Aerovette

Hey there,
I posted this problem once before and the answers were everywhere. Maybe this is difficult to diagnose. I have more details this time around. My 95 LT1 fires right up cold and runs pretty smooth until 160 degrees or so. Then it has a slightly rough idle. If I "hot rod" it around a bit, the idle gets a little worse. When it is warmed up, it spins over quite a bit before firing up. I then sometimes smell gas and it wil blow a visible, but light amount of black smoke out of the exhaust if I rev it. The engine is bone stock and has 75k on it. Any ideas?
:confused: :confused: :crazy: :crazy: :cry :cry

jpee

With the smell of gas, & black smoke it sounds like your running very rich... Check one of your spark plugs, if they show you are rich, look at your fuel pressure...

I'd think thats as good of place to start as any..

SpedRacr93

If it were me, I would take the 4 bolts out of the fuel rails, and lift the rails/injectors up. Then take paper towels and put underneath each injector. Then turn the key on to prime the fuel system and see if any are passing fuel. One could be stuck open. Also, check to see if you have gasoline going through the vacuum line to your fuel pressure regulator. This would mean that the diaphragm in the regulator is bad.:eek:

Both of these situations could cause what you're describing to happen. The computer keeps reading a rich condition (because of the excess gas you're passing :lol: :lol: ) and it continues to lean out the mixture... which is why the longer your car runs, the worse it gets. Then raw gas inside of the intake manifold on the restart is causing the car to flood and not start easily.

Hope this helps. :cheers:

GlockLT4

Check your spark ... :yesnod: :yesnod: (which means look at your plugs and wires)

-=Jeff=-

All posts are good things to check, but also check your O2 sensors as well.

if you have a Scanner to hook up that will help to diagnose as well

emoshn

Now hear me out. Recently replaced my opti/waterpump/wires/plugs. I wanted to fire it up to make sure I had installed the opti correct. So with everything hooked up (I thought), jumped in and with a quick prayer to the Corvette Gods...hit the key. It turned over nicely but didn't want to start...then finally it started. But it reminded me of the old days with a flooded carb...ran up slowly, puffing black smoke and didn't want to idle. Bummed me to the bone.

The I noticed I hadn't hooked up the snorkle or the IAT connector to the snorkle. Did that. Back in...one more prayer. Whhuummpp! I don't think the damned thing even made a complete revolution. Been that way every since.

So...check you IAT sensor/connection/wiring. It could be something as simple as that. otherwise...count me in with others.

emoshn

Didn't quite make my point. I think not having it connected at all was causing it to send NO signal to the ECM...causing the problem. If, however, it's hooked up it could be breaking down under heat conditions somewhere. Just a thought. Starts good cold...and then turns to crap. It has to be something to do with fuel supply. It's worth a look and cleaning of the IAT, IMHO.

Am I nuts?

Bluevette85

If your car had an EGR valve it could be stuck open.

BBA

I'm liking Jeff's idea...it goes into closed loop when warm...bad O2 sensors will make it run like crap and too rich.

Besides, once it starts running rich...the O2 sensors are toast anyway.

Aerovette

Based on the above, will replacing the O2 sensors be the fix? If I put in O2 signal senders( whatever they are called) it should be a permanent fix, right? I also had someone suggest a leaking injector. Is that a possible cause? Also where is the IAT? See these symptoms coincided with the addition of the K&N and open air box. The clowns that started to put it on started grabbing stuff and disconnecting it and I jumped in and stopped them. They did not get far and I thought that it was all reconnected. I have looked everything over about a dozen times and NOTHING is disconnected anywhere. I hate the though of paying somebody $75.00 and hour to diagnose a free fix.

h rocks

Before you start throwing $$$$, time and aggrevation at it, check for codes. There may a sensor that's bad, disconnected etc. that's causing the problem. Check your shop manual for the correct jumper locations. It's free!