09 impala ss no compression
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Teching In
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09 impala ss no compression so have a 09 impala ss with the 5.3 afm dod motor . Going down the road yesterday running fine not running hot checked the oil before left was full on oil. Then just shuts down on me going down the road no warning no cel pull over and try to crank it . It will crank but no start so start checking fuel pressure has 53 psi . Check spark has spark not the greatest but still has spark . So get it home and it sounds like it has no compression when cranking over but the starter is turning the front balancer and watched the valves moving but check the compression on cyl 1,3,5,7 and has no compression?????? HELP?
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Broken timing chain... not "broken" as in flopping or laying in the bottom of the pan, but rather, able to slip on the teeth of the sprockets. Could also be efffed-up sprockets and not the chain, the effect is basically the same.
Easy test: pop the driver's side VC off. Watch the #1 intake valve. Turn the motor by hand. Watch for it to open fully, then close. Turn the motor 180° more. #1 should be at TDC. If not, ... timing chain. If the #1 valves don't move, watch #6; when the exh is just closing and the int is just opening (end of #6 exh stroke and beginning of its int stroke) that's another good indication of the timing of #1 firing, as that's the other event that also occurs at the same point in the engine cycle.
Easy test: pop the driver's side VC off. Watch the #1 intake valve. Turn the motor by hand. Watch for it to open fully, then close. Turn the motor 180° more. #1 should be at TDC. If not, ... timing chain. If the #1 valves don't move, watch #6; when the exh is just closing and the int is just opening (end of #6 exh stroke and beginning of its int stroke) that's another good indication of the timing of #1 firing, as that's the other event that also occurs at the same point in the engine cycle.
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Teching In
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That will be my next step for the intake and the DOD solenoids out just checking everything I can . I can see the timing chain and it looks right but like you said could be slipping. Check that out and will get back with yall .
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From: Central Cal.
If the DOD lifters are affected, then the two middle cylinders of one bank and the end two of the other bank would be dead. Not all on one side. Do you suspect ALL cylinders lost compression? You just mentioned checking one side, the "near" side closest to the front, I suspect.
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Verdad Gallardo TECH Senior Member
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From: Central Cal.
Does the starter spin it as if there are NO spark plugs screwed in? If so, there is NO compression SHOWING, but I can't believe compression would just vaporize in a few seconds. NO WAY. Something else is going on here.
Possible that pcm lost track of crank or cam due to sensor failure? Trying to picture the timing chain jumping a tooth and staying on the sprockets but a broken chain should result in piston to valve interference while cranking. Think you would hear it happening if turning the motor with the starter.
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From: Central Cal.
PCM failure would not affect the compression. IF the timing chain skipped very much, it might be possible many valves got bent, causing massive compression loss. It would happen so fast you might not hear much happen.
OP, how have you tested compression? Sudden loss of compression across an entire bank is unusual unless the car was running like crap for some time. Weak spark can be an indicator of crank sensor failure, but who knows maybe your dod hydraulics took a dump and you left some valves hanging. Unexplained why it would happen all on one bank.
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Well after many test found that the only cause has to be jumped time and warped all valves did a leak down test and the air was going out all the exhaust valves as fast as I was putting it in. Had a video scope and went it though the spark plug hole and found a shiny circle on the top of every piston .