mountain goat

my 85 4wd fi toyota pick up is missing at every were when the motor warms up. not a ton and its not consistent making it fail smog. it has a new head, tps, cap, rotor,wires,and the tps is in spec as per 4crawlers directions. i have tryed searching for the last few days but havent been able to find anything. i dont know when the problem started because i just bought the truck because it failed smog. any suggestions? could it be the coil? ignitor? i dont know how to test eather of those so i dont know if they are good.
ps it isnt throwing any trouble codes.
thanks in advance

myyota

Have you changed the fuel filter ?, also check the air inlet hose that conects to the front of the throttle body, sometimes it can crack and that will allow unmetered air into the engine and that can cause a miss.

mountain goat

yep brand new filter. i will double check the inlet hose but it didnt appear to have any cracks.

mountain goat

do the computers in these trucks have to reset them selfs when you put new parts on? i was told that you had to drive 50 miles when you put new electronic parts on? is this true?

new parts so far = tps, coil, afm, cap, rotor, wires, and plugs and still missing. thinking about takeing it to a shop.

stangr351

did you try adjusting the valves? and does it still have all the smog equipment(cat,smog pump,etc)?

mountain goat

yes i have adjusted the valves multiple times.
yes it still has all the smog equipment,
update. i cleared up the high rpm miss but the i took off the egr valve and cleaned it and it brought back my high rpm miss!!

4Crawler

iTrader: (3)

Might want to test out the EGR modulator and valve per the Factory Service Manual procedure. Could be yours is connected wrong and opening the EGR at the wrong time.

1990yota-pickup

do u have a propely function knock sensor...

its the sensor just left of the oil filter..

mountain goat

i will try the egr modulator tommorow.
i dont know if my knock sensor is working or not. but its not throwing any trouble codes.

thanks!

1990yota-pickup

un plug your knock sensor and start the engine it should make the check eng. light come on...

mountain goat

i couldnt find anything other than how to clean the filter in the modulator so i cleaned it and it didnt make anything better.
i did figure out that it runs good cold and the miss gets worse as the motor warms up. then if you shut the motor off when its hot and restart it it runs like crap. so now im realy confused.
my knock sensor is working

4Crawler

iTrader: (3)

The FSM has a testing procedure for the modulator and other EGR stuff. For a quick test, pull and plug the vacuum hose from the modulator to the EGR valve and see if that helps. The BVSV up front of the engine opens when the engine warms up and sends vacuum from the throttle body to the modulator. The the modulator decides when to turn the EGR on based upon engine load. If it is plumbed wrong, it could be opening the EGR at the wrong time.

dropzone

iTrader: (6)

link to Factory Service Manuals

mountain goat

ok i talked to one of my buddys and figured out that all the vacume lines are routed correctly and my egr is working. but it has a lean miss. he thinks that one of the injectors isnt fireing right causeing the rest to get thrown off. does this make any sense?