Fluttering GTi

[Brian King]

Fluttering is the only word I can use to describe the engine of my GTi between 2500 and 4000 RPM,. Below and above that, fine, but in that bracket it's splashy and jerky. The plugs are new, the leads look OK, the distributor cap is clean and all 4 contacts and the rotor arm shiny, the ignition timing's been done and a new air cleaner element fitted. Any suggestions gratefully received.

[Way2go]

Have you had the injectors serviced and ultrasonically cleaned through? The spray patterns and duty cycles vary in use so some may be out of kilter due to congestion & coking.
The last time we discussed this there were some online firms recommended that offered the service as Lucas centres that did it are no more. Some Bosch centres may still do it though if you have one reasonably local.

[CaM]

air flow meter contacts and tracks could probably do with a tidy up
I've had this exact same problem.

[Brian King]

Thanks chaps. What exactly are the airflow meter tracks? And are the contacts the scart plug that plugs in the side? I should have thought of the injectors!

[sdelasal]

I think the Gti has the Bosch Motronic system with a vane/flap air meter - in which case a good description is given here http://mysite.verizon.net/vze7aq8e/site ... r_wilk.pdf The link is actually for the porsche 944 - same system though. Steve[/url]

[Brian King]

Thanks everybody for taking the time to reply. We've been through the induction system and cleaned it out including the rubber pipes, set the timing, and put a replacement air box on, with not much change. Thank you for the diagrams sdelasal. They're not for the 8v in question, but I'll keep them for the 16v.Now I'm looking for a Bosch agent in Glos to clean the injectors. I hope it's not a bent valve

[Jaba]

Brian
These people are very good and quick. They clean and post out the same day.
http://www.injectorcleaning.co.uk/txt.htm

Cost is less than £50 and you get a report of the performance before an after.

[Way2go]

Looks good, in fact ASNU was the equipment used by Lucas when they were in business and did mine.

[Brian King]

Thanks for that. Since my original message, in addition to new plugs and air cleaner element, and cleaning and setting the distributor timing and mixture, the car has been for two diagnostic checks, both of which show the emissions remaining steady up the rev range, and one technician suggesting an air leak after the Bosch air box. I have also, on advice from the other bloke, changed the petrol filter by the fuel pump. All to no avail. So it's the injectors next. Just a thought, could it be the fuel pump ?

[Brian King]

Sucess at last ! Discovered that the vacuum advance/retard wasn't working, so ordered a new one from Malcolm Lockwood, together with a set of 5 new plug/coil leads for good luck. No more fluttering.