Hi,

I'm just acquiring a W reg Felicia 1.3 to go with my Octavia as a family runabout. It's done 78k and is in brilliant condition. On the test run everything seemed in good order except that the throttle sticks a little at 2000 rpm, so that if you take your foot of the accelerator it keeps going. A blip on the pedal stops it. I'm guessing that a little cleaning around the mechanism in the venturi will solve it, but perhaps this is a regular glitch that needs more attention?

All advice greatfully received.

Michael L

maybe the cable starting to show signs of wear too mate

normally it's a sign that the throttle alignment needs resetting on it. tbh it should clear itself after a few days driving round

Check where the cable goes into its sleeve at both ends, behind the pedal and on the throttle linkage in the engine bay. people spray WD40 on them to keep them clean and lubricated but it ***** the rubber bits and it dries out and breaks up.

Use a teflon or "dry" lubricant spray to clean and lubricate them, and replace the rubber if it is buggered.

It is usually the engine bay end, as that gets the most dirt.

Thanks for all of the advice. I'll post a message when I get to the bottom of the problem!

Michael

I had the car serviced at an independent VAG garage. They cleaned the throttle up but this hasn't fixed the sticking; the revs don't drop back properly as you change gear. The mechanic thought that it was a question of living with it or changing the throttle body. Problem: he said that a new throttle body would cost about £400! So I'm wondering if there is a source of reliable reconditioned parts out there? I'm a bit reluctant to try scrappers because this part has electronics in it and you wouldn't know if a scrapped one worked until it is on the car.

Thanks

Michael

With a cable throttle, my thoughts on a sticky throttle would revolve around the return springs, a worn Bowden cable, or the quadrant sticking on something.

It's unlikely it's actually physically sticking, the spring on them is a bit of wound wire cable which is quite stiff.

It's unlikely it's actually physically sticking, the spring on them is a bit of wound wire cable which is quite stiff.

I agree. I should not have used the word "sticking". What is actually happening is that the revs fail to fall back promptly when you take your foot off. That's why the engineer thought the throttle body was faulty and thus my question about how to source a reconditioned unit at less than the value of the car.

Thanks

Michael

I've seen those multi-coil type springs break before.

Other thought; is there a throttle damper on this engine (looks a lot like a very small, maybe 4 inch long, suspension damper, typically with a ball and socket joint each end)? My Xantia had one, which was rapidly binned once I realised it was there, and was actually stopping the throttle closing as fast as I wanted (sometimes leading to the brakes and throttle fighting each other).

Michael.

First up, don't think that a s/h one should totally be discounted - you may get one for a tenner. But also I'm sure I've seen guaranteed recon ones on eBay for about £80. I've had a fair few MPis (including 2 rally cars), and never had a problem with them, including all the cars I've broken for spares.

Are you sure that there are no air leaks? And that the brake servo non-return valve is OK? Unmetered (or rather, unanticipated) air getting into the engine can cause similar problems.

Edited 26 March, 201016 yr by djaychela

fwiw i still think it's an alignment issue... it's really common for vdo/siemens throttle bodies to stick at 2000rpm and most vw's.. it is also quite common for them to go wrong, but for the sake of a tenner i would deffo get one from a scrapper

I also have the same issue, is the SPi throttle body the same as the MPi and is it worth swapping over to try and solve the problem or will the ecu still remember the previous valve position

it will still retain it's orignal learned values for the throttle valve yes, but it will re-learn them gradually by itself after a while assuming the throttle body is actually working properly.. i've never taken apart an spi throttle body before, on the mpi ones there is a variable resistor track for the main throttle sensor, a stepper motor to control the idle speed, and another variable resistor track to sense the idle posistion, plus a pair of contacts which close when the throttle is in the closed position.....

basically, the motor opens the throttle a little to make the thing idle but there is only a finite range of idle speeds available, the idle position operates inpedendantly of the main throttle lever. since the idle motor is opening the throttle the ecu needs to know how the resistance from the idle track so it can subtract it from the main throttle track, ie you get the same range of values from 0 to 100% throttle irrespective of what the idle speed is.... in this context the idle switch (contact closure) is not relevant, the ecu uses the idle switch to switch on/off the overrun settings, lambda control, and a few other bits...

i know this sounds a bit complicated but it does work very well, and like i said, the throttle body electrics needs to be correctly functioning for the adaption/learned values to work...

there are ways of tricking the ecu into thinking that a broken throttle body is working, i've done it at the side of the road to 'get me home' before now, but i dont recommend it as a long term ix becasue the engine wont run properly and the emmisions will be sky high

in reference to the op, 2000rpm is normally the speed they run at when the idle switch is busted or the contacts are worn/corroded or sticky.. you might find that if you rev it a few times the idle speed drops back to normal when the idle switch makes contact.... on the 1600cc models with the magneti ecu normally you will find it will rev up and down on it's own constanly to about 1500rpm when the idle switch is bust

Edited 27 March, 201016 yr by TeflonTom

This is getting a bit beyond my technical comprehension, but picking up on the last post, the sticking occurs at 2000 rpm and, as suggested, if I blip the accelerator, the revs fall back to the correct spot around 1000 rpm. The other thing I noticed is that when idling the engine hunts a little i.e. the revs rise and fall very slightly.

I'm getting the impression that the soluton is going to be to replace the throttle body, hopefully with a reconditioned one, rahter than the new one at £400. Goping back a few posts, I checked the action of the servo and its fine.

Thanks for the advice so far.

Michael

go for a scrapyard one, no more than £20 i'd say, but £400 for a new one is more than the value of the car

OK I finally got this sorted. I took the advice to try the scrapper route (thanks to those who suggested it) and got a replacement throttle body for £40. Easy to fit and problem was instantly solved. I got brilliant service by post from UK Auto Spares in Bishop Auckland. www.uk-autospares.co.uk

Thanks again

Michael L

glad you got it sorted in the end.. and thanks for coming back and updating us.

Yeah, might save someone spending £400 in the future - not all secondhand parts are broken, otherwise no cars on the road would work!