THROTTLE SURGE

Submitted: Saturday, Apr 24, 2004 at 19:48
ThreadID: 12339 Views:1239 Replies:8 FollowUps:2
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With a low range rock crawling gear set installed in my 3.0 litre TD nissan,I find the throttle sensitivity a real pain on rough tracks.
There have been many complaints in this regard,with suggestions ranging from fitting stronger springs to wedging foam behind the pedal.
I wonder if there is any electronic guru out there who can confirm my theory on a permenant fix for this annoying problem.
As the throttle works by sending a varied output to the engine management ,why could not an overriding signal be used to control the throttle.
I thought that if a "pot" of some sort was installed as a hand throttle,the adjustable output could be used to select the required speed.
Obviously some sort of isolation would be required for the normal accelerator signal.
This would result in the engine speed being controlled by the "pot" giving the same sort of control as provided by the old manual hand throttles.
Qualified opinions would be appreciated.
Regards
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Reply By: Rosco - Bris. - Saturday, Apr 24, 2004 at 19:53

Saturday, Apr 24, 2004 at 19:53
Hand throttle may be the patch answer.

Drive by wire is the way to go (notwithstanding the electronics and the inherrent worries about "black box gizmos")

Removes all throttle surge issues.
AnswerID: 55782

Reply By: navaraman - Saturday, Apr 24, 2004 at 20:28

Saturday, Apr 24, 2004 at 20:28
What you say makes good sense. How you would wire one up is beyond my basic electric skills.
I wonder whether all the electronic trickery on cars is just to stop us making our own mods and to keep the dealer service depts busy.
AnswerID: 55789

Reply By: joc45 - Saturday, Apr 24, 2004 at 20:36

Saturday, Apr 24, 2004 at 20:36
Agreed. I cannot see why the pot could not be substituted, or a couple of fixed resistors in series/parallel with the existing pot to limit its throttle range while allowing the full range of the pot to control that limited throttle range. This could be switched in or out by a switch.
Don't own a 3.0L, so haven't had the chance to see what could be done. Idea sounds good.
Gerry
AnswerID: 55792

Reply By: Truckster (Vic) - Saturday, Apr 24, 2004 at 23:17

Saturday, Apr 24, 2004 at 23:17
Most people put a hunk of foam under the throttle pedal...
AnswerID: 55813

Follow Up By: robb - Sunday, Apr 25, 2004 at 00:31

Sunday, Apr 25, 2004 at 00:31
I have a 60 series which does the same thing... An absolute pig around corrugated corners with a trailing throttle when the engine is just on boost, bumpy roads are the same... Someone told me that there is a mod that can be done but I am not sure, I will ask my diesel mechanic about it next week when I get the injectors serviced
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FollowupID: 317677

Reply By: Tim - Sunday, Apr 25, 2004 at 13:22

Sunday, Apr 25, 2004 at 13:22
fourstall2000
In answer to your question yes it can be done and I don't think it would be overly difficult.
I have fly by wire in my jack and have pondered over the same issue for cruise control.
Basically you would need a selector switch to select foot or hand control, a varistor (pot) to adjust the resisance in the circuit to the butterfly solenoid and that would be a about it. We use these quite commonly in heavy industry for this exact purpose.
The foot/hand throttle would have to be independant of each other as the 2 pots in parallel would alter the resistance and your speed control would be more limited.
There may also be an anolgue feedback to the engine management system which would need looking at but I can't see that being to difficult.
The other option you could investigate is attaching a cable to the foot throttle (the jack has a shaft going up past the pivot point on the pedal so as you pull it towards the back of the vehicle the pedal goes in, with a circular hole in it) then going to a threaded hand throttle so it controls the pedals position if that makes any sense at all.
Tim
AnswerID: 55851

Reply By: Foss - Sunday, Apr 25, 2004 at 18:45

Sunday, Apr 25, 2004 at 18:45
Bad news Boys & Girls.

I have attacked this problem from three fronts.

1. Removed pedal control from the vehicle and placed on the bench. With several meters similtaneously connected I discovered that there are two non linear resistances that operate in opposite directions, as one increases the other decreases. The mechanics of this was to much for me so I went to a company that manufactures engine control components and after a time was told that what I wanted would cost more than I could pay.

2. Several 3.0ltr owners and myself went to Nissan to express our concern about the overly sensitive throttle issue in low range. After some discussion with various techs and the "customer service manager" we were eventually told that it was a design characteristic and would not be addressed by nissan EVER.

3. As the same group we approached the NRMA vehicle safety committee from the viewpoint that the vehicle could be dangerous in certain circumstances IE. slippery wet track low range rough surface bounce over cliff everone dies. They took up the ball, inspected several 3.0 ltr patrols and made a report that the problem wasn't sufficiently servere to warrant any further effort.

I then gave up. sold the vehicle and purchased a 4.2tdi ute. No problems.

Save yourself some time and headaches. cut to the chase now.

Just a little aside. Landrover have a dual range throttle control the least sensitive of which is activated with the selection of low range. Wouldn't you think Nissan would be embarrased by not being able to duplicate that effort.

cheers
Foss
AnswerID: 55888

Follow Up By: Leroy - Sunday, Apr 25, 2004 at 19:47

Sunday, Apr 25, 2004 at 19:47
My solution is to bury my boot into the kick panel once I have achieved my desired speed to try and stop my foot 'feathering' the pedal. Works best with soft rubber soled boots!

Leroy
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FollowupID: 317770

Reply By: fourstall2000 - Monday, Apr 26, 2004 at 10:25

Monday, Apr 26, 2004 at 10:25
Foss,thanks for the information on the linear resistance,I had not got this far in my investigations,so you saved me a lot of work.
With this information in hand it makes Tims suggestion brilliant,The obvious solution in my belief (talk about thinking outside the square).
If the electronics are to difficult or risky to alter,just work on the mechanical location of the accelerator peddle.
It should be fairly simple to rig up a cable system to operate the pedal and allowing for overide if required.
Even an old 60 series system could be probably used in modified form,from memory these had a twist locking cable which acted directly on the pedal.
Thanks guys I will report if successful.
Great truck, 2000 gu,new Nissan 3.0 litre engine.auto,crawler gears,and-----hand throttle control?
Regards
AnswerID: 55982

Reply By: joshinthecity - Tuesday, Apr 27, 2004 at 12:39

Tuesday, Apr 27, 2004 at 12:39
Seriously, I have a car-washing sponge that I leave in the door pocket. When I shift into 4wd, the sponge goes under the pedal. Problem solved. Easy.

Josh.
AnswerID: 56181

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