back fire, bent pushrod

[black magic]

this car sat for 4 years its a 1987 ttype, i did a full tune up, plugs,flushed gass tank, fuel filter, coil pack, injectors, o2 sensor, 3inch lt1 maf, with translator. this car had a bent pushrod cylinder 3 intake pushrod, i put new lifters, and new pushrods, started car up drove it around a little and it bent the same pushrod, the lifters are good, and the rocker assembly is fine too, i think its caused by a backfire. the scanmaster shows a low o2 millivolt reading and it stays at 70. i tried 4 different oxygen sensors, im starting to think its a bad chip or bad ecu because it throws code 44 wich means o2 sensor lean, bad o2, bad 02 wires, vacuum or exhaust leak, wrong chip or fuel press too low. the fuel press is at 43 psi anyhelp would be greatly appreciated, also traced on wire in harnes no breaks????????????????????

 

[black magic]

also does it with stock and and old hypertech chip

 

[bison]

Check for broken/jammed spring or something that would allow spring to bind.


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[earlbrown]

You swapped out lifters on an old cam?

You might want to pull them again and verify the bottoms are convex.

 

[TurboTdr3.8]

Sounds like the valve is sticking for some reason and when it does it bends the push rod then causes the backfire .

 

[black magic]

i did new valve springs, all valves are free

 

[TurboTdr3.8]

Wonder how your timing chain and gears look , maybe something worn or jumped .

 

[Chuck Leeper]

What's the plug in that cyl look like?

 

[TurboBuRick]

Sounds like the spring or valve itself is getting hung up.

 

[black magic]

ill pull plug today, im more concerned why i have no/ low 70 o2 millivolt reading any ideas on that. also just had the driverside head off the car everything checked out ok

 

[TurboBuRick]

Being the factor o2 is a 1 wire sensor it uses the sensor body to get the ground. The ground has to transfer through the headers to the head then to the ground wires on the back of the head. I would check those grounds.

I can't see that fix the push rod problem though.

 

[earlbrown]

Those grounds supply the body with a ground. The engine gets it's grounding from the neg battery cable on the Jhook.

 

[pacecarta]

Those grounds supply the body with a ground. The engine gets it's grounding from the neg battery cable on the Jhook.

o2 grounds at passenger head in the back ,
the main ground from battery to front of passenger head is there for the starter

 

[TurboBuRick]

I'm not talking ground strap. I'm talking The ones in the main harness that go back to the ECM. One of those wires is a sensor ground.

pacecar beat me to it..


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[bison]

Alky is not an octane booster. It's an anti detonant the way most use it. There are some octane boosters that do work but the $$$ invested in them make them less useful and the fact that the mix can change too easily creates a lot of variable.


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[black magic]

thanks guys checkin the grounds now

 

[bison]

thanks guys checkin the grounds now

Grounding issue not causing valve train interference problem


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[pacecarta]

odds are the lobe is wiped on # 3 exhaust and the rod thats bending is #3 intake due to pressure build up in cylinder

but could be a s simple as a miswired plug wire

 

[chopped39]

odds are the lobe is wiped on # 3 exhaust and the rod thats bending is #3 intake due to pressure build up in cylinder

but could be a s simple as a miswired plug wire

Thats what I was thinking. I would look at the lifters that came out

 

[black magic]

one lifter is worn cylinder number three about a 1/16