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Discussion Starter #1
How do I say this...?
The accelerator pedal can be depressed through the normal arc but just the tiniest amount of movement down, like a centimetre (½ inch) and it seems to be at half throttle already. By the time it is a third of the way through the distance to floor it is running at full throttle.
It is way too sensitive.
Any ideas?
It is physically demanding to drive because my foot never really moves and it is really hard to rev match...
 

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Without knowing a bit more about your car it's a little difficult to help you.
Carbonated, Spica, Solex, Weber, etc.??
I lot of us here have given up on trying to use our sixth sense. ;)
A while back I had a Fiat 124 with the same problem. I fabricated a longer arm on the carburetor
linkage to slow things down.
 

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Have someone slowly depress the gas pedal while you carefully watch the movement of the throttle plate actuation arm. Hopefully you will see a problem.

Also, maybe a misaligned throttle position switch could cause this problem.
 

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Discussion Starter #4
Without knowing a bit more about your car it's a little difficult to help you.
Carbonated, Spica, Solex, Weber, etc.??
I lot of us here have given up on trying to use our sixth sense. ;)
A while back I had a Fiat 124 with the same problem. I fabricated a longer arm on the carburetor
linkage to slow things down.

Doh! Sorry. GTV6 2.5l
 

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Discussion Starter #5
The levers that actuate the throttle all seem correct and original but the air flow sensor has been opened at least twice. That is: before i bought it and then again when I had some work done. The runs strong and the mixture set a bit rich because it had issues. I have since replaced lots of the rubber parts in the intake system so those air leaks are not there anymore.
I have never "played" with an AFM before but it seems to me that the sensor might be a too sensitive but then again... I've never played with an AFM before. I don't know what I don't know....
 

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1986 Alfa Romeo GTV6
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Let's see if I get this right.
I have never floored my Gtv6. I don't need to. Half a pedal is more than enough.
Today i did about 80 miles on it, and I in 5th gear at 80mph only have about 1/2" of the pedal pressed. And I have to keep lifting the foot because it keeps gaining speed. Is this what you mean @Millsy ?
This happened in every Italian car I drove/owned.
That includes 2 different 75. A twin spark and a 1.6 I. E. A Lancia Delta, a Lancia Dedra, Fiat 124 special T and a 131 volumétrico.
I think that's what makes these cars what they are. Indicates an healthy engine and the heavy rpm they like.
 

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My only thought is to try lubricating all pivot points. A sticky pivot will make it difficult to be smooth with the throttle. And I'm trying to remember - is there a throttle cable? If so - and lube doesn't help - the cable could be fraying inside the outer cover.
 

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Discussion Starter #8
Sekal1978, I think it might be. I also have a 2 litre Dellorto Carb version and full throttle at the carbs is foot to the floor and so the experience is very different.
Either way, it needs taming. It is just too sensitive.
bhnl, The linkage system is smooth and tidy. I'm thinking maybe that I should try tightening the return spring. Perhaps the tension is inadequate.
 

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1986 Alfa Romeo GTV6
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I can take a pic tomorrow night if it help. Like guidance. My engine is a 3.0 but I think it's the same everything as the 2.5
 

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To me this sounds like the spring inside the AFM has been loosened excessively. The TPS could also be misadjusted.
 

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@Millsy have you had a good look at the cable portion of the set-up? the cable on mine is starting to fray, and if yours is doing similar, you may find the pedal jerky from the resistance in the sheathing. I had good luck lubricating the cable by dropping oil down the cable then using compressed air to force it through the length. Make sure that the plate is closed when idling and watch it as you slowly depress the accelerator to see whats happening
 

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Discussion Starter #15
JoeCab I tend to think this might be the case. Do you know where I might find instructions to tighten the spring?
Brendan, I checked this today. The mechanism is smooth and well weighted. It just seems to over react...
 

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Let's see if I get this right.
I have never floored my Gtv6. I don't need to. Half a pedal is more than enough.
Today i did about 80 miles on it, and I in 5th gear at 80mph only have about 1/2" of the pedal pressed. And I have to keep lifting the foot because it keeps gaining speed. Is this what you mean @Millsy ?
This happened in every Italian car I drove/owned.
That includes 2 different 75. A twin spark and a 1.6 I. E. A Lancia Delta, a Lancia Dedra, Fiat 124 special T and a 131 volumétrico.
I think that's what makes these cars what they are. Indicates an healthy engine and the heavy rpm they like.
Nah, what you say is not normal. I'm sure you floor the accelerator many times. And no, no car should just gain speed by itself. BUT Italian cars don't have heavy throttles like the "oh the accelerator is a dangerous pedal" type cars.

When I first got my 156v6, I thought I would have trouble keeping to speed limits; nope, no issues. Just had to get over the initial "I own a Busso v6" excitement
Pete
 

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1986 Alfa Romeo GTV6
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Nah, what you say is not normal. I'm sure you floor the accelerator many times. And no, no car should just gain speed by itself. BUT Italian cars don't have heavy throttles like the "oh the accelerator is a dangerous pedal" type cars.

When I first got my 156v6, I thought I would have trouble keeping to speed limits; nope, no issues. Just had to get over the initial "I own a Busso v6" excitement
Pete
Swear on my daughters.
It's impossible to keep under speed limits unless you take your foot of the pedal.
I Always have the GPS on just to hear the over the speed limit sound.
And it's no bs. Maybe the only that didn't do this that easy was the Lancia Dedra, all others were exactly the same.
I can only lose speed when climbing. Flat and obviously downhill it gains speed with 1/2" pedal pressed, usually untill the 90 mph.
 

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Instead of fiddling with the AFM flap spring more, would you be able to find a non buggered up/modified AFM instead?
 

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Swear on my daughters.
It's impossible to keep under speed limits unless you take your foot of the pedal.
I Always have the GPS on just to hear the over the speed limit sound.
And it's no bs. Maybe the only that didn't do this that easy was the Lancia Dedra, all others were exactly the same.
I can only lose speed when climbing. Flat and obviously downhill it gains speed with 1/2" pedal pressed, usually untill the 90 mph.
Sorry I miss read. So you were saying it accelerates with only 1/2" pressed ... heck that is sensitive. I thought you meant it was impossible to obtain a constant speed
Pete
 

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Sorry I miss read. So you were saying it accelerates with only 1/2" pressed ... heck that is sensitive. I thought you meant it was impossible to obtain a constant speed
Pete
No need to apologize. 1/2" it seems. I never measure ;)
 
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