Technical sticky throttle switch mystery

[tttom]

Hi, I've got a problem with my treasured bravo.

I got towed to the garage recently because my 98 1.4 sx was going all "lumpy", the acceleration feeling like it was bucking, loss of power, at 50 mph and slower too.

It had been smelling very petrolly at start-up for a while.

They read the fault codes and replaced the throttle switch with a second-hand one. I got a flush and new oil too, £140 all in, I think. Replaced the air filter at home also. Plugs have only done 3000 miles so I left them.

But now it's doing it again. There's no petrol smell on start up, but it's like it needed to relearn the throttling - it was stalling a bit at lights. And more importantly, it bucked on the motorway and then again at 30 mph, with loss of power. I could still crawl along with hazards, but it needs fixing.

I suppose I'll head back to same garage and see what they say. Any pointers or tips before I do much appreciated. Is it likely I've got another bad throttle switch, or more likely it was something else in first place?

 

[nedge2k]

you could try resetting the ECU. I forget the exact procedure but I think it goes something like this:

1)Disconnect battery for 45mins
2)Re-connect and run engine for 5 mins - don't touch throttle!
3)Kill engine, re-start and go for a run.

See how it goes!

 

[Adrian Bravo]

Trying to reset the ECU is a good idea.

I had a faulty throttle potentionmeter. It was causing my 1.4 to kangaroo and stall, that gradualy got worse and worse until i changed the part.

Have a look at this thread see if the symptoms match.
https://www.fiatforum.com/bravo-bra...v-throttle-potentiometer-position-sensor.html

 

[tttom]

Thanks for the replies, both of you. Adrian, that's a brilliant post you linked to there about the potentiometer. I didn't find it before - I suppose I was searching for "throttle switch".

The symptoms are exactly the same, though I suppose that's not conclusive in itself.

As I mentioned, the garage replaced my throttle switch / potentiometer with a replacement secondhand one. I'm heading back there on Wednesday so they can have another look. I suppose I should check whether they replaced the switch or the whole throttle body (given what you said in the other thread about not separating them).

You did that trick with the spray paint. I wonder if it would've been okay for the garage to have swapped in a new throttle switch so long as it's positioned exactly as the old one was? Or maybe the unique calibration is for the benefit of both parts, not just the butterfly?

Other thing is, if this fault is as common as your other thread suggests, maybe it wasn't the best part for me to go second-hand with. I suppose it's a gamble. My switch was £35 +vat + an hour's labour.

Anyway, thanks very much for the pointers.