KFC3S

Hi guys, i'll be sorting out a compression test soon, I just have to organize a trailer and find a rotary workshop with a compression tester.

The car is a 96 series 7 with stock everything except for downpipe and catback (stock cat in place), HKS EBC IV is installed but not tuned, and I have not gone WOT since installing the EBC.

I was driving home on Saturday night, doing 90km/hr and went to accelerate lazily to 100k, squeezed the throttle and the car went "POH!" and shuddered for a bit, engine note changed and I lost about 80% of off-boost power. I managed to drive it the remaining 20kms home.

I assume a seal has cracked as it does run, and it starts with a little bit of persuasion and idles a bit odd. You can see a video here:
http://www.youtube.com/watch?v=wCOfIe25TBU

Driving home, the boost gauge was really erratic (like flicking violently between -500 mmhg and .6 kgcm2) constantly. I had to adjust the throttle cable to have it idling at 2000rpm to avoid it stalling and getting up hills meant 1st gear.

It seems to be running on one rotor, and its at about the right mileage for seal problems to occur so I won't be too gutted if it is new engine time, but wanted to get opinions first if there is something else i could check that might give these symptoms. As mentioned before, I will be getting a compression test once a trailer can be organized and I can book it with a rotary mechanic.

Thanks!

linnadawg

iTrader: (14)

Its hard to hear in the video but you probably lost a corner seal like I did. My car was extremely shaky and I was able to get home. Fuel and vacuum pressure were erratic. If you dont want to spend money towing it just buy a piston compression tester and take the valve out. The test takes 5 min.

KFC3S

corner seal like this?


wtf where did it go? Or do they just sort of crack or come loose without leaving the rotor?

linnadawg

iTrader: (14)

My engine had been sitting for a while. I suspect with leaky injectors and built up carbon around the corner seal so it was stuck in place. One rotor had all 90psi and the other rotor was 0-0-75. The corner seal chunked out the edge of the rotor so 2 edges lost compression. Yes thats a corner seal. It was driving fine and right when I punched it BOOOMMM and the car started shaking.

twinsinside

iTrader: (34)

I know this has been beat to death, but you might want to check your map sensor hose too. Fluctuating vacuum is a sign the engine needs a rebuild though.

Like Linnadawg said the only way to be sure is a compression test, and no need to take it to a mechanic, its a very simple thing to do if you jack up the front and go in from the bottom. That will give you a definite answer.

A quality compression tester tool is useful for a healthy engine to give you an accurate idea of your exact numbers, but for a blown engine it will be real obvious even with a cheapo compression tester if 2 faces are at zero compression.