Stall starts

Submitted: Saturday, Mar 04, 2006 at 22:27
ThreadID: 31424 Views:2127 Replies:10 FollowUps:13
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We were discussing stall starts a while back and someone mentioned there was something you could disconect on a fuel injected petrol to stop them luching backwards. I have not been able to find that post in the archives. Does anyone know what you would disconect and where it is located ? Cheers Rob
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Reply By: peteC - Saturday, Mar 04, 2006 at 22:46

Saturday, Mar 04, 2006 at 22:46
I havent heard of that one and it doesnt sound like something I would like to try because all I can think of is expensive damage to the engine. My wife has a 94 Subaru Liberty 2wd manual. It has a "hill hold" on it. You apply the brakes with the clutch in and when you lift your foot off the brake it wont go backwards as the brakes remain on. When you let the clutch out it releases. It doesnt work when going forward. Its a great idea and it works brilliant. I cannot understand why all 4wd dont have them. Perhaps when the wifes car dies I will dismantle it and retro fit it to my car.
AnswerID: 158646

Follow Up By: Rob from Cairns Offroad Training & Tours - Monday, Mar 06, 2006 at 20:21

Monday, Mar 06, 2006 at 20:21
I think you are misunderstanding Peter. How do you reverse back down a hill with that system after you have lost traction or run out of power? Cheers Rob
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Reply By: fnqcairns - Saturday, Mar 04, 2006 at 23:01

Saturday, Mar 04, 2006 at 23:01
May have been the dash-pot?? stupid device anyway, it usually touches the throttle body/accelerator cable arm/linkage, anyway it works form that general area.
Adjusting it away makes city driving a breese.

cheers fnq
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Follow Up By: Rob from Cairns Offroad Training & Tours - Monday, Mar 06, 2006 at 20:29

Monday, Mar 06, 2006 at 20:29
Who are you fnqairns? Cheers Rob
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Reply By: Richard Kovac - Sunday, Mar 05, 2006 at 03:51

Sunday, Mar 05, 2006 at 03:51
Rob
Maybe you could ask the person who trained you

Richard
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Follow Up By: Rob from Cairns Offroad Training & Tours - Monday, Mar 06, 2006 at 20:23

Monday, Mar 06, 2006 at 20:23
They didn't have fuel injected petrol 4wds in those days Richard. Cheers Rob
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Follow Up By: Member - Davoe (Widgiemooltha) - Tuesday, Mar 07, 2006 at 00:02

Tuesday, Mar 07, 2006 at 00:02
wasnt it more of a case of Gidyap neddy back then?
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Reply By: Wayne (NSW) - Sunday, Mar 05, 2006 at 05:43

Sunday, Mar 05, 2006 at 05:43
Rob,

When we teach the stall start recovery we make sure that the right foot has a slight amount of pressure on the brake pedal. When the motor starts is has a slight retard effect with the brakes.

If too much brake pressure is applied and the vehicle stalls again, just go through the proceeder again.

Petrol vehicles that have high gearing are the worst but it can be controlled with this method to a point.

Got go to work this morning, Stockton Beach for the day. I love this job.

Wayne
AnswerID: 158660

Follow Up By: Rob from Cairns Offroad Training & Tours - Monday, Mar 06, 2006 at 18:48

Monday, Mar 06, 2006 at 18:48
Yes we do that Wayne but someone mentioned a way of stopping the surge problem in the first place. I trained some people in a v6 hilux the other day and for novice people the initial surge is scarey. Cheers Rob
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Reply By: Peter 2 - Sunday, Mar 05, 2006 at 09:24

Sunday, Mar 05, 2006 at 09:24
Most of the petrol fuel injected vehicles rev the engine at startup to varying degrees, some of the earlier ones it may be a physical thing on the throttle but most of the later ones are fly by wire and it is done by the electronics, no way to override it.
We've had some scary moments when stall starting different vehicles on training days.
Some vehicles are just not intended to be used for what they are 'supposed' to be designed for.
Peter
1996 Oka Motorhome

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AnswerID: 158669

Reply By: awill4x4 - Sunday, Mar 05, 2006 at 12:03

Sunday, Mar 05, 2006 at 12:03
Rob, I think the control circuit that has to pulled out is the idle stepper control because when the motor is turned off it automatically resets itself in readiness for a "cold start" giving that initial rise in revs of up to 2000 rpm in some cases.
I have heard that prior to 4x4ing to pull the connector off the idle control in the engine bay but to make sure that the AC is off and the wheels are pointing straight so no extra power is being used by the power steering pump thus making the idle stepper increase revs.
I have not tried this myself though. (auto's don't need to worry about stalling :-)
Regards Andrew.
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Follow Up By: Rob from Cairns Offroad Training & Tours - Monday, Mar 06, 2006 at 20:28

Monday, Mar 06, 2006 at 20:28
Hi Andrew I think it was you who told me there was something that could be disconnected? I looked everywhere under the bonnet of this v6 Hilux but coudn't find anything. If only the manufacturers were aware how we really used 4wds in true offroad conditions. I am sure it is something that could be over ridden in low range. Cheers Rob
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Reply By: Member - David 0- Sunday, Mar 05, 2006 at 19:54

Sunday, Mar 05, 2006 at 19:54
Rob it really depends on the make and model, but with most modern EFI it would be the stepper motor. On some earlier types, there was also an additional injector for cold starts.
AnswerID: 158763

Reply By: Mike Harding - Monday, Mar 06, 2006 at 18:57

Monday, Mar 06, 2006 at 18:57
Perhaps I'm misunderstanding you Rob but if I were stalled halfway up a 1:3 hill and wanted to do a reverse start to get back down the hill again I wouldn't really want to be trying to do modifications to the vehicle under those conditions.

Mike Harding
AnswerID: 158932

Follow Up By: Rob from Cairns Offroad Training & Tours - Monday, Mar 06, 2006 at 20:11

Monday, Mar 06, 2006 at 20:11
Yes Mike you are misunderstanding. Cheers Rob
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Follow Up By: Mike Harding - Monday, Mar 06, 2006 at 21:36

Monday, Mar 06, 2006 at 21:36
>Rob from Cairns Offroad Training & Tours posted this followup
>I think you are misunderstanding Peter. How do you reverse back
>down a hill with that system after you have lost traction or run
>out of power? Cheers Rob

Oh well... I'm totally lost here then Rob?Would you care to explain in more detail for the slower ones amongst us?

Mike Harding
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Follow Up By: Rob from Cairns Offroad Training & Tours - Monday, Mar 06, 2006 at 21:44

Monday, Mar 06, 2006 at 21:44
OK Mike lets establish where you are at. Are you aware of the reverse stall start method on a steep hill? Have you ever done it with fuel injected petrol? Cheers Rob
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Follow Up By: Mike Harding - Monday, Mar 06, 2006 at 22:02

Monday, Mar 06, 2006 at 22:02
I don't know the buzz words Rob but are you talking about a _downhill_ start after stalling (I was thinking up hill).

Can you please describe in words of one syllable - or less :)

I'm not trying to antagonise you Rob - I just don't understand what you're asking?

Mike Harding
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Follow Up By: awill4x4 - Monday, Mar 06, 2006 at 23:11

Monday, Mar 06, 2006 at 23:11
Mike, I think that what Rob is trying to say in a roundabout way is that when a fuel injected (manual) vehicle is "key started" in reverse to back down a hill after stalling the fuel injection system has reset itself ready for a "cold start" and it starts with quite a lot of revs. (usually between 1500-2000 rpm) the car then accelerates quite quickly rather than a controlled start and descent.
It can be quite disconcerting for the car to leap backwards down the hill on start up as you may imagine. If the correct efi connector is pulled prior to 4x4ing the car will start at whatever the idle speed is set at, (usually 600-800 rpm) it will start this way whenever the engine is warm as the "cold start" isn't required when the engine is hot.
When you've finished 4x4ing simply reattach the connector and your cold start is now operative.
Regards Andrew.
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Follow Up By: Mike Harding - Tuesday, Mar 07, 2006 at 06:51

Tuesday, Mar 07, 2006 at 06:51
Thank you Andrew, I understood that perfectly :)

I wasn't aware the engine management computer did that when it was starting a hot engine - maybe I've just never noticed - I shall contact my friends at Bosch today and ask them.

Mike Harding

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Follow Up By: Rob from Cairns Offroad Training & Tours - Tuesday, Mar 07, 2006 at 20:36

Tuesday, Mar 07, 2006 at 20:36
Thanks Andrew, great explaination. Cheers Rob
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Reply By: Wayne (NSW) - Monday, Mar 06, 2006 at 23:25

Monday, Mar 06, 2006 at 23:25
Rob,

The other thing that we make sure the driver has done is to turn the Air Con off. Having it on only adds to the already high revs.

Wayne
AnswerID: 159012

Reply By: Member - Bware (Tweed Valley) - Monday, Mar 06, 2006 at 23:56

Monday, Mar 06, 2006 at 23:56
Do you think that if you need to do those sort of things maybe you shouldn't be attempting those sort of hills? But I guess it's horses for courses; it must be a different theory for very low geared diesels/petrol vehicles/soft-roaders
AnswerID: 159015

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