Intermittent power when accelerating

TheChizler

Hi all, plenty of threads on this but the causes are so widespread that each thread is different.

I have a 09 1.6 petrol Vectra which passed the NCT no bother on Saturday. This morning dropping my girlfriend to work I noticed it was intermittently losing power while taking off, and there was a tiny bit of juddering while driving at constant high speeds. This progressively got worse. On the journey to my own work I suddenly lost all power in the overtaking lane at 100 km/h (probably shouldn't have been there since I knew something was amiss...). Managed to get onto a minor road where it semi recovered and I managed to get to the car park at work. During this time sometimes I'd get full power from it while accelerating but most of the time it would 'hang' around 1500-2000 rpm before 'coughing' and power coming back. About 4 spaces from where I was going to park I lost all power again, it would idle fine but any acceleration with or without clutch engaged there was no power. The rev counter would just wobble around 900 rpm (idle). Pushed it into the space and was able to start it fine, but just touching the accelerator in idle would result in it coughing and a popping noise coming from I presume the exhaust manifold, and a smell of unburnt fuel.

Any suggestions for things I can try myself before I call a garage? I'm going to go pull out the ignition leads one by one to rule out the ignition. Air intake should be fine, replaced the filter just before the NCT. I don't think it's the fuel pump as it starts fine. When I could get revs out of it the speed was proportional so nothing to do with the clutch. Would a clogged fuel injector or filter make the car go from fine to dead in a few miles? I'm guessing sensor or something in the fuel system anyway.

No lights on the dash except for the service interval indicator which I never got around to resetting, but I don't think that indicates a problem.

Appreciate any ideas!

gavman1

Initial thoughts would be the fuel filter.if it were a sensor you would have a light on the dash.a injecters would only effect one cylinder,what you described sounds like all the cylinders are effected.

brembo26

Do I recall an issue with coil packs breaking down on top of the spark plugs in these?? Still that would probably throw a light up. No harm to have a look at the plugs anyway if they havent been changed in a while.

TheChizler

Cheer's guys! I'll update I suppose. Was convinced it was the fuel pump not the filter as the service log is stamped saying the filter was changed by the dealer before I bought it, and I've done relatively little mileage since. Got it towed to a mechanic cause I just wanted it sorted asap and turned out it still had the original OEM filter! They cut it open and it was totally clogged. Fibres hard as rock and full of flecks of dirt. Really annoyed at the dealer. Last time I pay attention to service logs. I had bought a filter to a few weeks ago to swap as part of a bi yearly service so annoyed about that.

However problem still there with a fresh filter. Exact same symptoms after swapping in a spare pump as well so that hasn't been destroyed by the excess pressure.

They eventually got a code to come up on the reader and it's a CAN bus fault and ECM communication error. Local ECU expert won't touch it as it's a hybrid (?) ECU submerged in a gel and they're too much work apparently.

Got it towed to the main dealer today (very reluctantly) and they're doing a full diagnosis in the morning.

Feel sick bringing it into them but I'm not going to diagnose it myself without investing in equipment and taking it off the road for a month.

TheChizler

brembo26 wrote: »

Do I recall an issue with coil packs breaking down on top of the spark plugs in these?? Still that would probably throw a light up. No harm to have a look at the plugs anyway if they havent been changed in a while.

Going to swap them all myself the second I get it back. Along with every other consumable I haven't already changed with my own two hands!

pa990

Sounds like a coil pack.

Once the first one goes, the rest usually fail soon after.

TheChizler

pa990 wrote: »

Sounds like a coil pack.

Once the first one goes, the rest usually fail soon after.

That was one thing I thought of initially but wouldn't that normally throw a code?

I'll be sick if it turns out that's all it is.

Just to characterise the behaviour a bit more, it starts perfect, will rev once fine but after a few seconds subsequent revs lose power. Restart ignition and repeat.

brembo26

Stretched chain or air flow meter maybe? again though id imagine something come up on the dash. Keep us filled in tomorrow! Might not get much done before the xmas unfortunately.

TheChizler

brembo26 wrote: »

Stretched chain or air flow meter maybe? again though id imagine something come up on the dash. Keep us filled in tomorrow! Might not get much done before the xmas unfortunately.

Will do! Hopefully it's something silly they'll be able to fix there. If it's the electrics they said it could be well into January before I have it back. Thanks for the suggestions.

TheChizler

Dealer confirmed it was going into limp mode when losing power, I thought limp mode would give some low constant power, not intermittent full power and zero power.

Anyway, after 3 hours on the computer they've confirmed it was the fuel pump. Must check with my mechanic cause I was pretty sure he said he swapped in a spare one and had the same trouble. Said to go ahead with the replacement if they can get the part by Friday, if not I'll get one from a motorfactor's and install it myself.

As an aside the're asking for an extra €200 to replace the battery, told them to forget about that

gavman1

Limp mode will give steady lower power output in most instances,but if there is a fuel supply problem then even limp mode won't have enough to keep going.did they not do a full pressure test?I would have thought that would be one of the first things to check.maybe I'm just old school lol

TheChizler

gavman1 wrote: »

Limp mode will give steady lower power output in most instances,but if there is a fuel supply problem then even limp mode won't have enough to keep going.did they not do a full pressure test?I would have thought that would be one of the first things to check.maybe I'm just old school lol

Couldn't tell you just heard it was on the diagnostic computer for two hours.

Got it back today with the fuel pump replaced. Seems to be driving fine but there's a God awful smell of petrol in the car and the fuel gauge isn't working. I let them know about the fuel gauge right away so I'm just going to be careful over Christmas and let them fix that since it was working before. I'll do a few checks myself to see if I can avoid the hassle though.

Thanks for the suggestions guys, it was the obvious thing just hidden by the electronics.

brembo26

2 hours on the diagnostics to check a fuel pump?? :pac:

TheChizler

brembo26 wrote: »

2 hours on the diagnostics to check a fuel pump?? :pac:

I know :-). I just wanted my car back so I didn't argue.