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No compression on all cylinders yet car starts and runs

I’ve read that if there’s no compression on all cylinders then the car shouldn’t start. I did a compression test because the car vibrates when idle and in gear only, neutral makes it go away. Sometimes the engine would stumble and shutoff after quickly coming to a stop. Those issues started only a month or two ago.

Everything was followed for the compression test:
Disconnect fuel pump
Disconnect coil
Remove spark plugs
Screw in gauge
Hold pedal and turn starter 5-10 times

I’m thinking maybe it’s connected to the timing even though I re-did the timing thinking it was that originally.

Looking for ideas.

I’m looking for year/make/model/mileage of the vehicle.

And I still can’t find it.

Tester

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If you mean 0 compression on all cylinders then it cannot run…Maybe the gauge is leaking off; a not unheard of thing to happen.,

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If you’ve used that same gauge successfully for measuring compression, and are certain all cylinders register 25 psi or less, this is indeed a mystery. Any diagnostic codes there?

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You either performed the compression test incorrectly, or the gauge has some kind of a defect, such as the “schrader valve” . . . which is actually a rather common problem

The engine won’t start with 0 compression on all cylinders

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It’s a rental from O’Reilly Auto Parts.

Only P0400 (Exhaust Gas Recirculation) though that has been on there for a long time so I don’t think it’s related.

That’s actually good to know. I’ll pickup a different rental one from a different O’Reilly location.

There’s another possibility I forgot to mention . . .

Perhaps you didn’t properly assembly the compression tester. Did you clearly hear and feel a “click” as you assembled the hose to the gauge . . . ?

On the hose there is a metal part that lifts up to insert the end of the gauge into then releases back down. I didn’t hear anything click.

I solved the issue of the engine stumbling/shutoff when stopping quickly. A vacuum hose connected to one of the valve covers was 0.05" to 1" cracked upward from the base Looking at it it would not seem it would cause issues. I taped it with electrical tape. Another vacuum hose was not fully seated on so I made sure to push that all the way on. So that solved that as well as some of the vibration at idle in drive.

I went a different O’Reilly store and rented another compression tester and it worked.

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