Can any of you guys help me????

[Mrdoooner]

Alright, so i have this truck, it's a 1986 Nissan D21 4x4 v6 ext cab with 5 speed. I bought it off my uncle, a guy said it needed a computer, so i paid right at $400 for a new computer, and then i put new injectors in it, plugs,wires,and dizzy ca, i also checked fuel pump and all lines, clean not gummed up, both fuel filters are new,psi on gas is correct, and now i have nowhere else to look. The truck will run, as long as you keep it running, but as soon as you let off of the throttle it goes dead! anybody know what this could be?

Will trade for a running motorcycle:-)

 

[Mrzllewellyn]

Idles not set high enough... Not getting enough air maybe... Air fuel mixture could be off

 

[Daniel]

Vacuum lines can be leaking

 

[Mrzllewellyn]

Vacuum lines can be leaking

True that too lol

 

[Sti470]

There are a lot of things that it could be and without knowing what it was doing before, and what someone has done to it, it will be really hard to diagnose over a forum. You will need to start at the very beginning of the basics. If you can't get an accurate history then you should start with spending some time making a good visual inspection of all hoses and wires. If you have a manual, look it up and see if you can pull the codes by using a jumper wire in the tester port. It may tell you quickly what the issue is (for example bad throttle positioning sensor or mapp sensor) If there are no codes and everything looks connected, start with a compression test. When you pull the plugs look closely at each one and refer to the pictures in the manual to "read" what they are telling you. If all looks good then you need to verify both mechanical and ignition timing, since you don't know what someone might have messed with and changed. From there you will need to figure out if it is dieing from an individual cylinder issue or a general issue. For example as you slowly lower the rpms is there a skip or does it just die smoothly. If there is a skip you will need someone to help you. You will need to figure out if the skip is electronic or fuel related. While idling at an rpm that can be maintained steady, disconnect one injector at a time. Each time you disconnect a "good" cylinder the rpms will drop. Reconnect it and go to the next. Everytime the drop in rpms should be about the same. If you get to one that doesn't change when it is disconnected, then you know that cylinder is dead. do all six. (if you can't disconnect each injector, you can do the same test by removing a plug wire one cylinder at a time. Be careful.) If you find a dead cylinder you then need to find out if it because of a lack of spark or fuel. You can pull the plug and lay it on the engine with the wire connected, start the engine and see if it is sparking. If not trace it back from there. If it is, then pull the injector and see if it is spraying. This should get you in the right direction