AndyPlant 0 Posted August 31, 2003 Can anyone offer a solution I have a 94 VR6 with 108K on the clock. I have a missfire problem below about 1500 rpm under load, once above this engine runs fine. (most noticeable pottering about in 2nd & 3rd gears around town.) The problem is always there and is not dependent on weather or engine temp etc. Any clues? Andy Quote Share this post Link to post Share on other sites
vr6storm 0 Posted August 31, 2003 could be coil-pack......though that should be more noticable in wet weather,plugs or plug leads or head problems eg head gasket Quote Share this post Link to post Share on other sites
dazzyvr6 0 Posted August 31, 2003 might just need the ecu reseting Quote Share this post Link to post Share on other sites
Beetlebug_2001 0 Posted August 31, 2003 If it hasent had a service anytime recently that could be the cause down to bad sparks or knackered HT leads, if it hasent been serviced recently id start there, first with plugs then if the plugs do not fix it try the HT leads, HT leads can be pricy so try changeing the plugs first, could also be the distributer cap, check inside for wear on the pins inside the cap, then if still no joy could be down to the coil, also check the rotor arm inside the distributer, or if u dont mind paying out a few quid take it to a vw dealer and for about £20 they will hook it up to a computer and pin point the problem straight away. Quote Share this post Link to post Share on other sites
Bruno 4 Posted September 1, 2003 Can anyone offer a solution missfire problem below about 1500 rpm under load, once above this engine runs fine Five things worthy of investigation, which I have prioritised given that its a temperature independent but rpm dependent issue: 1. Check the cleanliness of your throttle body, and all pipes leading to the throttle body. Make sure it is pristine. Check the potentiometer and make sure it is smooth in its offered change in resistence as it is turned. 2. There is a small pipe at the rear of the engine near the air mass sensor, it is part of the breather feedback loop, and it can be cooked by exhaust manifold fumes to producing a hole and causing exactly the problem you have. Just run your hands over all of those pipes of 1" or less diameter and make sure there are no leaks. 3. The MAF sensor may be faulty. Rare but it happens. Disconnect it and see if the car runs differently. If it doesnt, then this maybe is the source. If poss, borrow one from someone else to confirm, before spending silly money. 4. The O2 sensor and its connections can be naff. Unplug it, spray its block connectors (near the firewall) with switch cleaner, and also wipe the sensor head with a dry lint free (also petrol and solvent free) cloth. Plug back in. Then disconnect the battery for 5 mins, then reconnect and see if the problem goes away (this last action is to reset the retard marker caused by a faulty sensor signal). 5. Wait until dusk and fill up a plant spray bottle with water. Run the engine on a fast idle (1500 rpm) and mist over the coil pack and leads systematically, and shine a torch over it. If you see any fireworks over any lead replace it. If the coil pack is faulty that will also be clearly evident as it will have its own pyrotechnics..... Quote Share this post Link to post Share on other sites
spoier 0 Posted September 1, 2003 I agree start with the simple cheap MAINTENANCE items that should be replaced every few years - spark plugs, dist cap and rotor, plug wires, air filter, fuel filter. As you are pulling the spark plugs you should see a nice tan colour with no large deposits on the old plugs. Skye Quote Share this post Link to post Share on other sites
