silvernblack

Hi,
I'm using s_aujp (edited for my RamJet 350) and it runs quite well. Once oddball thing is that when it is first started it tends to idle higher (that's ok), but it won't reset to normal idle (even after it warms up) on it's own. To get normal idle, after it warms up, I have to turn the engine off, and restart it, then it will idle at normal idle speed.

Any ideas on what I may have to adjust. It runs so well that I've been pretty much ignoring this, but I thought I'd ask.

JP86SS

iTrader: (1)

I've seen a few of these high idle issues lately come up.
Not sure if its due to cold weather or just not having a good set of IAC values to use on the manual setups.
I haven't had any issues running the auto.
Might want to try the automatic trans setting just to see if that localizes it to the added code for the manual trans.
You will get the SA from the main table until warm in all setups, might check the 100 Kpa cell in the main as it warms up to see if its the same as you want in the idle table.
You say it idles higher than it should, Does it run off the closed throttle coolant table like it should once warm?

silvernblack

I should have been more specific. It does this in the summer also whether the car is warm or not. I'll start it when it's hot and it goes right up to 1000 or 1100 rpm; typically if I stop it once, let it sit for ~10 seconds, then restart the idle is nice and set at ~750(where it is set warm).

On occasion I may have to repeat the stop/start sequence, but usually just doing it once will make the idle be nice, low, and normal.

JP86SS

iTrader: (1)

I don't know why this is, but I am seeing something on the bench that replicates part of the problem.
The RPM flare at startup could be caused by BARO multiplier table at L8684. By setting the first two (lower) cells I'm able to keep the amount of IAC steps lower at startup.

Try setting 8684 table, 65 and 75 Kpa cells to 0.2
They were 1.6 and 1.4 respectivly.
This made the steps less on the bench.

I also reduced the step timers to drop the IAC steps faster once it was opened.
865A from 37.5 to 5
865B from 43.75 to 0.0
This makes the response much faster for the IAC coming back down.
Other low values tended to make the IAC hold static and not move.

Try also reducing the setting at 8032 (diff coolant for Cold SA)
The default is 151 C but seems the "warm kickdown" would not be triggered. Lowering it to a small value may show results. I didn't have time to try everything I wanted with this setting. This would be the only thing I could see being set by restarting after initially running.

One very interesting thing did show on the bench.
If the VSS does not go to zero, you will ALWAYS have a bunch of counts on the IAC.
Confirm the VSS signal is not noisy from the buffer and does indeed report zero when stopped. A minimum speed indication could easily keep RPM high.

This was NOT tried on a running engine, only on the bench.
This experiment was to fix this issue only, not for any other, not sure what the overall effect will be on running. You'll have to try and see if the situation improves.
Jp

silvernblack

Many thanks. If I can get away from all these holiday obligations I'll do it this weekend....and report back.

silvernblack

Table (Loc 684->688): IAC PID Param, Table Multipler (0-2) changed.
Changed the 65 and 75 Kpa cells to 0.2 - They were 1.6 and 1.4 respectivly.

Constant: IAC Throttle Follower Step Timer (Drive) changed from 50.0 mSec. (0x08) to 37.5 mSec. (0x06).
Constant: IAC Throttle Follower Add Step Time in Drive changed from 50.00 mSec. (0x08) to 43.75 mSec. (0x07).
Constant: IAC Param, Idle RPM Deadband (Drive) changed from 25 RPM (0x02) to 75 RPM (0x06).
Constant: IAC Param, Idle RPM Deadband (Park/Neutral) changed from 50 RPM (0x04) to 75 RPM (0x06).
Constant: SPARK ADV Diff Cool to Disable Cold SA changed from 151.00 Deg C (0xFF) to 100.07 Deg C (0xBB).

My findings didn't match what I expected so I adjusted as above. I ran around town and drove about 10-15miles....didn't do the high idle at all anymore.....or it didn't do it on this short test anyway.

Anybody see anything that I may have changed that out-of-wack?

JP86SS

iTrader: (1)

I'm still thinking this one has most to do with it.
It would be neat if you had time to switch only this back and see if the problem comes back. Would at least confirm where to begin looking in the code as to why this happens.

That's the good news .

If you can re-create the problem (and know which one corrects it) you may want to put the step timers and deadbands back to the old values. I'm thinking there could come a time where the IAC will move too quickly and possible cause some up/down surges in the RPM. Not certain because I havn't see the response on a running motor but it could be if other IAC response parameters or deadbands are not adjusted to match the increased speed coming down, there may be a timing response issue when step changes are commanded.
With the deadbands adjusted to 75 RPM that response error may be covered/dampened in this instance.
The IAC code still not clear to me when I dare to look at it.
Just wanted to let you know my thoughts.

silvernblack

Constant: SPARK ADV Diff Cool to Disable Cold SA changed from 151.00 Deg C (0xFF) to 100.07 Deg C (0xBB).

Just want to make sure I understand. I had to guess at the value because I had no idea how low to set it.

I'll try to get to that today (looking dubious), and report back. Should be easy since I keep old BINs.

Thanks for all the help. Is there a "better" value I should set this at? I just picked 100°C out of the blue (kinda-sorta).

JP86SS

iTrader: (1)

Being that it is a differential temperature setting, a smaller number "should" cause the Cold SA routines and warm kickdown to occurr earlier.
The way it reads to me is "Startup Coolant temp - Actual Coolant temp" must be greater than the 8032 value to trigger the Warm Kickdown.

100 C is still 200 deg F differential and you will probably never see that unless its reeeely cold outside.

AXXC has a zero value here
AXXD has a zero value here
AXXF has Hex 21 Value (or about 70 deg F)
AXCN has zero value here

ANHT has this at max value
AUJP has this at max value

Not sure why the variance, seems some use it and its disabled on others.
Must be additional places that the kickdown can be triggered or bypassed.