c4mo

iTrader: (3)

Im hoping by posting this threads I can get some insight on what else to try to fix my idle issue. Ive searched and tried the advise given on the numerous surging idle and like nature threads on the board without really making any progress. I tried to make sure the mechanical side of the car is not causing me the actual problem by verifying that the valve lash, cranking compression, base timing with est unhooked, no vacuum leaks, and taking the injectors out to be ultrasonic cleaned. After checking these components along with having the injectors cleaned im still having the same issue. Im also having a problem with a false knock reading, but I can start another thread to address that.
Concerning the bin ive tried to make one change at a time over the past few months to help the idle and while somethings have made a small difference nothing has really helped. I can also say once I put the car in drive it helps to smooth it out by loading it, but in p/n it surges. I know that typically a surge is caused by it being lean, but my narrow band o2 and WBo2 agreed and its fairly rich at idle.
Bin changes
richen ve table
Locked idle state sa trying 17-22 sa
launched mode zeroed out
sa compensation zeroed
stall saver rpm lowered
Adjusted the iac 20-25 steps no load warm, you'll see steps are higher because it seems to be a little more stable that way

At times the idle will stay constant verying 50 or so rpm then it will start a surging fit as youll see in the datalog.
Attached is current bin and datalog.

RBob

iTrader: (1)

Looks to be a vacuum leak. The IAC starts high then falls to zero with the idle speed remaining above the desired idle speed.

There are some items in the tune I would change. In the low speed VE table, the 400 RPM row between 40 KPa and 60 KPa, bring those values up to match the 500 RPM values.

Then get rid of the trough at 65 KPa between 400 and 700 RPM.

RBob.

c4mo

iTrader: (3)

I will make the changes to the bin. I have the parts coming to build a diy smoke machine I’m hoping that will reveal something because I haven’t been able to pinpoint anything even after having the intake apart.

c4mo

iTrader: (3)

I got the smoke machine assembled today and tried in on the car. After testing it I found no vacuum leaks and I feel certain I would see something if present considering it produces a tremendous amount of smoke. I haven’t tried the bin changes, but will and report back. Other wise I’m very open to suggestions. Thanks

Larry

You don't seem to be getting much help so I will give you what I can from my experience. First your cam has enough overlap that a stock tune will not work at idle. i have a slightly smaller cam but I still had to make many changes to get a rock solid smooth idle. I run open loop idle at 750 rpm's. My SA at idle is 28 degrees and the WB reports 13-13.5 AFR. Any leaner and it is not happy. I can release the clutch at idle without stalling even with the A/C running. Like they say, give it what it wants not what you think it should be. And don't forget any miss fire will cause a false reading from the o2 sensors. Good luck

Larry

I dropped my idle to 700 rpm's to see if it would still be stable. It still makes happy sounds.

c4mo

iTrader: (3)

Thank you Larry for your input. I haven’t tried increasing the idle sa that high I will give it a shot and see what happens. I have throughly been through the ignition system trying new plugs, ohming all the plug wires, then trying another set. Having the ignition module checked, replaced the ignition pickup, and tried multiple coils. I did each thing one at a time with no changes overall. I’m not detecting any misfire, however I’m wondering if the o2 sensors are off because last I checked the plugs they were whiteish color and at a 12-13 afr at idle they should be darkened. The NB and WB do agree however and they are on separate banks.
The ve table is after many ve learns with the larger injectors so it’s pretty far from the stock tables. The lower idle cells being manually adjusted. The strange thing is the car runs ok everywhere else except for the idle issues.