91 Prelude Electrical Issue

wrote:
> On Feb 8, 9:01 am, jim beam > wrote:
>> wrote:
>>> On Feb 6, 3:56 pm, Erdos2 > wrote:
>>>> On Feb 6, 6:38 am, jim beam > wrote:
>>>>> wrote:
>>>>>> On Feb 5, 1:31 pm, Erdos2 > wrote:
>>>>>>> My daughter is reporting some strange electrical behavior with her 91
>>>>>>> Honda Prelude.
>>>>>>> Sometimes when she does one thing electrical, then it affects other
>>>>>>> electrical things as well. For example, when she lowers the window or
>>>>>>> turns on the wipers, then the radio is affected and lights dim. Today
>>>>>>> when she pressed on the brakes, the car died (she only was slowing
>>>>>>> down some).
>>>>>>> She has had no trouble starting the car and the voltage at the battery
>>>>>>> is over 12v (I can't remember what I saw when I tested it) when no
>>>>>>> load and not charging, and 14.2v when the engine is running. The
>>>>>>> battery was bought last July, and the alternator was replace last
>>>>>>> summer too. I could not find any wires that were grounding out in the
>>>>>>> engine area. The fuse box under the hood did not show any signs of
>>>>>>> moisture or arcing.
>>>>>>> I'm not sure where to look next to solve the problem. Could it be an
>>>>>>> electrical relay.
>>>>>>> Any ideas might help.
>>>>>>> Thanks
>>>>>>> Jerry
>>>>>> Let the engine running at idle. If the idle speed drops under
>>>>>> electrical loads, then the throttle angle sensor (aka throttle
>>>>>> position sensor or TPS) might be out of adjustment
>>>>> rubbish!!! never touch the tps - it's set at factory and never needs
>>>>> adjusting.
>>>> Either way, I don't see this behavior anyway.
>>> Then you can check for ground connections.
>>> When the engine is not running, measure the voltage between the
>>> battery terminals and compare it with the measurements you get from
>>> the
>>> (+) terminal to the valve cover
>>> (+) terminal to the engine block
>>> (+) terminal to the transmission housing
>>> (+) terminal to chassis
>>> voltage drops should be no more than 0.05 - 0.1 volt
>>>> I did find that one ground was only held on by a partially stripped
>>>> nut on top of the engine, near the alternator (that was replaced
>>>> by a local repair shop last summer), I tightened it with a new
>>>> nut.It might have been the issue since it was slightly tighter
>>>> than finger tight. I also cleaned up the connection if a wire
>>>> brush.
>>> make sure you check and tighten the nuts on the alternator terminals
>>> too!!!
>>>> I don't know if this fixes it or not yet because I never experienced
>>>> the problem, only my daughter has. I drove it for about 20 minutes
>>>> after that, playing with all the electrical devices I could and it
>>>> worked
>>>> fine. Nothing got dimmer or reacted like it had any problem when
>>>> something else electrical was being adjusted or operated. It might
>>>> be fixed now or it might not be fixed. Only time will tell.
>>>> Jerry
>>> Was the rear defogger on when she experienced the problems? the
>>> defogger typically draws 25A !!
>>> Still, i don't see how the engine dies when the brake is applied, if
>>> the TPS is good,
>> that's because its not the tps!!! apart from anything else, tps gives
>> you code.
>>
>
> Except for the signal it receives from the TPS, the ECU has absolutely
> no other reference to the position of the throttle plate.

correct.


>
> The signal from the TPS is in form of electric voltage, and falls into
> a certain range (corresponding to the throttle positions at idle and
> WOT) The ECU only throws a code when the voltage it receives is out
> out range,

it doesn't know enough to understand "out of range" - all it checks for
is whether there's any connection. three leads - one at each end of the
carbon track and one for the brush - just like a potentiometer. if the
track is broken, code. if the brush is worn and doesn't contact, as
happens at high mileage where a spot wears on the track, code.


> and then defaults the throttle to a certain position.

the throttle position is entirely mechanical, so no change in actual
throttle position. as for assumptions, if it doesn't get tps signal,
injection stops.


> Your
> car will start, but will not be drivable as the gas pedal will not
> work.

that's not my experience - it cuts completely.


> Note that the ECU is completely blind to how you calibrate the
> TPS to the physical postion of the throttle plate.

you are not supposed to touch the calibration. period. the eacv exists
entirely to remove the need to ever go near tps calibration. that's why
it's shear-bolted into position - so as to be non-adjustable.

you can of course adjust the throttle plate's idle position, but the
throttle plate and the tps remain synced and in calibration.


>
> The links you sent regarding the codes for TPS doesn't work. But
> thanks for the turkey dog treat recipes. My dog loves it!!
>
> Cheers
>
>
>>> i would suspect vacumm leaks
>> that's more like it.
>>
>>> or other causes of
>>> mechanical malfunctions
>> welcome to psychic car care 101.
>