the right way? Set it where it is supposed to be, forget it and adjust the VE fueling table?

Your BLMs will change day to day and weather to weather, it's the beauty of EFI.

Only BLMs that count for adjusting the VE table are when fully warmed up, no DFCO, no EGR, no Air, no Hiway, no PE. Try to drive with a steady throttle position because AE will through them off as well, but you can't drive without AE and there's no way to filter in TP, unless you export to spreadsheet...

[damanx]

It's still at 144.

Going to run it for a few days and get a few days worth of logs.

During that time, I am going to spend time reading up on the info about tuning on the 3rdgen forum.

[chevmasta]

damanx,
what's the maximum RPM you honestly want to spin your engine up to?

[damanx]

What do you mean?

Max rpm at idle? WOT?

I'm never going to push this thing to redline and I can't recall ever hitting 4k on purpose.

I want it around 700-800 at idle though.

[Fast355]

What do you mean?

Max rpm at idle? WOT?

I'm never going to push this thing to redline and I can't recall ever hitting 4k on purpose.

I want it around 700-800 at idle though.

My 87 shifted about 5,500 rpm at WOT. I think thats what he is getting at. Remember a V6 has 25% more time to fire the injectors than a V8.

[damanx]

My 87 shifted about 5,500 rpm at WOT. I think thats what he is getting at. Remember a V6 has 25% more time to fire the injectors than a V8.

I'm not sure what you mean.

As it stands, there are a couple things I am seeing.

1st. It appears that the knock counts so far, have been below total of 20, seem to occur before the coolant reaches operating temp. It also seems that anywhere from 0-10 counts occur at startup and just after.

2nd. Seems the software won't zero out the knock counts on the dashboard unless you exit the software and restart.

3rd. After adjusting the idle rpm, I've not made any adjustments. The tps was set to .59 volts and the iac counts were running between 15-20, in gear at idle at operating temp. After 4, 15 mile each way trips, the tps is sitting at .62 and the IAC counts are between 25-30. Now the IAC counts could be due to the drop in temp here from 80's to 60's.

[ony]

my 4.3 always has start up knock counts,8-12 then when I get to the hy way and wind it up a little 3500 rpms some time I will pick up 30-40 more. the cool compensation spark adder adds spark till I pass 55degrezz centagrate. I also get kcs when I shut the engine off. after its warm usely 1-3 on start up then some times I have to wait on a knock so it will go into lean cruise. if you get the history tables up in tp and push clear it should clear them out, you have to clear 1 table at a time with out having to restart tp.

[damanx]

You know, I've done a lot of searching and have not been able to find definite answer on how many knocks are actually considered normal.

In regards to the knock counts not resetting, I am referring to the dashboard. That count doesn't seem to clear regardless of clearing the tables in the history pane.

[ony]

before I started tunning my chip when it would get 95-105 temp out side I would get any where from 160-pass 255 cause the counter would rest stock chip,that was at 70mph start up a incline kkkkkkkkk guess gm didn't think it would hurt nothing? I run the digital dash it always resets when I shut the key off.

[EagleMark]

There's a direct correlation between BPW/BPC and time injector is on, as motor RPM increase available time decreases. Lower BPC = higher RPM before injectors go static/open always or not enough time to close. None of this will matter in a stock engine, stock fuel pressure under 5000 RPM.

There's always some knock counts because it's an accumulation. Start data logging and there they are. Some engines will get some more from stating do to noise or? Stop worrying until you find cells increasing, there is no number that is acceptable or unacceptable. If it's moving in a cell or cells is not acceptable. If it's climbing is the key, not the number.

Dashboard holds last value it got and won't reset until it get's more data or TP is restarted.

If your having some increasing during cold running take out some cold spark timing. It is a V8 bin in a V6 engine. You've done it more then once and know it's there, remove some cold spark advance that is added to Spark Advance.