Throttle dead spot
17 December 2014, 07:42 PM
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Throttle dead spot
My throttle has recently developed what seems to be a dead spot in the lower part of the range.
By that, I mean when gently feeding in the throttle for more power between, say 15% to 40%, not much happens until I get to a point where all the missing power comes in at once which can get a bit lively.
Being a Hawkeye STI, with drive by wire, I'm tempted to think the throttle position sensor has worn away the "variable resistor" at the lower more used part of the range. It seems strange that it didn't appear to deteriorate over a long period of time.
I would add the car has recently had a 60k service plus cambelt so the plugs will have been changed along with other items. Could it be that one of the plugs is breaking down?
Has anyone else experienced anything like this and can you point me in the right direction for a fix?
By that, I mean when gently feeding in the throttle for more power between, say 15% to 40%, not much happens until I get to a point where all the missing power comes in at once which can get a bit lively.
Being a Hawkeye STI, with drive by wire, I'm tempted to think the throttle position sensor has worn away the "variable resistor" at the lower more used part of the range. It seems strange that it didn't appear to deteriorate over a long period of time.
I would add the car has recently had a 60k service plus cambelt so the plugs will have been changed along with other items. Could it be that one of the plugs is breaking down?
Has anyone else experienced anything like this and can you point me in the right direction for a fix?
17 December 2014, 10:21 PM
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Some ideas
If its a plug , simple change em and check again , but a failing Power coil would have same symptom.
"edit" As you just had it serviced Id tend to suspect this first , getting the plugs fitted is not everyones cup of tea , its possible to damage a plug while taking the socket out , if the insulation is hairline cracked you will get problems.
If it seems like it misses a beat for just 50-100 rpm low down at say 2400 ,
then I have seen this when applying full throttle , even produced a tiny little hesitation , during my road tuning . Go see your mapper and you might get it ironed out , mine did.
You say it "developed a problem" would you describe it as over a wider rev range ?
The waste gate actuator also needs to operate smoothly , to check it moves right you will need an air line and a pressure regulator to gently feed on 0-1 bar if it judders at all as it opens you will find the car behaves erratically on pickup as the rest of the closed loop control tries to deal with the spike caused.
If its a plug , simple change em and check again , but a failing Power coil would have same symptom.
"edit" As you just had it serviced Id tend to suspect this first , getting the plugs fitted is not everyones cup of tea , its possible to damage a plug while taking the socket out , if the insulation is hairline cracked you will get problems.
If it seems like it misses a beat for just 50-100 rpm low down at say 2400 ,
then I have seen this when applying full throttle , even produced a tiny little hesitation , during my road tuning . Go see your mapper and you might get it ironed out , mine did.
You say it "developed a problem" would you describe it as over a wider rev range ?
The waste gate actuator also needs to operate smoothly , to check it moves right you will need an air line and a pressure regulator to gently feed on 0-1 bar if it judders at all as it opens you will find the car behaves erratically on pickup as the rest of the closed loop control tries to deal with the spike caused.
Last edited by Linksfahrer; 17 December 2014 at 10:26 PM. Reason: added idea on plug
18 December 2014, 09:00 PM
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I have a similar issue with my Hawkeye STi, mine is hesitation on mid throttle.
Is yours mapped?
I was going to clean the boost solenoid with MAF cleaner to see if that is it.. first then...
Is yours mapped?
I was going to clean the boost solenoid with MAF cleaner to see if that is it.. first then...
08 January 2015, 10:36 AM
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An update - It's gone!! ....and it took me a while to realise although, in defence, I didn't use my car much over Christmas!
In answer to some questions, yes, it was mapped by JGM who improved the low revs driveability significantly. I would say it happened over a rev range of approx. 2,250 to 3,500. ie before the turbo kicked in but well into it spinning up hence the "excitement" once power was resumed.
In answer to some questions, yes, it was mapped by JGM who improved the low revs driveability significantly. I would say it happened over a rev range of approx. 2,250 to 3,500. ie before the turbo kicked in but well into it spinning up hence the "excitement" once power was resumed.
08 January 2015, 01:28 PM
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An update - It's gone!! ....and it took me a while to realise although, in defence, I didn't use my car much over Christmas!
In answer to some questions, yes, it was mapped by JGM who improved the low revs driveability significantly. I would say it happened over a rev range of approx. 2,250 to 3,500. ie before the turbo kicked in but well into it spinning up hence the "excitement" once power was resumed.
In answer to some questions, yes, it was mapped by JGM who improved the low revs driveability significantly. I would say it happened over a rev range of approx. 2,250 to 3,500. ie before the turbo kicked in but well into it spinning up hence the "excitement" once power was resumed.
so own up what caused it ?
Owner or Driver error
08 January 2015, 03:39 PM
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No idea!
I now recall a similar situation after a previous service where the plugs which were used were 1 grade colder and I thought they were "oiling" up owing to light use. I can't recall fixing that either so maybe if it was the plugs they bed in or something!! (grasping at straws here
)
I now recall a similar situation after a previous service where the plugs which were used were 1 grade colder and I thought they were "oiling" up owing to light use. I can't recall fixing that either so maybe if it was the plugs they bed in or something!! (grasping at straws here
)
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