mazdaverx713b

iTrader: (91)

on my 88 TII the power steering likes to come and go. when i first start the car in the morning i have no issues. the steering is normal. after a few minutes of driving or after i get on it a tad, the steering feels as though its no longer power assisted. then after a bit, i have my power steering back. i have adequate fluid, i have bled the air from the system, no foamy fluid, i have no leaks, the u-joints on the steering shaft have been lubed and the belt has proper tension and is new. its odd to me that its intermittent. where should i start looking?

dgking99

This happened a few years ago with my 88 GTU. It stopped doing this after a few days & has not done it since so I never did find the problem. I always suspected that it was a wiring problem.

Don

mazdaverx713b

iTrader: (91)

my suspicions are leaning towards the electronic portion of the steering as well...

Icemark

Yeah, on an intermittent one, the power steering CPU is the most common issue.

If it was an actual error in the speed sensor, or position sensor, or fluid, it defaults to always on about 25%.

Some 88 models do not have the diagnostic beep like the others do.

mazdaverx713b

iTrader: (91)

is there any way to adequatly test the power steering CPU? are there any other electronic components in the power steering system that i should be looking into or anything i can test?

ecko

iTrader: (57)

mine seems to harden up a bit too but not too much.....it really gets annoying.

mazdaverx713b

iTrader: (91)

it does get annoying. it seems as though if the problem is occuring where the steering is stiff and feels as though its non power assisted and the engine is shut down and restarted the problem goes away temporarily....then its back to the stiff steering. i really dont mind the stiff steering, i'm just going to have to get to the bottom of it. is there a way to test the p/s CPU (i get no beeps and as Icemark had suggested, perhaps my car's CPu was never manufactured with the diagnostic beep) while on the vehicle or backprobe it at all? and as Icemark advised, i may have to look further into the speed and position sensors as well..

ecko

iTrader: (57)

well if you ever find out how to fix it let me no...dont really have time to find it myself.

Icemark

The other thing that occasionally happens is cold solder joints in the power steering CPU, where on the vehicle speed sensing power steering jumps.

With the vehicle speed sensing power steering, the power steering CPU switches to different levels of boost when driving based on your speed (for example 40% boost at under 5 mph, 20% boost between 5 and 10 MPH and down to about 5% boost at 35 MPH (and of course no boost above 40 MPH).

But if there is a joint that has failed in the power steering CPU, it may drop from 20% boost to no boost instead of dropping from 20% to 15% to 10% to 0 boost.

That is probably what is happening to ecko.

Remember the power steering computer is a pretty sophisticated unit. If it looses speed sensor, after 5 minutes it defaults to 15% boost all the time. Or if it looses engine RPM signal it defaults to 20% boost all the time (making it operate much like the engine speed sensing units on the S5 models).

If it is a bad solder joint, generally it works fine either first thing or after you drive it for a while or visa-versa. For example on my old vert when it went out it wouldn't work when cold, but as the interior warmed it worked fine. But I have seen them only work when cold, and not work warm. It is usually temp related if it is a bad solder joint in that computer.

mazdaverx713b

iTrader: (91)

thats very very good advice Mark!! have you ever attempted repairing the solder joints in the p/s CPU?? my idiot light panel has bad solder joints and i can imagine that the p/s CPU could very well have bad solder joints as well. my 10AE has a good idiot light /clock panel but poor solder joints in the CPU in the driver's kick panel. if its not one its the other... i think its about time i purchased a solder sucker...

Icemark

Yeah, I used to repair them (power steering CPUs). But stopped when I sold my vert as I don't have anyway to test them before shipping other than putting them in a car, and my 10thAE doesn't have power steering.

Texas_Ace

iTrader: (18)

I am also having this problem, it doesn't work at all, then all of the sudden it would come on when i was going into my driveway, it would work perfect when i was turning hard right, but not every right turn.

Got me stuped.

turboIIrotary

iTrader: (9)

mine only works when i turn it alot for example when i clock it out it will work but if i barely turn it it won't work.

mazdaverx713b

iTrader: (91)

i guess it wouldnt hurt to pull the cpu ou and check the solder joints.

Icemark

Usually where the pins for the plug meet the board is where you will find the issue.

Mazda did a good number of CPU's like that. The supported the brain, but didn't do a great job of supporting the harness going into it. This is what causes the solder joints to go bad over time. Just the minor vibration of the harness meeting the circuit board.

So they really are not cold solder joints, but rather time failed joints, but it is tough to tell everyone that, as they rather believe that it is bad solder jobs.

13Brandon

i have the same problem.. very annoying when you're in the hills and powersteering goes out

mazdaverx713b

iTrader: (91)

Mark, that makes sense. i can see how the harness vibrating over time could cause some wear on those joints. i guess the best thing to do will be to take it apart and throw up some pics if i'm not seeing the problem.

ecko

iTrader: (57)

it does make sense hasnt happened to me in a while tho.....but still this is somthing good to check out.

Texas_Ace

iTrader: (18)

Mines the same way, except it doesn't work everytime.

OK, so now to what i am doing now. So i got out there and swaped the Power Steering computer from the 86 to my 87. And it does pretty much the same thing as before. Works hard right and left, it just seems to work more ofthen now and with a "wider working zone". But still only works sometimes, not everytime.

I know the pump and all the mechnicals are good since it works at all, so it has to be a sensor of some kind. It will not work, then all of the sudden kick in and work perfect until i leave the "working zone", but it doesn't work everytime, it seems to change if it works depending on gear, speed, or something else like that. Have not been able to tell exactly yet.

So what all controls the Power steering? what else should i swap over or test?

This is really the only thing that is keeping this car from being real fun to drive, it is fine when going stright but when you are in a parking lot it is no fun anymore.

Icemark, do my problems sound like the computer is bad on both cars? it does seem to work a little better with the second computer. or something else?<!-- / message --><!-- sig -->

rotary 817

i just swapped a t2 motor into my 87 s4 gxl and while tinkering with electronics forgot to plug in the spedo cable behind the instrument cluster. so i take it out for a test and once i start boosting i get the beeping and lose power steering. this might help your situation by leaning the problem more towards speed sensors

Texas_Ace

iTrader: (18)

Thats possible, though my speedo works fine (well it did cut out ONCE and only once). Where are said speed sensors and how do you test them?

rotary 817

not to sure look up some schematics to track them down and get an electro tester

Boosted11

iTrader: (11)

I have the same problem with my power steering. One of these days im gonna have to get to the bottom of it.

Texas_Ace

iTrader: (18)

Already did that, and had a real hard time findind a good one. The only one i found was not that great and:

1: i can barely read a wiring diagram.

2: the diagram just tells you that X wire goes to X thing. Not where that thing is mounted in the car.

clokker

iTrader: (2)

I wouldn't be so sure about this (I've seen you say this in your other thread too).
You could have bad seals in the steering rack or air in the system and get the same intermittent response.
Personally, I'd just swap to a manual rack and be done with it (yeah, I realize this is a workaround, not a fix).