Just another catastrophic cam follower failure

[Trickassfoo]

After engine replacement I have been having on and off issues with misfires. Swapped coils and plugs around and I'm always getting a random multiple cylinder misfire and a cylinder 4 misfire. Mostly at cold start, sometimes under load (usually runs excellent under boost). Did a compression test (165-175 on all 4) so that's not it, moved coils around changed air filter, new plugs, always cyl 4. Had a vac issue, replaced n80 valve so that's gone. My thermostat is bad so I'm changing that (, temps swing from 75-90c, can't see it being related) and I tried seafoam in the intake manifold. I inspected the valves on cyl 1 and 2 with an inspection camera, they don't look awful to me (there definitly is quite a bit of carbon) but I'm hoping it's a carbon buildup issue. Not really too sure where else to check. I took some pics but it's hard to make out the valves

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[Jet08]

Trickassfoo I suspect that the injectors are coated in carbon, if you have VCDS then check injector error no sure which block you need to measure, seafoam does nothing useful.

[Theiceman]

Your follower has lasted 50k? Nice

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Sorry i meant cam and pump have lasted (km) i have put a couple of followers in but they were hardly worn


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[Nollywood]

I don’t have a ton of experience with the VAG 4 cylinder engines, so I may be wrong here.

Does the cam lobe actuate the HPFP via a cam follower, with nothing in between the lobe and follower?

[Charles.waite]

Yup. It’s just a flat tappet essentially. The follower has some oiling holes and the cam profile is ridged to induce some spin on the follower to reduce/even-out wear but essentially it’s a flat thimble that rides between the pump piston and the triangular cam lobe.

The ea888 TFSI engines use a roller cam follower because it’s very clearly a better design and doesn’t have the inherent flaws of the FSI design we’re all stuck with.

IAbed makes a retrofit kit but it’s a bit expensive. Probably worth it if you’re running above stage1 tune levels though.

[Nollywood]

Yup. It’s just a flat tappet essentially. The follower has some oiling holes and the cam profile is ridged to induce some spin on the follower to reduce/even-out wear but essentially it’s a flat thimble that rides between the pump piston and the triangular cam lobe.

The ea888 TFSI engines use a roller cam follower because it’s very clearly a better design and doesn’t have the inherent flaws of the FSI design we’re all stuck with.

IAbed makes a retrofit kit but it’s a bit expensive. Probably worth it if you’re running above stage1 tune levels though.

That’s what I was thinking - rollers, like the later roller rocker arms to reduce friction.

[Charles.waite]

Yea pretty sure it was a cost reduction decision. The RS4, which was developed and sold at the same time, has roller followers. And they switched to rollers for the next gen. They definitely knew it was a inferior choice but realized for the b8s that the added cost was worth the reduced warranty costs.

[Trickassfoo]

Trickassfoo I suspect that the injectors are coated in carbon, if you have VCDS then check injector error no sure which block you need to measure, seafoam does nothing useful.

My vcds cable was stolen, but I use obdeleven for now and it does live data, so I'll check with that

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[Trickassfoo]

Sorry i meant cam and pump have lasted (km) i have put a couple of followers in but they were hardly worn


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I checked my follower on this engine after about 2k and there was no wear. The cam is in great shape. After this I'll be checking it every oil change and replacing it every 20 or 30k I'd say

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