Idle/decel surging problem

[BlownAlaskan]

Hey Guys,
I was working my VE/autotune the other night and everything was cool until my third flash of the evening:

The truck is surges really bad at idle now. The timing oscillates, and so does the afr. It seems to drive ok, but when I slow down to stop it dies. It also dies switching from Park to Drive or Reverse.

What could I have messed up? Is there something mechanical that could be wrong? I hate to start changing stuff in the tune when all was doing was working on the VE table.

Running SD Cust OS 3. Fuel pressure good and no logged misfires.

[Dirk Diggler]

Check the RAFIG pid and see how much air the car wants to add or subtract. This pids goes right back to your desired airflow table and esp check this if you are drive by wire

[BlownAlaskan]

Can't seem to find that one. Is it a custom PID?

[Dirk Diggler]

Do you have the latest version if not you have to make a calc pid

*CLC-00-945
gps -32.0 32.0 .2 "{GM.IAC_LTD_DMA.gps}+{GM.IAC_STD_DMA.gps}"
lbpm -5.0 5.0 .2 "{GM.IAC_LTD_DMA.lbpm}+{GM.IAC_STD_DMA.lbpm}"



CALC.RAFIG F53D CLC-00-945 "gps,lbpm" Idle "Idle Airflow Correction AC Off, In Gear"

[BlownAlaskan]

Ok I put that in the slot definations section, what do I put in the Parameter Reference Numbers section below it? Sorry, I'm slow.

[Dirk Diggler]

That goes there but if you have the latest version it should allready be included and if you are adding it you will get an error. If you dont have the latest and greatest then you need to add it.

CALC.RAFIG F53D CLC-00-945 "gps,lbpm" Idle "Idle Airflow Correction AC Off, In Gear

[BlownAlaskan]

Ok, I got her in there... Now Iam going to go and log it. What am I looking for? Is there a good write up on how to pursue this?

[joecar]

It's already in the latest version which is downloadable from the website.

[BlownAlaskan]

yea, I downloaded the latest version tonight. What is the procedure for using the new idle pids to correct the idle? I have already constructed the maps, so is it just a matter of logging and then pasting the data into the tables in the tune? What is the procedure?

Thanks for the help.

[Dirk Diggler]

Make the maps log the startup with the pids and paste them to the desired airflow table, startup tables and startup friction tables repsective of course

[BlownAlaskan]

So is that tables:
B4307 des airflow
B4304 start up correction
B4342 start up delay
B4343 friction airflow correction
B4344 friction airflow decay
B4345 friction airflow delay

Now, do I use RAFIG/RAFPN to correct ALL of these tables, or are there other pids I need to use?? In other words, do I make maps to represent each table and then the logged values to the current values in the tables? Will this help my warm idle?

Thanks again.

[Bruce Melton]

Following this, please continue>

[Dirk Diggler]

Use RAFIG/RAFPN to correct B4307
Use the startup correction pid to correct b4304
Use the startup friction airflow pid to correct b4343


The later two tables are used to control startup problems that linger around for 10-20 seconds.

[BlownAlaskan]

so: IAC_SUP_DMA and IAC_FRICTION_DMA for 4304 and 4343?

[Dirk Diggler]

Yup sorry i didnt have the software open in front of me to tell you the pid names

[oztracktuning]

I logged IAC_STD and IAC_LTD today along with IAC_STDAC and got idling RAFIG figures of -minus 1.00 g/swhat does this indicate i need to do?? My idle learn limit lows are set at minus 1.00 g/s

IAC_STD was sitting at around -3.76 g/second but went as low as -3.97g/sec with IAC steps below 10. My dyncylair (speed density) is at 0.20 , AFR was abt 14.1 on a desired 14.78. , my RAF table at 100c ECT is 7.70g/s

MY IAC steps are in the low numbers in gear but sometimes come to zero.
I havent drilled by TB - but the screw is wound around a bit.

[Dirk Diggler]

when you populate any of these tables they should miminc the tuner all you have to do after that is copy and paste with add and that will take car of it. The screw may be caracked open to far and will cause hanging and idle issuses when you iac hits 0 and cant adjust anymore. I would suggest bringing them back to around 40-60 at hot idle and then proceed

[oztracktuning]

So i should close up the Throttle Body more until its 40 or so in gear.

Then then if the RAF difference says minus 1 - what should i do with it. Subtract 1 from the RAF table at that temp??

[Dirk Diggler]

40 at idle and yes if its -1 you subtract 1 from that temp

[oztracktuning]

Just put the screw back so the TPS Voltage is 0.62V it was 0.68V - i think its close to stock.

It now has warm IAC steps in gear in the 70s. Idling gentler the whole time , no surging (so far but it was a short drive) and slow down stall tendency is less , it was a positive step!! The car now sounds heaps quieter on idle ??!!

[oztracktuning]

I just turned off spark rpm error control and went for another idle log.
It was varying rpm steadily between 480rpm and 900rpm for a desired Rpm of 675rpm. The AFRs were varying from around 15.0 (desired 14.8) to 12.5 - the 12.5 seem to be happening on the downswing of rpm. (Most of the focus was on idle in gear - its an A4 with a SS3600 stall)

I have now made all timing equal 400-600-800-1000 in the effected tables and have leaned out the 400rpm cells in the VE table - to see if i can smooth it out.

I will attach the log and a snapshot as an attachment.

Once i get this as good as it will get i will turn back on timing rpm control and hopefully have an idle to be happy with.

[Dirk Diggler]

That is a good start once you get the idle solid wihtout the spark adjustments your idle will be golden

[oztracktuning]

Damn it - i just did 3 adjustments and logs and everything went backwards ?????#@!^&

Its now hunting worst between 400-1100rpm in gear.

Can someone have a look at those logs and see what you think?? Im confused.

[Dirk Diggler]

send em to ldhastyatgmaildotcom

[oztracktuning]

Just tweaked the afrs a bit in the 400,800,1200 cells and did another log - it seemed a significant move in the right direction. Now it will come to stop sometimes and have a perfect idle for a few seconds before launching slowly into the up and down rpm swing.

[oztracktuning]

Just did another log and noticed that Voltage is varying during the surging when rpm varies 1160 to 425rpm the Voltage changes from 12.3V to 13.7V ( i have a 25% UDP) at a steady 750rpm its 13.4V.

For my SVO 30 injectors i have updated the IFR table but have not changed the injector offsets for voltage change. Maybe this is a culprit??