Starting question - ZR-1 Net Registry Forums

SharkPilot · 10-16-2009

There's nothing wrong I'm just curious about how this car starts up.

Most of the time it cranks about two seconds before it lights off and is running. There are other times, usually when it's hot, that it will crank just a bit longer. Then there are times that it cranks and starts almost immediately. Recently it sat in the garage for a week while I replaced half-shaft u-joints. When I started it for the first time it fired almost immediately, less than one second of cranking. That's not the only time it has started that quickly either.

I have read that the DIS ignition needs to get all of its ducks lined up before it will start firing sparks. I'm just curious about how variable it seems to be. The car has a Rippie chip and runs perfectly so this is more curiosity than anything else. It does always start so that's a great thing. It's driven nearly every day so lack of use isn't a factor. I also use Chevron fuel all of the time so it's not a question of different fuels.

Does anyone have any ideas why the cranking time can vary?

Jason 91 · 10-16-2009

I have wondered the same. Sometimes after a month it seems to fire up right away and then other times the next day it will crank for a bit.

Everything I've read and heard tells me this is normal, but I still wonder.

Thanks,

Jason

tomtom72 · 10-16-2009

This is how I understand our ignition system works on starting the motor......this is not gospel, only my meager grasp of the event

The DIS needs the crank signal and the cam signal and a reference signal to be fully operational. Number 6 has to be at TDC exhaust so that the DIS (?) knows that 1 is on TDC compression. That's the end of my knowledge of the events that are needed. If the DIS breaks I wonder if the car just stops or is there a limp home mode programed in somewhere?

Now I don't know how it all fits together, but all that has to line up correctly in order for the motor to fire up. Oh, one other thing that is a result of the "guy in the loading lot blowing up our 90 cams"....they designed back in the delay in the programing so we get some oil up top at the cams before the motor lights off.

Sorry that's all I can bring to the dance. But, we were the first vette NOT to have a distributor!

No opti-spark for us!

10-16-2009	#1
SharkPilot Join Date: Aug 2005 Location: Anaheim, California Posts: 105	Starting question There's nothing wrong I'm just curious about how this car starts up. Most of the time it cranks about two seconds before it lights off and is running. There are other times, usually when it's hot, that it will crank just a bit longer. Then there are times that it cranks and starts almost immediately. Recently it sat in the garage for a week while I replaced half-shaft u-joints. When I started it for the first time it fired almost immediately, less than one second of cranking. That's not the only time it has started that quickly either. I have read that the DIS ignition needs to get all of its ducks lined up before it will start firing sparks. I'm just curious about how variable it seems to be. The car has a Rippie chip and runs perfectly so this is more curiosity than anything else. It does always start so that's a great thing. It's driven nearly every day so lack of use isn't a factor. I also use Chevron fuel all of the time so it's not a question of different fuels. Does anyone have any ideas why the cranking time can vary? __________________ [CENTER][SIGPIC][/SIGPIC] 1991 ZR-1 #1135 Red/Red with both tops. Stock except for an open topped K&N filter.[/CENTER]

10-16-2009	#2
Jason 91 Join Date: Mar 2006 Location: Denver, CO Posts: 124	Re: Starting question I have wondered the same. Sometimes after a month it seems to fire up right away and then other times the next day it will crank for a bit. Everything I've read and heard tells me this is normal, but I still wonder. Thanks, Jason __________________ 1991 Quasar Blue ZR-1

10-16-2009	#3
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Starting question This is how I understand our ignition system works on starting the motor......this is not gospel, only my meager grasp of the event The DIS needs the crank signal and the cam signal and a reference signal to be fully operational. Number 6 has to be at TDC exhaust so that the DIS (?) knows that 1 is on TDC compression. That's the end of my knowledge of the events that are needed. If the DIS breaks I wonder if the car just stops or is there a limp home mode programed in somewhere? Now I don't know how it all fits together, but all that has to line up correctly in order for the motor to fire up. Oh, one other thing that is a result of the "guy in the loading lot blowing up our 90 cams"....they designed back in the delay in the programing so we get some oil up top at the cams before the motor lights off. Sorry that's all I can bring to the dance. But, we were the first vette NOT to have a distributor! No opti-spark for us! __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member