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Rebel_Yell69
29-11-2007, 03:41 PM
We have a 1999 TH Magna and earlier this year we had to have a new battery fitted. Sat idling for 30 minutes after fitting battery and idled ok. However, if you turn the air conditioner on the revs drop too much and the car stalls. Have read some posts that mention the idle stepper (where is that located?) but I cant understand why it wouls stop working after fitting a replacement battery.
Any ideas on how to cure this problem?

RuSSiaN
29-11-2007, 03:53 PM
It sounds like the Idle controller (ISC), when any model magna turns on the aircon the revs drop, it sounds like your idle might be set to low. I doubt it has anything to do with the battery, however people with a 3rd gen might be able to tell you. Setting the idle higher is simple on the 2nd so assume 3rd has something similiar.

Are all battery cables connected firmly? It could be somehow the aircon fan aint kicking in or getting power to it (AIRCON FAN RELAY/FUSE), but id look at the ISC first as this works in conjunction when the aircons turned on.

TPS might be an issue too, difficult to tell without visual, some would guess ecu/temp sensor but id check the idle first.

Satan
29-11-2007, 03:58 PM
But because its only happened after new battery maybe an alternator issue?

Draws too much current straining the motor?

RuSSiaN
29-11-2007, 04:07 PM
But because its only happened after new battery maybe an alternator issue?

Draws too much current straining the motor?

If that was the case the car would be stalling all the time not just with the aircon on, relay/fuses could be an electrical fault but I'm pritty sure its the ISC as this is the sympton most magnas experience, however its usually unconsistant (ISC, TPS, ECU).

Try upping the idle speed control first.

Rebel_Yell69
29-11-2007, 05:18 PM
If that was the case the car would be stalling all the time not just with the aircon on, relay/fuses could be an electrical fault but I'm pritty sure its the ISC as this is the sympton most magnas experience, however its usually unconsistant (ISC, TPS, ECU).

Try upping the idle speed control first.

To clarify things further, I noticed that if I start the car and then turn on the air con the revs drop for a split second and then come back up to 900rpm and idles normally, but if I turn the air con off and then back on, the car will stall or if I drive down the road and take my foot of the throttle the same thing will happen. It seems as though the problem gets worse as soon as the motor warms up. Just cant understand why a change in battery would cause the ISC to suddenly have a fault.


Try upping the idle speed control first
How do I go about adjust the idle speed control?

doddski
29-11-2007, 07:16 PM
cant understand why a change in battery would cause the ISC to suddenly have a fault.


i wouldnt think the two are directly related, might just be a case of they where both going to 'die' / change at the same time.

if it was a efi xe, i could tell you how to increase the idle speed, but its not, so i cant! lol

MitchellO
01-12-2007, 09:39 AM
I had this problem when I disconnected my battery. After about 150km the idle reset itself and the problem went away. While I waited I had to slip into neutral and gently massaged the accelerator to stop for stalling :P

MitchellO
02-12-2007, 12:19 PM
so its the ecu relearning everything, when battery disconnected it reset the computer?

Yeah, it was over 100km before my car would idle correctly again after disconnecting the battery. Been fine ever since.

Rebel_Yell69
15-12-2007, 06:23 AM
The car has done well over 10,000 klms since the battery change so I think it's safe to say that the ECU has reset itself by now. Could be the ISC, can anyone tell me where it is located?

raven
15-12-2007, 02:54 PM
try slightly increasing the idle speed - there's a screw located directly to the right of the intake manifold, facing upwards.

i had this same problem with my verada. even after adjusting, the ecu drops the idle speed back to normal after a few drives but it stopped the stalling problem for me.

EZ Boy
28-12-2007, 08:51 PM
Clean your PCV. I know I always say this in a 'stall' thread - but it's a 1minute jobs that just might save the day ;)

darcy
28-12-2007, 09:37 PM
my brother is having this same issue with his soarer, its ended up being the air con compressor ceasing.. may be different in your case.. but could be something to look at..

magna buff
29-12-2007, 04:04 AM
dont know about your engine
the ISC " intake speed control" on a V6 TR/TS is located near the opening of the throttle body
held on by two screws 8 mm and has a 6 pin connection
close to the black TPS

it either works or it doesnt

wired into the ecu and air con on auto