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Cold Engine Start Up

Posted: Sat Aug 29, 2009 1:21 pm
by cchan
I was just wondering if anyone knows why a cold motor is hard to start up while a warm motor is not.

On my GTV6 if the temp is around 50 degrees to 60 degrees it takes about 5-7 cranks for it to hold the idle. Once it is warm it starts up on the first crank.

Today, it is around 80+ degrees and when I tried to start it it started up on the 1 crank. We are going to work on this in the near future but I was just wondering the logic behind this. My GTV6 runs perfect after warm up but I want it to start up faster when cold.

Thanks for any insight on this.

Re: Cold Engine Start Up

Posted: Sat Aug 29, 2009 4:52 pm
by Murray
Cchan one of the best explanations of the principals involved is on Greg Gordon's website http://www.hiperformancestore.com/Ljetronic.htm
Scroll down to "Cold start system"
Basically your engine needs a richer mixture on cold start than it does otherwise and on the L-Jet system there are 2 devices that accomplish this task, the Cold Start Injector and the Auxiliary Air Valve.I believe your car no longer runs the stock L-jet but the principals still apply and your aftermarket controller would increase injector pulse time based on coolant and intake air temperature.Probably needs a little tweaking of the programming to get it right.

Re: Cold Engine Start Up

Posted: Tue Sep 01, 2009 1:34 am
by kevin
Need to remap cold start at cold temp(winter) and it should be perfect on first crank(richer mixture). I think you can map gotech from -5 deg. Thats why the car is normally left overnight at dyno shop so they can do cold map following day. To rich and you wash the walls of barrels.