i recently bought an 89 4x4 with a 4.3l. i took it down today to get emisssons test done on it and it failed. they said it wasnt burning enough fuel at idle. too many Hydrocarbons left over at idle speed. it is idling at 880. anyone have any suggestions on how to correct this issue. i purchased a new air filter for it the old was extremely dirty.

 

check/clean the iac valve (idle air control valve) its located on your tbi . that should be stuck or dirty and it wont burn the fuel right. Good luck

 

thanks i will have to try that.

 

ok i pulled out the IAC valve it looks new. i put it back in when i went to start it started and now sputters spits black smoke and then dies. what did i do wrong? she ran fine, no idle trouble. now its sputterin and dieing after it starts.

 

did you open the pin with the spring?

 

no i dont think so? whats that? was i supposed to? how would i do that?

 

did you turn that needle? on the valve if you did close it a bit its chokeing the engine

 

i dont think i turned it at all, i will pull it back off and play with it a little see if i cant get some improvement.

 

if it gets stuck that means your gonna need a new one i got the same problem on my truck and i ordered an ac delco one

 

is there a certain height that it should sit at? or is it a trial and error type of deal? because i will take it out and twist it a little one way and it will get worse, then another way and it will get a little better, then i will keep turnin it slightly then it gets worse again. idk what i did but she ran fine til i took it out. i know the iac is new from autozone. i just cant get it runnin right again so i can figure out the real problem. now its like i have 2 to deal with. if i ordered a new one would it just screw in and then the truck should run the way it did before i messed with it? and then i can figure out the emissions issue?