Results of tuning in my new cam

CC306 230/244 112 .544/.576 9.1:1 compression

Idle speed set to 900rpm(N)
Throttle blade adjusted to IAC steps about 14-16
TPS 0.59
Adjusted the lower VE table BLM ->124-134range
Zeroed out "rpm error vs SA" tables
"Unlocked" BLM cell4 at idle
Closed Throttle SA 22 deg
MAP was around 70kPa
BPW 2.4-2.5 mSec

Increases Closed SA and logged the results, picture starts at 28 deg SA and ends at 38 deg SA.

Results
MAP 58 kPa
BPW 1.9 mSec
Much more stable idle, dont stink gasoline anymore, no more glowing collector :lala:

Next thing is to try enable "rpm error vs SA" again to se if it can get even better, then its part throttle tuning time.....

 

Can you show O2 sensor voltage INT, BLM and SA?
Where is the o2 sensor? I just finished ruffing in my car's idle by messing with the PID o2 controls and it idles now REALLY well at 600rpm with not even the slightest surging. All tuning was with the prop gains and duration, nothing else was changed in the calibration. I just sat there with the Romulator and messed with it. My next step is to play with the timing at idle and adjust the offset idle bias that's added to the o2 window (keeps idle richer in my code).
After I see the rest of the data I'll be able to comment further.

 

I must have deleted the O2 voltage from the excelfile, but I still have the *.csv file in my laptop. If you really want to see the O2 voltage I can fix it.

I've changed my O2 swing point at idle (-100mV) to pass emission easier.

I also suspect that my base timing has moved? so take the nbr on the x-axle with some sence, I will check it this weekend.

The x-axle is the same in the previos pictures I've posted.

 

Have you flattened out the Main SA table at your idle rpm and between 55 and 65kpa? Those values and probably down to 45 and 70 should be pretty flat where at 70 it should be less than were it's idling. Also check to see that the Main VE table has a relatively flat area to idle, the MAP changes with just a little too much fuel or too little.
Once those are checked out okay you might want to adjust the PID controls for the o2 sensor feedback. You said you leaned out the idle window which is the opposite of what GM does (they richen up the window for a stable idle). Might want to try and get the idle with no bias in the window (0mv offset).
From there adjust the proportional gains and duration tables. Read http://www.diy-efi.org/gmecm/papers/747fuel.txt and it'll make more sence. I thought that my little dinky 212/222 .435/.460 110ls cam wouldn't require any modifications to idle since the MAP is around 50kpa.... I was WAY wrong. After a fresh o2 sensor the idle was so unstable I thought it was going into stall saver... up down up down up down!! I multiplied the tables by 2/3 and got the idle to sit at 600rpm with awesome oil pressure on a hot engine! Frankly I think everybody that has something other than stock should first tune these tables ALONG with the VE to get a fresh motor to idle.
RBob wrote the letter so if it helps stablize the idle, might want to thank him.
I believe all that I suggested will help you get a stable idle but my discamer; Don't do anything that I suggested .
Also might want to play with the timing at idle, anything too retarded and you'll get a big stumble off idle. You can tell you've got to much timing when the idle seems REALLY strong, then it'll almost stall, then save itself and back again moments later.
Good luck!

 

Just came from the garage, tha base timing was of 6deg So I'll have to start over again.

The reason I lowered the O2 swing point was due to emission, not to stabilize the idle, I must pass emissiontest soon! Then I'll se if I can get the idle even better by richen it up....

The main SA is adjusted to the closed SA table so there is a nice translation between them and as you write the main SA table at 70 kPa is lower then the closed SA table.

Time to tune in the Ve tables again.........

Thx for the link.....

/N.

 

Today I tried to raise my Idle O2 swing point back to stock setting, and my Idle was a little more stable but my MAP readings whent up to almost 70kPa...........

I'll try to change SA and see if I can get better results.............

/N.

 

You may want to varify header surface temp to be sure you are not to rich still due to cam. Even thogh you do not see the glow the temp may be very excessive.. My last cam which had alot more "Total" overlap ( 102* @.006 ) than my current cam 84* caused alot of problems, all the overlap fooling o2 sensor. I would see surface temps of 650+ .. After playing with swing voltage alot not to get it down to where I was safe, I just started tuning open loop alowing me to get surface temps down below 400 degrees keeping my spark plug boots in a happy place.
With current cam I can run closed loop no problem.
Some people may argue with you on this board they run fine with (x) amount of overlap @ .050 but there is alot more to the story than that. IE: Total overlap,Cubic inches, cam timing.

 

Car runs fine now at idle at 14.0 AFR.....Closed loop.

Next year I will probably tune Idle in open loop with my p/h injectors....

/N.

 

Well just trying to alert you.
Though the a w/b may read 14.0 that may actually be a good bit more rich due to unburned 02 in the exhaust stream from valve overlap..

Glad its running well.

 

I can't tell from your chart above: Are you running about 36* advance timing at idle?
That is higher than I have tried, so I am curious how it is working for you.

Thanks

 

The pictures start at 28 and goes to 38. THen my base timing was 0 deg so you have to subtract 6deg from it so in reality they shows 22-32 deg.....

I now have 30 deg at idle.

 

I'm having trouble finding the 'O2 Sensor bias at idle' value in the '8746 hac -- can anyone give me a location ?

 

In this regard the '8746 code is better then the '747 code. In the '747 there is only a bias term that enables one to decrease the AFR at idle.

In the '8746 there are actual O2 window terms that set the AFR at idle. This allows one to both lean and en-rich the idle AFR:

RBob.

 

87_TA, I like this idea. An good method to get the idle AFR and timing in line. Point a temp gun at the headers for a reading, observe how well the engine is idling, and adjust from there. Some driving around for off-idle response/driveability. . .

Another tool in the bag of tricks

RBob.

 

Thanks alot RBob,
Its a pretty handy tool that can be purchased from under $50 at your local sears.