Throttle hesitation and overrun.

I have a 2004 MGTF 135. For a while now I have noticed a slight hesitation on pressing the throttle and an overrun where the engine speed does not reduce immediately when the throttle is released. The result is that on changing up through the gears there is always an 'overrun' as I press the clutch.

Is this normal? I have been recommended to clean the throttle body. Is this straightforward? Is there a howto? I cannot find anything here.

I should add that I have changed the throttle cable (OE from Rimmers) to no effect.

As always, advice appreciated.

First thing to try is a Throttle position sensor reset. There should be a description on the how to section, or a google search will find it. It takes a few seconds to do and costs nowt.

If that does not work, then its time to look at the idle air control valve, they have been known to stick, again the how to section should have info on this.

I keep a spare second hand one in my spares box just in case.

Sundance

Thanks, Sundance. I've done a throttle position reset but it didn't seem to make any difference. Perhaps I did it wrong? Is there any sign that the operation has been completed successfully?

I'll have a look at the IACV, when I get a chance. I have a feeling it's a completely sealed unit; is that right?

It is on later Fs and TFs. You can clean it with carb cleaner spray. :yesnod: You can clean the internals of the throttle body with the same spray.
It would be worth disconnecting the throttle cable and operating manually to see if it is definitely the throttle body.

IIRC the TPS reset should work on all models but only if you do it correctly.

I have seen various suggestions but the correct method is

1) switch ignition to position II but do not start the engine
2) firmly and fully press the gas peddle to the floor and release 5 times in 30 seconds
be slow and deliberate, do not jab.
3) wait 30 seconds
4) start the engine

Thanks, TC. That is the method I followed but, as I say, it made no difference. It's a shame that when the (correct) procedure has been followed there is no indication that the recalibration is successfully completed. A beep or something.

Entering my EKA code certainly makes plenty of noise but that is another story!

Check the throttle cable is running free and not slack by the throttle body. Also the peddle isn't sticking.

BruceTF135 wrote: …….It's a shame that when the (correct) procedure has been followed there is no indication that the recalibration is successfully completed. A beep or something...….

If you were standing at the back of the car you would hear the stepper motor moving in and out for a few seconds.

Bob wrote: Check the throttle cable is running free and not slack by the throttle body. Also the peddle isn't sticking.

Thanks for the input. But the throttle cable is new, runs freely and the pedal doesn't stick

talkingcars wrote:

BruceTF135 wrote: …….It's a shame that when the (correct) procedure has been followed there is no indication that the recalibration is successfully completed. A beep or something...….

If you were standing at the back of the car you would hear the stepper motor moving in and out for a few seconds.

Thanks, TC. That is very helpful. I'll check that.

To demonstrate the symptom I have made this little video clip. Note that a blip on the throttle body raises the engine speed, as expected, but also notice the clear overrun after the control is released.

Video here on YouTube



I've tried to insert the video without success. Is there a 'how to insert a video' somewhere?

Hi Bruce

AFAIK there isn't a "How To" on inserting a video but it looks like you nearly got it right. I've edited your post to show the video in the web page. All I did was copy your You Tube link, hovered on the film strip icon in the ribbon, selected video and then pasted the link to the clip.