won't start hot

re-animator · Post by **re-animator** » Mon Aug 28, 2006 1:52 pm

OK, I dinked around with a priming pulse, and then it didn't start at all. I'm guessing that I'd need to richen up the -40 to 170 boxes at the same rate, i.e.:

-40 is at 2.0 and I increase it to 2.5, and 170 is at 11, I'd go up to 11.5.

sounds about right?

I put the priming pulse back to 0 and the car starts up fine when it's cold, but still no go when hot.

thanks!

dragbike1300 · Post by **dragbike1300** » Tue Aug 29, 2006 5:30 pm

I'm also having the same problem. It's very embarassing. I've had more than enough of the hot start problems, so I am getting rid of MegaSquirt this winter and going with something else.

Bernard Fife · Post by **Bernard Fife** » Tue Aug 29, 2006 5:40 pm

re-animator,

OK, I dinked around with a priming pulse

The prime pulse should not be used to start the car. It is intended for clearing out any air that may have entered the fuel system. It is not dependent on engine temperature (except in the latest beta MS-II code and maybe MSnS-E).

Instead, you should be adjusting the cold cranking pulse width and the hot cranking pulse width. There's lots more here: http://www.megamanual.com/v22manual/mtune.htm#howto

-40 is at 2.0 and I increase it to 2.5, and 170 is at 11, I'd go up to 11.5.

This is backwards. The cold cranking pulse width should be about 3 to 5 times the hot prime pulse width. Yours is the other way around.

If you have port injection, reasonable numbers are about 20% and 80% of your req_fuel number (the 'upper' number in the calculator that is not adjusted for the number of squirts, etc.)

Lance.

dragbike1300 · Post by **dragbike1300** » Wed Aug 30, 2006 11:38 am

I think it's a voltage problem.

re-animator · Post by **re-animator** » Thu Aug 31, 2006 2:10 pm

Thanks, Lance.

As usual, I'm looking for a HUGE solution to a very small problem. I finally figured out where and what to do, thanks to your help, and the help of all the others.

I'm running a converted LT1 manifold (that's off a '94 vette) and my req_fuel is 12.7. I'll set the -40 to 10.16 and 170 to 2.54. The ECU will automatically adjust and that should do it? Maybe a few adjustments, but that should be in the ballpark. I'll post soon and let everybody know how is goes.

Dragbike1300, hope you can get yours figured out, too!

Thanks

re-animator · Post by **re-animator** » Mon Sep 04, 2006 5:10 am

OK, it looks like it's fixed. I increased my cranking PW to 3.0 and 11.0 and it started hot twice yesterday. I'm going to try it again today but I think we have it solved. Thanks for all the help.....

If anybody else has questions how I did it, PM me and I'll tell you how I got there.

thanks again!

MicroSquirt.com read only forum (Jan.15,2018)

won't start hot

Won't start Hot!