Slow starting, cam sync?

[Gregconboy158]

Hi, wondering if i could get some help please. Ever since i've owned the link g4+ ecu i've always suffered with slow starting. The ecu is a civic PnP 95 on a B18 engine. On the previous Hondata ecu it would start instantly nearly, on the link it takes ages to turn over before catching, is this something i can sort? I've attached a copy of my map and hopefully a trigger scope (hope i've done it right) It is using the OEM distributor for the cam and crank sensors with K20 COP.

Also seem to be really rich on cold start i've noticed too, i have had fuel pressure issues which i have now sorted via replacing the fuel components (pump, filter and regulator) 

 

Any help be great thanks would love to get it starting a bit better, sometimes when it won't catch to it'll give the loudest backfire out of the exhaust you've ever heard! If you didn't know it did it you'd think it had blown up!

 

Thanks,

Greg

204whptrigger.pclr Trigger Scope Log 2020-12-6 10;40;23 am.llg

[Adamw]

It is really just down to the old fashion trigger design in these engines.  I believe the factory system probably used the extra 4 tooth wheel in the distributor to sync quicker in batch fire mode during cranking, that would allow it to sync within 180 deg of crank rotation.  However, that system only works with a distributor, you would never be able to convert to COP or even wasted spark with that technique so hence we dont support it. 

So with only one sync tooth on the trigger system, the engine potentially has to rotate up to 720 deg before it can sync.  If you changed to a missing tooth crank trigger then you could halve that worst case sync time to 360deg.  

Having said that - are you sure it is a sync problem?  Even 720deg should only take about 1.5 second to sync.  

[Gregconboy158]

2 hours ago, Adamw said:

It is really just down to the old fashion trigger design in these engines.  I believe the factory system probably used the extra 4 tooth wheel in the distributor to sync quicker in batch fire mode during cranking, that would allow it to sync within 180 deg of crank rotation.  However, that system only works with a distributor, you would never be able to convert to COP or even wasted spark with that technique so hence we dont support it. 

So with only one sync tooth on the trigger system, the engine potentially has to rotate up to 720 deg before it can sync.  If you changed to a missing tooth crank trigger then you could halve that worst case sync time to 360deg.  

Having said that - are you sure it is a sync problem?  Even 720deg should only take about 1.5 second to sync.  

Thanks for reply Adam, in all honesty I'm not sure i thought it would of been sync as it starts fine on the old hondata. I will do a log and send it over tomorrow if that's ok?

[Gregconboy158]

Here is 2 logs of starting it, TPS is because i've got no idle control valve so need revs to keep running until it'll idle on it's own, worse so now it's colder in England.

 

Hope these help

start.llg start2.llg

[Gregconboy158]

Anyone able to give some guidance on a possible solution?

[Adamw]

I had a quick look over the logs.

In the log "start.llg" it took 1.4 seconds to sync from when the starter was engaged, it then took a further 2.7 seconds of cranking, before it started (RPM=500).  So, a total of 4.1seconds of cranking to start.

"start2.llg" was a little better, it took 1.2 seconds to sync, then a further 1.6 seconds to start, so a total of 2.8 seconds.  

To improve the sync, you could try lowering the 0RPM cell of both trigger 1 & 2 arming threshold tables.  Im not sure how much that will help, but it may shorten the time to sync by a few teeth.  

So I suspect most of the problem is just tune/fuel related.  To get a rough idea of what direction you need to head I would suggest making a drastic change to pre-crank prime and first crank enrichment - say double the current numbers.  If that doesnt help, then next cold start try halving them.  

Another thing I notice is your start position signal on DI#3 is not working.  I dont know Honda's well enough to know if that is normal for some models or not.   But without this working it means your pre-crank prime happens at key-on (when often fuel pressure hasnt built up yet so it doesnt have much effect).  So what you could also try before starting is turn the key just to the on position (so fuel pump primes), then turn it off and on again before cranking so you get a pre-crank prime with full pressure.  If that helps then you could look at fixing the starter input so that pre-crank prime can happen in start position instead.

 

[Gregconboy158]

Thanks for reply Adam I will give that a go. The reason for the start position is because its got a switch panel which turns on the ignition and triggers the starter. Not sure if I can get around the digital input at all?

 

I also usually turn the pump on first before ecu 1&2 powers

[Gregconboy158]

I doubled the pre crank prime which seemed to have help a lot, only tried once though so will carry on trying every day for next week. The first crank enrich is already at 50%, I didnt want to double that to 100%? Seemed excessive but unsure? I left it at 50% for now. 

 

Because I've got a switch panel should I change the start input to start position or will this not make a difference?

[koracing]

The DI input for start position needs to see 12v when the starter is engaged to function.  You can connect from your start switch output to that input wire, or like Adam said you can instead keep the pre-crank prime to be at key-on instead of start position, but that means you are only getting that prime right when the ecu turns on.