C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

rough running below 2000 rpms

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Old 10-30-2017, 07:22 PM
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belairbrian
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Default rough running below 2000 rpms

I got the car back together and started it up. It seemed to be idling too fast but I found that the purge valve to throttle body hose was off causing a leak. reconnected that and idle came down to where it should be. Looks deteriorated so I'm ordering a new one.

Out of caution I pulled the battery cable to clear the ecm again.

Took it out for a drive and there is a slight vibration at idle and from idle to 2000 it runs rough after 2000 it smooths out and accelerates.
Will rev to redline.

To fully set the picture the following parts have been replaced.
All coolant hoses
radiator
water pump
thermostat
temp sensor
opti-spark
coil
harmonic balancer
throttle body was removed and cleaned

So far I've checked fuel pressure 47psi with key on.
39 running up to 45 with FPR disconnected

TPS reads .63 at closed 4.06 at WOT.

Problem exist regardless of transmission being in park or drive.

Did not exist prior to changing these parts. All of this was from a leaking upper radiator hose.

Any ideas?

Could it be the new balancer? Could swap old one back but I think that means pulling water pump.

Could a stronger coil and new opti be plating badly with the wires ans plugs? Didn't change them since PO said they were just over a year old.



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