lakeffect2

Symptoms Initial start:

Catches but stalls out on first attempt after 2-3 seconds
Second attempt catches but stalls out after 5-6 seconds
Third attempt almost stalls , rpm goes low and finally continues running

Since it catches each time, I would think crank pulse is ok. I'm not sure how the choke, decay and delays work to help carry over the fuel during the initail stages of open loop.

Symptoms hot restart:
Will catch and chug, usually stalls out. wide band AFR reads out in the 17-20 range , maxing out at 20. staret up temps can be anywhere from 170 -220 at that point. Obviously AFR and temp related, but I don't seem to enhance the correct tables to make any difference.

Thoughts?

RBob

iTrader: (1)

This catching and stalling can also be caused by having too low of an IAC count. Make sure that there is a decent RPM flare on start up.

As for the chokes (after start) there is both SA and fuel added. The decays are likely OK, probably need to work a little on the choke AFR:

Choke - AFR

Recall that the values in that table are subtracted from the open loop commanded AFR, this makes it richer. Try adding a 1/2 AFR to 1 AFR to those areas where it is troublesome.

Any chance this table was modified:

Open Loop - AFR Multiplier vs CTS

As it too will affect start up.

RBob.

lakeffect2

Yes, chances are... they were likely modified from the original settings.

I don't recognize that there is an initial rpm flare, so I also look at the IAC settings per your suggestion.

RBob

iTrader: (1)

For the start up flare it is controlled by the steps in the power up init table:

IAC - Powerup Init Steps

The other thing is to have the IAC at between 20 & 25 steps on a warm idle and no other loads.

RBob.

lakeffect2

Thanks RBob. can't say that I'd ever noticed that setting before you pointed it out. I'll report results in a few days.

lakeffect2

Made sure the initial Iac Power up was at 25. it was, so no chnage occurred in it's multiple crank s to start up. Will advance it to 30 and see what happens.
Would you be kind enough to make a suggestion as to what would be a "NORMAL" range for SA start tup, and which way to go to with decays and delays, which by the way, I not sure if I understand the significance of how they would interplay.


dave, Rochester NY

RBob

iTrader: (1)

Go back to the supplied values in the IAC power up init table. 25 is way too low.

Check the choke tables to see if they too have been changed.

RBob.

lakeffect2

I found a run down to idle setting that looks mistyped it has low/high values of 0.20/0.40 seconds. Wondering if that should have been more like values of 2.0/4.0 or 20.0/40.0 seconds to rundown

Initial values of what little I happen to have on file all had initial IAC value of 22, so entering 25 was up from what I saw. Are values of 30-40 likely to be more appropriate? Or is that still way off as well?

RBob

iTrader: (1)

Don't go looking for problems where there aren't any...

RBob.

lakeffect2

Ok, seem to be making some possible improvements, but inconsistantly.

Observationally, There is not a problem on warm retats, like went to the store a few miles down the road, after 15 minutes shopping, come out to car.. start up is just fine.
So the problem exists at lower CTS temps at initial startup.

I'm using the base bin EBL-3005

My son happens to own a 2002 Corvette. I notice when he starts it, it has a nice flare and settles down after about three seconds. I'm trying to make mine flare on start like his does.
I need to know what factors/entries to consider that will help increase the initial flare on startup within the base EBL-3005 bin.

Any takers? As always, much thanks to those taking the time out of their day to share that knowledge.

Dave

Street Lethal

iTrader: (16)

You are experiencing what I was experiencing Dave. Upon cold startup, the IAC steps would read 145 at key on, but then something would drive the steps down way too much once the engine started despite my Init-Steps embellishing the correct values, essentially choking the engine and stalling out. You have to balance your CTS/RPM/IAC/MAP settings at ambient temperatures during cold start. My engine went from stalling upon a cold start, made some changes, then wanted to stall upon cold start but would catch itself and stay running, made some changes, then it started up and maintained target RPM which was too low at cold start, made some changes, and now it starts up when cold and has a flare to it (hovers at 1200-RPM) then slowly comes back down. You have to balance it out...

lakeffect2

Lethal, Do you recall fiddling with choke settings as part of that?
It's definitely correlated to temps. My impression was been it was likely to be "choke" related during those opening moments.

Do you remember which way you had to move those settings. Any specifics as to directions to move would prove helpful.


Thanks again for the insight.

Dave

Street Lethal

iTrader: (16)

How I have mine setup (stock TPI throttle body, big cammed 305);

IAC - Idle Speed Park/Neutral (stays at 1200-RPM until 100 degrees, then gradually settles down to 900-RPM once I reach 160 degrees, my driving range is between 160 and 200 degrees)...

IAC - Idle Speed Drive (same as above, just 200-RPM less)...

IAC - Minimum Idle Steps (I keep steps at 145 in conjunction with Idle Speed settings above to allow 1200-RPM, but then decrease down to where the steps need to be at 160-degrees and 900-RPM, which in my case is 55 steps because of the big cam)...

IAC - TF Gain (I left alone)...

IAC - Idle Down Rate (I left alone at first, but then adjusted with Powerup settings below)...

IAC - Init Position vs Baro (matched amount of steps w/kpa needed with the CTS setting above)...

IAC - Powerup Init Steps (set mine to 145 because of the big cam and stock throttle body, adjusted down rate percentage to reduce amount of flare/hang time)...

IAC - Max Steps (set to 145)

IAC - Minimum Steps (set to 35 steps, mainly because stock setting is 4/5 steps. I am idling at 55 steps, 30 steps higher than the stock 25 steps, and just added 30 to 4/5)...

Ronny

iTrader: (1)

Lakeeffect? Do you have a WB installed? While the choke is "on" I see around 12.5-13.0 on WB. Idle is 900 rpms once it can run on its own w/o my assist holding 1000 rpms with throttle. That is especially when environmental tems are <50Fand is about 30 secs or so and then it idles 650 on IAC. Due to my cold manifold a lot of atomized fuel is being lost. I think I need more cranking fuel and will add 10% once the cooler temps prevail her in WI.

lakeffect2

As I understand it, if it fires up, then dies, it's likley not crank fuel at fault. It if keeps cranking with a sputter of two, but never really fires up, then it could be crank fuel.
In my case it fires up very quickly, every time, so I know I have a sufficient supply of fuel being introduced while cranking. I know it is reaching an RPM sufficient for the ECM to take over, and crank fuel to end.

It's after that point where I would think things like " choke" (in the old school carburetor terms) would be engaging.

At lunch I had my laptop with me, made some changes as suggested by Street Lethal, and loaded them for the drive homenoticed it started, tried to die and came back to life. I noticed two things. The coolant temp was still up at 95F. When my wide band meter came on line I was seeing 15.5-17.0 AFR. Since the temps were not in the "sitting overnight" range, I'm not sure if it proved anything yet. I'll recheck in the AM when it's cold again.

Ronny

iTrader: (1)

I see you have port fuel. you are right crank fuel may well be adequate. I see a Table for choke delay. It may not be occuring soon enough. A transitional thing after crank fuel fires engine.

Also a choke decay multiplier. I see at cooler coolant temps the values are larger in that the neg # is smaller. so a larger number may allow the choke on longer....

lakeffect2

From RBob's EBL calibration info

Choke - Decay Multiplier

Table of values used to decay out the choke AFR. A larger value will decay out faster.


Seems counter intuitive, at least until I caught onto the point that the "multiplier" is kind of a misnomer, as it really acts like a divisor It's talking about Time, and when you divide by a larger number, it makes sense that the time becomes shorter, or in this case faster. .

At least , that's what I get out of it, but every time I think I've caught on to something around here, I usually need a big dose of penicillin to cure it

Dave

Street Lethal

iTrader: (16)

From the sound of it it doesn't sound like it is tune related at all. Can tell you that a bad battery, poor charging system, or bad connection in the charging system will be just enough to cause those exact symptoms. Ida over at Ida Performance, the guy that wrote the article TPI-101 told me that a long time ago and he was spot in, it directly effects injector voltage during cranking, during running, during correction, etc...

lakeffect2

T key on, many times I am seeing battery voltage reading on the dash guage at 10.5-11.7V

Is this the range where you are anticipating issues?. Once started and running, I see 13.5 consistently for long periods of time. Maybe a cell going bad in the battery?

RBob

iTrader: (1)

At those low voltages it does look like a bad cell in the battery. Do a key-on, engine-off and note the voltage. Then turn on the headlights (low beams are OK), and note the voltage.

A good solid battery usually shows between 12.2 and 12.4 volts (which can vary dependent upon how long ago the battery received it's last charge).

RBob.

lakeffect2

Per RBob's suggested I checked key on and lights on voltages. (10.2v and 9.5V)
I handed to have a spare fresh battery and swapped it over. Key on volts at 11.9V

Instant start first time. Some flare, rpm fell off but didn't die.

I'sd still like the flare to last a bit longer, it's only about one second , would like about 2-3 to carry it over the rpm falling off area better. I will go back to the original suggestions in this thread to see if they correspond to the change needed.

RBob

iTrader: (1)

Getting there, here is the parameter to adjust:

IAC - Run to Idle Down Delay

That is likely the one you are looking for. It does exactly what it says. Once the engine is running, the ECM will delay that amount of time before stepping the IAC closed.

The IAC steps will remain at the power up initial steps until the delay is done. Then step the IAC down to the idle setting (by steps and then by RPM).

RBob.

lakeffect2

That parameter is limited by the program to 3.19 seconds and gets maxed out at that point.
Raising IAC initial steps to 150 also helped carry it iver the faltering stage abit as well. Might raise that even more to allow it run down from a higher point to get it pass that dipping idle area.

I don't quite get the relationship of choke settings, if more or less choke is valuable to help the drop off to stall. I've also raised the stall saver settings from 500 rpm to 700rpm to catch it before it drop s off the face of the earth as well. seemed to have helped.

Ronny

iTrader: (1)

I believe is also a iac-fuel setting to add fuel when the IAC opens to save stall. May be grouped with AE tables

lakeffect2

Thanks Ronny, I'll check it out in the morning.

RBob

iTrader: (1)

Three seconds is a long time to hold the IAC that far open. I get the feeling that there is something else wrong.

The purpose of the choke fuel & SA is to prevent the engine from stalling right after start up. Don't need much as the commanded AFR is also being adjusted via the CTS multiplier table.

Are the IAC steps low at idle? It may be that there is a small vacuum leak. That can cause the issue with the RPM dropping too quickly at start up.

RBob.