Vauxhall Corsa: persistent idle problem - throttle position sensor?
Peter Lonsdale
it was suggested in this group that there might be a problem with the idle
air control valve, a known problem with this engine (973cc X10XE) but alas
my local dealer cannot find a problem with this and say they need to
investigate the throttle position sensor.
the basic problem is rough idling and the stepper motor not engaging when
the engine is cold.
anyone any ideas on how much this is going to end up costing me? is there
anything I can do about this myself, or is it a non-DIY job?
this car has cost me about 700 quid in the last 6 months and I'm determined
not to spend any more!
TIA for any suggestions/info
Peter Lonsdale
Mark Craft
loan ) a known good air idle valve, fit this to the car and test it over a
couple of days and see what happens. Is hot idle dodgy or just cold idle ?
If its only cold idle I wouldn't suspect TPS as it would play up all the
time, if its both hot and cold I guess its a possible TPS alignment fault
but I would of expected this to show up in other situations too.
"Peter Lonsdale" <p...@psychology.nottingham.ac.uk> wrote in message
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Tim (Remove NOSPAM. Registry corupted, reformated HD and lost alot of stuff :(
single point injection cars with an idle stepper motor acting directly on
the throttle linkage there is often a microswitch in the end of the rod that
the motor drives back and forth. When the throttle is closed and against
this mircoswitch it signals the ECU to begin controlling idle speed. The ECU
would also need to see the TPS at ~0.6-0.7v signalling a closed throttle. So
you may have a fault thats temperature related, and fixing itself when it
warms up.
Check the TPS voltage with it cold (ign on, engine off) around the idle
position, making sure there is no sudden drop to zero. Should be a linear
increase to ~4.5v at WOT.
If fitted check the stepper motor microswitch. There will be 2 terminals on
the connector for this. Touching the switch should change the state of
continuity. If the switch does prove faulty when cold- alas you'll have to
change the whole stepper motor assemble, they're not dismantleable.
Hope this helps.
Tim..
"Peter Lonsdale" <p...@psychology.nottingham.ac.uk> wrote in message
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Peter Lonsdale
corupted, reformated HD and lost alot of stuff :( at
the....@NOSPAMbtinternet.com wrote on 7/1/02 16:28:
> I'm not familliar with the 3cyl set up, but broadly speaking with respect to
> single point injection cars with an idle stepper motor acting directly on
> the throttle linkage there is often a microswitch in the end of the rod that
> the motor drives back and forth. When the throttle is closed and against
> this mircoswitch it signals the ECU to begin controlling idle speed. The ECU
> would also need to see the TPS at ~0.6-0.7v signalling a closed throttle. So
> you may have a fault thats temperature related, and fixing itself when it
> warms up.
ah now this is interesting - I have noticed that with the current
adjustments on the throttle linkage, when the throttle is closed it does
*not* rest against the stepper motor, most likely due to the inexpert
tinkerings of the non-Vx garage who have been trying to fix this problem for
many months. if I press the end of the stepper motor (which BTW is brand
new after diagnosis indicated a fault) then the stepper motor engages and
puts the revs up to what they should be. so, would one possible fix be to
adjust the screw on the throttle arm so that it presses against the stepper
motor when closed? I asked this question a while ago on this group but was
told to leave well alone...
Tim (Remove NOSPAM. Registry corupted, reformated HD and lost alot of stuff :(
not familiar with the SPi on the Corsa, but 99% of the time the following
applies.
If the TPS has slotted mountings, release them. Also unhook the throttle
cable so its not holding open the throttle. remove the inlet duct so you can
see the throttle plate, and with a 0.10mm feeler gauge, adjust the stop
screw so the butterfly just clamps the feeler against the wall of the body.
Then hook up the linkage so it will contact the end of the stepper motor
when at rest. You will need to make sure the s/motor is retracted when you
do this.
If the TPS is slotted, set it up to read 0.6-0.7v with a closed throttle-
disconnect the stepper motor so it doesnt jack open the buterfly first when
you turn on the ignition.
If there is an idle bypass screw, again with the throttle shut and s/m
disconnected, set it up so the engine dies slowly. I dont know if there is
such a fitting on this car, some have them, some dont.
Hook up the s/m again and ***hopefully*** your idling quality will be how
Vauxhall intended.
Otherwise your going to have to visit a dealer who knows what he's doing, or
a fuel injection specialist.
Tim..
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Alistair Hutton
idleing? I have got a 1992 K reg Astra with a vibrating problem and i have
been unable to find the problem so if your car is the same then i might try
the same as you.
Alistair Hutton
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Peter Lonsdale
> Right. So you need to sort out the 'in-expert' tinkerings. As I said I am
> not familiar with the SPi on the Corsa, but 99% of the time the following
> applies.
>
> If the TPS has slotted mountings, release them. Also unhook the throttle
> cable so its not holding open the throttle. remove the inlet duct so you can
> see the throttle plate, and with a 0.10mm feeler gauge, adjust the stop
> screw so the butterfly just clamps the feeler against the wall of the body.
> Then hook up the linkage so it will contact the end of the stepper motor
> when at rest. You will need to make sure the s/motor is retracted when you
> do this.
>
> If the TPS is slotted, set it up to read 0.6-0.7v with a closed throttle-
> disconnect the stepper motor so it doesnt jack open the buterfly first when
> you turn on the ignition.
>
> If there is an idle bypass screw, again with the throttle shut and s/m
> disconnected, set it up so the engine dies slowly. I dont know if there is
> such a fitting on this car, some have them, some dont.
>
> Hook up the s/m again and ***hopefully*** your idling quality will be how
> Vauxhall intended.
>
> Otherwise your going to have to visit a dealer who knows what he's doing, or
> a fuel injection specialist.
I'm afraid this kind of tinkering is beyond my meagre car DIY skills - the
only things I'm willing to fiddle with are the 2 screws on the throttle arm
that allow you to adjust its position.
one screw is at the bottom of the arm and adjusts the position the arm takes
at rest, so I assume this allows me to adjust the base idle speed.
the other screw is at the top and is the part that actually contacts the
stepper motor - I assume that this screw allows you to adjust the influence
of the stepper motor on the throttle position.
the problem is that with the screws in their current position, when the
throttle is closed and the stepper motor retracted, there is no contact
between the upper screw and the stepper motor. so when I start the car from
cold the ECU does not get a signal to regulate the idle using the stepper
motor and the revs stay low.
the engine currently seems to idle a little fast when warm, so my plan was
to adjust the base idle speed using the bottom screw so that I have a
reasonable warm idle, and then adjust the upper screw so that when cold the
stepper motor will be activated.
does this sound like a good plan?
or maybe a trip to the dealer is a better idea... but they want 64 quid
just to investigate!
--
Peter Lonsdale +44 (0) 115 95-15281
School of Psychology p...@psychology.nottingham.ac.uk
University of Nottingham http://www.psychology.nottingham.ac.uk/~prl
Tim (Remove NOSPAM. Registry corupted, reformated HD and lost alot of stuff :(
You could try what you suggested above, but you may still have some problems
with idle control, as it wouldnt be set up as Vx intended, but as a short
term fix it may work. Your base idle should be a slow one- about 500-600rpm
and the ECU / s-motor should then hold this up to ~900rpm and abit faster
when cold.
I think I'd find another dealer if your local one wants Ł64 just to open the
bonnet!
Tim..
Tim (Remove NOSPAM. Registry corupted, reformated HD and lost alot of stuff :(
"Alistair Hutton" <alistair...@hotmail.com> wrote in message
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> Does your car vibrate heavily through the body and the steering wheel when
> idleing? I have got a 1992 K reg Astra with a vibrating problem and i have
> been unable to find the problem so if your car is the same then i might
try
> the same as you.
>
> Alistair Hutton
No he was suffering from lack of idle control and subsequent stalling due to
a mal-adjusted stepper motor and throttle linkage.
You may have a too low idle or it could be running on 3 cylinders at ide, or
you could have a broken engine mounting.
Peter Lonsdale
well, they have already done a preliminary inspection after which they
reported a need for further investigation of "throttle position". I managed
to get away with not paying for this since they had the car in for recall
work at the same time...
so the 64 quid they want should cover it - I just wanted to know if I could
do anything myself. I suspected that the set-up should be as you have
described above, but it has all been put out of whack by the non-Vx garage
who thought it was a good idea to fiddle with the base idle without touching
the other screw, and then couldn't figure out why the stepper motor wasn't
working...
anyway, I think I'll give it back to the dealer to have it sorted properly.
thanks for the advice though - at least I have learned a lot and so can now
tell them exactly what I want!
Peter Lonsdale
adjustments this morning. I managed to adjust it properly for cold starts,
ie by making sure the arm is always in contact with the stepper motor, but
unfortunately it would seem that when the engine is hot the stepper motor is
not moving out far enough to give me enough revs, even with the adjustment
screw fully extended. is there a way of adjusting the position of the
stepper motor, or is this something that needs to be done electronically?
Tim (Remove NOSPAM. Registry corupted, reformated HD and lost alot of stuff :(
idle, how can you not do so for a hot idle. There's alot less oil drag etc
etc etc when the engine is hot and you'd more likely to be suffering from a
too fast hot idle- and the stepper motor cant -WITHDRAW- enough to make the
engine run slowly...
You should set the hot BASE idle first (i.e. without the stepper motors
help), then allow the stepper motor to rise it to ~900rpm with abit of
extension thats governed by the ECU. When you switch off the engine, the
stepper motor should extend automatically after afew seconds ready for the
next re-start, be it hot or cold.
If you start without gas the idle should jump up to ~1200rpm as the engine
catches, then drop back to ~900rpm or so with a correctly operating system.
Tim..
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