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Toyota 86 MOTEC

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Hey guys,

So im running a Toyota 86 supercharged with a motec ecu. (crappy Tuner bricked the original one) Got it tuned at another "Good" shop with the motec after that and it constantly had starting issues where it would crank for extended periods of time cold and hot after it had sat there for a while. I kept taking it back there and they "tried" to fix it but what they came up with was that the ecu takes longer to find cam and crank signals.. I didnt really believe it but if thats all they can do then there is no point going back because they clearly dont know. I fiddled with it and added more cranking fuel now it starts within 5 cranks 9times out of 10 which is ok. So my question is, Because its an aftermarket ecu perhaps its not set up properly with the dual injectors and perhaps the wrong ones are firing when cranking which is why I've had to add 100% on fuel enrichment while cranking. Just wondering has anyone ran into something like this with aftermarket ecu's with port and direct injection? I am sick of paying top $ tuners for really pathetic knowledge and work. I do see a few turbo 86's running motec so im hoping someone can shed some light on the topic. Thanks guys.

With the laptop connected, it's real easy to find (using M1 Tune) how long it takes for the engine to be achieve Cycle Lock. That is when fuel and spark will begin.

What is the battery voltage while cranking? Often the coil dwell (charge time) needs to be increased if there is low voltage while cranking to have adequate spark.

Not sure what the OEM strategy is for starting an FT-86, but it would be interesting to know. It's not unusual to need 200% (or more) fuel while cranking at lower temperatures. BTW -- are you running E85? -- that is also a challenge to start when cold.

Cranking is never below 10v. Im glad you said some cars run 200% fuel because mine is only at 100% and to me I thought that that was insane. My tuner left it at 0% and said dont touch it, even after I showed how much better it made it start by adding 50%. Also it just runs 98 pump fuel which is Australians "premium" Ill add a bit more fuel every morning, see if it improves. I appreciate you assistance and feedback. Thanks.

What pi ratio u using? If you enabled pi ratio on cranking. Ur car is hard to start

The Base 86 File has numbers over 300 for the Engine Crank Fuel Volume Compensation.

which base file dean? mine has zero all the way

There are two main things that will influence your cranking fuel enrichment.

First off, the fuel you use will play a massive part. As an example ethanol does not atomise very well in cold conditions. As a result, a lot more fuel enrichment is needed to try and mix the fuel with the incoming air on cranking, instead of sitting on the intake runner wall (on port injection), or the bore and piston on a DI.

The next influence is your contribution of port/DI on cranking. Port injection takes more time for the fuel to reach the combustion chamber, therefore you tend to add a little bit more to try and aid getting it in there. With direct injection you still want a decent amount of extra fuel in the combustion chamber to ignite and get the engine running, however you don't need the enrich in for as many cycles, as you don't need it to essentially run down the port wall and trickle in to the combustion chamber.

On the M1, you need to keep in mind that the cranking enrich is against engine cycles. So if you are adding in 200% for the first 2-5 engine cycles, its not all that much. If its in there for 50 engine cycles, thats a lot more fuel. I have used 200% in some DI cars on 98 for the first few cycles (where building oil pressure isn't a concern) to help get them to fire up.

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