Momentary power loss

[Bodge]

Morning lads, wondering if anyone has any ideas on this:

Let's assume I was on a section of unrestricted Autobahn....

I had been pushing the car along at about 100-120mph for about 30mins, on a typical motorway. I then came to a very very long steep hill on the motorway, and decided it would be fun to let the turbo do some work, so planted it. Full boost, full load, at about 5krpm and about 120mph for a good 5+mins. Upon almost reaching the brow of this monster climb, the road curved to the left, obviously putting a bit of g-force on the car at this speed. Suddenly the power backed off instantly, so I lifted off for a second, then put my foot back down and got full power again. The issue never showed itself after this, and no CEL appeared.

I got to my destination so late last night that I haven't run a fault code scan yet. But I will do this afternoon.

My fuel light was on at the time, and the needle was just in the red on the gauge, so not sure if it was fuel starvation or not. Car runs a standard map, and was last filled with Shell V-Power 99.

Does anyone have any guesses as to why the engine would do this?

I'm thinking it must be related to the high exhaust gas temperatures or high in-cylinder pressure/temperature that would have been occuring at the time. Possible spark plug/coilpack issue. Coilpacks are the originals, and I changed the plugs for standard NGK from Skoda about 20k miles ago.

Thanks in advance for any ideas guys

On a side note, the new Audi A4 I was driving along with had a bit of a problem keeping pace with me! After losing him on the long climb I slowed down, and let the Audi pass. But I suddenly noticed there was red hot metal flying out of his exhaust! It looked like a furnace in his tailpipe, with red hot glowing material chucking out of the back, and a permanent burn coming from the tailpipe. I backed right off at this point as I sensed imminent engine failure for the poor chap. He then slowed way down, but the car seemed to keep going, with no smoke. I'm guessing his cat was breaking down or something. Looked nasty anyway. Need to check my bumper for chunks of platinum!

[Guest westallc]

sounds like a bit of crap from the fuel tank went through the system

[David 8]

Starvation or too much G force lol, thats my guess, although.......... when my coil pack popped last week, the first sign was a very slight blip in power whilst going up a big hill at about 4 k rpm, then it got progressively worse until it gave up about 10 mins later.

[Bodge]

sounds like a bit of crap from the fuel tank went through the system

Yeah good thought. That reminds me actually! I've never changed the fuel filter, and I think it's the cars original! Must have a fair bit of crapola stuck in it.

The engine was sucking up the fuel at a fair old rate! 24mpg average for the 60mile trip

[chicken_eyebrow]

Probably fuel starvation, if you were on a hill and the fuel level was almost empty then it might have not quite reached the pump pickup at the point you turned into the corner.

[Brimma]

Sorry which dual carriageway/motorway autobahn were you on when this happened

Edited 18 May, 2010 by Brimma

[craig180]

I would imagine as you were pulling G at that speed and given the fact you were caning it for some time before the oil was as thin as **** and sloshed over to one side of your lump and ran dry for a sec or two.

Baffled sump would sort this, or perhaps driving more sypathetically

[SideshowBob]

Bodge, me owd china, me old chestnut, old bean

vRS's don't like being driven so sedately, plain and simple. They like to be given a bit of welly every now and then, so I suggest if you're gonna continue to potter around like this you might consider swapping for a diesel, or a Kia Rio.

Must try harder.

On a sidenote, when you gonna stop mincing about and get it remapped?

[Bodge]

Probably fuel starvation, if you were on a hill and the fuel level was almost empty then it might have not quite reached the pump pickup at the point you turned into the corner.

I think you're probably right there.

I've done a full fault code scan and given the engine a good inspection, turned nothing up.

[David 8]

I would imagine as you were pulling G at that speed and given the fact you were caning it for some time before the oil was as thin as **** and sloshed over to one side of your lump and ran dry for a sec or two.

Baffled sump would sort this, or perhaps driving more sypathetically

Wouldn't that screw something though ???

[Bodge]

Bodge, me owd china, me old chestnut, old bean

vRS's don't like being driven so sedately, plain and simple. They like to be given a bit of welly every now and then, so I suggest if you're gonna continue to potter around like this you might consider swapping for a diesel, or a Kia Rio.

Must try harder.

On a sidenote, when you gonna stop mincing about and get it remapped?

Haha you slag!

Yes I know I need a remap! I'm rubbish at saving money though!

I'll try and push the car a bit harder for you next time!

[Bodge]

Sorry which dual carriageway/motorway autobahn were you on when this happened

The A61 from Koblenz to Mannheim.

There's a section on the road very similar to the M62 between Manchester and Leeds. Shame we have such tight speed limits on our motorways though.......

[Bodge]

Riiiiiight! So this happened again at 1am on Wednesday morning. Similar scenario, but motorway was flat and I was cruising at like 110-120mph. Again, the fuel light was on and the level was well into the red.

This is only the second time this has ever happened. Common factors appear to be very low fuel level, high speed. and time of day.

Again no error code. The only error code I'm currently struggling with is the knock sensor one, which after replacing the sensor and checking all the wiring, is still popping up, but with no running issues. I'm going to try another new sensor, and use a calibrated torque wrench, hopefully that works because there is nothing else I can do after that.

The power reduction is short and sharp, and only lasts for a second. Then I get full power back again, the fault does not re-occur, and the car drives as normal.

Confused!

After the last time (3.5 months ago), I changed the fuel filter, and I have had a Stage 1 remap from Shark since it last happened. So it's not map related.

I'm wondering if it's a fuel supply issue. Could the pump be on its last legs (I'd surely see an error code)? Could it be something to do with the transition between main and reserve tanks?

The car spends most of it's time parked up at the moment, so the dregs of fuel in the tank could be many months old. I'm not saying the fuel is dirty, because I'm sure it's spotless, but I know fuel does go off. Wonder what the performance degradation is of V-Power. I hope it's not the Tesco Momentum that I used alot of earlier in the year....

Totally stumped, so again any thoughts welcome

[felicia16v]

fuel supply problem i would think mate, after all its trying to burn a gallon every 7 miles at that speed (well mine does anyway) which is a lot of flow thru the pump and if the level is low it may be emptying the swirl pot chamber built in the pump for a split second. try getting a fuel pressure gauge fitted for now so you can see what is happening

[VRS Mike]

don't run your car so low on fuel!!!!

[KenONeill]

I'd think it's a fuel supply or surge issue too. Most modern cars rely on supplying excess fuel wrt requirements, and returning the excess to the tank, so when you're down under 1 gallon (based on volume remaining in mine when the light comes on) anyway, it's not inconceivable that you could have a situation where most of the remaining fuel is in the lines, you turn a bit, and the pickup is left dry, feeding an air bubble down the supply line. And, frankly, if it's surge, other than a new filter, madmike's suggested the only cure!

[SideshowBob]

Your poor vRS

Sits there all sullen like an unloved ginger stepchild for most of the year...then as a treat, gets taken out, thrashed senseless down the M62 autobahn a couple of times a year on a thimble-ful of 6 month old fuel, and gets parked up again. :'( :'(

I think it just needs a little lurrrrve

And some fuel.

Btw how you gettin on with that map?

[chicken_eyebrow]

All I can say Bodge is you must go to Germany very often!

As the other guys have said I reckon its just running it low on fuel. I'm notorious for it, I've lost count of the amount of times I've rolled it into Tescos with zero showing on the miles left, and I do get little blips in performance when the tank is low (although just driving at 30-60 mph, not those kind of speeds!). I bought a new fuel filter to replace mine thinking (same as you) that might help but reading this perhaps not.

If you do end up taking the pump out of the tank and checking how clean the tank is then please post some pics, I might have a go at it myself at some point

[vrs180]

Hi Andy

This does sound like its a fuel related problem......my guess would be fuel pump cavitation due to insufficient head of fuel.

I've noticed with my Octy vRS that it generally seems to perform better when the fuel tank is full.

Bill.

[Lew_VRS]

A solution, stop giving it 3 figures on the M62 AUTOBAHN! when the fuel light is on..

[Bodge]

Cheers for the responses guys. I think I agree with the general concensus on this one. Also, most of the replies got me chuckling!

I needed a laugh after the day I've had at work so muchos grassyarse!

I try to run the tank dry, and then brim her up rather than topping up regularily, so every now and then I'm on fumes! I'm not a petrol pikey honest!

I am a bit of a speed slag though! It's far too addictive! Also the car loves it really. Blows the cobwebs out!

I was thinking of removing the pump/sender just to have a butchers, so will do a how-to if I get the time.

Off to get 55litres of V-Power now...............

[Bodge]

Your poor vRS

Sits there all sullen like an unloved ginger stepchild for most of the year...then as a treat, gets taken out, thrashed senseless down the M62 autobahn a couple of times a year on a thimble-ful of 6 month old fuel, and gets parked up again. :'( :'(

I think it just needs a little lurrrrve

And some fuel.

Btw how you gettin on with that map?

Hahaha!

Yes, loving the remap. Drives like normal when I want to, but goes like a stabbed rat when poked! Nice and smooth and fast! Need to write a review actually, but wanted a RR graph first...

[SideshowBob]

Off to get 55litres of V-Power now...............

...must be good, to be able to fit an entire year's worth of fuel in your tank.... :yes:

[karlbar2k]

:rofl: Edited 27 August, 2010 by karlbar2k

[Bodge]

...must be good, to be able to fit an entire year's worth of fuel in your tank.... :yes:

Very funny SideshowBlob! You rascart!

I wish it would last a year! I've got well over a thousand miles to do this month, so she'll see enough use!