Quote:
Originally Posted by Steve Tinker
I'm a little confused here (as normal)...surely a failed CPS won't make the engine sound like it has no compression when cranking.
The OP (rah rah) says in his opening question that the car sounded as though it was "cranking with low or no compression" which says to me that the starter motor was turning over the engine @ 600 rpm instead of 350 rpm) - just like if there were no spark plugs screwed in the heads.
While leak down tests are all well & good + more accurate than a simple compression test, as a couple of people has mentioned you have to get it right otherwise you can have some misleading results as with his comment "And EVERY cylinder is down 75-90%".
At this stage with engine out (which I think was a premature move) removing the spark plugs, opening the throttle body and conducting a simple compression test - even with a cold engine - will give some indication of the condition of the valve seating and piston compression on each cylinder.
I mean, this could be just a couple of cylinders that have collapsed hydraulic valve lash adjusters causing the starter motor to turn over faster than usual.....and yes the CPS can be the rout cause of the original problem too!
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Depends upon how he defines "no compression" appearance while cranking. We have had several similar customer comments that were on cars with bad CPS and which aimlessly spun over very rapidly, but made no attempt to start.
If he really believes he has no compression, a quick compression check would either bear that out or prove it wrong. But based upon the number of times we are told the car seem not to have compression, only to find a bad CPS, I still think it is worth a look.
I am also somewhat circumspect about the leak down results; unless you have done one of these a few times, is very easy to miss TDC and get weird results, and because of the way these alloy engine's change, I would prefer to do a leak down on a warm engine.