tuning idle

[oztracktuning]

I had a breakthrough today that has improved my idle 100%.
Maybe i was stupid before - but what i did was make sure the cause and effect of AFR was lined up properly.

The usually awesome logging maps - done in idle mode in the 400-800 cells at around 50 MAP dont display the real picture accurately it seems due to the lag of exhaust gas from what the injector does. It had tricked me into having too rich a cell at 55, 56 and too lean at 45-50 when the car idles on average at around 50. What i have done is look for peaks and troughs and then go backwards frame by frame looking for the corresponding event identified by pulse width peaks and lows.

I then adjusted the corresponding VE cell and it has made my idle AFRS heaps better.

[BACKinBLACK]

Are you running Closed or Open Loop?

If running closed loop, you need to recalibrate your VEs {B0101}:

In the VE table, try subtracting:
20% from your 0-400 rpm row.
15% from your 0-800 rpm row.
10% from your 0-1200 rpm row.

See how you go after firing up on cold startup. If it still stalls after driving off then you might need to increase your IAC settings. Drilling a hole in the TB might help.

I have already trimmed the ve table but i took off 20% from 0-1200. I guess that i will try adding back 5 in the 800 and 10 in the 1200 range and see what that does for me.

actually now that im looking at my tables it was the ve while cranking table that i modified by 20% so now i changed my main ve so we will see what that does for me today.

also i have already opened my throttle body via the throttle stop screw. Currently my tps voltage is between .5-.6 so i cannot open it up anymore and be able to reset my tps correct.?

[oztracktuning]

Use the pulse width identification method and it wil be more accurate than the scaling method.

[SSbaby]

I have already trimmed the ve table but i took off 20% from 0-1200. I guess that i will try adding back 5 in the 800 and 10 in the 1200 range and see what that does for me.

Yeah that might be too radical. You are essentially exiting a potentially lean condition and perhaps entering an overly rich condition. That could lead to driveability issues especially at idle. Try to limit these kinds of 'steps' in your VE curve (i.e. smoothen it where you can).

I haven't tried the 'pulse width' approach?

[BACKinBLACK]

yeah i was mistaken when i typed that, i took 20% off the cranking VE table. I looked at my main and backup VE tables and i didnt take anything off of them, so i used to stated values...

20 % 400rpm
15 % 800rpm
10% 1200rpm

im gonna go load this onto the car today and see what happens. I also added some timing to the base timing table to see what would happen at idle. Guess we will find out.

[VetPet]

I'd like to add just a word of caution here. Steps are best taken one at a time and then evaluate your results. Change your VE table values and see how the car starts and idles first. Adding more timing at idle can certainly help but avoid adding more than you really need or you will start getting other driveability problems. Making just one change at a time will make it easier for you to identify which change made the difference and help you with future changes.

Just my 2cents for what it's worth. Good luck with your tuning and keep us posted. We all can learn something.

[oztracktuning]

I am not sure if people understood the method i was talking about.

The aim is for steady afrs - this will make idle better.
This is in open loop.

Look for a peak eg 15.1 and then trace backward to a smaller than the rest pulse. It might be back 0.6 or so of a second. This is the rpm and map that caused the lean spot.

Then look for a low eg 13.8 - then look backward for a higher pulse width peak - this will give the corresponding rpm and map for the rich spot.

Working in this way should smooth out idle afrs and idle rpm steadiness will improve.

As for the 400 , 800 and 1200 cells
here are my latest numbers in g/cylinder if this helps anyone.

35 MAP 40MAP 45MAP 50MAP 55MAP 60MAP
400rpm 3.540220 3.618923 3.779064 3.939558 4.466479 5.922836
800rpm 7.105144 8.065108 10.289789 10.704303 12.159072 16.055396
1200rpm 12.621760 14.060647 16.871188 19.590145 22.588620 26.131840

[joecar]

Can you post some pictures with scribble showing what you mean....?

...I've had 3 Mondays in the last 72 hours...
I'm unable to abosrb text anymore...

[BACKinBLACK]

ok guys i added the new changes to the ve and a lil timing and it seems to be idling quite a bit better now and idles sooner by itself so that is good. now my next question

My injector duty cycle got up to 101%, obviously i need new injectors but in the meantime will this get better or worse when the car gets tuned...

I am planning on going with SVO 30lb i guess, ill see if i can find a good deal, does anyone have any other brands/recommendations?

When i get my new injectors will my pump be able to handle the new injectors + 150 wet shot?

[oztracktuning]

Here is an image of a log with labels.

Not sure the principles are all correct -
but the method works well for idle - at least with my car.

Steve