Missfire when idling
#1
05-10-2017, 06:07 PM
Missfire when idling
Hello , I have a 2005 Audi A4 1.8t . The other day I stopped a light and my car started to run rough when it's idling. The CEL came on and it is throwing Random - multiple misfire ,
cylemder 1 misfire , cylinder 2 misfire , cylinder 3 misfire , cylinder 4 misfire . I changed the spark plugs and coils . Didn't do anything . I unplugged the MAF and the car ran the same . And I was told that you can only run NGK spark plugs in an Audi . I don't know if that's true . I put Autolite Double platinum in the car . And is it okay to drive how it is ? Or is it best to let it sit ? Thank you !
cylemder 1 misfire , cylinder 2 misfire , cylinder 3 misfire , cylinder 4 misfire . I changed the spark plugs and coils . Didn't do anything . I unplugged the MAF and the car ran the same . And I was told that you can only run NGK spark plugs in an Audi . I don't know if that's true . I put Autolite Double platinum in the car . And is it okay to drive how it is ? Or is it best to let it sit ? Thank you !
#3
05-12-2017, 03:34 PM
Never heard the NGK plug thing but are they gapped correctly? Should be 0.032" They come from the factory with Bosch plugs. I'm currently running NGK's in my A8 because I didn't feel like paying double for the Bosch units. Any other OBD codes being reported by the ECU?
Also do this check. Crank it and loosen the oil filler cap. Slowly try to lift it from the hole. If you feel it being sucked back down to the valve cover, your PCV Valve is defective. This will lead to excessive oil consumption.
Also do this check. Crank it and loosen the oil filler cap. Slowly try to lift it from the hole. If you feel it being sucked back down to the valve cover, your PCV Valve is defective. This will lead to excessive oil consumption.
Last edited by dave944; 05-12-2017 at 03:41 PM.
#4
05-14-2017, 04:35 PM
Sounds like a classic unmetered air leak (a.k.a. "vacuum" leak) if it's only rough at idle or just above. Add in the oil leak and my first place to look is the PCV system. The plastic parts tend to crack or break off totally. When this happens you will have a rough idle (or no idle) from the extra air downstream of the MAF causing a severe lean condition, and oil vapor comes out the cracked tube. To make it worse, the pcv system is no longer functioning that way which can cause even more oil to leak from excess crankcase pressure.
Look under the intake manifold and follow the hoses and tubes up the back of the engine. If the tube from the PCV valve up to the "Y" hose on the back of the valve cover is plastic, most likely it's broken off right at the spot the hose hooks to.
In most cases (if this is the problem) you end up having to replace the majority of the PCV plumbing. The big elbow at the oil separator under the intake also has a tendency to crack. Look online, there are places that sell sort of a pcv repair kit with al the parts you need. Much less expensive than buying all the parts from the dealer.
Look under the intake manifold and follow the hoses and tubes up the back of the engine. If the tube from the PCV valve up to the "Y" hose on the back of the valve cover is plastic, most likely it's broken off right at the spot the hose hooks to.
In most cases (if this is the problem) you end up having to replace the majority of the PCV plumbing. The big elbow at the oil separator under the intake also has a tendency to crack. Look online, there are places that sell sort of a pcv repair kit with al the parts you need. Much less expensive than buying all the parts from the dealer.
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