what part of the system (electrical or not) detects the amount of load on the engine and compensates for it by raising the throttle? (for proper idle)

ive got a suspicion that mine isnt functioning properly..

everytime it raises the idle to the proper level, it drops down again, and if the lights are on, it will close to stall (drop lower than w/ NO loads), and w/ brakelights on it will usually stall (w/ headlights on too, etc etc)

its almost like the device is cutting in and out..

what part of the system does this? BAC? TPS?

 

it's the BAC.

the TPS tells the ECU that you are at idle (if properly adjusted)

Have a peek at my web page for more info

Hugues -

 

hmm makes sense

i drove for a week with the BAC unplugged accidentally, and there was no change in the idle quality..

im gonna guess my BAC is trash..

 

A few things to check:

- Make sure your charging system is up to snuff (alt + battery + cables + grounds)

- Make sure your BAC works (See FSM for how-to) and that the ECU reacts to engine load change

- Make sure your TPS, idle speed is properly adjusted (see FSM for how-to)

and be aware that if your compression is so-so, you may have trouble idling when loads are put on the engine (probably not an issue for you but something to consider)

For FSM,
look at user SURESHOT sig

Hugues -

 

The ECU needs good clean grounds for it's low voltage signals to function.

Mine was idleing inconsistantly.

I replaced the bell housing ground & added an alternator to body ground.

Now idle is right on..

 

ive got the FSM on disc

im suspicious of my alternator.. it WORKS but.. but out such crappy amps.. 60 amp stock im told, which is like.. nothin!

anyways.. the TPS is properly adjusted, the battery is new, ive added new grounds to the chassis straight from the battery (which improved the running greatly) cables are good

ive have NOT inspected the BAC which im about to do

ive done the ghetto compression test (remove spark plugs and listen for a constant poof on cranking) and the compression was strong and steady..

anyways.. im about to check the BAC - ill post with results..

 

well i cant do much without a DMM (which ill get tonight from work)

but anyways i started the car (and it was still warm) and idled it..

keep in mind the thing is already almost choking to death at "idle".. and i unplugged the BAC.. it ran for a few seconds still and then died.. didnt cut out die, but choked itself to death as it usually does..

Amur_ and I tested the BAC by giving it 12 volts a week or so ago, and it made a very faint click..

and after that test, we forgot to plug it back in and i drove it around for a week like that, with no change in the idle.. none at all..

thats all i can tell you now though without having a DMM handy

 

Have you tried to set the idle speed as per the FSM ?

That's the first thing I would do. If your idle speed is not set right, then you'll always have problem with loads at idle.

If you can't set it correctly (idle speed too low), then your BAC could be quack (or the signal from the ECU is not coming) or you could have a vacuum leak.

For vacuum leaks, check the obvious stuff but also the diaphragms in the ACV (air control valve) and EGR.

To check if the ECU reacts to load, you can see if the voltage to the BAC is going down as you put on electrical loads. See my web page (in sig) under 'idle' for more info.

Hugues -

 

Forgot to say that I have just added a post about idle
in the sticky 'FAQ for FC'.

hugues -