rough when accelerating

[sam2.0 10]

Following on from this thread: http://the-corrado.net/showthread.php?80030-9a-issue-with-timing-next-issue/page6

 

In summary: I've changed the head gasket and had a garage do the timing for me. Since then the car was laid up for a month while I dabbled with an E30. Now the C is back on the road, and it's running rough. Initially I thought it could be low fuel/crap getting sucked into the engine, so I've topped her up and still bad after 30 miles (tank was at 1/3 full before).

 

The car has had a new fuel filter only 3k miles ago. It sounds like a tractor/go-kart when going through the revs but when its decelerating, it sounds fine. It also will jump from sounding rough to sounding fine for a second and back.

 

Ideas?

[VR6 Gar 10]

Not firing on all cylinders?

Check the leads to see if they are broken and arcing and check the plugs and dizzy/ rotor.

Guessing its a 2.0 16v?

[sam2.0 10]

Bang on, there is arching.

 

Going to clean the dizzy etc tonight, all ignition is fairly new though, 6 months maybe

 

Yea, 2.0 16v

[VR6 Gar 10]

That was easy, lol.

My old 16v mk2 did this when it was wet and I found a lead arching to the inlet manifold.

[sam2.0 10]

Well HT leads replaced, still running badly. Sounds like a fuel starvation issue. Fuel filter is new, over 1/3rd of a tank of ultimate fuel. Nothing restricting the air flow or the butterfly valve.

 

I've recorded the sound, see attached. Both with me fully 'revving', and you can see the revs hesitating.

 

http://tinypic.com/r/54hm47/5

http://tinypic.com/r/c58nd/5

[sam2.0 10]

bump.

[destructiv dave 0]

Could it be injector related? I'm not sure how you can test them on the 9A but on the old k-jet you took them out and placed them in a container, disconnect the coil and held the air meter flap up whilst cranking the engine. If they are bunked up they can present with similar symptoms to what you are describing.

[Ruggy 10]

Does it do it mainly when the engine has warmed up a little? Possibly lambda sensor knackered, screwing up the mixture.

[seanl82 23]

Is your fuel pump louder than you'd expect? Usually begins when your low on fuel, but if its well past it, could be that the pump is on its last legs.....

[easypops 8]

Unplug the 5th injector, my old valves had a faulty one and it constantly gave out fuel. I ran it unplugged for 4+ years with no ill effects

[sam2.0 10]

Today was possibly the worst day upon start up.

 

Firstly it didn't fire, it turned over but didn't fire. I gave it some 'gas' and it finally started, but tick over was about 300rpm, a few blips of the throttle and it levelled out to ~800rpm. It stunk of fuel though, proper unburnt fuel when driving along.

 

When its warm it does act better, but still a bit rough when putting my foot down.

 

I'll try looking at some of those suggestions tonight. It's booked into the garage tomorrow as I'm fed up with it!

[sam2.0 10]

Well with or without the 5th injector connected, it still seems lumpy. But the car is warm now, so not a direct comparison.

[sam2.0 10]

With the garage all day yesterday and they're stumped too. Problem is, bits will need replacing to rule it out.

 

They've not had a reading from the lambada sensor, so they're assuming its either a car or sensor or both.

 

They've tweaked the mixture, and got it to run well when hot, and have kept it over night to test what its like when cold, as thats the main issue.

[sam2.0 10]

Maybe speaking too soon, but all of the issues seem sorted. Well, all bar a slightly high ISV, they've said mine is temperamental, if you give it a tap it works, then will stop.

 

So on the hunt for a new one.

 

I'll run her for a week or so and then treat her to an oil change.