cold start M800 E85

[terryo]

i have on-going issues starting when cold, and then 'getting away"

it is a track only car using a 2GR V6 Toyota engine and running E85. Once warm/hot, its mostly fine. its below about 20C ET or around 0-10C AT, where i'm having issues

My ET and AT sensors appear to be giving sensible results

Ive read other related posts and cant get a handle on this. in particular, in my table on fuel crank % trim , the values that have been set by the tuner are many times higher than MOTEC HELP suggests and what others have published when discussing this topic (see attached screen dump).

my air temp compensation is exactly as per MOTEC HELP, eg 4% at 0C and even if i double that, it makes no difference. My Ignition AT compensation is also exactly as per MOTEC HELP, but i've yet to try to adjust that.

I would be grateful for any comments/guidance

[Stephen Dean]

Hi,

It isn't uncommon to need a large amount of fuel compensation for a cold start on E85, my car for the initial start has a 700% compensation at 10 degrees C on E85, but only needs 250% on straight petrol.

The information in the help files was written using engines that only ran on Petrol (E85 wasn't really know back in the mid 90's when it was done) so they are only to be used as a guide as to the sort of direction that the compensation is normally done.

If the engine needs extra fuel to start at lower temps, give it to it. I've had "experts" tell me that I have too much fuel being injected as a first pulse on cold start, and that I should reduce it to a figure closer to the Petrol value, but the engine just doesn't start at that lower level without a lot of cranking to build the fuel film up. This is due to the location of the injectors being higher in the inlet tract and spraying on the inlet manifold wall, rather than the valves.

[terryo]

many thanks Stephen. i'm happier now to try pushing a lot more fuel in

does the M800 have any "throttle pedal squirt" provision like some of the older M4's etc. a 'throttle pump" often helped get obstinate engines to start

[Stephen Dean]

Hi,

Have a look at the Fuel Stopped Injection as this allows for a pulse of fuel to be injected when the engine is not running, this is done to provide a inlet wetting function pre-start.

[terryo]

i have tried to richen cranking but cant. The software wont accept any value about 500% which is where i am now

[AdamW]

You could use Fuel Comp 1 or Fuel Comp 2 table, put Crank time on one axis and you can add a percentage to the already commanded fuel. So if you have 400% in your cranking comp table and 50% in your Comp 1 table, you will effectively get 600% cranking enrichment.

For example:

[terryo]

thanks Adam & Stephen

i've programmed both suggestions and will give it a go soon

[Scott@FP]

As suggested it can really take a lot more than gasoline below about 20c, the first two engine cycles need to be a very heavy wetdown, then you can taper it off via crank time or engine cycles.