Trigger angle issues (not Code bug in 029!!!!)

[volvorod85]

Heres my setup 1990 765 turbo.
B230FT IPD Turbo cam
MSnS extra on a V2.2 board with spark output to Fidle
megatune 2.25 and i was running 029l as of yesterday i updated to 029q.
Ive got the volvo LH 2.2 dizzy for my rpm signal

The problem happened, after my cam change. Ive got the IPD cam with the notch in the back off 20 degrees.

My idle is set to about 1200 for cold start reasons and i have A/C. So warmed up the idle is 1200, ive got no hesitation or miss problems. If i turn the A/C on, or just turn the idle down to anything below, oh id say starting at 1000 or so, or lower, you hit the gas slowly it will rev no problem, hit it hard, or moderatly, or like your gonna take off in 1st gear it misses, stumbles and revvs, like ive got my accel enrich off, but its on, and working. If you watch the timing gun when you rev it, the light goes away, im loosing my spark signal.

Before the cam change I had the trigger angle set to 0. It has run fine like this for near 2 years with the T cam (stock cam). If i set the trigger angle to 20 and anything close to that, the timing map does not work properly, it will advance 10 more degrees and stay at 21. then after like 2500 rpm the timing will advance. I had to set the trigger angle to 40, turn the dizzy to the stop, and i could time it properly, follows the map perfectly, and ive now got my stumble from idle.

Ok, now, with the trigger angle at 40, i had my max point in the timing map at 39. Its 39 from about 3000 to 6000 and 5 bins up from the bottom. At 3500 RPM at right around 100kpa, the ignition would cut out completly. The tach on the dash would drop to zero. Every time id pass that point in the map it would just cut out, and only at that point. I changed a few bins in the effected area to 38, and the problem went away. my stumble is still there.

Yesterday i had the poi come over (chris) and we went through my issue. We got the trigger angle set to 90 on trigger return cranking (before i was using time base when i had it at 40 and also at 0) It runs at 90 and follows the map fine, I also had to put -10 in the trim angle cause the dizzy is maxed to one side and i was 10 degrees off. now i should be able to bring the trigger angle back 10 degrees, BUT HERE IS THE BIG PROBLEM....

If i have the trigger angle at 90 it runs, the hesitation is nearly gone, but if i bring the idle down to 600 it comes back sometimes. If i set the trigger angle to 89 the car wont run, if i set it to 91 using the trigger addition it wont run, 85 it wont run 80 it wont run etc etc, it sounds like the timing went way advanced, and was really cranking oddly. Now 1 degree of change shouldnt do that.

So my 3 problems are, the stumble at low RPM's, the inability to set the trigger angle to anything but 40 on time based, and 90 on trigger return and have the car run. and if i set it to 20 the timing advance goes all wacky. whats the dillio?

Mark

NOTE nothing changed except the cam, and beacuse of the offset grind in the dizzy notch, i have to adjust the trigger angle and now i cant! This was a problem with 029l and 029q, before that with the stock cam on 029l it was ok, and before 029l i was running an old version of megatune and i think 024 code.

[jsmcortina]

Some notes on trigger angle.
When using low trigger angles keep it below 15 deg or you will have idle problems as you cannot run less then the trigger angle. The code will likely limit you to trigger angle + 2 deg.

When using high trigger angles 60-70 deg is preferred but you must allow 5-10 deg between the trigger and the max advance. Setting a trigger angle of 40deg and trying for 39deg advance will not work - the code needs time to calculate the delay and set the timers.

The max trigger angle that can be entered is really 89.5 deg. Entering 90deg may be allowed in Megatune but might be using some other number (-10?) instead.

While turning your dizzy did you rephase the rotor? If not you may well be getting the spark jumping to the wrong tower.

hope this helps

James

[the poi]

Thanks James, will try it out. I figured it had something to do with this and next cyl mode with a high or low trigger, but when it worked at 90* and nothing above or below, it kinda threw me for a loop.

[volvorod85]

Ok, well Ive set the trigger angle to 10, fixed the timing to 12 and retimed it, set it back to follow the map and it all seems to be times properly now. Stll have some starting issues with trigger return, it just doesnt start very well, and ive got some accel issues still with low rpm accel. After some brainstorming with poi we came to the conclusion that im still running the dumb 124 ign module and not using dwell control. And then i realized i didnt have any issues untill the code update. Cause i was running such an old version (024 ish?, then went right to 029 what ever was done to the code messed with the origional setup, so i shall implement dwell controll and/or eventually put in my 139 module and see what happens...
Mark