I recently changed the sparkplugs in my 1995 Vette (LT1) and replaced them with platinum tipped BOSCH spark plugs gapped at 0.050. The first couple of days I did not have any troubles. The engine would start within the first second of turning the key. Now, the car does not start up as cleanly as it used to (starter has to crank for several seconds), specially when the engine has been sitting for 30 min. or more, but is still warm (as in when you go to a store and come out.) Otherwise it runs OK once it's been started. Is it the plugs? do I need to change to wires? Could it be something else (like the gas filter) that just happened to coincide with the change of the plugs? HELP!!!![sm=drlove.gif]

 

My 94 did the same thing to me before i changed my plugs. I went on a 4 day vacation out of state and when I came back to drive my car, i had problems with it for about a week. Right when i got aggravated and took the car in to have it checked out, the darn thing stopped having the problem and made me look like an idiot. I never found out what the problem was and was assuming it was because it had sat so long, but i dont think that could be it because other people only drive theirs on the weekends and they probably have no problems with theirs starting.

 

make sure your plug wires are seated well on the plugs. A shot of wd40 may help. I was going to change mine tonight but never got around to it.

 

I got fed up with it, and changed the spark plugs again. The ones I removed had a lot of carbon deposits. Sure enough, it started up quickly, but am having the same issue again. I changed the air filter just in case that was the issue, but to no avail. I made sure the gap was correct at 0.5, what gives?

 

Need to check your fuel pressure. You might have a bad fuel pressure regulator. If pressure is to high (stuck regulator or vacuum diaphram leaking) will cause a very rich fuel mixture, hence gas fouling your spark plugs. Pull the vacuum line off the regulator to see if there is gas in in the vacuum line, if there is, diaphram is leaking. Does your car black smoke @ idle? Rich fuel mixture if it does. I would stay away from Bosch plugs and run AC Delco plugs in your car. Also, check for codes to see if you have a sensor, O2, Coolant sesnor, etc. might be out of range causing a rich fuel mixture. [8D]

 

I am totally confused abou one thing: I have both the Chilton and the Hanes repair manuals. Hanes gaps the plugs at 0.050 for 1992 and later engines, Chilton gaps ALL years at 0.035. What is the correct gap?

 

You can co the Delco's website and probably find the correct plug gap for your car, Delco. Also, you car should have an emission sticker, probably on the radiator cover or around there, that will tell you the correct plug gap.

 

It was a fuel problem after all. The fuel pressure regulator just happened to be faulty, and it went bad about the time I changed the spark plugs. I changed it and the problem disappeared. I hate it when the obvious is not the problem.

 

SUPER! [8D] Glad you got it fixed.

 

Your car may now run good but use the correct spark plug gap as well. My original gm service manual shows it to be 0.035"