Starting

[Mrbarry]

I have my zero running quite nicely these days. All re-trimmed inside, everything working well, temperatures are all healthy etc. It drives a treat and the fuelling is good too, but starting can be a bind.

I have a new battery fitted and cranking voltage stays around 11v so that’s all ok, I have two earths to the block, one from the battery direct and one via the chassis, and the positive conductors are clean 35mm CSA, electrically it’s as good as it gets. 

I have questioned the starter motor, it seems to be a bit slow turning over some times, but my biggest suspicion is mapping. I have an emerald K6 and it was mapped by Aldon Auto, I have had Motec ECUs in the past and starting is never as good as a factory ECU. I would like to know what other people experience with after market ECUs regards to starting.  It’s poor hot and cold and can be embarrassing in public, I know it always starts but it can take a few turns. 

Edited December 28, 2019 by Mrbarry

[blue]

Ok is battery large enough to supply enough AMPS to starter.  Do any cables /starter get warm while cranking Also which engine are you running. 

[Mrbarry]

It’s a Mazda 1800cc MX5 engine. Cranking amps are fine or starting voltage drops, V/IR ohms law. I’ve covered the electrical side that’s my trade. Just looking for experience with mapping and starting with aftermarket ECUs. 
I have Jenvy ITBs too btw, and fueling is metered via MAP not MAF. Engine compression is good. 

[nelmo]

I had a similar problem (zetec and Emerald) - I emailed Emerald about it, sending them my map and they sent me back a new map with some figures updated (cold start enrichment or something like that) and it's been great ever since - starts on virtually the first few turns. 

If you need me too, I can get a screenshot of the numbers they changed (need to go onto my laptop for that)... 

Are you sure about the cranking voltage? I'm sure I read in the Emerald manual that the K6 needs an absolute minimum of 11v to work properly. Could be wrong but worth checking... 

Edited December 29, 2019 by nelmo

[brumster]

In my experience most Emerald maps I've seen are very conservative on the startup fuel map and enrichment. Assuming your throttle bodies are all balanced and in correct adjustment, I'd look at the startup enrichment and also the ignition map. I'm sure you'll be happy fiddling around with the laptop making a few tweaks here and there ;). A good way to see if it's that is to just up the fueling on the base map temporarily at the startup load sites (zero throttle, <1500rpm) and see if it suddenly improves... obviously don't keep the changes, but at least you quickly prove it's not getting enough fuel. Otherwise do the same with the ignition map.

Given your location, if you get real stuck, you're welcome to meet up and I'll help

[theduck]

With options available on aftermarket ecu’s, startup should be able to be just as good as a factory ECU. Problem is, it takes lot of time and tinkering and letting testing them car at different temps etc and so most tubers won’t do it properly if they touch those areas at all and those that do often times the customers don’t want to pay for the extra time and hassle of leaving the car with them!  Anyway, point was, you should be able to get it to start quickly on the key and idle nicely from cold with a little time and effort. 

[Mrbarry]

Thanks guys I’ll have a tinker. I’ve been working 14 hour days all over Christmas (have to work every other Christmas) so I haven’t had chance yet. 
Brumster you’re always welcome to pop over, I’ll get the laptop out the weekend and play a little. I am an Emerarld virgin, on MoTeC I was happy to add and assign inputs and outputs etc, but fueling I only touched once, added 3% globally and removed 1 degree global ignition advance when I swapped engines and didn’t have time for a remap before a race event, was a risk but paid off nicely. 
 

 

[Mrbarry]

Thought I would add some updates to this. 

I have put off making any changes but have been messing for a few days now. I downloaded the manual for the K6 ECU, it’s a bit long winded in places but very easy to follow. I’ve learned loads about the ECU and have to say I’m impressed with it on paper. 

As for start up Enrichment, I looked at their suggested numbers and was sure my start up was too lean, I have added masses of fuel at first, second, third, fifth and tenth cranking cycles, I abandoned the standard 1,2,3,50,100 resolution, who holds the key and cranks for 100 cycles? I was able to map it at 20 degrees C because that was my current load site as the engine was at 19 degrees. I warmed it to 30 and did it again, then 40, 50 and kept adding fuel at each site, results getting better and better. As soon as she fires she runs a dream. The biggest improvement came from increasing the initial injector prime values, these where all extremely low. Now it’s very close to how I want it. 
 

I still get the occasional spit from the throttle bodies when starting and that indicates either weak mixture or cross firing of the plugs due to poor timing or HT leads shorting under load. I have new leads and plugs to fit tomorrow and try again. I am confident it’s not a timing issue because she runs sweet once started. I’ll be running the engine in the dark later, hood off, to look for cross firing due to HT lead break down. Then it’s a bit more tweaking to the fuel enrichment until I’m happy. The initial injector prime is going to get more attention first, that’s what gets the engine firing early in the cranking cycles according to the manual. 
 

I will add more info once I’ve got there. Might help someone else.