GTI 16v cutting out intermittently...

[Pete Taylor]

If the car dies after 10 minutes it sounds like the vac hose from the ECU to the inlet manifold sucking itself closed, this will cut the engine out. Go on ebay and get yourself a metre of 4mm silicone hose

http://cgi.ebay.co.uk/4MM-ID-QUALITY-RED-SILICONE-VACUUM-HOSE-TUBING-1-METRE_W0QQitemZ290170998197QQihZ019QQcategoryZ72205QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

A metre is enough to replace all 3 hoses on a mk3 16v ABF engine. If you take off the rain scuttle panel in front of the windscreen you'll see where the hose goes from the ECU to the inlet manifold and chances are it'll be soft, weak and crispy. Use the shortest route for the new hose through the bung by the ECU. You don't need to clip the hoses on either, just push on. The other vac hose to replace is from the inlet manifold to the fuel pressure regulator valve. The third is under the PCV valve which will need changing too.

That's the most common fault on them. After that i'd clean the throttle body. Then i'd clean the ISV too. Another one to check is the switch on the throttle body where the accelerator stops. Spray the small switch with WD40 and make sure it moves in and out freely. If you have an induction kit (or not sometimes) then make sure that any parts of the throttle body that have vac hose ports not in use are blocked up. If you have an induction kit then sometimes where the hose from the throttle body to the airbox used to be, the hose is pulled off and the throttle body is not blocked off causing a massive air leak and poor running. VAG COM will not show faults with relays so i'd change the ECU and fuel pump relays too. VAG COM will however show faults with the crank speed sensor so a quick scan will reveal whether or not it needs replacing. VAG COM will also show faults on the coolant temp sensor too which can fail. It's worth replacing though because VAG COM sometimes doesn't pick up faults with them. They might only be broke when reading between certain temperature tolerances. The normal fault is when the engine is hot and the temp sensor is telling the engine it's actually cold. The ECU will push more fuel in because it thinks it's cold which causes over fuelling and poor running. On a mk3 of this age it really needs a hardcore service..

Coolant flushed and topped up with pink ready mixed (NOT WATER!)
Oil flushed and changed
Oil filter changed
Fuel filter changed
Spark plugs changed
Air filter changed (or cleaned if a performance one)
Ignition leads changed
Dizzy cap and rotor arm changed
Coil changed

If your car isn't starting, it's highly unlikely to be the temp sensor causing this. My bets are on the ECU vac hose or an elctric problem with the dizzy/coil/ht leads/rotor arm

[bunter]

thanks for the reply, i have just ordered that tubing and will give it a go at the weekend.

thanks. bunter

[CraigDavid]

A buddy of mines got a mk3 GTi 16v and had the same problem, would run for something like 10mins then suddenly cut out and wouldn’t start for another 20-30mins or so!! He changed the crank sensor twice with cheep parts to no joy then he changed for a third time with a good quality official part from the dealers cost him about £160 but he’s had no problems since. That was about 6 months ago!!

Part No: 037 906 433 A

[Pete Taylor]

Next step is definately VAG COM after this and it's not as expensive as you think! All you need is a laptop that hasn't got windows vista on it...

This cable..

http://cgi.ebay.co.uk/USB-KKL-Vag-Com-Cable-Interface-VW-Audi-Scanner-VAG-COM_W0QQitemZ140168050054QQihZ004QQcategoryZ30921QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Cheapest UK one I could see.

Then download this software (you can check fault codes on shareware so you don't need to pay to have it registered)...

http://www.ross-tech.com/vag-com/download/archives.html

You want the one at the bottom left, "for MODERN SERIAL interfaces"

Seriously worth doing it mate, it can diasgnose engine faults, ABS faults etc etc and will pay for itself in the end

[bunter]

have had a little play with mine this morning and found that no fuel is getting through to the engine, the plugs are bone dry atfer cranking it over for a good minute

might be some light at the end of the tunnel yet......

[bunter]

still no luck here so far!!

done so far:

Spark Plugs
Leads
Dizzy Cap
Rotor Arm
Coil
ECU Relay
Fuel Pump Relay
Crankshaft Speed Sensor
Vacuum Hoses
Cleaned Throttle Body
ECU Checked

its been suggested it could be the MAF so il be looking into getting a replacement next. hopefully that will solve the problem of the fuel not getting into the cylinders. was also thinking about the oil pressure switch, do the 16vs have one and where is it located?

just read in the haynes manual that the ABF engines have 2 knock sensors?? i have replaced the one under the engine mount at the front but it says there is another one located under spark plus no1 on the front of the engine somewhere??? :s

[Pete Taylor]

Is VAG Com still showing the fault with the sensor?

[bunter]

yes it is but only because the engines not running, as this fault shows until the engine starts, which mine doesnt

[Pete Taylor]

If you've replaced the crank sensor but still get the fault then it's a timing issue

[bunter]

If you've replaced the crank sensor but still get the fault then it's a timing issue

but the crankshaft sensor fault shows up on vag-com when the engine isnt running as standard, unless i can get it running i cant be certain its that. timing does sound about right though seeing as the spark is there but no fuel into the cylinder, which brings me to the oil pressure switch, could that possibly be the problem?