I recently bought a 94 Z71 4 wheel drive, with a 5.8 motor. I love the truck except if I try to drive at 5 MPH in a parking lotthe truck loads up and sputters. When I give it gas it will then leave a trail of blue exhaust for a few seconds. I gave it a tune up but that didn't change anything. One person suggested a sensor on a manifold?

I don't know if it's related but the throttle works very hard. Anyone with any ideas?

 

Well unless your runnung something after market it should be a 5.7L. Thats the same truck I have and I have no idea whats going on, never heard anyhting like that. Sorry I am no help. Maybe Argon will know.

 

Yeah I had a 93', thats a 5.7. Going out on a limb, but that could be your exhaust O2 sensors. Get under the truck and look about a foot behind the cat(s) and you should see a sensor. 70$ or so a piece.

 

Thats a real nice looking truck......

Is there a way to check if they are bad. I had another person also say it's a sensor.

Another thing I might ask. I tried to put it into 4 wheel drive tonight and the floor lever wont go either way. I looked in the manual and it doesn't say you have to force it so I thought I'd ask here. I tried it rolling forward once and pulled quite hard into 4 high and I heard it grinding, but it wouldn't go far enough for the 4 wheel engaged light to come on. Do you have to pull the lever quite hard in these trucks?

Thx for taking the time to help.... And I mistyped, it is a 5.7

 

The four wheel drive should go into 4-high easily but it prob wont go into 4-low unless the truck is in nuetral. Try putting it in nuetral and then going into 4-high, but it should into 4-high without doing that.

 

they should look charred and rattle, the same happened to my 94'.

 

If the pedal seems rough(which is what I'm assuming based on your first post) check to make sure the throttle cable isn't boogered up somewhere. Also try moving the butterfly on the throttle body by hand and make sure it isn't boogered up there. Might need some WD40 on the cable and some car cleaner in the throttle body. Other than that as far as blue smoke goes I'm thinking the valve seats are worn and it's leaking oil into the cylinders. But that's a wild guess until you actually tear the motor apart.

 

What have you tuned up so far? List everything you can think of that you replaced.

Does an engine light come on?

Can you smell gas?

Does it consume any oil?

 

So far I have changed the plugs, wires, cap and rotor. I alsocleaned the throttle body with seafoam. No engine lights are on.

The truck has 140,000 miles and burned a half quart of oil the first 3,000 miles. I guess that could be normal for a vehicle that old.

I undid the throttle cableand the cables fine but the throttle bodyseems to be sticky. I worked the 4 wheel drive and finally got it to engage. The more I work it the easier it seems. After dinner I'm going to go out and locate the O2 sensors and see how they look.

I want to thank everyone for the replies and help.

 

I think I found the O2 sensor. Right in front of the convertor there is a small sensor that threads into the exhaust. It has 2 wires going to it but I cant tell where they go to, lol. To replace it do I thread it out and do the wires plug into something and have to be replaced also?