Need help with starting my VW bus

[panel]

Hi guys.

I'm having a hard time getting her running. I've just finished my MS-II conversion and the VW bus doesn't want to start. Can some of you have a look at the logs/MSQ file ?

I have my ignition running from the megasquirt similar to that of when I was running the MS-I Extra code. Now I'm just running the regular MS-II. I have a V2.2 board if this helps. Here is a quote/reply from Matt C.

So you'll need to remove that jumper from the LED and run it to the point marked on the picture above. Using MS1/Extra style input with MS2 requires slightly different settings - you'd set Ignition Input Capture to Falling Edge instead of Rising Edge.

I hope the start up/cranking log works for everyone ?

[Matt Cramer]

That's a lot of cranking pulse width. I suspect you're flooding the engine.

[msoultan]

Too bad I don't have my logs with me because I could compare yours to mine.

What are the specs on your engine? I have an essentially stock 78 2L engine. I'm running fuel and spark with the ms3 and using the v3 board, but I might be able to help compare settings and get things straightened out for you. Also, what are you using for a trigger? Wheel or distributor?

[panel]

Well as I was brushing my teeth this morning I had a brain fart! I realized I had got some machine work done on my EDIS pulley this winter and it came to me that I might have the EDIS wheel 90* out. Sure enough when I got home from work I changed it to where it was supposed to be and she started up. Little rich but it did start.

Now to put her on the road again and do some driveway and road tuning.

My bus has a 2275cc turbo motor in it and running the crank fire EDIS set-up.

I'll post some better logs when I get used to the different features that the MS-II has. Looks a little more complicated than the MS-I.

[panel]

Hi again guys!

Well now after some accel help and fine tuning I'm ready to really tackle the start up. Right now it seems to back fire when trying to start In my msq I had the cranking pulse width at 8.5 then dropped it down to 4.5 after reading the formula for fine tuning the cranking. This hasn't really helped. In the msq below I upped it to 6.6 but haven't tried it yet.

You can see the backfire just before the red line in the log. Hopefully someone can tell me why it does this.

[panel]

I had a look at lunch and noticed the cranking timing was at 18.5. Is this to much advance for cranking? I just have the cold advance settings from the default. I usually idle at around 14 when hot.

And I also noticed lots of red lines so it's hard to make out the difference between cranking red lines and the one I put in there.

[devastator]

Try using the skip pulses, (I think that's what it's called, but I can look it up of you want), to skip that high timing value until it makes a few revs. Hopefully, it'll start before the advance kicks in this way. I had to do this on mine because I idle at 23 degrees.

[panel]

Try using the skip pulses, (I think that's what it's called, but I can look it up of you want), to skip that high timing value until it makes a few revs. Hopefully, it'll start before the advance kicks in this way. I had to do this on mine because I idle at 23 degrees.

This?

Skip Pulses (no_skip_pulses) is the number of ignition pulses at start-up that MegaSquirt-IIâ„¢ (or MicroSquirt) uses to calculate the rpm before sending calculated advance signals.

I'll try it out.

[panel]

Well it still doesn't start very well What I've done is disconnect the PWM idle valve cause when I have the valve at '0' or a bit of duty cycle on cranking when cold it seems to start ok. But when warm/hot operating temp the motor just screams like you have the throttle stock open then dies down to the regular RPM for the 5sec (or whatever I set it to).....and to the duty cycle at that CLT temp.

This happens when you go into a store or something.......come back to the car and start it up and then it cranks I guess at the low % and then ramps down to the closed or nearly closed postion.


I've tried a cold advance and adding some advance to the high map low RPM area but doesn't really want to idle high enough like 1200RPM or 1300 etc like I thought it would . I always have to keep my foot into it to keep it running.

Here's a log/MSQ.

I also bumped up the skip pulses to 10 to see if this helps but I don't think it did really.

[panel]

I could also be chasing a possible problem like having to little or to much 'cranking pulse widths'. Can someone tell from the datalog?

I've tried the 88% and the 23% and with the idle pulse witdths I did end up lowering those %tages.

[LT401Vette]

It looks to me like it needs a little more fuel while cranking. In the log your PW's while cranking are about even with your idle PW's or maybe a tad lower, I usually find them to be better at about 30% over idle PW.

[panel]

Thanks Phil.......... I was try this process but I'll give the 30% a go.

So what we have is four times as many injection events when cranking compared to running. Now let's assume we have tuned:
the idle so that the best idle PW = 2.2 ms,
our "well-tuned" injector open/close time is 1.0 ms (this is important!), and
Then we get our "best idle" fuel delivery amount of:
2.2 - 1.0 = 1.2 milliseconds fuel deliver per injector pulse
Split this up into the 4 times as many injector events we see during cranking, add in the Open/Close time and get our hot cranking PW.
(1.2/4) + 1.0 = 1.3 ms
Now for cold we want 1.5:1, which is close to ten times as rich as 14.7:1, so just multiply that first part by 10 and we get our cold cranking PW.
(1.2/4)*10 + 1.0 = 4.0 ms
This calculation requires:

Good idle tuning to get that initial pulse width, and
Good tuning of the open/close time so that the actual fuel delivery number from the first

[panel]

Here's the latest log/MSQ. I just realized my advance was off by about 11 degrees advanced. I finally got a timing gun and used the trigger offset to make the adjustments necessary.

I tried earlier in the day with the cranking pulse widths at 8.6 and hot 2.3.This seemed rich I think. I thought I'd go back to some basic constants as I think having my timing off could have contributed to some bad starting. I know dropped those by 7.8 cold and 1.9 hot. Maybe a little to rich cause I think I opened the throttle a bit. I think this might mean it's rich.

Phil........I know you said richen up the last time but this was before I figured out that I had the timing off. I haven't had the bus running yet long enough to have a warm idle since the new found problem

Have a look if anyone can.

[panel]

Ok.......here's the latest in my cold starts. I try this for about 5-7 mins before it comes alive. I did also have a problem with not having the right coil/charge setting. I had it set to standard coil and I'm EDIS.....so this was definitely an improvement. I've tried a few different cranking pulses and I can't really seem to get a great first few starts with it. I'm not sure if it's cause the CLT sensor is just below the cylinders when maybe it's better screwed into something but it does read ambient I guess when cold out.

Hot starts by the way are flawless!

Here is a log .......I didn't start doing it right away but thought after that I should really get this taken care of. Also it backfires a few times while trying to start.

[panel]

It looks to me like it needs a little more fuel while cranking. In the log your PW's while cranking are about even with your idle PW's or maybe a tad lower, I usually find them to be better at about 30% over idle PW.

Hey Phil and others

When you say 30% higher than at idle is that temperature related? So if I idled at 3.0ms lets say when hot (engine up to full temp) then at my -40F am I putting in a value of 4.29ms? Or does this 30% number need to be in the 60F(lets say...ambient of motor that morning) area? If so then do I need to put 4.29ms in between the -40 and full CLT temp ...right? I only have a -40 bin and 160F bin to place these values.

Did I loose ya in this example?

[LT401Vette]

It is temp related. If i really look at it, 30% is probably on the rich side for fully warmed up. My car is actually at about 15% larger PW than idle at full warmup, but it get a good bit richer from there. By 0 degrees it is about 100% higher.
But, the engines I usually play with are not very much like a VW, so i don't know how much my ranges mean there.

[panel]

I'm not sure if this is really the right spot to post all these questions and help etc

I think I'm ready to roll the bus off the cliff. This morning it took me about 15mins to get her running And after work about the same........maybe longer. I tried lots of different 'cranking pulse widths' to make it work. Maybe I'm missing something Hot starts like I've said before are great. Could it be where I have the CLT sensor? I'm just grasping at straws now. I have tried different settings in my PWM valve but I should be able to start this without it don't you think?

When running though the bus runs SO well This is why I'm VERY fustrated

Anyhow........have a look at some logs and see maybe where there is room for improvement

First one I think is in the morning and the second one will be in the afternoon.In the second log I think the battery was getting low.........I don't think this mattered because it did finally start.

Also here is a pic of my coolant location.It is in the airstream but actually I think it's now facing up more into the head not horizontal like in the pic.Shouldn't matter but thought I'd comment just in case.

[Heribert]

Panel ,
getting frustrated or peed off is a great way to shut down your analytical skills. Go have a beer.
A few tips :
Check your cold cranking rpms.Should be maybe 20 % lower than warm cranking. How is your fuel set at lower cranking rpm?
EDIS is great. The slower it cranks, the closer to TDC the cranking spark fires. Try unplugging the SAW ( pin 3) on a cold start. Any difference.
Is your TPS correctly calibrated , so that you actually inject fuel at cranking? Recalibrate the TPS, just to be sure.

Cold starts put additional strain on the battery. I have actually had about the same trouble on a MS1Extra EDIS 6 cyl car. It would sometimes fire up after I gave up and returned the key to run from crank. The culprit was an off spec optocoupler, 1 out of a batch of 10 Siemens 4N25 had a trig current that was 10 times the 9 others and the spec sheet!
And it was just on the verge, with a newly charged battery it would start cold. With a below full power battery it would sometimes catch when i stopped cranking. A look at RPM solved it for me, after about 3 weeks of tinkering ( in a peed off frame of mind)

[LT401Vette]

Hmm, maybe there is something else going on here...
How does it do if you give it a heap more fuel during cranking?
Have you checked to see if the spark is visually hot during cold cranking?

[panel]

Heribert and Phil.....thanks for looking and advising.

I put the trickle charger on to see if this helps and I'll try some more fuel at start. I have a buddy who has his -17.6F start at I think around 146%.His Req fuel is 6.6 Maybe I'll try that? I have a req fuel of 9.7 so this'll mean if I run the same I'll have 14.1ms at the similar temp. Is this the best way to add heap more fuel during cranking

Also what should my 2 point prime pulse be at? 6 and 2

I have no way really to check to see if the spark is visually hot during cold cranking. No one's really around to help early in the morning

I'll try this and report back.