Sensitive throttle

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rover45
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Sensitive throttle

#1 Post by rover45 » Thu Mar 04, 2021 10:19 am

Hello fellow members, this is my first post.
The car is a 2001 Rover 45 1.4 hatchback.
The problem is that in pressing the throttle the rpm jumps immediately from idle to 2000 rpm. Impossible to hold any rpm between 1000 and 2000, even if the throttle valve is gently moved by hand. Same in reducing rpm. This of course leads to difficulty driving in slow speed traffic and car parks etc. Other than this problem the car starts, idles and runs well.
Components changed so far; throttle position sensor, idle air control valve, coolant temperature transducer. Also inlet manifold gasket when I did the head gasket. Throttle valve cleaned. I looked for an inlet manifold leak but couldn't find anything. Cleaned the MAP sensor and the O2 sensor.
This is the only K series car with an ECU that I have ever driven, is this perhaps a characteristic of these cars? I have a Rover Metro with a carb engine which drives normally.
Any suggestions or help much appreciated.

itcaptainslow
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Re: Sensitive throttle

#2 Post by itcaptainslow » Thu Mar 04, 2021 2:45 pm

Have you tried simply adjusting the throttle cable by releasing it from its clip and screwing the plastic adjuster back/forwards as necessary? It might be a tightness in the cable causing the problem.
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RoverRevival
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Re: Sensitive throttle

#3 Post by RoverRevival » Thu Mar 04, 2021 4:03 pm

stepper motor reset
the ignition on but not started, depress accelerator 10 times, ignition off

Possibly dirty AIC valve if it stays at the 2krpm
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rover45
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Re: Sensitive throttle

#4 Post by rover45 » Fri Mar 05, 2021 8:41 am

Thanks very much for the replies.
Throttle cable - yes I adjusted that and tried eliminating it by working the throttle by hand at the quadrant to see if it made a difference, but I'll have another look as I may be missing something.
Stepper motor reset - I tried that but only 5 times so I will try again this time depressing the pedal 10 times.
Dirty AIC valve - I replace that after first cleaning it, but unfortunately it made no difference.

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Re: Sensitive throttle

#5 Post by 220 GSi turbo » Sat Mar 06, 2021 2:50 pm

Well, I tried this on my spares donor Rover 25 1.4 this morning and it behaves more or less as yours does! Lowest rpm achievable with the pedal pressed slightly is 1750 and a similar thing occurs when moving the quadrant by hand (couldn't see the tacho for an exact reading!)

The car is being scrapped because of corrosion and although I haven't driven it myself, I was not advised of any running issues with it when I bought it.

Does the issue cause a problem when you drive yours at low speed? (is it like a large dog on a lead trying to pull you along?!) I was wondering if having a load put on the engine would stop it surging.
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Re: Sensitive throttle

#6 Post by itcaptainslow » Sat Mar 06, 2021 5:46 pm

Does the problem occur all the time, or only when the car is warm?
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rover45
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Re: Sensitive throttle

#7 Post by rover45 » Sat Mar 06, 2021 8:48 pm

Replies;
220 Gsi turbo - yes it's at low speed when it causes the problem, trickling along in traffic is all but impossible without riding the clutch as the throttle is either on or off. On the open road it's fine unless you are cruising at lower speeds in a higher gear when it also becomes noticeable.
itcaptainslow - much worse when the engine is warm, although you can see it's doing it even from cold. Another symptom is that when changing gear whilst accelerating the revs rise when you put your foot on the clutch even with no throttle input.

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Re: Sensitive throttle

#8 Post by crepello » Sat Mar 06, 2021 11:08 pm

Would it be worth an ECU reset, in case it has learned 'bad habits'?
It would then re-learn from factory settings according to your usual driving style.

itcaptainslow
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Re: Sensitive throttle

#9 Post by itcaptainslow » Sun Mar 07, 2021 12:20 am

If this particular car has a plastic throttle body they’ve been known to stick. Might be worth sourcing a metal one-cheap from a breaker or on eBay.
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Re: Sensitive throttle

#10 Post by 961tat » Sun Mar 07, 2021 9:12 am

itcaptainslow wrote:
Sun Mar 07, 2021 12:20 am
If this particular car has a plastic throttle body they’ve been known to stick. Might be worth sourcing a metal one-cheap from a breaker or on eBay.
I've had the issue with plastic throttle body takes age's for the rev to rest i sprayed damp start all over inlet and body looking for the air leak no rise in revs and in the end changed to metal throttle body issue fixed , my mate is a ex rover dealer and said just try it ! over the years he's changed sensors ecu etc and he says it was well know at the time when they finally bottom it out .

rover45
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Re: Sensitive throttle

#11 Post by rover45 » Sun Mar 07, 2021 6:53 pm

thanks for the input everyone
replies;
Plastic throttle body - no luck there this has a metal throttle body which I have cleaned and lubricated.
ECU reset - how do you do this?

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