rough idle and hesitation when taking off from a stop

[90rangersuper]

I have a 90 ranger supercab, 4.0, a4ld and a 1354 electric t-case, when i start the truck cold it idle very rough, it gets better when the truck is warmed up but it is still there. the idle when it is warm is about 500rpms higher than it usually is. Sometimes when i go from park to reverse or to drive it will just die on me. the check engine comes on some times, that all started when it was really cold (-20)and it would not start, tried for 15 minutes and it finally started ever since then the check engine light came on and the rough idle got worse. I am thinking i have fouled out some spark plugs but that is my guess, or a O2 sensor giving me a bad mixture, my gas milage has also decreased since this has all started. Any help would be great. thanks

 

[reno]

Have you pulled any codes yet? Sounds like either a vacuum leak or the beginings of the Mass Air Flow, the IAC can do this also. Pull the codes first and go from there, post your codes here on the forum so we at least have a little more direction. Kind of hard to diagnose without being at your truck.

Also we need to know if you changed or replaced anything recently i.e. K&N filter added, spark plugs, etc...

 

[97ranger4x4]

I know this vehicle is pre OBD II

What is the extend OBD I will throw codes? I thought OBD I didnt have the extend of codes such as OBD II. Anyways if it does throw codes those will be helpful. Did this happen all of a sudden or has the problem slowly come on?

Keith

 

[reno]

Yes, OBD I will throw codes, do you have a haynes manual? I think there is a section here on this site to show how to get the codes with a analog volt meter and also to get the codes using a jumper wire and counting the flashes from your check engine light.

 

[90rangersuper]

this just happened all of a sudden, one day after work it ran like shit

 

[reno]

Go here and do some reading.... http://www.therangerstation.com/tech_library/OBD_I.html
This will explain how to obtain those codes.

 

[90rangersuper]

Have you pulled any codes yet? Sounds like either a vacuum leak or the beginings of the Mass Air Flow, the IAC can do this also. Pull the codes first and go from there, post your codes here on the forum so we at least have a little more direction. Kind of hard to diagnose without being at your truck.

Also we need to know if you changed or replaced anything recently i.e. K&N filter added, spark plugs, etc...

just got to working on the truck this weekend, truck would not stay running, i changed the plugs and wires, all the plugs were fouled out, after replacing the plugs the truck will now stay running, it still runs rough, wont rev over 3000 without fluttering, have not seen the CEL come on since the plugs then again i only drove about a mile, I am gonna get back to fixing the truck here next week, just wondering where i should go from here, plugged cat, o2 sensor. i am gonna try the MAF but i have no clue what the IAC is, ne help would be great, you guys are awsome

 

[90rangersuper]

BTW, working on the truck on saturday, i had it running for about 10-15 minutes ideling and then it just started running rough and black smoke came from the tail pipe, i know this means the mix is to rich, just thought this might point to the problem better

 

[90rangersuper]

go it fixed, pulled my codes, o2 said it was lean when it was already rich, replaced o2 runs like a champ, thanks for all your help