Annoying Idle issue (you could win a license)

[GMPX]

Hi All,

Decided I'd better try to fix a really annoying problem I had with my car after a cam swap. Mind you, it's been like 6 months I've put up with this, everytime it happened I'd say, damn, gotta fix that and never did.
What prompted me was her indoors telling me one day "you should take this to someone that can tune a car and get it fixed". :cry:
So this morning I decided to actually do some tuning, I've heard this EFILive program isn't too bad for that. :lol:

The scenario, cold start, engine fires and runs fine, shifts into gear no problem, start to back out the driveway and the engine would almost stall, stop the car, it would hunt and carry on until stable (about 5secs), repeat once I got moving again.....
If the engine was warmer (like only 40 - 50degC water temps) it was fine.
Logging the engine data there was no 'major' changes happening to the spark or WB02, but the IAC was going from approx 140 steps to 50 within 2 or 3 frames, this was the problem.
Apart from this issue all idle controls were great, no driving on, no stalling when warm etc, oh, the car is MAFless with a cable throttle not ETC.
So, why was the PCM all of a sudden dropping 100steps as the vehicle got moving?.

Before I tell you what it was does anyone want to take a guess, or share with others the solution if they have been there before.
Again, keep in mind, my IAC Parked and IAC in gear tables are pretty good, they were not the problem in this case.
It's first in first served, the first person to share with us what causes this wins a free license. So please only personal and commercial users post.

Cheers,
Ross

[Dirk Diggler]

Was it IAC effective area

[GMPX]

Was it IAC effective area

No.

[Tordne]

Damn, my guess was going to be {B4403} IAC Effective Area also. That has caused similar problems for me...

But apparently that isn't it, so after having a look through some things I'm going to take a guess for the free license...

Was it anything to do with {B3629} Initial Park To Drive Enrichment?

I am working on the assumption that the solution was visible/fixable within the calibrations in the latest GA version of EFILive (i.e. 7.2.2)?

Cheers,

[bink]

B4315
B4316
B4317
B4318

(Throttle Follower tables - IAC) IAC steps dropped as the decay rate fell like a rock. Need to boost B4315 and reduce decay. Not sure if "In Gear" B4317 applies to reverse. :?:

Cheers,
joel

[Dirk Diggler]

Damn, my guess was going to be {B4403} IAC Effective Area also. That has caused similar problems for me...

But apparently that isn't it, so after having a look through some things I'm going to take a guess for the free license...

Was it anything to do with {B3629} Initial Park To Drive Enrichment?

I am working on the assumption that the solution was visible/fixable within the calibrations in the latest GA version of EFILive (i.e. 7.2.2)?

Cheers,

I wouldve said this also but from his posts it looks like he has gotten past that. And his WB still read fine from what i understood

[Black02SS]

Here is just a few guesses.

B4324
B4325

OR

B4515

I think it has to do with how the car is learning. The car I feel is adjusting too much for the airflow.

[TAQuickness]

I'd guess it's operator error

[zrx1200]

try opening the throttle stop a bit

[Scoota]

I'd guess it's operator error

Ross doesn't make errors. It's more like laziness.
The only reason why Ross has fixed the problem now is "the minister of war and finance has stamped her foot down".

Scotty.

[GMPX]

I'd guess it's operator error

:cry: :cry: That hurts :cry: :cry:

It may very well be there is another issue that this was being affected by, however, apart from this it idles like a bought one.

It was basically transitioning into a different idle state above a certain speed, so if you can think what table comes in above a certain speed then you get a license, it hasn't been guessed yet, not many to go.
All I had to do was increase two paramters, not actual tables.

Cheers,
Ross

[GMPX]

Ross doesn't make errors.

Oh I do, just ask our Beta testers :wink:



The only reason why Ross has fixed the problem now is "the minister of war and finance has stamped her foot down".

Scotty.

You know it :)

[Black02SS]

Hmmm...

B4311
B4312

It was throwing you into the throttle cracker state, forcing too much air into the car causing it to stumble.

Increasing both values would change the speed at which it is enabled and disabled, allowing for more time without the extra airflow.

[GMPX]

Hmmm...

B4311
B4312

It was throwing you into the throttle cracker state, forcing too much air into the car causing it to stumble.

Increasing both values would change the speed at which it is enabled and disabled, allowing for more time without the extra airflow.

We have a winner folks, it was indeed the throttle cracker.
But, in this case I was losing IAC steps (from 160ish engine cold and idling fine, then it would drop 80 - 100 steps to 60ish and nearly die), this is when the throttle cracker was kicking in.
Bumping this upto to 15 or so KMH certainly fixed the problem.

I am going to look at this in a bit more depth, but I think the throttle cracker kicking in disabled another offset table, in other words, the cracker table has values like 0.02 - 0.05 in the area the engine was running in, whereas say the Idle Air in gear is like 5 - 8 when cold, that is a massive difference. It's like the Throttle Cracker disables a major table (just thinking out loud here).
I'd like to get to the bottom of this, maybe I should get those Idle DMA PID's finished one day :?

Paul will contact you with your unlock code Chad.

Cheers,
Ross

[Black02SS]

Thanks Ross!! I wasn't really expecting this. Its good information to have as I had this problem, but don't remember how I fixed it. I think mine just fixed itself.

[Black02SS]

But, in this case I was losing IAC steps (from 160ish engine cold and idling fine, then it would drop 80 - 100 steps to 60ish and nearly die), this is when the throttle cracker was kicking in.



I do have a question after I think about this. I was under the impression what when you have lower IAC steps, the car was allowing more air into the motor. I have always fixed this in some instances by closing the TB blade cutting off the amount of air.

[GMPX]

Simple task for you to answer your own question.
Run the IAC overides in the Scantool and move the steps from 100 - 0 and see what happens.

Cheers,
Ross

P.S - I like tuning problems that fix themselves (as yours did!!).

[Black02SS]

Thanks, I was sitting in my car when you posted that. I tried it out and sure enough, 100 the idle raised, 0 it fell and died. What threw me off was I put my TB set screw on top and got it backwards. Right theory, wrong thinking.... :oops:


PS. I love hands on experiments.

[Tordne]

OK, I vote that Chad (black02ss) not be allowed to enter these competitions anymore :D :D :D First the dash competition, and now the idle problem!!!

Man, when I get the head/cam thing I might just fly you out to NZ to help me out :D :D :D

Nice one mate, I knew you would win this!!!

[Black02SS]

:) I would love to do that, but dunno what the wife would say.

[GMPX]

OK, I vote that Chad (black02ss) not be allowed to enter these competitions anymore :D :D :D First the dash competition, and now the idle problem!!!

:lol: :lol: I forgot about the dash competition, actually Chad works for EFILive, we really aren't giving out free licenses :wink:

Cheers,
Ross

[GMPX]

Thanks, I was sitting in my car when you posted that.

I sometimes sit back in think in amazement that these days we consider it 'normal' that we are having electronic conversations with people on the other side of the world whilst sitting in our cars!!. Imagine telling someone that 20 years ago.

Cheers,
Ross

[Black02SS]

OK, I vote that Chad (black02ss) not be allowed to enter these competitions anymore :D :D :D First the dash competition, and now the idle problem!!!

:lol: :lol: I forgot about the dash competition, actually Chad works for EFILive, we really aren't giving out free licenses :wink:

Cheers,
Ross

:lol: I must have missed where to pick up my check this week Ross. I'll let it go just this once. :)

[Black02SS]

Thanks, I was sitting in my car when you posted that.

I sometimes sit back in think in amazement that these days we consider it 'normal' that we are having electronic conversations with people on the other side of the world whilst sitting in our cars!!. Imagine telling someone that 20 years ago.

Cheers,
Ross

I know, but it is cool that you can be talking to someone on a messenger program that is 1000 miles away, and help them with the car like you were there. I don't know if I could have lived 20yrs ago... I like my technology. :)

[Tordne]

:) I would love to do that, but dunno what the wife would say.

She can come too if she wants :D

[Black02SS]

That would take the fun out of it. I'd have to make that run solo. ;)

[Tordne]

Hope she doesn't read the forums :wink:

[Black02SS]

Not at all. She hates my car and wishes it would disappear. :(

[Tordne]

:lol: :lol: I forgot about the dash competition, actually Chad works for EFILive, we really aren't giving out free licenses :wink:

Let me know when you are recruiting again, I'll be in!

[dfe1]

Ross, just for drill, did you try setting the throttle cracker speed at the original values and bumping the values in the 4309 throttle cracker air flow table? In theory, if the throttle cracker disables IAC, you should be able to bump the cracker values sufficiently to compensate. I think the cracker control is designed exclusively to control engine speed when the vehicle is rolling at a decent rate of speed. Judging by the values I've seen in most cracker tables, it's just keeping the throttle open lightly during decel from road speeds, and is obviously not designed for any idle control. But it would be interesting to see if it could be used as an auxiliary or secondary idle control.

[GMPX]

I didn't try that, however, I think the result would be when the engine is upto temp and it's happy to idle with say 40 - 50 steps, the cracker table might add another 30 - 40 steps which would result in crusie control effect.

You are right about the throttle cracker, it's not really designed as a major idle table but just a 'touch up' during certain idle modes, like decell.

Cheers,
Ross

[joecar]

Questions...

a. what is the throttle cracker (cracks the throttle blade open a tad, right...?)...?
b. how does this work on a cable operated throttle blade...?
c. how does this work when the throttle cable first goes to the cruise control module* and then from there to the throttle blade...?

I know that my WS6 does the following:
1. cruise control module manipulates the throttle cable when cruise enabled;
2. traction control uses the cruise control module* to reduce throttle opening when wheel slip is detected (pushes back on accelerator pedal);

* EDIT->correction:
actually it uses the "Accelerator and Servo Control Module" (ASM), which controls the "Accelerator Control and Adjuster" stepper motor.

So does the throttle cracker use the cruise control module to crack the throttle, or does it use the IAC to achieve the same airflow...?
:?:

[joecar]

d. what is the throttle follower (and how does it work...?)...?

[Tordne]

Not at all. She hates my car and wishes it would disappear. :(

I'm sure my wife is fine with my car, in fact she won't let me change it cause I've "invested" too much in it :wink: . She would just like to not travel with the computer on her lap all the time :D :D :D

[joecar]

Questions...
Ugghhh.... It gets ugly real fast... What were they thinking/drinking...

Edit: I edited this to make more sense... (ha...)...

Perusing my CD manual, it seems that the following components are involved in throttle manipulation (directly or indirectly):
1. Accelerator Control and Adjuster
2. Accelerator Pedal
3. Cruise Control Module (CCM)
4. Accelerator and Servo Control Module (ASM)
5. Electronic Brake Control Module (EBCM)
6. Powertrain Control Module (PCM)

Accelerator Control and Adjuster directly manipulates throttle blade
Accelerator Control and Adjuster is directly manipluated by Accelerator Pedal
Accelerator Control and Adjuster is directly manipulated by CCM
Accelerator Control and Adjuster is driven by ASM (stepper motor controls)
ASM has input from EBCM (Requested Torque signal)
ASM has input from TPS
CCM has input from PCM (VSS, CC Inhibit)
EBCM has input from PCM (Engine Speed)
EBCM has input from ASM (Delivered Torque signal)

Accelerator Control and Adjuster is the last component before the throttle blade, and cable from Accelerator Pedal wraps around this on its way to the throttle blade.

I don't see how the PCM controls the ASM to crack the throttle.

[joecar]

And... PCM and EBCM talk on the serial bus...

[dfe1]

Throttle cracker control almost has to be through IAC. The PCM configuration is designed to be adaptable to a wide variety of vehicles. Throttle cracker functions have to be usable on vehicles with or without cruise control, traction control, with cable throttle linkage or with electronic throttle. The only thing all these combinations have in common (relative to cracker control) is IAC cabability. This would also explain why standard IAC counts suddenly change when the throttle cracker function is active.

[Black02SS]

The Throttle Follower is used so when you take your foot off the accelerator you don't suddenly choke the engine, so although the blade slams shut, the IAC is kept out a bit and then decays back to the park position, if you log your IAC steps and TPS you will see how the IAC tracks TPS movement, that's the 'follower'.

The cracker is like a small offset table to the base table, it generally has small numbers in it, I think it is used to help smoothness when shifting gears etc as the higher the speed & RPM they tend to add more offset into the table.
As far as the decays etc go, lets say the Throttle Follower has added 40 steps onto the base idle airflow, once conditions are met to disable the Throttle Follower, those additional 40 steps will be reduced to 0 over time instead of just dropping 40 steps instantly, this is the decay, the higher the numbers the faster it will reduce that number back to zero.

[joecar]

dfe1,
black02ss,
Thanks, I vaguely thought the IAC may be used for cracking, but I really wasn't sure.
8) 8) 8)
So, the cracker allows more airflow ("cracks throttle") by using IAC.
So, the follower smooths (ramps down) the transition from throttle blade airflow to idle (IAC) airflow by using the IAC.

Ok, makes sense.
And I learned a bunch of other junk regarding my ASM, CCM etc.... lol :lol: :lol: :lol:

[bink]

Throttle Cracker and Throttle Follower airflow are only functional off idle. Seems simple - but is very important in evaluating idle transitions. FWIW.

Cheers,
joel

[BowlingSS]

I had the same problems and made the changes and my surging when I back up has gone. I still have a little surge when I come to a fast stop.

Bill

[dfe1]

I had the same problems and made the changes and my surging when I back up has gone. I still have a little surge when I come to a fast stop.

Bill

Living in Lawrenceville, you probably have to make quite a few fast stops.

[BowlingSS]

I had the same problems and made the changes and my surging when I back up has gone. I still have a little surge when I come to a fast stop.

Bill

Living in Lawrenceville, you probably have to make quite a few fast stops.

Yes I do. I have 26 red lights between home and work.

Bill