compression, no compression, compression-what the hey???

[WGUNGHO]

I have a stock drive train '97 Cobra. This morning, the damn thing wouldn't start. The starter turned the engine normally, but upon closer exam, the motor was turning but there was no compression. My mechanic said he had seen this twice before and suggested cranking at WOT for 30 seconds, letting the starter cool, and repeating the process. On the second try, the engine started right up, with the only unusual thing being a strong raw gas odor. What the heck happened???

 

[Tx_Diablous]

Are you saying you did a compression test and had 0 on the gauge for all 8? Our cars will not start at WOT. If you lose the crank sig they will not start. All I can think you did was to blow out fuel that leaked from the injecters but sounds weird to me.

 

[WGUNGHO]

Negative on the compression test. I had someone turn the ignition while I observed the engine. The starter spun the motor, but at a much higher speed than normal. There was NO air movement out of the exhaust pipes. With compression, the starter turning the motor would still move air, regardless of whether the motor is running or not. I did as my mechanic suggested, and cranked the starter with the pedal to the floor, which should have given me WOT. I'm ASSuming putting the pedal to the floor equals WOT. The car started immediately on the second attempt, with a strong smell of raw gas out of the exhaust, which faded after a brief moment. I didn't spend last night at Holiday Inn, but everything I know tells me that there was no compression. The motor was turning freely at a high rate with the starter engaged. I cannot imagine the senario where all eight injectors would leak down? And if there was compression, why did the motor turn over so fast with no air pressure at the exhaust? ????????????

 

[Tx_Diablous]

You had compression, you just did not have fuel. These engines can not lose compression and then get it back. The valve control is fixed and rings do not fix themselves. Without combustion you would have felt almost nothing out the pipe. Not sure what went wrong but you had no fuel.

 

[redfiredroptop]

How cold was it?

I think the problem was the opposite from what you have described. In cold conditions, if the engine doesn't fire right away, it can easily become flooded. If the engine is not running and the computer detects WOT, it will completely shut off the injectors. Cranking the engine clears out the excess fuel. The engine will smell very rich when it does start, but that will quickly burn off.

Compression had to be present. The engine probably sounded different than normal due to the conditions and extended cranking.