ive got a service engine soon light on my pickup up that will not shut off, i recently had the truck in the shop and when they would clear the codes they would be back at the next startup. for some reason the truck is running to rich and is causing misfire in the motor (the dealer did not dig into it as i only asked them to fix a few things that i was having trouble with.)

what kinds of sensors/solenoids would be telling the computer there is a misfire, i talked to one of the technicians at the dealer ship and they were saying it may be a temperature sensor but i would like to get another opinion.

 

I would check o2 sensors. What were the codes that were pulled?

 

theres a lot of codes that will turn on the mil, unfortunately can't help you much without knowing the vehicle or codes you had

 

did you pull all the plugs one at a time and check for spark?

 

the truck is a 1990 3/4 ton 4x4 (k2500) with a 350 engine and a 5 speed manual transmission, i havent checked much recently as ive only had the truck back for two days now but would like to correct and get this vehcile back to a better condition

 

i ran a jumper wire from the aldl connector under the dash and counted flashes/ codes

i got the following:

code 12
code 13
code 33
code 34

in looking online i found a website for OBD1 code for Chevrolet there it says the following:

Code 12- system normal
code 13 oxygen sensor circuit open
code 33 map sensor signal out of range High
code 34 map sensor signal out of range Low


please correct me if my translation was in correct

 

U didnt say anything bout tune up,like how long its been,check distributor cap,rotor button,plugs, for wear and gap,park truck in dark spot at nite, with engine runnin look for glow or low lite in plug wires,mite need changin,if not then go for o2 sensor change and always check connector,mite b corroded,what about air filter? map will also cause probs.

 

new plugs, wires,cap and rotor back in November (only have put maybe 1800 miles since then) im going to be replacing the map sensor here later on today (figured it might need it if i am getting a high/low voltage reading at the same time.) what would the code 13 mean?

 

if the map sensors bad and you replace it that will likely take care of the 02 code

 

Hope i'm doin this rite,not real savy with this forum or p/c's,give me a book and a wrench,ok here goes,replacin map sensor,if u know its bad,would probaly resolve the o2 code because engine would run better,if it doesnt a general full tune up should help,or replace o2,sometimes its a bad connection,close examination of connector pins could reveal corrosion,wiggle test sometimes works. Hope this helps.