EZ EFI New Tune every time engine is started.

[Webby]

Lim34 don't think you have the same problem as me.
My car starts perfect from cold. I don't even need to be in it. Just press the button and away she goes. Idles higher as it should until warm then drops to set level. Then when warm the hunting starts.
I would say without any further info that either your fuel pressure is higher than what is set in the software so making the mixture very rich until the engine warms enough for learning to switch on. Learning will then correct the richness however the same problem will occur next time you start from cold until learning comes on. Or your idle is adjusted so that the IAC is unable to keep the idle high enough when engine is cold. Just my thoughts.

[FAST Tech Maxwell]

Lim34
Double check your IAC number at a warm idle. 20 is usually a good number. Sounds like you may need to open up the throttle blades a little bit.

Webby may be on the right track. Maybe double check the fuel pressure with a different gauge than the one on the car. Also, make sure that you have the vacuum line hooked up on your fuel pressure regulator too.


Webby
Any chances of vacuum leaks on your engine? Just a thought.

[Webby]

Thanks Matt,
Don't think I have vac leak but I will check. Problem has occurred since I installed new throttle body and 8 injector manifold so its possible. Will take a while as engine not running after water pump failure at weekend.

[lim34]

Thanks for your replys.

IAC when idleing warm is around 48.

Fuel pressure is at 43psi.

Vacuum line is connected to regulator ok.

[Webby]

Throttle blades need opening up a bit to get IAC down to 20 (some people run with 10) This will allow the ECU to speed up the tickover with cold engine more. That may solve it.
When I first installed my EZEFI I set the fuel pressure to 43 with the engine running and the vac line still connected thinking that it would make little or no difference. I had exactly your symptoms until I removed the vac line and had to reduce the fuel pressure significantly to get 43. Pressure at idle with vac line connected now reads nearer to 35 which is correct. Also it is not unheard of to have a pressure gauge that reads incorrectly. That difference in fuel pressure was giving me about 20% too much fuel! WHen engine gets warm and learning kicks in it can correct for this but cold start will always be crap because ECU is fuelling for a lower fuel pressure and hence giving the engine too much.
Plugs will foul if engine is overfuelled but the plugs wont cause the problem.

[lim34]

Will try that Webby, thanks for your reply.

Ian

[SoCal]

... That difference in fuel pressure was giving me about 20% too much fuel! WHen engine gets warm and learning kicks in it can correct for this but cold start will always be crap because ECU is fuelling for a lower fuel pressure and hence giving the engine too much.
....

I just wanted to make a quick point about this. You are correct that the engine does need to warm up for learning to occur. But it is always running in closed loop to get your AF ratio as close to your requested target as possible. Now there are limits to how much correction you can get from closed loop alone. And with learning active, fuel can be altered even more since the underlying fuel tables are then being adjusted. But in normal operation (no goofy issues, ECU has had time to learn, etc.) regular closed loop should keep the engine happy even before learning becomes active.

You are also correct that getting the fuel pressure right and connecting the vacuum reference are important. Closed loop and learning will work to compensate for mistakes there. But a proper installation will always make for a better running system. General observation - not aimed at anyone in particular.

[Webby]

Thanks I wasn't aware of that. I repeatedly saw -25% correction on my fuel mixture when engine was cold and fuel pressure too high. It would then go almost instantly to 0% when the Auto Learn kicked in.

[lim34]

Have reset IAC down to 20 and fuel pressure to 40psi.

Engine seems to behaving correctly now.

Thanks again for your input.

Ian

[Webby]

Excellent!
Fuel pressure with engine running and vac pipe removed should be the same as what you have programmed in the handheld unit