Engine revs on it's own! 480 1.7 Catalyst

deadpheasant · Oct 9th, 2009, 09:00

The 480 has started to do a weird thing. Last night on the way home after about 10 minutes of driving, the revs became quite erratic. Jumping from about 800 to 1400 (at idle) and the car just shuddering - felt very strange. It did this while driving too, just sort of spiking while accelerating. When I got to the traffic lights, I turned off the ignition and restarted and all was fine from then on.

It did it again this morning and again, it disappeared after I restarted at the traffic lights.

My voltage regulator needs changing and should be arriving soon, could it be anything to do with this or is more likely to be something else? I've read on here that I probably should check most of the pipes for air leaks and clean the idle control valve. I don't know know these cars very well at all as I've only had it a couple of weeks, so it's probably going to be a bit of trial and error.

Any advice would be greatly appreciated.

Georgey dee · Oct 9th, 2009, 10:28

I would start by cleaning the throttle body.

Give the butterfly valve a good spray with carb cleaner and If you can clean out the Idle Control Valve then do that too.

Baffler · Oct 9th, 2009, 12:55

Good advice there from Georgey and definitely the best place to start

As a matter of fact the IAC valve and throttle housing should be cleaned at each service. Don't forget to disconnect the negative lead from the battery while you clean these...it will also reset the ECU if disconnected for more than an hour

If the voltage regulator is not functioning properly the engine will try to compensate for the lack of charge from the alternator.

deadpheasant · Oct 9th, 2009, 13:15

Sorry to sound like such a noob, but it's ok to reset the ECU is it? As I'm going to change the regulator this weekend, is it best to disconnect the positive lead from the battery as I do this? Or, can i just keep the negitive lead off (and leave the positive lead on) while I change the regulator and clean the idle control valve and the throttle body?

It's great learning curve having a 480!

Baffler · Oct 9th, 2009, 13:56

As a rule of thumb, as with most things electrical, always disconnect the negative lead first. It doesn't matter if you leave the positive lead on just as long as the negative is out of the way.

By disconneting the battery you'll reset the ECU to default factory settings and eliminate any error codes. If you have a radio with a code you'll need it when you re-connect the battery.

These are great little cars to work on but you'll discover that it has some tempermental electrics that you'll just learn to live with. The engine is easy enough to work on and regular preventative maintainance will keep it 100%.

deadpheasant · Oct 9th, 2009, 13:59

Brilliant, thanks Baffler. Looking forward to getting it sorted. There's a great deal of satisfaction from fixing something yourself.

deadpheasant · Oct 12th, 2009, 10:52

Well, I managed to change the voltage regulator. I think I did it right as the lights are no longer pulsing. The brushes were very worn on the old one.
As for the revving on it's own. I cleaned out the idle control valve with carb cleaner and i cleaned out the two hoses that come from it. One of them - the one that goes out at 90 degrees to the large tube before the throttle butterfly had a hole it in. It looked like it had worn through from the red sensor connector block that attaches to the engine.

I Gorilla Taped over the hole and put it all back. A bodge I know but it seems to work ok now - well, for the time being anyway. the engine had a bit of a fit after i connected the battery terminals - the ECU adjusting itself after losing it's settings?

Anyway, it seems ok. Until next time, thank you everyone!

Baffler · Oct 12th, 2009, 12:14

Quote:

Originally Posted by deadpheasant

the engine had a bit of a fit after i connected the battery terminals - the ECU adjusting itself after losing it's settings?

When I connected the terninals on my 480 the wipers used to flicker along with the driving lamps and sometimes the horn might give a bip, all due to a faulty CEM...I think? Eccentric little cars these

As for the idling...also check the rubber bellows going from the trottle housing to the air filter housing. Seen a few of these deteriorate on the bends and groves.

Don't forget to get some carb cleaner on the butterfly valve in the throttle housing...an old toothbrush works a treat

Glad you're getting it sorted

Paul240480 · Nov 1st, 2009, 16:23

Quote:

Originally Posted by Baffler

When I connected the terninals on my 480 the wipers used to flicker along with the driving lamps and sometimes the horn might give a bip, all due to a faulty CEM...I think? Eccentric little cars these

As for the idling...also check the rubber bellows going from the trottle housing to the air filter housing. Seen a few of these deteriorate on the bends and groves.

Don't forget to get some carb cleaner on the butterfly valve in the throttle housing...an old toothbrush works a treat

Glad you're getting it sorted

They do a series of 'self tests'. Can also be triggered when using the diagnostic box thingy to 'fault find'. Some thing like three presses of one of the buttons & it wiil 'test' various items like:

Indicators flash once
Leccy windows will drop an inch or so then raise
wiper will do one sweep & squirt too
Horn will beep.
H'lamps will raise & lower on 480's
etc....

Not in right order & it may do a few more.
I nearly jumped out of my skin when me horned beeped!
Good Luck.

dcw · Nov 1st, 2009, 19:45

The hole you described in that pipe may well be your problem as it connects directly to the Idle Control Valve and could be confusing things....

As others have said, the electrics on these can be great fun! Another thing worth checking, though, is the distributor cap and rotor arm: a previous (1987) 480 that I had used to "eat" these with regular monotony, and that used to cause poor idling.

Keep us all posted!

David

Oct 9th, 2009, 09:00	#1
deadpheasant New Member Last Online: Jan 11th, 2011 15:16 Join Date: Oct 2009 Location: Bradford	Engine revs on it's own! 480 1.7 Catalyst The 480 has started to do a weird thing. Last night on the way home after about 10 minutes of driving, the revs became quite erratic. Jumping from about 800 to 1400 (at idle) and the car just shuddering - felt very strange. It did this while driving too, just sort of spiking while accelerating. When I got to the traffic lights, I turned off the ignition and restarted and all was fine from then on. It did it again this morning and again, it disappeared after I restarted at the traffic lights. My voltage regulator needs changing and should be arriving soon, could it be anything to do with this or is more likely to be something else? I've read on here that I probably should check most of the pipes for air leaks and clean the idle control valve. I don't know know these cars very well at all as I've only had it a couple of weeks, so it's probably going to be a bit of trial and error. Any advice would be greatly appreciated.

Oct 9th, 2009, 10:28	#2
Georgey dee Premier Member Last Online: May 1st, 2024 06:21 Join Date: Dec 2005 Location: Norwich View Photos By: Georgey dee	I would start by cleaning the throttle body. Give the butterfly valve a good spray with carb cleaner and If you can clean out the Idle Control Valve then do that too. __________________ HAD; 440 GLT(Loved it), 850 GLT auto(Loved it), S70 2.5T(Nothing but problems!), 850R auto(Loved it!!), S60 D5 SE (Nothing but problems!) GOT; S60 D5 SE Lux Auto RAF Marham Track Day Co-Ord'

Oct 9th, 2009, 12:55	#3
Baffler Premier Member Last Online: May 17th, 2024 18:21 Join Date: Dec 2002 Location: Co. Limerick, Ireland	Good advice there from Georgey and definitely the best place to start As a matter of fact the IAC valve and throttle housing should be cleaned at each service. Don't forget to disconnect the negative lead from the battery while you clean these...it will also reset the ECU if disconnected for more than an hour If the voltage regulator is not functioning properly the engine will try to compensate for the lack of charge from the alternator. __________________ Liam... '96 854 TDI SE, '99 V70 2.5D S, '05 C70 2.0T Collection, '05 S80 2.0T SE, '15 V70 D4 SE Lux Nav.

Oct 9th, 2009, 13:56	#5
Baffler Premier Member Last Online: May 17th, 2024 18:21 Join Date: Dec 2002 Location: Co. Limerick, Ireland	As a rule of thumb, as with most things electrical, always disconnect the negative lead first. It doesn't matter if you leave the positive lead on just as long as the negative is out of the way. By disconneting the battery you'll reset the ECU to default factory settings and eliminate any error codes. If you have a radio with a code you'll need it when you re-connect the battery. These are great little cars to work on but you'll discover that it has some tempermental electrics that you'll just learn to live with. The engine is easy enough to work on and regular preventative maintainance will keep it 100%. __________________ Liam... '96 854 TDI SE, '99 V70 2.5D S, '05 C70 2.0T Collection, '05 S80 2.0T SE, '15 V70 D4 SE Lux Nav.

Oct 9th, 2009, 13:15	#4
deadpheasant New Member Last Online: Jan 11th, 2011 15:16 Join Date: Oct 2009 Location: Bradford	Sorry to sound like such a noob, but it's ok to reset the ECU is it? As I'm going to change the regulator this weekend, is it best to disconnect the positive lead from the battery as I do this? Or, can i just keep the negitive lead off (and leave the positive lead on) while I change the regulator and clean the idle control valve and the throttle body? It's great learning curve having a 480!

Oct 9th, 2009, 13:59	#6
deadpheasant New Member Last Online: Jan 11th, 2011 15:16 Join Date: Oct 2009 Location: Bradford	Brilliant, thanks Baffler. Looking forward to getting it sorted. There's a great deal of satisfaction from fixing something yourself.

Oct 12th, 2009, 10:52	#7
deadpheasant New Member Last Online: Jan 11th, 2011 15:16 Join Date: Oct 2009 Location: Bradford	Well, I managed to change the voltage regulator. I think I did it right as the lights are no longer pulsing. The brushes were very worn on the old one. As for the revving on it's own. I cleaned out the idle control valve with carb cleaner and i cleaned out the two hoses that come from it. One of them - the one that goes out at 90 degrees to the large tube before the throttle butterfly had a hole it in. It looked like it had worn through from the red sensor connector block that attaches to the engine. I Gorilla Taped over the hole and put it all back. A bodge I know but it seems to work ok now - well, for the time being anyway. the engine had a bit of a fit after i connected the battery terminals - the ECU adjusting itself after losing it's settings? Anyway, it seems ok. Until next time, thank you everyone!

Nov 1st, 2009, 19:45	#10
dcw VOC Member Last Online: May 1st, 2024 19:45 Join Date: Jan 2007 Location: YORK	The hole you described in that pipe may well be your problem as it connects directly to the Idle Control Valve and could be confusing things.... As others have said, the electrics on these can be great fun! Another thing worth checking, though, is the distributor cap and rotor arm: a previous (1987) 480 that I had used to "eat" these with regular monotony, and that used to cause poor idling. Keep us all posted! David

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