Throttle Plate Adjustment?

[michbc3]

Is all the "bleed air" that is needed to keep the car running at idle coming from the Idle Air Control valve? Or does the throttle blade still have to be open just a little bit - like a carburetor?

Sorry for the simple question, but this is the first electronic fuel injection car that I've ever worked on.

Thanks, Bob Crow

 

[Jan Larsson]

There is a throttle blade adjustement screw but you're not supposed to touch it ... and yes I do beleive there's some blead like on a carburetor as I had to adjust mine at one point after I rebuilt the engine and have had the throttle body apart

 

[72firebird]

Like Jan said, there is adjustment by the throttle screw but you really on need to adjust it so that you're idling around 800rpm and then just leave it and the air control will be through the IAC.

 

[michbc3]

Thanks for the feedback gents. I have an Accel GEN7 which controls the idle speed - about 800 RPM. At idle the injectors are open for only 1% duration - yielding about 13.5 to 1.0 A/F. If I wanted it leaner, the injector duration would be 0% - and with no fuel of course the engine wouldn't run at all. So I was wondering if the throttle butterfly might not be open wide enough. If opened wider, it might increase the injector "open" duration beyond 1% - giving me some range of A/F adjustment at idle. Obviously I have an emissions test on my mind...

 

[WS6]

My duty cycle at idle is 1.7% and those are 50# injectors. My A/f is anywhere from 14.23 down to 13.XX.The IAC counts are 17ish and the TPS is rock solid at .42. The fatter the idle A/F the better it idles. I don't put much faith in magic 14.7 idle a/f's. The LC2's seem to like it richer.

Here's a log...



....

 

[michbc3]

What software do I need to use to view your log? Anyway, my IAC counts run between 5% and 7% - as recommended by Accel. Emissions aside, I've got really lousy idle quality. Yesterday it was unusually bad and stalled twice as I was about to put it in the garage after driving it mildly for a few miles. I'd better check the plugs. I have been doing some tuning and may have sooted them down from running around at 12.8 to 1.0 for too long. I'd like to get a recommended igntion advance setting for idle. Perhaps I'm not set correctly.

 

[WS6]

Go herehttp://www.fullthrottletech.com/showthread.php?t=2627 down to post #7 and download the zip file. Unzip it and install it.

When you open the powerlogger folder there will be a "PLC" jif that is a grey box. Run it and that's all that's needed from that download.You don't need to install drivers,etc.

Now, when you've opened it you'll see the PLC or "power logger console" and it'll open up on the graphs screen.

On the left edge you'll see 6 tabs. click the "config and download" tab and click "load" button.

BUT! I've gotten ahead of myself. First you'll need to click on my .zip folder that I attached above. It'll download and you'll unzip it and save it somewhere,I save them to desktop.

Now, back on track, after you've clicked the "load" button it'll ask from where to laod the file from? You'll pick the desktop area and click on the Unzipped .dat log file. Click open and it's now ready to view.

Spend a few minutes looking over the help tab on the powerlogger console to aquainted with features and check out the runs.

When you get this figured out I have a couple minute "idle" only file that maybe you can compare to.


...

 

[michbc3]

Thanks. Success with download. Your instructions were good. The graph shows Voltage in to 4, voltage in to 5, IAT and TPS. 4 has no signal. Input 5 varies from 2 to 3 volts over 24 seconds. At closed throttle, idling it looks like you are at about 28 degrees BTDC. How do I interpret your IAC postion? Is that related to input 5?

 

[WS6]

Okay, hold on, go into the config and download page and be sure "analog 5" is set in the drop down to " pressure 100 PSI" that's the FP reading and analog 4 is an unused parameter.I also don't log EGT's...yet.

You can see all the data in the "data" tab including IAC position. Using the right and left arrow keys on your keyboard you can run up and down the log and that applies to all 3 "views" Gauge,graph and data.

One thing to note, when I hit the record button it starts out with about 5 seconds of previous frames. This one does not because I was sitting idling for a bit before I started logging. But usually you'll see peoples coast down and then the blast.

 

[WS6]

One more thing...the wideband input for my logs is the LC1 in the dropdown menu.

And voltage offset for analog5 is 1.954...that needs to be in there for accurate FP readings.

 

[michbc3]

Ah. I see now. Your IAC is rock steady at idle = 17 counts. I have been logging my IAC in % of opening, so our units are different. I can probably log it in counts though. I'll check into that in a few days - when the rain stops. That PLC logger is a nice setup. I'd get one if I didn't already have my Accel DFI. Best, BC3

 

[WS6]

Well?? 7% as you're using works out to be 17.85 counts as a percentage of 255,which is the range of steps in the stepper motor of an IAC. so maybe you're closer than you think.