3200GT Oversensitive throttle adjustment
Discussion
.. from the comfort of the drivers seat but do read very carefully. If you are not sure of what you are doing, leave it to someone who does!
1) Reset the mechanical zero position
- Put gear lever in neutral
- Switch on ignition (to MAR position) but do NOT start the engine
- Do not touch the throttle pedal for 2 minutes
- Switch off ignition
2) Reset the mechanical Full Throttle position
- Put gear lever in neutral
- Switch on ignition (to MAR position) but do NOT start the engine
- Fully depress throttle pedal and hold for 5 seconds
- Release throttle pedal completely
- Switch off ignition
The full text does not specify waiting until the various warning lights have extinguished themselves after switching on ignition, but I do not depress throttle (item 2) or start timing until they have.
Hope this helps
Source: Offical Factory Workshop Manual (Engine) page 96 of the Fuel supply section.
1) Reset the mechanical zero position
- Put gear lever in neutral
- Switch on ignition (to MAR position) but do NOT start the engine
- Do not touch the throttle pedal for 2 minutes
- Switch off ignition
2) Reset the mechanical Full Throttle position
- Put gear lever in neutral
- Switch on ignition (to MAR position) but do NOT start the engine
- Fully depress throttle pedal and hold for 5 seconds
- Release throttle pedal completely
- Switch off ignition
The full text does not specify waiting until the various warning lights have extinguished themselves after switching on ignition, but I do not depress throttle (item 2) or start timing until they have.
Hope this helps
Source: Offical Factory Workshop Manual (Engine) page 96 of the Fuel supply section.
At a guess number 1 sets the minimum throttle (tickover) number 2 sets the maximum.
Perhaps it's for cases where the computer thinks full throttle should be when the pedal is only half depressed, which would make the accelerator too sensitive.
I don't think I've explained that very well.
Perhaps it's for cases where the computer thinks full throttle should be when the pedal is only half depressed, which would make the accelerator too sensitive.
I don't think I've explained that very well.
bad loser said:
At a guess number 1 sets the minimum throttle (tickover) number 2 sets the maximum.
That's correct. The no throttle setting (tickover or lower value) is 350/650mv whilst full throttle (upper value) is typically 3,100/3,300mv.
Apparently, the management system strategy gradually reduces the full throttle value by 5mv (for the next switch-on) every time the ignition is turned on (whether engine started or not) UNLESS full throttle is applied for 5 seconds at least once in that cycle (eg climbing a steep hill with full throttle etc). Therefore, under certain circumstances, the full throttle setting will gradually reduce leading to over sensitivity at the pedal. The manual reset procedure restores the upper and lower values to their default design settings.
>> Edited by Nigelo on Wednesday 9th February 10:09
Just thought I'd bump this up to the top.
I've currently got a dodgy throttle potentiometer which means that suddenly I'll be restricted to low revs or the car will 'die' at the most inconvenient times. It's like somebody has shoved a wedge under the accelerator pedal - nothing happens when you put your foot down.
When this happened, the engine management light came on so I took it in to Greypaul who diagnosed the fault and they are now waiting for the part.
Meantime, I thought I'd try Nigelo's trick and it works a treat for about 50 - 100 miles until it goes again (and the engine management light comes back on) but at least it's keeping me moving while waiting for repair.
Also, after carrying out the procedure the acceleration feels much smoother but that could be my imagination.
I've currently got a dodgy throttle potentiometer which means that suddenly I'll be restricted to low revs or the car will 'die' at the most inconvenient times. It's like somebody has shoved a wedge under the accelerator pedal - nothing happens when you put your foot down.
When this happened, the engine management light came on so I took it in to Greypaul who diagnosed the fault and they are now waiting for the part.
Meantime, I thought I'd try Nigelo's trick and it works a treat for about 50 - 100 miles until it goes again (and the engine management light comes back on) but at least it's keeping me moving while waiting for repair.
Also, after carrying out the procedure the acceleration feels much smoother but that could be my imagination.
Bad loser
I assume that Greypaul used an SD2 / SD3 tester to diagnose the problem - If so, be very careful. The potentiometer needs dual circuitry to operate as a failsafe and in fact is a dual unit itself. You are therefore totally relying on the electronics (with a known problem) to flag an error and perform a power shutdown - Therefore strongly suggest you avoid anything more than the lightest of throttle at any time until fixed. There is potential, however unlikely, for throttle to stick open with disasterous consequences.
That said, if Dealer did not use an SD2/3 why not and how did they do the diag checks. Greypaul have a good reputation but always be wary of (expensive) part replacement on a suck-it-and-see basis.
HTH
I assume that Greypaul used an SD2 / SD3 tester to diagnose the problem - If so, be very careful. The potentiometer needs dual circuitry to operate as a failsafe and in fact is a dual unit itself. You are therefore totally relying on the electronics (with a known problem) to flag an error and perform a power shutdown - Therefore strongly suggest you avoid anything more than the lightest of throttle at any time until fixed. There is potential, however unlikely, for throttle to stick open with disasterous consequences.
That said, if Dealer did not use an SD2/3 why not and how did they do the diag checks. Greypaul have a good reputation but always be wary of (expensive) part replacement on a suck-it-and-see basis.
HTH
I had a problem with the throttle reponse completely dissappearing and the management light coming on, the first diagnosis at the dealer (main agent)was a throttle potentiometer but they revised it to a fuse panel connection that needed re making (over £400), It was ok for a week but failed again, this time they said it was "something in the wiring loom" on the left side of the engine in the plastic harness that runs along the top of the injectors, the plasitic on this side all looks new now and it has been fine for three weeks so I guess that this was the real problem, no additional charge and a job well done. Dealer is in Colchester Essex.
Nigelo, thanks I'll take your advice. I won't be driving it much at the moment as I'm having a couple of minor scratches removed tomorrow and the plan is to take it from the body shop to Greypaul's.
I don't know what they used to test it but they want to re-test it to make sure they don't get the wrong part as a potentiometer allegedly costs almost £900.
It's under warranty anyway so all I really care about is getting it back in working order.
I don't know what they used to test it but they want to re-test it to make sure they don't get the wrong part as a potentiometer allegedly costs almost £900.
It's under warranty anyway so all I really care about is getting it back in working order.
Vulcan
Lancs are my nearest and as good as any. I know the plastic conduit to which you refer and is actually split along its length to allow the wires to be inserted easily. Problems occur when moisture enters.
Bad Loser
Sensible approach and judging from GP's request to retest, Maser UK have probably requested just that. FWIW, there have been some odd symptoms recently on some 3200s where insufficient earthing has been the cause. Would be interested to know the final diag + cure even though under warranty.
Take care
Lancs are my nearest and as good as any. I know the plastic conduit to which you refer and is actually split along its length to allow the wires to be inserted easily. Problems occur when moisture enters.
Bad Loser
Sensible approach and judging from GP's request to retest, Maser UK have probably requested just that. FWIW, there have been some odd symptoms recently on some 3200s where insufficient earthing has been the cause. Would be interested to know the final diag + cure even though under warranty.
Take care
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