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Help! Please Rb25neo Conversion Wont Start.

beRwick_GTRage

By beRwick_GTRage,
in General Maintenance

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beRwick_GTRage Rising Star

beRwick_GTRage

Posted
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i just finished putting an rb25neo from a stagea into my r32

i did a rough wiring job just to get the car started

im getting spark, injectors are pulsing and im seeing fuel getting squirted into the cylinder.

all timing marks on the belt are lined up

compression test results where 120psi on all cylinders on a cold engine.

but it wont start.

and it doesnt fire at all.

when i remove the cas and spin it manually while im cranking the engine, the engine fires

and when i spray aerostart into the manifold it also fires.

what could be the problem?

timing? firing order?

thanks

beRwick_GTRage Rising Star

beRwick_GTRage

Posted
  • Author
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whats the cas drive in the camshaft like?

thanks for the reply

the drive is ok. and the cas is a secondhand item off an r34 rb25neo

are there two series of neo engines? would they have different cas's.?

beRwick_GTRage Rising Star

beRwick_GTRage

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Posted (edited)
Correct me if I'm wrong, but isn't 120 a bit low for compression? My r34 neo came up at 160 to 165 across all 6. Or are the stag neo's different?

it was done on on a cold engine and the engine hasnt been started for over a year. i would expect it to read alot higher if it was at normal operating temperature and properly lubricated.

the only reason i would be worried is if it wasnt even.

my understanding is that even if compression is low in one cylinder or across all cylinders it should still start.

Edited by beRwick_GTRage
R32oNate Contributor

R32oNate

Posted
Posted

hey there, is you cas aligned properly because i had a similar issue on my rb20 when i took it out. it wouldnt crank over until i put it in the right position. otherwise try running an ecu diagnostics check if you can. one of your sensors might not be working properly hence why your car is not starting. hope that helps!

beRwick_GTRage Rising Star

beRwick_GTRage

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hey there, is you cas aligned properly because i had a similar issue on my rb20 when i took it out. it wouldnt crank over until i put it in the right position. otherwise try running an ecu diagnostics check if you can. one of your sensors might not be working properly hence why your car is not starting. hope that helps!

hey

it shoudnt matter which position the cas is in, should it?. ive tried starting it in different positions anyway.

ive done a diagnostic check, came up with no errors.

beRwick_GTRage Rising Star

beRwick_GTRage

Posted
  • Author
Posted

update! please help

when i remove the cas and spin it manually in reverse! while im cranking the engine, the engine fires. but when rotating it in the correct direction it doesnt fire.

also when i remove the cas and spin it to fill the cylinders with fuel. then replace the cas and try starting the engine it starts and runs for a few seconds then stops.

is my problem fuel related or cas related?

its obviously getting fuel when i turn it manually.

blind_elk Grand Master

blind_elk

Posted
Posted
hey

it shoudnt matter which position the cas is in, should it?.

yes it does
ive tried starting it in different positions anyway.
Then clearly the matching key inside the EX cam has broken. If the key was still there, then you could only mount the CAS in 1 position. (I don't know how many times that point has been made in previous threads!)
beRwick_GTRage Rising Star

beRwick_GTRage

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yes it does

Then clearly the matching key inside the EX cam has broken. If the key was still there, then you could only mount the CAS in 1 position. (I don't know how many times that point has been made in previous threads!)

why would it be clear that the key inside the ex cam is broken lol. he was asking me if the cas is properly aligned not wether the key was inserted the correct way.

i took the black plastic cover off the cas and watched the disc spin as the engine was cranking. as i said the cas drive is ok

blind_elk Grand Master

blind_elk

Posted
Posted

because the key is what causes the CAS to be correctly aligned!

There is a semi-circular hole in the end of the CAS shaft, and a semi-circular protrusion on the end of the EX cam (well, there's supposed to be). The protrusion on the cam is supposed to fit into the hole in the shaft end. It serves two purposes - make sure the cas is in the correct position relative to the crankshaft (#1 piston), and it also helps drive the CAS. That protrusion is prone to breaking off, causing the problem you now have (incorrect CAS alignment).

beRwick_GTRage Rising Star

beRwick_GTRage

Posted
  • Author
Posted
because the key is what causes the CAS to be correctly aligned!

There is a semi-circular hole in the end of the CAS shaft, and a semi-circular protrusion on the end of the EX cam (well, there's supposed to be). The protrusion on the cam is supposed to fit into the hole in the shaft end. It serves two purposes - make sure the cas is in the correct position relative to the crankshaft (#1 piston), and it also helps drive the CAS. That protrusion is prone to breaking off, causing the problem you now have (incorrect CAS alignment).

thanks for the explanation. as i said the CAS drive is ok!!!!

engine is now running

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