996 turbo loss of compression

[olddirtbiker]

Hello,

I'd like to ask the group for some advice regarding my 996 turbo. This car was recently bought by myself after hankering after one of these for years. The 996 turbo was chosen for the specific reasons of power, handling and reliability.

My car is a 2001 tiptronic model that I purchased in Abu Dhabi which is close to where I currently live in Oman. I brought the car over the border and got it registered here.

I was delighted with my car. Tons of power, great on the back roads we have here and real smooth for taking to work down the highway.

Anyway, I pull away from the lights and the car suddenly develops a misfire. Really bad from zero upwards. Once the revs build it is still down on power but the misfire seems to smooth itself out.

I did a quick look around the net and found out about the issue with the plugs and coil packs. The car was getting due a service anyway so prior to leaving on holiday I left the car with the local dealer here asking for a full service with new coil packs to be fitted.

On my return I find that the fault still exists despite the plugs and coil packs having been changed. (Old coil packs had numerous cracks in them).

In order to eliminate possibility of mechanical damage causing the issue a compression test was done with the result that there is zero compression on No 4 cylinder.

I am now being faced with a possible 900 gbp bill to pull the engine and strip to investigate.

There is another part to this story that might have relevance. After I have had the car about a month I get hit from behind by a truck that knock the car in to the middle of a roundabout. I am talking a real hard thump that really shocked the car. Expecting total carnage at the back I get out the car to find really minimal damage. A split to the little rubber extrusion and very light creasing of the paint on the bumper. A check underneath revealed no visible damage. From the time of the collision to the start of the misfire is less than 1000 kms. Immediately after the accident there was something differnt about the way the car drove that i find difficult to pinpoint and describe. Still plenty powerful but slightly less so on acceleration. Not something that you would say was real problem. I felt that the engine may have moved about a bit more as well although this may have been the case since I bought it.

So my questions are:-
1.) Do you think it is possible to get the compression test on no 4 cylinder wrong due to access issues. The tool used was a press in rubber cone type. Not a scew in type. The zero reading is ringing alarm bells for me.
2.) Only one cylinder has zero compression. How likely is this. I am tending to point to a valve problem.
3.) Can you think of any scenario that could cause zero compression on one cylinder as a result of the collision.
4.) If the zero test is a red herring is there anything that should be checked prior to pulling the engine (thinking fuel injector connectors that might have been displaced etc)

Thanks in advance for any advice received. I've spent all my money buying this car and need to keep costs down in trying to repair it.

[cd1957]

Hi you can getting high lift tappets that can stick in the high lift postion instead of switching back to normal lift for low rev operation,you should get a fault code for the misfire which may ask you to carry out large lift test on the road with diagnostics connected.

Chris

[Trev450]

Check that your bump up the rear hasn't damaged or flattened the exhaust in any way.