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MG MGF Technical - Sticking accelerator and whistline noise
|I've just driven into work and not only is the accelerator sticking at around 1200 rpm when in traffic and in neutral gear, there was also this really nasty whistling noise coming from somewhere under the dash (or so it sounded like). The whistling kind of came and went, and stopped when the accelerator started behaving itself again.|
HELP - anyone with any ideas what the noise is and how to fix both it and the sticky accelerator?
P.S. It's a 2000 my 1.8i F, just in case you were wondering !
|Fiona M3 GFE|
It could be you need to reset the throttle sensor..
You do this by switching the ignition on (dont actually start it) then fully depress the throttle and release 5 times... gently!
Then just switch the ignition off and try it..
Failing that it could be the throttle cable sticking...
Not sure about the whistling from the dash ?
The accelerator is simply a top hinged, spring loaded pedal attached to a cable, the cable then runs under the carpet along the cill up, onto and then through the parcel shelf into the engine bay to the throttle body. Therefore i can't think of anything throttle related that would make a whistling noise intermittant or otherwise in/under the dash, or anywhere at the front of the car - there simply aren't any related parts in this area.
I suggest that you may have two independant problems?
The 'sticky' throttle could be a number of things, try resetting the stepper motor using the technique described above, from there look at the throttle cable - it may be kinked or routed poorly - may even be poorly adjusted, has the throttle cable been replaced/adjusted recently? The first two are easy, cheap fixes, but it sounds to me like a throttle body problem - what model is your F/TF? Is it an early F? In which case it will have a plastic throttle body and the butterfly valve inside them has been known to stick partially open. Replacement is usually the cure, if you are going to do this i would recommend replacing it with a later model alloy throttle body, or even a Trophy throttle body if the Dark Side calls. Clearly, this isn't an open and shut case - there are a number of potential causes.
Regarding the whistling noise - the only thing that immediately springs to mind is the fan in the heater, was it on at the time (even position 1)? Could be the fan on it's way out, but it more likely to be something as simple as a leaf or similar trapped in the system - this could also explain the intermittant nature of the noise (the leaf moving inside the pipework). I could be barking completely up the wrong tree here, any chance you can expand upon your description of the noise? Try to pin down exactly where it was coming from, maybe describe it in a bit more detail?
|Dear SF & Stu|
Thanks for your responses. As a girly with not much techy know-how or ability, I'll definitely try Stu's solution first and see how it goes.
To describe the sticking in more detail, I'd say it was exactly like having an old fashioned manual choke fully 'out' when the engine wasn't cold.
As far as I know the throttle cable hasn't been replaced or adjusted. It's a 2000 1.8i F. If resetting the stepper motor doesn't work, then who is best to check/replace the throttle body? MGR dealer or an mg specialist, or the other half? Any recommendations?
As for the whistling - the heating fan was on, in the 1 position at the time (mind you it's always in the 1 postion). I'll have to check for leaves etc - sounds quite plausible.
|Fiona M3 GFE|
|Hey hey, I can think of two related things - do I get a prize?|
Coolant temp sensor: The coolant temp sensor tells the ECU when the engine is
too cold, so it applies the same rules as a choke (overfueling and high idle)
just right, normal, game rules apply
too hot, so it turns on the fan
If the ECU cannot sense a coolant sensor then it defaults to 'safe' mode, - over fueling and fan on.
If this is the case then yes you have two problems, one is just a problem waiting to happen:
1st, there is a dodgy connection to the temp sensor, either a part broken wire, a loose plug, a dirty plug (although dirty usually just reads cold rather than absent), or a failing sensor. All of these are very cheap parts, finding out which is which is trial and error and may takes some time.
2nd, Your fan should make a wooshing noise, if it's squeeling then the bearings are shot, fix this now before it actually dies and causes overheating (and potentially HGF)
|Thanks for your comments Wil - v.useful, if a bit scarry !|
Just one question for the time being - where do I find my coolent sensor thingy ?
|Fiona M3 GFE|
|(don't be daunted by this, the road is long, but all just simple spannering)|
pull the carpet out from the rear shelf (it should be glued to underlay, remove that as well)
Undo the five clips which hold the rear screen down.
Hinge screen up and tie up
on the parcel shelf there are (11 or 12) 10mm bolts, undo all
Lift parcel shelf out, taking care with your hands on the bottom of the T bar (which is sharp)
Now, in the centre of the engine bay, you should see some water pipes attached to the end of the engine.
The water pipes attach to a stubby piece of alloy with two sensors in it, one is brown and has a brown plug, the other is blue or black with a corrosponding coloured plug. The brown one is for the ECU, the blue/black is for the gauge.
to unclip, squeeze the plug (pressing the wire clip into the plug) and pull the plug free (should slide easily if you have pressed in the right place)
Wiggle wires to work out if you can turn on/off the fan/ hear a diffrent engine note, if you can then visit an auto electritian and they will solder in a new wire for you. note MGR _will not_ do this work, they will insist on a complete enging bay wireing loom!!
|Just wanted to say a big 'thank you' to everyone who posted help and advice last week in response to my slight problems.|
The good news is I tried Stu's fix first (reset throttle sensor) and it seems to have worked. There has been no repeat so far of the whistling noise either. I will keep all the rest of the advice though just in case something should heppen in the future.
|Fiona M3 GFE|
|"I will keep all the rest of the advice though just in case something should heppen in the future."|
Oh it will, don't ever doubt it ;)
This thread was discussed between 02/04/2004 and 06/04/2004
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