Fuel & IAC @ Startup

[Mad_Trbo]

Warm startups, would most of you say the car requires more or less fuel on a warm startup than a cold? Additionally what about the IAC motor should this be opened more or less?

I am asking because my car does not start as easily on the warm start up as it does on the cold. Honestly it cranks over more than I would like on the cold start up as well. I never have gotten the one turn and vrroooom of the stock ECM. I am thinking because it takes a minute for the crank sensor to register, but I can't help to think this is not the real reason.

I think my start up parameters are not dialed in. Any of you using the XFI get a stock like crank up?

Thanks for the feedback,

 

[RickWI]

You would have less cranking fuel on a hot startup versus a cold startup. cold can be as high as 20 to 25 MS and hot in the 7 to 13 MS range. i suspect you would want to go into the coolant temp vs cranking pulse width table and raise the PW's up where the water temp is in the 150 to 180 range. I'd do small changes like .5 to 1 ms increases at a time.

The IAQ motor position should be lower as well on a hot start.

 

[Mad_Trbo]

You would have less cranking fuel on a hot startup versus a cold startup. cold can be as high as 20 to 25 MS and hot in the 7 to 13 MS range. i suspect you would want to go into the coolant temp vs cranking pulse width table and raise the PW's up where the water temp is in the 150 to 180 range. I'd do small changes like .5 to 1 ms increases at a time.

The IAQ motor position should be lower as well on a hot start.

Increasing the pulse widths won't give me more fuel?

 

[HighPSI]

Keep in mind, the Cranking Fuel Table is dependent upon the injector size and engine c.i.

 

[Mad_Trbo]

Keep in mind, the Cranking Fuel Table is dependent upon the injector size and engine c.i.

I am running 83lbers on the 3.8 liter.

I would love to know if there are any XFI users who get a close to stock cranking time.

 

[RickWI]

That is true Carl, good point to mention.

Yes, increasing PW's will give you more fuel.

 

[Mad_Trbo]

Is there anyway to determine if my start up issue is to little fuel or to much fuel.

And can those of you using FAST or other EMS's tell me whether you are getting a relatively quick start up or not????

 

[RickWI]

Turn the key on, start up the FAST program, go into the cranking fuel versus temp screen and raise or lower the PW at the intersecting point. Try and start the car. If it's better, your going in the right direction, worse, your going backwards.

Yes, we can get quick light offs with the FAST.

 

[Mad_Trbo]

Quick light question

Ok so I have gotten better, so much to the point that on cold start it only turns over a few times and then it catches. It isn't smooth, kind of hiccups and then runs strong.

But if I cut it off and then start it immediately after cutting it off, it cranks right up. Does this sound like the cold crank is to rich or to lean.

I think it is to rich, I am thinking the reason it cranks right up after having run a minute the combustion chamber is warm and can make use of slightly to much fuel better than if the combustion chamber is stone cold. So I probably need to take out even more fuel out. Any suggestions from the experts?

 

[TurboJim]

Mine is a batch setup, but starts as fast if not faster than the stock ECM.

 

[Mad_Trbo]

Mine is a batch setup, but starts as fast if not faster than the stock ECM.

I can't seem to get mine to start on that first turnover. It turns over probably 3 times and then fires. I don't know why this annoys me but it does.


If you wouldn't mind sharing your crank table that might help from a conceptual stand point.