popping, spluttering, kind of backfiring... oh an oily smell

[peasant]

The smell from the air vents is sort of normal ...the engine is hot and the vents act like chimneys, taking the hot air away.

Hot engine smell is normal ...fuel smell is not so good.
Check all your fuel lines for leakage ...you don't want your engine to go up in flames.

As for the spluttering, I'd say that's jsut a question of the right engine/fuel/air setup ...but I don't know enough about that to give advise

[clartsonly]

mine coughs and splutters in the same manner, this is due to the exhaust manifold being cracked

[coilspring]

popping and spluttering sounds like unburnt fuel, i.e mixture too rich. This could be a few things for example: air-filter assy clogged/blocked, choke sticking on etc. These would be the first things i'd check mate. It sure does sound carb orientated anyway, so have a good poke about there. hope this helps you mate. happy hunting!

[OLD ONE]

Check for exhaust problems. Hole. Leak.Etc.

[DevonAid]

Yes, agree with the exhaust leak and popping/backfiring being linked. I noticed our van was starting to pop and splutter on overrun, which steadily worsened over the weeks as the exhaust got noisier.
In attempting to fix it, I discovered the exhaust bolt threads into the engine were stripped. The exhaust and the van now sound like a tank, and it now pops and backfires like a good 'un.
And I found the front to rear coolant pipes were leaking. I read an earlier post that said these vans don't like being tinkered with. If only I'd listened.......

[Hacksawbob]

they dont like being tinkered with and they don't like being neglected! be prepared if you start a job to see it through, or put up with "idiosyncrasies" of an old vehicle I have just spent over £200 replacing various coolant parts from VW which started as a £20 job HSB's theorum if you fix the weakest leak, there will be a new weakest link to fill its place.