1993 z71 running rough

[RingMaster4x4]

I just bought a 1993 Z71 that has been setting for a while.. I got it running and now the truck does not like to run in the 1000-2000 RPM range but if you get on the gas so it down shifts it will rev on up fine. if you just ease in to the gas it will bog and backfire.. I have replaced the cap, rotor, spark plugs and changed the injectors to a pair that was not clogged. I have checked for vaccum leaks also. some mornings I have to pedal the gas to keep it moving after in gear or it will stall..

 

[AJMBLAZER]

Check to make sure the MAP sensor is hooked up and working. I put a throttle body spacer on my '92 and the sensor harness plug fell down a ways and we forgot about it. Ran like **** sorta like yours for a few days and then when we plugged it back in all was golden.

Also, you might consider posting about this in the garage as the engine was basically the same as the 87-91 350's.

 

[RingMaster4x4]

I will post there too.. well I think that I have the backfiring fixed.. the timing was off.. I checked the MAP and it is hooked up.. now I just need to fix the bogging and it will be good..

 

[dhcomp]

I will post there too.. well I think that I have the backfiring fixed.. the timing was off.. I checked the MAP and it is hooked up.. now I just need to fix the bogging and it will be good..

Timing will do that.

Did you disconnect the advance wire (brown) under teh glovebox when you set base timing?

 

[RingMaster4x4]

The manual I have had me disconnect a wire under the hood over by the fuel relay..

 

[dhcomp]

The manual I have had me disconnect a wire under the hood over by the fuel relay..

Thats probably it.

94 was under the dash, 91 was by the steerign shaft under the hood.

One wire connector, i think brown?

 

[AJMBLAZER]

Thats probably it.

94 was under the dash, 91 was by the steerign shaft under the hood.

One wire connector, i think brown?

Brown wire sounds right. On my '92 it was on the passenger side of the firewall in the engine bay under a cover.

 

[RingMaster4x4]

not sure of the color but yes just a single wire under the just like AMJ said.

 

[dhcomp]

not sure of the color but yes just a single wire under the just like AMJ said.

sounds right. Just learned more about the location variances.

 

[RingMaster4x4]

yea learn something new all the time myself.. I was driving it today and I could feel the truck surging while I was holding the gas steady. it would bog if I eased in to the gas but if I made it down shift it seemed ok..

 

[RingMaster4x4]

well the timing chain was badly worn causing the ramdom backfire and one injector was clogged some what causeing the surging.. all is good now.. thanks for the help guys.