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nissan pickup still not running right

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  • country_boy

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    got a 93' nissan hardbody 4 cylinder and once it gets to operating temp. it wont idle right. It drives fine on the highway. Ive changed the plugs, wires, cap, rotor twice in the past 2 months. The weird thing is, it isnt throwing a engine light. Any ideas? Vacuum lines all seem to be in good condition.
    Hurley's Gold
     

    MadMo44Mag

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    C-boy need some info to help
    Is the a Frontier?
    2x4 or 4x4?
    Auto or Std?

    It sounds like a TPS - Throttle Position Sensor

    Also any SES on? Service Engine Soon light

    More info
    "
    The throttle position sensor responds to the accelerator pedal movement. This sensor is a type of potentiometer which transforms the throttle position into output voltage, and emits the voltage signal to the ECM. In addition, the sensor detects the opening and closing speed of the throttle valve and feeds the voltage signal to the ECM.

    Idle position of the throttle valve is determined by the ECM receiving the signal from the throttle position sensor. This sensor controls engine operation such as fuel cut."
     

    country_boy

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    this is before the Frontier. This is a small pickup aka the hardbody. 93' d21
    2wd. auto transmission
    No check engine light is on. It is fuel injected(mpi)

    I was thinking it was the tps. However, I think a trip next month to Lambs is a good idea just to see what else might need replacing.
     

    MadMo44Mag

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    This is a likely cause.

    Classification: EF&EC94-O16
    Section: Engine Control System
    Models: Trucks (D21) with KA24E Engine
    Reference: TECHNICAL BULLETIN NTB94-106
    Date: November 22, 1994
    TRUCK(D21) ENGINE IDLE FLUCTUATION
    APPLIED MODEL:
    Truck(D21) with KA24E Engine SERVICE INFORMATION
    42141782.jpg

    Some Trucks may exhibit a surge or an intermittent idle fluctuation. The incident may be difficult to diagnose, causing several repair attempts to be made. Such incidents may be caused by a poor electrical connection at a splice joint where the ground wire (B/G) from the E.C.M. meets three other wires from the Engine Coolant Temperature Sensor, Exhaust Gas Recirculation Temperature Sensor and the Throttle Position Switch. If the splice joint connection is poor, the ground for these sensors is intermittently interrupted, causing improper E.C.M. input readings. The incident may be induced or alleviated by moving the engine/injector harness by hand as shown (Figure 1).
    SERVICE PROCEDURE
    42141783.gif

    1. Remove air cleaner assembly and detach engine harness from engine (section between valve cover and throttle body). (Figure 2) 2. Remove the harness covering (plastic shield/electrical tape) and locate the splice connection. A single ground wire (B/G) is connected to three other wires (also, B/G) with a pressed metal connector.
    42141784.jpg

    To ensure a positive connection at this splice, solder the metal connector to the wires to form a permanent connection (Figure 3).
    3. Wrap soldered splice with heat shrink tape to ensure a waterproof seal. Reinstall plastic shield and wrap with 3M Electrical Tape (3M P/N 88) or equivalent. 4. Reattach harness to engine and replace air cleaner assembly. 5. Test drive vehicle to ensure that incident is resolved.
    42141785.jpg
     

    MadMo44Mag

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    Also -

    Throttle Position Sensor (TPS) Operating Characteristics
    42131105.gif


    PURPOSE
    To provide the ECM with a voltage signal that corresponds to the opening angle of the throttle.

    LOCATION
    Mounted to the side of the throttle housing.

    OPERATION
    The Throttle Position Sensor has both a linear potentiometer (sensor) and Idle/Wide Open Throttle (WOT) switches.

    Throttle Sensor:
    The sensor receives a 5 VDC reference signal from the ECM. At idle, the sensor will output approx. 0.4 VDC to the ECM and upwards of 4.5 VDC at wide open throttle. The ECM uses this voltage signal to calculate throttle opening angle and the speed at which the throttle was opened.

    Throttle Switches:
    The Throttle Switches (Idle and WOT) are NOT used by the ECM to manage the ECCS system. The switches are used by ECM for self-diagnostic purposes only.

    Testing

    Fig. 153 Throttle Sensor Inspection
    42317139



    1. Disconnect throttle sensor connector.
    2. Using an ohm meter, check resistance across terminals e and f. Resistance value should change smoothly, without any glitches, from approximately 1 to approximately 9 ohms as the throttle is moved from idle to WOT. Replace sensor if it fails the above test.

    REMOVAL


    1. Turn the ignition key off.
    2. Remove the intake air duct from the throttle chamber.
    3. Disconnect the idle switch and throttle sensor connectors.
    4. Remove the 2 bolts securing the unit to the throttle chamber and remove the unit.
    Throttle Sensor
    42318131.gif


    INSTALLATION AND ADJUSTMENT


    1. Install the unit to the throttle shaft, aligning the flat area on the shaft with the flat area on the unit.
    2. Install the screws and tighten slightly.
    3. Reconnect the throttle sensor and idle switch connectors.
    4. Install the intake air duct.
    5. Start the engine and warm to operating temperature.
    6. Using a volt meter, check the output voltage between terminals as shown.

      1. If the voltage is between 0.4 - 0.6 vdc at idle, the sensor is adjusted properly.
      2. If the voltage is not between 0.4 - 0.6 vdc at idle, proceed to step 3.

    1. Loosen the throttle sensor securing screws (2).
    2. Rotate the sensor until 0.4 - 0.6 vdc is measured between the terminals at idle.
    3. Tighten the screws and recheck the voltage.
     

    country_boy

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    I appreciate it, I will show this to my uncle, Im not good with electrical and or computerized sensors on vehicles. That and I dont own a soldering iron yet.
     

    M. Sage

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    Doubtful that it's the TPS. The bad splice connection is more likely, but I'd try cleaning the throttle body with carb cleaner first.

    Hold the throttle wide open; note where the throttle plate sits close to the bore, spray the bore with cleaner and wipe the area where the throttle plate rests near the bore with a rag. Give it another spray to get the rest of the gunk off (may have to repeat the second step a couple of times if it's really bad), then start the truck.

    It'll be hard to start since it's flooded. You can either let it sit overnight and try in the morning, or you can hold the accelerator to the floor to turn the fuel injectors off. Once it starts it'll take maybe 10 seconds to clear the cleaner out of the engine.

    Probably 90% of the idle problems (not counting misfires) I run into at work are fixed with a throttle cleaning.
     

    country_boy

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    Cant be the throttle body, I ran three cans of b-12 chemtool and cleaned it.
    I also dont run 87 octane, I run 89 octane with seafoam so everything stays clean,
    I bet it is the splice.
     

    M. Sage

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    Stop, back up. You ran three cans of B-12... through what? Did you put it in the tank? That won't clean the throttle body on a port-injected vehicle, since the injectors are at the ports, which are quite a ways downstream of the throttle. You'd have to run it through the throttle, engine off (I prefer a cold engine so I don't catch fumes like mad).

    Running 89 octane is honestly a waste of money. You won't gain anything from added detonation resistance, which is all that octane is a measure of. Seafoam is killer stuff, but again it's going in the gas tank, which won't affect the throttle. Unless your vehicle is tuned for higher octane fuel, running the "better" stuff is as good as pissing money away.
     

    country_boy

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    running the 89 octane makes the truck better in my opinion. I get better gas mileage too. I made three long trips one in each month, one full can each trip in the fuel tank.
     

    M. Sage

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    Ok. Running the cans in the fuel won't clean the throttle. Take the air cleaner off and use an aerosol can of cleaner. B-12 is a good spray cleaner.

    There's nothing that higher octane can do for you unless the compression of your engine or ignition timing curve have been altered to take advantage of it, and then you'd need to run it to avoid preignition (ping).
     

    MadMo44Mag

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    C-Boy rechecked all my info on this vehicle as well as called a friend that is a 20 heavy line Nissan tech and he agrees - check wire connection 1st and check the TPS regardless.
    I find no documented issues with carbon on the throttle plate and per AJ tthis year vehicle had little to no problem with carbon on the throttle blade or body.
     

    MadMo44Mag

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    There's nothing that higher octane can do for you unless the compression of your engine or ignition timing curve have been altered to take advantage of it, and then you'd need to run it to avoid preignition (ping).

    I will argue a bit there Sage.
    The higher octane has a better additive package as part of it's chemical make up.
    It will reduce carbon deposits on the back side of the valves and piston tops.
    What separate top tier and bottom tier fuels is this additive package.
    This package increases the octane rating while at the same time reduces carbon build up.

    And to share a little known fact;

    The oil in you car has no lubricating properties any more.
    By the mid 70's oil companies were refining motor oil to a higher purity standard due to damage caused by sulfur and other contaminates in engine oils.
    Sulfur is a good anti knock compound and works well in automotive fuels but plays hell on bearings and gaskets over time. Sulfur is a mild corrosive.
    Added note; Sulfur has almost been fazed out of automotive fuel completely today. It also has been replaced with man made additive packages.

    As time and technology went by, the lubricating properties of oil were refined out till only a viscus carrier remained.

    Keep in mind it take less than 2% of the oil volume to lubricate the engine. The rest is used in cooling the bearing and reciprocating parts.

    Now with only a viscus carrier remaining a man made lubricating additive package was added to the oil thus giving it back it's lubricating properties.

    This is how on so many new cars the manufactures only requires a 20SAE oil. There is no need to up the viscosity because of the additive package.
    It also reduces carbon build up in the low tension oil control rings.

    There is a lot more to this but this is the Sunday afternoon version. LOL!@!!!

    Not trying to be a know it all just sharing some automotive knowledge most folks don't know and may find interesting.
     

    M. Sage

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    Yes, the higher-grade fuel has a slightly better additive package, but there's no reason to run that package all the time. You'll get as good additives in brand-name fuels. Talked to a petro-chem engineer about it once. :D

    It takes more than 2% of oil volume for the lubrication system to work properly. It typically requires 1-2 quarts. The oil doesn't technically lubricate, but simply creates a hydraulic barrier between the moving parts. It's flow that's king, which is why 5w20 oils work so well. They actually lubricate better, since you have more flow at the same pressure. More oil flowing between parts means more sure lubrication. Most cars would be more than happy with 0w20 or even 0w10 oils.

    There are also a couple of other reasons to add volume besides cooling (though that's a big one). Dilution of contaminants for extended service intervals is a very big reason these days. Other lesser reasons are to keep the pickup tube covered in higher g loading a car might experience (turning, accelerating, braking) and to keep the system working properly under higher RPM operation when much of the oil can wind up higher in the engine while draining back to the pan.

    Every new oil API rating has half the additive package. ;)

    - ASE Master/L1 tech, been in the biz around 10 years now. ;)
     

    MadMo44Mag

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    - ASE Master/L1 tech, been in the biz around 10 years now. ;)
    OK not to start a pissing match but we hold the same certs and I got 15 years on ya.
    Also spent 10 as an auto/ diesel machinist. crank grinder, align bore man and engine builder. M1G Gasoline Engine Cylinder Head Specialist, M2 Cylinder Block Specialist, M3 Assembly Specialist
    Add to that 3 years wrenching a blown funny car.



    Deleted Post

    I deleted my response because I value you as a fellow TGT member and do not wish to offer up any reason to damage our general forum relationship, but you have some facts that are incorrect and some that are miss applied.
     

    Texas1911

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    Guys, the pissing match has nothing to do with this guys problem.

    The KA24E, and it's twin cam brother KA24DE, are both finicky in the idle department, especially late in life. Odds are your idle air control valve is gunked up and when it goes into the warm idle the opening is choking and causing the motor to hunt. Sometimes cleaning it out with carb cleaner while the motor is running, or taking it off and cleaning it out well, works.

    Another issue on alot of Nissans that causes warm idle issues is the AIV (Air Injection Valve) it's the little black box that has a big vacuum line attached to the air intake tube by the airbox. Pull off the vacuum line, block the hole in the intake, start the engine and let it warm up. Once it's warm blip the throttle to about 2 - 3K RPM and lift off. See if you get any backflow out of the valve. It's supposed to have a backpressure transducer valve that prevents backflow of the exhaust into the intake, alot of times on the SR20DE / KA24E / KA24DE engines they fail and it will backwash exhaust gas causing the car to surge and drop idle.

    I don't have certifications, but I know my fair share about Nissans.
     

    country_boy

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    Is that something a certified nissan mechanic will know to check?? I just dont know much about nissans and imports in general to know what does what etc.
     
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