srgould41

I previously posted on this, but didn't post well so I am starting over.

I have an '83 305 with a 7747 ECU $42 mask. I have VE dialed in and am working on timing via PE. The distributor is set at 0* and the bin is set to 0*.

At some point in the process the cold start idle became messed up. The idle is surging. As best I can tell from TunerPro the idle is bouncing off the stall saver RPM (425) up to 800 or so then back down. It does this for about 15 seconds before achieving a steady idle. Warm idle is awesome after some open loop idle changes which I don't get because it idles closed loop.

SA tables are stock. Stall saver settings are stock.

I made changes in the following Open Loop idle tables, but I don't honestly remember if this surging started before or after the change. These changes are just changing from an automatic trans bin to the settings in a manual trans bin because I was having issues with the RPM taking too long to drop when stopping.

Idle Threshold MPH from 2 to 4
MPH Decel Threshold from 0 to 6
Decel CTS Threshold from 38.13 to 164.13
Idle AFR Enable Time Delay from 8 to 4
Idle AFR time delay from 12.75 to 2

Could any of the above settings cause the cold start surging?

The suggestions I have read about at to flatten the VE table idle area. - I tried this and it didn't help.
Incorrect SA table. - Mine is still stock and has not been altered.
Too fast IAC reaction. - I never changed the values, still stock.
Stall saver set too high. - If anything it is too low for my cam.

The engine smells rich at cold idle. I am thinking about adding 4 degrees to the Startup Spark table. Have not tried yet.

Any suggestions based on the above info?
Attached is my current bin.

Thanks,

Steve

RBob

iTrader: (1)

Surging is usually caused by the engine leaning out some. See which area of the VE table the upward surge is traveling, then add to it there.

RBob.

srgould41

Thanks for the reply RBob.

Makes sense that it might be too lean. I can't log it because it is open loop at that point and just shows 126 in the log. I had tried to lean out the 400 RPM row in the main VE table to be closer to the 800 RPM row, but it didn't help. I will try to make it richer.

Am I using the wrong fuel table for the first 30 seconds of run time? Should I instead be looking at the "Cold AFR vs. VAC kPa" table? Or maybe the "Time Out vs. Cool" table?I am using the V.5.9.3.xdf file to get these names from.


Steve

srgould41

Fixed.

The first time I adjusted the VE table I used the 3D graph. Looking at it again I realized I ended up adjusting the 20 MAP column, not the 400RPM row. Went back and added some fuel in the 400 RPM row and it started and idled normally. Thanks for the tip RBob.