Porsche 944: low on power

[Matt16]

Hey everybody, I have a 1984 944. I had a shop put on a new oil pan because mine got cracked and they found coolant in cylinder 4 and suspected a head gasket leak. So I decided to try to tackle it with a couple friends. Everything is back together now but now the car feels very low on power and its vibrating a lot more than it did before. The car ran for a little bit while it was one tooth off in terms of timing. It may still be off and i will triple check it soon. To me it seems like one or more of the cylinders is not getting compression or something. Seems like its misfiring and just not making power. I saw somewhere in the forum that the fuel strainer can get clogged if it sits for a while. My car only sat for a month probably, just put new gas in it. Spark and fuel is good on all four cylinders as far as i can tell. I cleaned the connections in the AFM because I am also having a idling issue where it keeps bouncing up and down like its trying to find the right air fuel ratio or something or it just falls down and stalls or it drops super low and takes full throttle and a couple seconds to get back up to 1000 and then drops back down. I am at a total loss for what to do. I just ordered a compression test tool and it will be here tomorrow so I can check compression. I am suspecting that a valve got bent. is it possible that having timing off by one tooth could bend a valve? I also saw that somebody had a bad ignition coil and that fixed his low power. I can check that soon but my coil is fairly new and the car was working great before the rebuild. I will also check the distributor rotor and clean it off. I am also partially suspecting vacuum leak. I am almost positive that I did it right but i could be wrong. Last thing, pretty sure one or two of my hydraulic lifters has gone bad, could that lead to the lack of power? If you guys have any suggestions please let me know I really appreciate it. Thank you guys.

[wwdwgs]

If it vibrates after 3000 rpms, the one balance shaft or both may be 180 degrees off - check it.

[walfreyydo]

Sounds like balance shafts not aligned properly (vibration issue) and a pretty substantial vacuum leak (idling issue). Also verify your plug wires are in the correct order on the distributor. A surging idle is almost always a vacuum leak or issue with the idle air control valve (which runs off vacuum).

The only way a valve got bent is if you majorly messed up your timing alignment. One tooth wouldnt do it but more than one tooth would.

Have you seen clarks garage? Might be useful to give the shop manual section a good read through:
www.clarks-garage.com

[wwdwgs]

There two great videos on how to install (PROPERLY) Timing and Balance belts. This guy is very informative and explains every step very well:

https://www.youtube.com/watch?v=jpR6dWWiILk
https://www.youtube.com/watch?v=iBxOboQNQ6U

And, there's another video about incorrect positioning of Balance shafts/belt:

https://www.youtube.com/watch?v=I3ld-SyqULg&list=PLt3Qhjl4f69JE0_EBVRZ9z1TPl4KERdY1&index=10

[Matt16]

Thank you! Did a compression test and 2, 3, and 4 were healthy but #1 got 0 compression. Opened the engine back up and found cylinder 1 had a bent intake valve. Absolutely no carbon build up in #1. New valve and valve guide coming today. I’m still very confused on how this happened though. Everything that I think of doesnt make sense. If timing was off shouldn’t all the valves be f’ed? Then i was thinking that I need the thicker 1.4mm gasket to make up for the clearance I lost when I machined the head but I think the HG that I put on was the 1.4. Ill double check that but if i didnt have enough clearance I would think that all the valves would have bent. My last thought was that could a bad lifter have caused this? I had a bad lifter that was squishy in there. I can not remember if it was on that valve or not but. This is killing my brain trying to figure it out. any ideas? Thank you again

[Matt16]

Also I guess we will just have to see but hopefully when #1 starts firing again the vibration should go away and hopefully the idle too. It is possible I have a vacuum leak too.

[walfreyydo]

Well if you have a shaved head and timing was off a tooth that could potentially cause piston-valve impact. In regards to why not all the valves were bent, thats just sometimes how it goes. Many years ago I had a tensioner fail on my subaru and only bent 3 or 4 valves.

I would recommend when you get everything back together to go ahead and turn the engine by hand with the spark plugs out. Make sure there is no obstruction and the motor turns freely. Also make sure your timing marks are spot on after a few rotations - do not run the car a tooth off. Yes, you should replace that lifter (although collapsed lifter usually means the valve doesnt open fully).

I think the vibration and issues you were having were likely due to one cylinder not firing.

[Matt16]

Thanks, i will do that. I should be getting my parts in today. Thank you again.

[Matt16]

Intake valve was bent! I got the thicker gasket and replaced the valve and everything is good now