Engine cranks,will not start

1998 TOYOTA 4RUNNER
271 MILES • 2.7L • 4 CYL • 2WD • AUTOMATIC
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CYNTHIA HAYNES
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Had to replace with a new head.Engine had gotten hot an cracked old head.Temp gauge was not working at the time.New head,2 cams,spark plugs an wires new,an getting spark. Fuel all seems ok. Fuses checked an seem good.Cranking will not start.Do not have air flow connected when trying to crank.Getting compression of 115 or 125 on all 4 cylinders
Jun 8, 2022 at 3:48 AM
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AL514
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Hello, you don't have the mass air flow sensor and the air intake tube on? You'll need that to be plugged in and the air intake tube sealed up correctly. The mass air flow sensor also includes the Intake air temperature sensor.

https://www.2carpros.com/articles/how-a-mass-air-flow-sensor-works-maf
Jun 8, 2022 at 5:21 AM
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CYNTHIA HAYNES
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I was mistaken the air flow sensor was still hooked up, did hook the tube back up. Still not cranking. Possibly the cam positioning sensor believe possibly bad from when engine got so hot, not sure. Going to take radiator, etc., apart early am. Possibly the timing jumped, seemed perfect when put back together. Did try to fire up 2 times initially. What is your experience with these two things? Thank you
Jun 8, 2022 at 8:08 AM
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CYNTHIA HAYNES
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Guessing there is no way to check the positioning sensor before having to remove timing gear.
Jun 8, 2022 at 8:09 AM
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CYNTHIA HAYNES
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Did get the info on checking the sensor answered.
Jun 8, 2022 at 8:19 AM
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AL514
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If you just replaced the cylinder head, and I'm assuming you got a new head with new valves and the whole assembly. 2 new cams, did you replace the timing chain and chain tensioner? The minimum compression for a used engine is 127psi, Compression with a new head and components should be up around 178psi. 115 is definitely too low and 125 sounds too low too for a new cylinder head.
The diagrams on All Data look different than what I would expect. This is a dual overhead cam, correct? And does it have a 2-chain setup? The 1st diagram below is supposed to be the 2.7liter and so is the 2nd diagram, but it only shows 1 cam on the 2nd. I think this service information is wrong. But if you have low compression like that, I'd say the timing chain might be off by 1 or 2 teeth on either cam, or the crankshaft. But they don't give any information as to where the timing marks are. Same information on All Data and Mitchell. But if you reused the old chain, and/or tensioner, that might be where things went wrong. The low compression is the clue to what's going on.
Jun 8, 2022 at 12:04 PM
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CYNTHIA HAYNES
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Going to replace the timing chain and gear. Thank you for the help.
Jun 9, 2022 at 2:11 AM
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AL514
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Try lining up the cams and see how far the chain jumped. If you find that the chain tensioner is extended all the way out, or the timing chain guards have worn a groove in them from the chain, that can cause it to be loose too. It might not be anything to do with the cam or crankshaft gear. It's the components that deal with keeping the chain tight.
Jun 9, 2022 at 3:53 AM
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CYNTHIA HAYNES
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Thanks, will do.
Jun 9, 2022 at 3:56 AM
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