1989 Nissan Truck Runs Rough after tune up

[dan b]

My daughter Has a 1989 d21 pickup with 95.000 miles on it. And a z24 4 cylinder engine with a throttle body. My question is the throttle position sensor has two different plugs. I checked the one that the plug goes right on to the sensor and my meter set to 20k ohms the reading is 1 if you turn the sensor it blips some readings but not much then when i check the other plug that is attached with a pig tail it seams to register appropriately it gives me a scale reading low to high like .45 to 10.28 does this mean that it is a dual reastat and one side is shot. The truck seams to be over fueling and does not pick up when you hit the throttle like a bad vacuum advance. We have completely tuned up the truck and cleaned the throttle body. new oxygen sensor.

[htbyrico]

i had one do this before.. it was my boys hard body truck.. he spent like 665 dollars and nothing.. he took it to me and i check the air flow meter sensor .. it should be right on side of the body on side of the fuel injector unit.. it seem like it was not right so i changed it.. well needless to say aftermarket is not the way to go, still running like ... i had to buy it from Nissan.. cost me 456 dollars that was 3 year ago.. no telling what they go for now.. no promises but im 90% sure ..need hands on buddy.. in other words i need to look at it.. let me know okay.. just remember aftermarket to Nissan parts on this kind of repair..

[dan b]

is there a way to check the air flow meter i took it apart and it looked like the wires were still connected like a light bulb filament thanks for the response today i am changing the fuel injector in the throttle body be done about an hour

[htbyrico]

there is but if its doing to same thing i would change it.. carb cleaner work good..

[dan b]

I used crc throttle body cleaner. It worked great i had to remove the throttle body to access the bottom end their was a lot of crud in one passage about the size of a dime. Ounce i sprayed cleaner in it the stuff just melted away i separated the throttle body to clean more of the passage it was full. i reassembled the t. b. and the truck runs better but will kill after about 5 min. It idles low but when u rev it up it sounds good so i took it on the road ad it died about a block away my daughter towed me home i could not get it to start. I'm going to test the fuel pressure tomorrow night. May be a few things all at ounce. one question the throttle position sensor has two plugs i tested one it tested good the other plug should it read the same way it shows open or short when you turn the cam. on the second plug which is the one that has a pigtail the one they show on u tube only has a single plug right on the sensor not a pigtail just wondering I will prevail thanks a lot

[htbyrico]

okay sound like your moving froward.. i have a auto tec software so you run in a jam ill fax you over some diagrams.. im here for ya..

[dan b]

I Have hit a brick wall. The engine will not start there is spark to the cap on both coil wires there is spark to spark plugs. I pulled one spark plug it was dry after trying to start it for awhile. It will run with a little gas if i pour it in the throttle body It appears that the fuel injector is not firing can it be the computer. When we started this process we smelled electrical burn in the cab of the truck a little bit. Im going to pull the seat and check out the computer and see if it is working. we checked all the fuses and they are good i have fuel pressure 39 pounds when the truck was running but fuel pressure comes up when u hit the key then drops off to 5 psi This is when the truck is not started should the pressure be constant 39 all the time the key is on. or only when the engine is started maybe the f.p.r. is bad. should it maintain the pressure or leak down. thanks dan

[dan b]

Wow Pulled the passenger seat electrical smell at computer. opened the cover I found a power transistor that the screw that holds the transistor to the case came apart and dropped the bolt part in on the board and shorted several components. Im off to the junk yard to see if i can find one with no smell of course or find one that i can cannibalize and try to repair the board i have some elec. back ground from years ago. it could be fun anyway or the holly grail a good replacement.

[htbyrico]

sorry haven't been on.. been working hard... please e-mail me [email protected] we going to have to chat on the phone.. thanks

[dan b]

She runs It took a new transistor and a large resistor a little soldering and patience and a lighted magnifying glass. In about a hour installed the computer and hit the key, and put a smile on my face. She runs great. Thank you i hope this can help others down the road. I think the heat generated by the transistor created expansion & contraction loosed the fastener and caused all the fuss. By the way i used lock tight on the transistor screws to keep this from happening again . total cost for parts $2.55 I had to find a cross for the transistor NEC.B1099 The resistor i took out of another computer board free.

[htbyrico]

wow good job man and yes this will help others... nice work .. im here any time you need anything help..