Time consuming start up

[prorider17]

Hey guys, whenever I start up my 95' T/A, it takes roughly 3-4 seconds for the engine to start. That's when it's cold. When I run into a store and the car is still hot. It takes usually about 1.5 seconds or so. I live in Florida so it's 95 degrees out all the time. When I had a mechanic at Ayers Goodyear look at it, he said that it's normal and that the stroke ratio in starting just takes longer. My friend has a 93' camaro V-6 that starts right up. What's going on?

[Steel2686]

Have you had a full tune-up lately? My Bravada was doing that until I changed out the cap and coil, plugs, wires, and fuel filter. Starts up within a second or so now. My T/A takes roughly a second and a half in warm weather also. It only has 17K on it, so I'm guessing it's normal.

[Injuneer]

Extened cranking time in the LT1 can often be traced to a problem with the fuel system losing pressure on shutdown. This can be caused by a faulty fuel pressure regulator, a bad check valve in the fuel pump or a leaky injector(s). Hook up a fuel pressure gage and check the system pressure on shutdown.

A second cause is difficulty in the PCM finding the low resolution oulse from the Optispark distributor. That would be setting a DTC 16 trouble code.

I would ignore the comments regarding the "stroke ratio"...... the LT1 generally starts almost immediately if its running right.

[prorider17]

like I said, it starts up quickly when it's hot. It doesn't really matter to me really, but it isn't doing anything to damage my car is it?

[94 formula]

I remeber reading somewhere that an opti spark that is functioning properly greatly reduces the amount of time that it takes to start an LT1 because of being so exact and that greatly helped reduce emissions. Is that true?

[Injuneer]

The Opti optical sensor provides data that allows the PCM to more accurately know the position of each cylinder of the engine in its 4-stroke cycle, and relative to TDC. This reduces spark scatter, meaning the actual spark occurs closer to the correct time in the cycle, with less variability. That should improve power, fuel efficiency and reduce emissions. Not sure if that also includes faster starting. There is an SAE paper that GM had published to document the system's capabilities.

Interestingly, the LT1 is not the first engine to use the "opti" concept. The idea was developed by Chrysler/Mitsubishi, and used on the 3L V8 that was used in many Chrysler and Mitsubishi car in the late 1980's. If you open up the Opti, and look at the sensor module, its made by Mitsubishi. They just had the common sense to put the distributor in the "conventional" location, rether than under the weep hole of the water pump