Stuttering!

My sportline's developed an intermittant stutter!

I can't really tell if its ignition or fuel related.  :dontknow:

Its like its runnning on three cylinders a bit, I called the RAC out at weekend and they thought it might be frozen fuel as by the time they arrived it was running fine! I though it could have been the head gasket gone.

It idles ok and you don't notice anything, but when you accellerate maybe above about 2000rpm the stuttering starts. It will rev right up but the stutters always there, even if you hold it at a certain rpm.

I've since used almost a full tank of fuel when I went to Newquay on Sunday and it behaved fine! But yesterday it started again and is still like it today. Its started to happen again with about the same amount of fuel in the tank but this could be coincidence?

After I've switched of the engine I've heard a kind of buzzing noise from around the fuel pump a couple of times that never used to be there. I took the fuel filler cap off and there was a larger than normal rush of air. a bit of fuel came out too! (this was with the tank only 1/4 full).

I dont know if its related but No. 2 plug is always a bit sooty (not oily!) compared to the others, what could be causing that?

I did a compression test at the weekend and the readings were ok I think.
14 - 14.25 - 14 - 14.25

I've recently fitted new:

plugs
dizzy cap
rotor arm
air filter

The HT Leads are pretty new looking but I havent ruled them out from past experiences.

Any one have any ideas please? I'm hoping to make it to Surrey at the weekend!

Cheers,

Ross

Have you checked the injector on cylinder number 2?

hi could be early sign of pump failure.

I havent had a chance to look at it really yet, the weathers been shocking. I don't want to make it damp too!

All I've had a look at is the HT leads, but theyre are slightly different to the other cabrios so they weren't going to be a quick swap in the rain last night. I need to take off the nipple bits on the plugs to get the other leads to fit!

i'm going to fill up on the way home from work and see if the problem goes. Just need to try and rule things out.

I have some spare old injectors that I could try, and I could dcheck the speay pattern. I just hope the weathers better to do some more tests, but as the problems intermittant its going to be hard to trace.

If a plug is sooty, doesn't it mean its over fueling? Or maybe not burning? i.e no spark/not a good spark?

volkswarren - do you think this is a known symtom of a fuel pump problem?

Cheers,

Ross

yeah a black plug tends to indicate that it has too much fuel - but this could be because the plug is not sparking correctly so try those other leads and let us know what happens.
I had two fuel pumps fail on a mk1 and they both just 'went' and stopped priming the system. If you have excessive pressure check to see if the breather is blocked with crud from the road - just an idea? I've had mk2 GTIs fail in the way you describe as they have a lift pump in the tank as well as a push pump underneath the car. The problem was always worst when it have around a quarter of a tank or less. Do the late cabbies have a lift pump??? This was a common problem on some makes of lift pump for the mk2 GTI?

Yeah, I'll swap the leads and get back to you.

Cabbys do have the lift pump so it could be the problem, I havent heard of it being a common problem on mk1s but have seen this on www.matey-matey.com

Failed Lift Pump: The in-tank lift pump (GTi only) can often fail and will cause the car to hesitate and suffer bunny hopping style fuel starvation before eventually conking out. This can be masked by keeping the petrol tank full, so be wary of a car with a full tank. Luckily the pump is inexpensive at ?30 and easy to change.

The plastic liner that covers the breather pipes under the arch is missing but the pipes all seem intact and clean. The cover is on my wanted list as is a flywheel cover!

Well the journey from work was practically fine! Typical! I filled up with fuel and there wasn't any pressure when I got home, but the journey is only 5-6 miles in total.

I've swapped the leads over anyway so now at least they are known good. I cleaned No2 plug up as well so I'll be able to see if it still gets sooty.

I've been for a test drive too and its still fine. I'm going to Surrey straight from work tomorrow, will be taking a few spare parts  

I had the same problem recently, with one plug sooting up along with rough running. I eventually found the fault after pulling out the injector and checking the spray pattern in an empty coke bottle. The injector was pouring out petrol even after the engine was off! Changing the injector solved the problem.

Good luck

Well, I'm back from my trip to Surrey and its had no problems. So hopefully its just the leads. I ran it down pretty low on fuel again too.
I've not checked the plug yet to see if its got sooty again though.

Cheers for your help everyone

Ross