Help, I've got a hiccup.

[Road2Ruin]

Hello Chaps,

The S3 has developed a rather annoying hiccup (check for spelling). I recently changed the plug leads and checked the plugs incase that was the problem, but no. There doesnt seem to be any pattern to it, sometimes it will not happen for miles ither times two or three times in a a minute. The car lurches and feels like the engine has cut out for a fraction of a second and then carries on. If you leave it idling then you see the revs drop to about 700 then pick up again like it almost stalled. It seems to severe to be a missing cylinder but could be missing two or three in a row to make it lurch that much. Where do I start looking? The coil maybe?

Many thanks
Peter

[bridgdav]

Clean the AFM..?

[Road2Ruin]

bridgdav said:

Clean the AFM..?

Hi Dave,

That hadn't crossed my mind. I was thinking it could be fuel filter too but I will into the AFM at the weekend too.

[ketvrin]

Throttle Pot ?
Rotor arm ?
Brake servo - if holed it will be leaking and mess up signals to ECU from Plenum
Check the small hose on the Fuel Regulator that travels to the throttle just below the TP.

discuss/ compare/ commiserate with Elfin - sorry Tim...

good luck

K

[Road2Ruin]

ketvrin said:

Throttle Pot ?
Rotor arm ?
Brake servo - if holed it will be leaking and mess up signals to ECU from Plenum
Check the small hose on the Fuel Regulator that travels to the throttle just below the TP.

discuss/ compare/ commiserate with Elfin - sorry Tim...

good luck

K

Rotor Arm and cap changed 2 years ago. Had a quick look and both seem in good nick. Would the throttle pot be an intermitent fault? The brake servo I would never have guessed but will have a look at too. How best to check the throttle pot, other than replace it?
Thanks
Peter

[Elfit]

Road2Ruin said:

ketvrin said:

Throttle Pot ?
Rotor arm ?
Brake servo - if holed it will be leaking and mess up signals to ECU from Plenum
Check the small hose on the Fuel Regulator that travels to the throttle just below the TP.

discuss/ compare/ commiserate with Elfin - sorry Tim...

good luck

K

Rotor Arm and cap changed 2 years ago. Had a quick look and both seem in good nick. Would the throttle pot be an intermitent fault? The brake servo I would never have guessed but will have a look at too. How best to check the throttle pot, other than replace it?
Thanks
Peter

Commiserate with me!
Great weather and I'm either sat by this "lovely" computer or busy with other stuff when I should be driving.
Also daily runaround has died and I've been sorting a new motor.

So Peter, you're an accountant with a grey TVR giving problems.....me too, except mines an S2 and the fault isn't intermittent ~ it's permanent.
AFM cleaning/ swapping is my next port of call.
I have a spare throttle pot which I can send you if you wish ~ easy to change and easy to post! If it doesn't make a difference just post it back ~ PM me with your address.

As Kev says check the small hose ~ that was where he had problems
Leaking Servo ~ a friend told me a way of checking this ~ park on a (slight)hill and with the engine off and see how many times you can easily stop the car just using the brake pedal. If the servo is knacked/leaking you will not be able to do this much. I can't remember how many times this ought to work but the principle seems sound. Prehaps some brave soul who isn't near Beechy Head can let us know!

Cheers
Elfit/Tim

[Road2Ruin]

Elfit said:

Road2Ruin said:

ketvrin said:

Throttle Pot ?
Rotor arm ?
Brake servo - if holed it will be leaking and mess up signals to ECU from Plenum
Check the small hose on the Fuel Regulator that travels to the throttle just below the TP.

discuss/ compare/ commiserate with Elfin - sorry Tim...

good luck

K

Rotor Arm and cap changed 2 years ago. Had a quick look and both seem in good nick. Would the throttle pot be an intermitent fault? The brake servo I would never have guessed but will have a look at too. How best to check the throttle pot, other than replace it?
Thanks
Peter

Commiserate with me!
Great weather and I'm either sat by this "lovely" computer or busy with other stuff when I should be driving.
Also daily runaround has died and I've been sorting a new motor.

So Peter, you're an accountant with a grey TVR giving problems.....me too, except mines an S2 and the fault isn't intermittent ~ it's permanent.
AFM cleaning/ swapping is my next port of call.
I have a spare throttle pot which I can send you if you wish ~ easy to change and easy to post! If it doesn't make a difference just post it back ~ PM me with your address.

As Kev says check the small hose ~ that was where he had problems
Leaking Servo ~ a friend told me a way of checking this ~ park on a (slight)hill and with the engine off and see how many times you can easily stop the car just using the brake pedal. If the servo is knacked/leaking you will not be able to do this much. I can't remember how many times this ought to work but the principle seems sound. Prehaps some brave soul who isn't near Beechy Head can let us know!

Cheers
Elfit/Tim

Thanks Tim,

Gave me a chuckle anyway. I will look into all possible probs and if all else fails drop you a line about the throttle pot, you are a true gent. If it makes you feel any better I think mine was nearly and S2. It has s2 mirrors and switches on the inside and no driving lamps, but does have the longer doors and the in line dash....hmmmm, a TVR then. Its more anoying at the moment than anything else but I know it will turn out to be more.....

Nice looking car by the way, sorry its off the road.

Pete.

[Longers]

Had exactly the same problem on my 1st S and it was the throttle pot.

Being a technical numpty an auto electrician sorted mine I'm sure TP's have been discussed here already so will be worth doing a search - I think I read somewhere that one way to confirm if it is the problem is to disconnect it....?

[Barkychoc]

[bridgdav]

I think you need a bit more Background on that pic..

[Barkychoc]

Pic shamelessly stolen from Mycroft - but what I'm trying to say is some have had running problems due to the dodgy yellow connector in the steering column.

[Road2Ruin]

Barkychoc said:

Pic shamelessly stolen from Mycroft - but what I'm trying to say is some have had running problems due to the dodgy yellow connector in the steering column.

Not the dodgy yellow conector. Shame on it.

Seems I have got my weekend sorted then.

Thanks All.

Pete

[ketvrin]

Road2Ruin said:

Seems I have got my weekend sorted then.

Thanks All.

Pete

if you are really really lucky it will be a case of:

Lift Bonnet
Notice small tube has become dislodged from Fuel Regulator
Cut inch off tube (or 25.4 mm if you are younger than 50 )
refit tube to fuel regulator
secure bonnet
get in car and have a great days drive...

fingers crossed for you

K

[bridgdav]

Any Joy..?

[Road2Ruin]

None so far. I am leaning towards it being the throttle pot as all the easy stuff looks ok. The only annoying bit is that it takes so long to test each bit. The hiccup is so random it might drive for 10 miles with nothing so you really have to get out there and take your time. I will have a another look over the bank holiday. Fortunately I can still drive it ok.

[MickS2]

Road2Ruin said:

None so far. I am leaning towards it being the throttle pot as all the easy stuff looks ok. The only annoying bit is that it takes so long to test each bit. The hiccup is so random it might drive for 10 miles with nothing so you really have to get out there and take your time. I will have a another look over the bank holiday. Fortunately I can still drive it ok.

I had a similar problem which (after months of frustrating fiddling with various bits) I eventually traced it to a dodgy connection in the multiway connector that sits just under the coil. (This takes all the signals to/from the TP, ISCV and injectors). Replaced the connector and loom with one from the breakers and the problem went away for good.
I then moved the coil to the bulkhead (behind/above the washer bottle) to allow the cable/connector to be lifted up a bit and not suffer from the high temps it was probably suffering from before.