valaske

so i have a 1990 4runner v6 with an auto transmission. About 3 days ago i was driving up a hill and started losing power. i originally thought it was the transmission and proceeded to change the transmission filter. after doing so the car ran fine for a minute. now it runs fine for about the first 30 seconds and then starts having no power. I did a check to make sure it wasn't the torque converter. The speed sensor has been out for a year now and has caused no prblems. i plan on replacing the speed sensor and mass air flow sensor tomorrow. any ideas what it might be? i put the pedall to the floor while going up a small hill and it won't gop over 2000rpm and slowly builds up speed when on flat ground.

Bassmastry101

iTrader: (1)

When was the last time you changed the fuel filter?

valaske

2 months ago

eric924run

do you have a way to check fuel pressure. also make sure theres no cracks or tares in the air intke boots. Also any differance if the cars hot or cold.

valaske

Haven't noticed any difference if it's hot or cold but will check. Could any of the sensors cause these type of problems?

gorillaman2012

just curious but how did you test the torque converter? did you check it in every gear? Also wondering if the throttle valve in the transmission valve body is having a problem. when you go up a hill does it downshift at all?

valaske

I only checked it in drive. I don't recall it down shifting when going up a hill

valaske

here's an update. i checked the torque converter in each gear by being at a complete stop on level ground and releasing the brae without putting my foot on the gas. each gear worked fine. when in park once in a while it sounds like two tin cans knocking, but only for a second then it sounds fine. it seems to run the same way hot and cold. when going up hill it does downshift, but slips when the rpm is over 3k. Feels like i'm driving with a governer on because it won't go over 2.5k on the tach. Any ideas or new things to check? not sure about how to check or where the throttle valve in the transmission valve body is located.

gorillaman2012

alright how your suppose to check a torque converter is you do what you did but your suppose to apply the gas to the floor for 5 seconds. write down your rpm in each gear besides neutral and park. between gears put it back in neutral and let it idle for about 5 min. come on back and tell me what your rpm was. as for the slipping at 3k are you driving highway speed or like around 30 to 45 mph?

in order to check anything in the valve body you gotta take it out of the transmission and I highly, HIGHLY suggest you dont do that unless you know what your doing and know where each and every check ball, spring, and accumulator goes. although i can help you check the torque converter at least and see if maybe the turbine or one way clutch in it is bad. not a whole lot you can do to fully check a transmission unless you can pull it out and disassemble it.

If anything just redo the torque converter stall test again like i told ya about and come back with what rpm you have in drive first, then 1st, 2nd, 3rd, and reverse. remember to let the trans cool between each one. Good luck to ya sir!

gorillaman2012

and make sure when you do that your brake is pressed as hard as you can along with the parking brake being engaged. wouldnt want that to move anywhere while you do this test

valaske

D: 1600
L: 1600
2: 1550
R: 1600

just an fyi, this problem just started suddely. I had driven the car up a big hill ealier in the day and it ran normal. then leter on that day i was coming up the same big hill and it suddenly started bogging dopwn really bad.

gorillaman2012

alrighty then. well for all of them they are suppose to be up around 1750-2050 rpm. problem that could cause them to be low would be the stator one way clutch in the torque converter is going bad or its something in your motor. you keep saying its bogging down when your goin up hill. is there any kind of engine code coming up? also you said you replaced the fuel filter not to long ago. now is that the one in the tank with the fuel pump or the other one on the firewall? another curious question is have you checked your spark plugs lately? im thinking do all of these other easy engine performance checks and if theres nothing wrong there then your torque converter is the problem and will need replacing.

valaske

No check engine lights are on, but i am going to run a diagnostic tester on it tomorrow. the fuel filter i replaced was the one underneath the rear passenger door. i was only aware of one filter though. i replaced the spark plugs, cables, distributor cap and rotr abou 2 months ago. a month after i replced the fuel filter.

gorillaman2012

hmm strange. id agree and run a diagnostic tester on it and see what your fuel pressure readings and all that are but im leaning more towards your one way clutch in your torque converter is slipping. you've done all the other work engine performance wise besides checking the fuel pump itself but i dont think thats one of the problems because it runs fine everywhere else but hills/under more load. really hate to say it cuz i know they are a pain to get out and replace but think its your torque converter going bad on ya. sorry man.

valaske

What is the most effective way to test the fuel pressure? No sweat, thank you for the input.

gorillaman2012

get a fuel pressure tester and find a place before the fuel rail in the line to hook it up to it. before you take the fuel line off though pull the fuel pump relay then start the motor and let it run till it dies to relieve fuel pressure in the line so you dont spill fuel all over you and the engine bay. then hook up the tester and plug your relay back in and then turn the key to the on position to check for leaks then start her up. at idle pressure should be 33-37psi. next find the fuel pressure regulator (should be somewhere on the fuel rail) and disconnect the vacuum line thats on top of it. pressure should go up to 38-44psi. if they are both to low then either you have something in your fuel line thats restricting fuel or your fuel pump isnt putting out enough. which then you get to go into diagnosing that. if you want help with that id be glad to tell ya what to do.

also your welcome and glad to give ya some info!

Sansocal

When you leave the truck in neutral can you rev it past 3500 rpm?

Does it sound like the engine is ever miss firing?

I would take a look at your throttle position sensor.
The tps has two jobs:
1. Tell the ecu where the throttle is so the ecu can properly adjust air/fuel mixture.

2. Tell the transmission where the throttle is so it can choose the appropriate gear.

If the tps isn't working the transmission won't down shift and the engine will run rich or lean. (no power)

Read this article and test/ adjust your tps. BTW I think in his picture of the tps its backwards, so be sure you are testing the right terminals.

valaske

it only revs to 2400 in neutral and does sound like it is running rough and rich

Sansocal

Yeah I would definetly check that fuel pressure if you haven't yet, $30 bucks at autozone or they might let you borrow one for free.

If it is up to specs check your tps and double check your timing.

Yotard

Take off your cat its probably plugged solid. Unbolt it and run it and see what happens. Happened to me once before and I thought it was the tranny as well.