new exhaust still blowing

Hi all

I've recently replaced the complete exhaust on my S3 88 station wagon as it was getting a bit elderly and was blowing at the manifold joint (not surprising, as I discovered that only two out of the three studs had nuts on...)

I've tightened everything up evenly and properly snug, having applied a good dollop of firegum to all joints first, and used a new gasket at the joint forward of the back box. But it's now popping on the overrun somewhere at the rear, which it wasn't with the old exhaust. Before I re-make all the joints, any suggestions for anything obvious I'm overlooking?

Thanks

Is it the old exhaust ? if so a hole or something ?

is exhaust blowing or misfire type issue

No, it's a new exhaust all through. Don't think it's misfire as the engine is running pretty sweet. Puzzled.

Leaking exhaust shouldn't cause misfire. So it may be a blow.
Was the old exhaust really noisy so you didn't notice the misfire?
If I put a new exhaust on, I put copaslip on the joints which shows up any blows. Save the firegum for rusty old ones.

Just reread your post. Popping can be exhaust if there's an air leak on the inlet or it's a less restrictive exhaust. Is it std?

Popping, do you just mean put put put puttt on the overrun? I thought that was normal...is your vacuum advance pipe still connected?

Yes, put put put on the overrun. Didn't seem to be doing it before I renewed the exhaust. Or maybe I couldn't hear it because it WAS blowing from the manifold joint (nut missing). The vacuum pipe is connected, tho' it's at a tightish angle so the rubber section is quite squashed.

Anyway, we passed the MOT today so that's good enough for now!