New Start-up Problems

[TurboCamaro]

I've been running megasquirt on my car for over two years with a lot of sucess.

Recently I've been tweaking the fuel and spark a little more, especially to get better acceleration enrichments using MAP-dot-Accel.

I'm running a V2.2 board and MSnS-Extra 025n9.

Somewhere along the way I started having major start-up problems. Whenever I try to start the car it will fire right up but then immedeatly die. If I hold the throttle at maybe 5-10% it will chug and run very slowly and roughly for about 3-4 seconds and then suddenly jump up to a steady operating condition. Sometimes I have to restart 4-5 times if it's not already warmed up.

I thought this would either be afterstart enrichments, or possibly priming/cranking pulse widths. I tried increasing and decreasing all of these values but it doesn't affect the problem. After increasing the afterstart enrichment all it did was make the engine run a little richer once it is finally started and running smoothly. I can watch the A/F ratio on my wideband slowly come up as the afterstart enrichment decays as it should.

I'm very frustrated as I don't know what's causing this. It seemed like it came on rather suddenly and I can't figure out what I may have done to cause it. The fact that I can adjust values and not have a change is also frustrating. Could there be some corrupted value somewhere that I can't fix w/ megatune?

Thanks for the help!

[chrispel]

I had problems with my IAC causing my car to stall and do the same as yours. So the MS2 will be running my IAC as soon as my connector comes in the mail. I would reset your stock pcm if it controlls the IAC and see if that helps.

[TurboCamaro]

Thanks for the tip, but I've actually blocked my IAC off. I just cracked the throttle plate stop screw a little to get the idle where I'd want it most of the time. The only thing my stock PCM controls is my AC and my speedometer.

The only time I have the problem is at startup. Idle is solid otherwise once the engine is running for a few seconds.

[PSIG]

... Whenever I try to start the car it will fire right up but then immediately die...

I had similar symptoms when the TACH input degraded. I thought it was ASE or WUE too. We're shooting in the dark - please post a datalog.

David

[TurboCamaro]

Here's a good one with a few restarts at the very begining of the log. It looks like it finially staied running after the 5th or so time.

I'm using an Innovate LC-1 wideband 0-5v, 10-20 afr.

Another problem is that I can't see exactly what's going on with the A/F ratio because whenever I hit the starter, my voltage drops to a point that the LC-1 doesn't like and it enters its warm-up cycle again so I can't see the true A/F ratio until a few seconds after the engine has been running.

[bluetrepidation]

My car does this sometimes too. I noticed if I cranked up my timing for the idle area from 13 deg to 27 it starts much easier and doesn't stall like that. Just a thought.

A.J.

[PSIG]

Wayne, I noticed repeatedly that as the rpms rose the map would fall and so would the pulsewidth, causing the rpms to drop again. I'd say it's lean on the warmup. Set your log viewer to see RPM, MAP and PW together to see what I mean.

There is very little noise to worry about. For your WB, perhaps jump start with cables to raise the available power during cranking so it doesn't dip so low?

David

[TurboCamaro]

I think I found it!

I did see what you were talking about w/ the dropping PW.

Anyway, I loaded a previous config file that started up just fine. Then I imported my current fuel and ignition tables from the config that caused the starting problems. But it still started just fine. I then changed the accel enrichments settings and values to my current ones. It then wouldn't start up right away. I tried changing all the AE settings back to that of the previous one at a time.
In both configs(old and current) I had the AE duration set in cycles. The old one was set to 6 cycles while the current one was set to 10. As soon as I set that value to 6 cycles it started up just fine. Even 8 seemed to work ok. I'm not sure why this small setting kept it from staying running right after start-up but I'm glad I got it working with my most recent fuel and advance tables. I'm running MAP-dot AE by the way.

Thanks for all the tips.