Odd running 96 impala ss 5.7L LT1


#1

Hey guys 'n gals! ok so my “Roxann” has had very minor to just odd behavior over the last few months. First, back in April, I had trouble starting her twice, two days in a row. Waited about five minutes, and she fired right up. Acted like a poor cold start, but it was 70 degrees out. Anyway that only happened twice and was never again a problem.

Well, now about a week ago, I was going to a local parts store (only a 15 min drive) for my other hot rod. Two traffic lights away as I was approaching the stop light, she just died. Now, when I had started her before I left home, I got a check engine light, but it went out as soon as she had cranked over and resumed a normal idle speed. So I thought not much of it.

Now at the light, she fired right back up and I made it to the parts store. So I’m in there about fifteen minutes and start up, runs fine for about 10 seconds and then sputters out. Try again and 5 seconds then out. Again and nothing, just a cranking motor. So now I’m pissed as hell and wait a few minutes and still nothing. So I try to get a diagnostic readout, but there is a connection error, so I get no codes for help.

So I get a ride home from my gal. At this time, it’s about 7pm. When I come back to investigate with a pal at around 2am, she fires right up as normal. Only strange thing is that there was a definite smell of gas. But all the same ran fine, good throttle response so I drove it home.

Got me home, no problem at all, but I let it idle for about five minutes, and it started to sputter again, so I gave it some throttle up to 3000 rpm and let off. But the engine continued to rev 3000. Then a few moments later, dies. That’s how I left her.

Days later, she starts just fine and I let her run for an hour! Putting the engine on load, reving up to 5000, and holding. All these things I tried to get a sense for an abnormality, but nothing. She ran like a top. I drive about forty miles a day to work and home so I dare not take this one out again till I defeat this phantom gripe. Thanx y’all!


#2

As near as I can tell, the car isn’t running all that well, sometimes won’t start, sometimes idles high, sometimes stalls. So you’re looking at any one of a number of things.

First the basics - what is your approach to basic maintenance? How old are the plugs & wires? Fuel & air filters? If anything isn’t up to date, make it so.

I’d check a number of things - the smell of fuel you mentioned would have me checking the fuel pressure regulator & coolant temp sensor. In general, I would put a fuel pressure gauge on it. The sticking at 3000 rpm would have me cleaning the throttle body. When you check your air filter, clean the MAF sensor too.


#3

Some of these cars had an issue with the power distribution lug. That’s the big post off the positive battery terminal with the red plastic cover on it. It may be attached to the fuse/relay center, I don’t remember exactly. If it’s melted or gets hotter than heck, you need to replace it. This can cause all sorts of different problems.