Engine rebuild.. shaky idle

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Finto_316
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Post Wed May 11, 2016 11:07 pm

Hi,
Just fully rebuilt my 1989 m20b25 with all new everything.
Started her up and noticed a very light heek up on idle , more noticeable when you hold car with your hand. The engine revs fine and no splutters. Exhaust is clean with no smoke or steam. The engine sounds perfect but just slightly has the heek up.
Things I've done/checked
Compression 150 psi across all 6 cylinders
No smoke from dip or oil cap (when dip lifted engine rev drop but rev back up)
Spark plugs golden brown
Getting strong spark
Continuity test on tps (good)
Ohm test on icv (good)
Changed fuel regulator
Coolant bled perfect with heat coming into cabin
Changed AFM for a m20b20 unit and made no difference

Could it possibly be
-timing off a tooth?
-injectors?
-ecu?
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Finto_316
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Post Thu May 12, 2016 5:44 pm

Changed crank position sensor ( from working engine to make sure) -made no difference.
Checked ht leads for any cracks or wear , seam ok no wear.

Any suggestions?
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Brianmoooore
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Post Thu May 12, 2016 7:31 pm

Checked out the plug and socket for the injector loom under the inlet manifold? Check under the rubber boots.
Finto_316
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Post Thu May 12, 2016 11:23 pm

Got sorted Brian. The little triangle piece on inlet manifold was loose and sucking more air in.
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markus_74
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Post Tue Jun 28, 2016 5:15 pm

Hello, Finto can I know what little triangle do you mean? I have same symptom like your car.

Does is it intake gasket? Or..

Thank you
Markus
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andysheep
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Post Tue Jun 28, 2016 5:22 pm

Exhast side of inlet,were to fuel pressure regualator gets its air :D
markus_74
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Post Tue Jun 28, 2016 6:27 pm

In the back of inlet manifold? That has small hose to pressure regulator?
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reggid
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Post Tue Jun 28, 2016 10:51 pm

yes, near bracket that bolts manifold to the valve cover
E30 325is with M20B31
markus_74
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Post Wed Jun 29, 2016 12:58 pm

Ok thank you, I will check again all intake manifold gasket