Misfire? sticky tappets?

[superfans]

I am wondering if anyone know why would a sticky hydraulic tappet or tappets cause a misfire or backfire upon acceleration? Thanks in advance.

[domster]

I'll attempt an answer to get the ball rolling.

In theory, yes, any valve train problems could cause misfiring/backfiring.

In practice, whenever I have experienced sticking hydraulic tappets, they have really just caused an annoying noise like a sewing machine (normally when cold before the oil is thin enough to get them working properly).

The big problem is isolating the specific tappet so you often replace a few at a time. You can go for the full set if you feel rich. Remember that other engine noises can sound tappety... from fuel injectors to broken valve springs to big end bearings about to give up (LOL, I have made this mistake before).

[clubsport]

I thought I had a noisy tappet,,,turned out to be a dodgy HT lead arcing, this gave a clicking in time with the engine and resultant misfire under load.

I would check everything on the ignition / fuel side of things is spot on before taking the cam covers off.