Throttle response problem - sometimes sharp - often dull - why?
03-12-2009, 06:19 PM
#1
Three Wheelin'
Thread Starter
Throttle response problem - sometimes sharp - often dull - why?
Hi guys,
I have a high milage S2 that, once in a while - is a rocketship. Most of the time it's a bit of a slug.
Something is causing the throttle response to change, once in a while the response is razor sharp, the car feels smooth, and pulls like a train in all gears, and is a ton of fun to drive.
Most of the time it feels like the throttle response is "soft", not that sharp. The car still goes sorta quickly - but it sure doesn't feel like 200HP pulling 2800 lbs.
Since it sometimes DOES make a lot of power - I assume it's something that is intermittent - like a connection or a sensor?
Thougths on what could be causing this?
Thanks in advance,
RK
PS. The car recently passed a clear air test with flying colours and dilution of 14.74:1. Not sure that matters though?
I have a high milage S2 that, once in a while - is a rocketship. Most of the time it's a bit of a slug.
Something is causing the throttle response to change, once in a while the response is razor sharp, the car feels smooth, and pulls like a train in all gears, and is a ton of fun to drive.
Most of the time it feels like the throttle response is "soft", not that sharp. The car still goes sorta quickly - but it sure doesn't feel like 200HP pulling 2800 lbs.
Since it sometimes DOES make a lot of power - I assume it's something that is intermittent - like a connection or a sensor?
Thougths on what could be causing this?
Thanks in advance,
RK
PS. The car recently passed a clear air test with flying colours and dilution of 14.74:1. Not sure that matters though?
03-12-2009, 07:51 PM
#3
Three Wheelin'
Thread Starter
Yeah - thought about the AFM too - I DID replace the AFM with a used one a couple of years ago - but maybe this one's bad too.
I'll pull it and test it.
How do I check test the throttle body?
Anything else to check?
Thanks,
RK
I'll pull it and test it.
How do I check test the throttle body?
Anything else to check?
Thanks,
RK
03-12-2009, 09:11 PM
#4
Three Wheelin'
You can bend the little arm in the AFM to use a different track on the contact area. There's a write up on www.clarks-garage.com
I would also try cleaning the throttle body like V2 eluded to.
I would also try cleaning the throttle body like V2 eluded to.
03-12-2009, 09:20 PM
#5
Three Wheelin'
Thread Starter
Yup - familiar with the "move the wiper arm" strategy on CG - will try that.
Is there a proceedure for throttle body cleaning?
One thing that's NOT clear on the CG AFM section is testing the temp sensor on the AFM. As I understand it - the temp reading is critical - else the voltage to the DME will be wrong.
Anyone know how to test it?
Thanks!
RK
Is there a proceedure for throttle body cleaning?
One thing that's NOT clear on the CG AFM section is testing the temp sensor on the AFM. As I understand it - the temp reading is critical - else the voltage to the DME will be wrong.
Anyone know how to test it?
Thanks!
RK
03-13-2009, 01:17 AM
#6
Three Wheelin'
the only way I know to clean a throttle body is remove the intake up to the throttle body (the J-tube in the case of the 944) and manually move the butterfly valve/flap while spraying carb cleaner to remove carbon deposits.
03-13-2009, 04:39 AM
#7
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03-13-2009, 10:56 AM
#8
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03-14-2009, 02:17 PM
#10
Three Wheelin'
Thread Starter
Okay - interesting update. Pulled the AFM this morning. Strangely - the cap to the electronics was LOOSE! It just popped off!
And underneath - it's not too pretty. Deep tracks in the substrate - so moving the arm now.
I vaguely recall the "old" way was to move the arm holder up or down on the spindle to realign the contacts on the track and that's how I did it a few years ago on another AFM. But C'sG now just says "bend the arm".
Thougths on the two approaches?
RK
And underneath - it's not too pretty. Deep tracks in the substrate - so moving the arm now.
I vaguely recall the "old" way was to move the arm holder up or down on the spindle to realign the contacts on the track and that's how I did it a few years ago on another AFM. But C'sG now just says "bend the arm".
Thougths on the two approaches?
RK
03-14-2009, 05:04 PM
#12
Three Wheelin'
Thread Starter
Success! Bent the arms - put everythign back together and WHAM! I have a rocketship!
Pulls like a train - runs more smoothly and is way faster. Thanks guys!
Based on this success - I'm going to replace the AFM with a rebuilt one or a MAF set up.
Any one got a source for either?
Thanks to all for your ideas and support - yet another mystery solved by the great Rennlist crew!
I think the interesting point here is that SOMETIMES the car ran amazingly - making me think it was something binary, like a sensor or something, but it turns out that somehow - the AFM can "self heal" for a bit - provide correct readings and then go back into "broken" mode.
Hope this helps someone else with these symptoms.
RK
Pulls like a train - runs more smoothly and is way faster. Thanks guys!
Based on this success - I'm going to replace the AFM with a rebuilt one or a MAF set up.
Any one got a source for either?
Thanks to all for your ideas and support - yet another mystery solved by the great Rennlist crew!
I think the interesting point here is that SOMETIMES the car ran amazingly - making me think it was something binary, like a sensor or something, but it turns out that somehow - the AFM can "self heal" for a bit - provide correct readings and then go back into "broken" mode.
Hope this helps someone else with these symptoms.
RK
Last edited by Rally Guy; 03-14-2009 at 08:04 PM.
03-14-2009, 09:38 PM
#14
Three Wheelin'
Thread Starter
Yeah - it's Kms - 300,350kms! Just rolled over 300k kms last weekend.
Amazing to me - and the car's running well. And it LOOKS like it's got 150,000 on it. Seat boldster? Perfect condition. Shift ****? Mint. I"m very pleased.
Needs paint - leaking some oil - but generally - it just soldiers on. (Fingers crossed!)
RK
Amazing to me - and the car's running well. And it LOOKS like it's got 150,000 on it. Seat boldster? Perfect condition. Shift ****? Mint. I"m very pleased.
Needs paint - leaking some oil - but generally - it just soldiers on. (Fingers crossed!)
RK
03-17-2009, 10:04 AM
#15
Three Wheelin'
FWIW, I had about 165k miles on mine when I had to do this.