93 Z28 LT1. i just put new plugs and wires about a week ago as well as a new alternator. been running good since. until this morning. when i turn the key sounds like it wants to start, but doesnt. if i give it a lil gas while turning the key it will start up. i have to hold the gas it she will stall out. will not idle on its own. PLEASE HELP!!

 

Does it smell flooded when you try to start it? "Giving it a lil gas" doesn't do anything but let more air in. Putting the pedal all the way to the floor before turning the key to start puts it in "clear flood" mode. See if it starts faster with the pedal all the way down.

Is it possible you knocked the coolant temp sensor (water pump housing) connection loose when you were working on the plug wires? SES light on? Any codes?

 

i do get a smell of gas when trying to start, but just a small amount. it did start a lot faster with pedal all the way down b4 turning the key, still wldnt idle though. i tryed starting it again normal way, gave me same problem. sensor is still connected. no ses light and no codes.

 

Bad idle air control valve, maybe? Injuneer, what do you think? If it stays started with gas, it sound like something with the idle or intake systems. I would say something wrong with the fuel line, but it stays started if you keep your foot on so that doesn't make sense.... It usually won't even start with a fuel line problem.

 

On my jeep when the coolant temp sensor went out it would start fine when it was cold. It's when it warmed up that it was hard to start. My $.02 would be the idle air control is not working properly.

 

You need to check the coolant temp sensor first, as I suggested. Peyton has explained why.

If that's OK, you need to figure out why its flooding. Could be excessive fuel pressure, or some leaking injectors. You can check for leaking injectors by pulling up the fuel rails with the injectors intact, and pressurizing the fuel system, looking for drips. Also check the vacuum line to the fuel pressure regulator for wet fuel - shouldn't be any.

And yes, the IAC motor could have failed, or the harness wire is "off". And since its a 93, a problem with the inlet air temp sensor, or the MAP sensor will mess with the speed-density calculation, and mess up the fueling.

 

I agree with Injuneer, I had a similar problem I had to hold the gas down to get it to crank and to keep it running after it was cranked. My code scanner showed me the problem (engine temp showed -15 deg. on a 90 deg.day). A new coolant temp sensor and it was running good. Hope it is that simple for you. Injuneer has given you a good troubleshooting path. Keep us posted.
LF

 

Just out of curiosity, but would a bad inlet air temp sensor also cause a camaro to run a bit "rough" even if the compression is like-new? I notice that decelerating under 5mph, between 45-50 mpg (just after it shifts into 4th) and while at idle that the car shakes just a bit....."rough?" I already checked the compression and it was virtually perfect. I've heard some people say it's just the magnaflow and cat that I have, but I'm not sure that's necessarily true. Haven't tried to pull codes yet, though. Anyway, car still runs great at higher speeds.

 

The IAT doesn't do much of anything in the 94-97 MAF cars. Just a timing offset at high IAT temps. But in his 93 speed-density, it makes a huge difference, because accurate pressure and temperature are required for the ECM to calculate the mass air flow.

 

Ah... Gotcha. That makes better sense, then.