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Zafira losing power on the motorway
smart51 - 1/4/16 at 10:22 AM

My inlaws have come down to help us move house. They had a bit of bother with their car losing power on the motorway. They pulled into the inside lane, slowed down to 50 and it was alright. Its a 2003 1.6 petrol with 115,000 miles.

I've had a quick look. There's plenty of fuel. The air intake looks sound. It starts straight away and idles smoothly, though it sounds like you're shaking an empty spray can. It revs cleanly at fast idle. Any ideas what it might be? I might take the spark plugs out and have a look.

adithorp - 1/4/16 at 11:58 AM

Could be a lot of things but... I'd be suspicious of a blocked exhaust. Can be either a silencer that the internals have collapsed or a cat' monolith thats broken up and wedged itself in the outlet pipe (I've seen them that have rattled about until theres just a ball left thats a perfect fit in the pipe).

jps - 1/4/16 at 01:51 PM

I used to have a Citroen C3 (albeit diesel) which would suddenly go 'gutless' sometimes. I think it was down to a DPF problem that then told the ECU to cut the power, which I think then stopped the turbo working - i.e. it went into a sort of 'limp home' mode.

Obviously those components aren't relevant to your case, but is it also possible it's a 'limp home' mode kicking in?

britishtrident - 1/4/16 at 02:01 PM

Could be a few things including a choked or restricted fuel line
The restricted exhaust is easy to check provided the upstream lambda sensor will unscrew OK -- take the sensor out and start the engine, if at 2000 rpm it just about blows your head off the exhaust is blocked.

However ISTR these have a MAF sensor, OK at idle but loss of power when the throttled is opened is a sign of a contaminated MAF.
The proper way of testing is look at the air flow grams/s in obd live data when the throttle is snapped open or look at the output with an oscilloscope.
The rough and ready test is simply disconnect the MAF and see if the power improves, however this will throw up fault codes and may not work on this model.
Most MAF sensors can be cleaned

[Edited on 1/4/16 by britishtrident]

smart51 - 1/4/16 at 04:25 PM

Thanks guys. I plugged in my OBD tester and found and O2 sensor fault, a cam sensor circuit fault and an EGR flow fault. I'm not going to be able to fix it with spanners and gaffer tape.

rusty nuts - 1/4/16 at 05:20 PM

Have you checked the oil level? , had a customers car that kept going into limp home due to low oil level causing the knock sensor to detect a knock . It had been to a couple of garages that didn't spot it

smart51 - 1/4/16 at 07:21 PM

quote:
Originally posted by rusty nuts
Have you checked the oil level? , had a customers car that kept going into limp home due to low oil level causing the knock sensor to detect a knock . It had been to a couple of garages that didn't spot it


That's an interesting one. There was enough oil in it. It's over due a service, they said. They might get a bigger bill than they were expecting.

Toprivetguns - 1/4/16 at 08:49 PM

MAF sensor is a common culprit.

big-vee-twin - 2/4/16 at 07:27 AM

Had exactly the same with a dirty fuel filter, replaced it issue gone.

turbodisplay - 2/4/16 at 09:33 AM

2nd fuel filter as a posibility.
Had a deisel that had that problem, the flow at higher speed/power could not be met by the filter.

Darren