Hi guys,
I have recently done quite a bit of maintenance on the car and now it sounds like a WRX and has a heavy rumble.

Maintenance carried out:

Replaced distributor o-ring (was leaking)
New distributor cap + rotor
New spark plug leads
Ultrasonically cleaned injectors
Replaced valve stem seals
Lifters cleaned out


Symptoms:

When I put my hand on the exhaust it fluctuates between pressure and vacuum (so my hand gets sucked onto the tail pipe, then pushed out etc)
Though I have not driven it, the rpm hesitate to rise when throttle is given, so lack of power
Sounds like a WRX
Rumbles/vibrates quite a bit


What I have tried/tested:


Checked spark leads are in correct spot - They appear to be correct
Disconnected each spark lead out - idles worse on each lead taken out
I have disconnected 3 of the front injectors, the middle one seemed to make no difference in idle. Replaced this injector with my old one but made no difference in how it runs


Any help or advice is greatly appreciated

Did you prime the lifters? They can take some time to purge the air out of them.

Yes I did, and when I started the car there was a loud tick but it went away after a few seconds.
The engine is quiet, it is the exhaust that is making the odd noise.
Do you think a valve may not be opening or something?

looking at the list, valve timing would be where I'd have a look. ( were the cams removed?)

I had a similar sounding thing happen. After spending time doing stuff to the engine it occured to me to check the muffler and , :headbange yep. there was a split seam. The rumble gone and performance up. Your prob sounds like it may be a bit more serious though.

Could just be a co-incidence that the exhaust system has rusted through at the same time you did the work.
Feel the outer curves of the pipes starting at the rear muffler and feel for holes.

Unless you have had the cam belt off and the heads off when you did the valve stem seals, valve timing shouldn't be a problem. How did you do the valve stem seals?

The cams were not removed.
The valves were held up using rope in the cylinder.

I rotated the engine (with spark plugs removed) using the crankshaft bolt via the wheel well. I had to spin it backwards a couple of times to be able to get the rope out but seeing as the spark plugs were removed I don't think this would cause an issue?

I did the front bank first, then drove the car, then did the rear bank and now this happened. Though when I did the rear bank obviously many more things were done (leads, distributor cap and rotor, injectors)

I wonder if rotating backwards can cause the belt to misalign? Compression test but what a pain that would be. Would not hurt to have look at the timing marks,. I guess you took note of the distributor and rotor shaft position prior to removal? Loss of power and unusual exhaust note sounds like valve train. Sorry , all the ideas I have.

Rotor button re-installed correctly? I believe it will go on in 3 different positions, 120 degrees apart.

I fear I have a bent valve to be honest.

6g75 Verada, I considered this but at 120 degrees out the car wouldn't run at all

How confident are you of the injectors?

I may try installing the original back after a compression test (if that turns out ok)

Considering the exhaust is pulling back I think it must be an exhaust valve which is bent/damaged. Though oddly the engine is quiet