1993 RX-7 Idle Quick Rev Engine Rough

jamesg302 · 02-19-2011, 06:07 PM

Hello again. We have completed some more testing and would like your feedback/suggestions.

2/19/2011

The MAP sensor was checked and is within specification.

A compression test was done with the car run hard then tested right after 10 minute cool-down. The circuit opening relay was removed, the coil box under the cruise control was disconnected, and both trailing spark plugs were removed. We used a standard compression test gauge with the valve removed. The followed average readings were taken at the cranking RPM for each side of the rotor.

== Back Chamber ==
80 PSI
78 PSI
80 PSI

== Front Chamber ==
65 PSI
45 PSI
30 PSI

The car seems to drive fine except for the rough idle which is now evident even without the extra load of the A/C turned on. The 3rd gear boost test at WOT yields 10-8-10.

Is it possible that one of the front chamber apex seals is stuck or do the PSI numbers indicate that the seal must be cracked, chipped, missing?

We added SeaFoam to the gas and a small amount to the oil in an attempt to un-stick the seal if in fact that is the problem and put one gallon of water through the intake to clean any carbon deposits that may have existed.

What is the risk of running the car in this condition if a seal is bad? The car is manageable to drive and the $4,500 engine re-build cost is difficult to accept at this time.

Thank you again for taking the time to read this post and offer your advice.

Regards,
James

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02-19-2011, 06:07 PM	#10
jamesg302 The Newbie Join Date: Aug 2010 Posts: 7 Rep Power: 0	Hello again. We have completed some more testing and would like your feedback/suggestions. 2/19/2011 The MAP sensor was checked and is within specification. A compression test was done with the car run hard then tested right after 10 minute cool-down. The circuit opening relay was removed, the coil box under the cruise control was disconnected, and both trailing spark plugs were removed. We used a standard compression test gauge with the valve removed. The followed average readings were taken at the cranking RPM for each side of the rotor. == Back Chamber == 80 PSI 78 PSI 80 PSI == Front Chamber == 65 PSI 45 PSI 30 PSI The car seems to drive fine except for the rough idle which is now evident even without the extra load of the A/C turned on. The 3rd gear boost test at WOT yields 10-8-10. Is it possible that one of the front chamber apex seals is stuck or do the PSI numbers indicate that the seal must be cracked, chipped, missing? We added SeaFoam to the gas and a small amount to the oil in an attempt to un-stick the seal if in fact that is the problem and put one gallon of water through the intake to clean any carbon deposits that may have existed. What is the risk of running the car in this condition if a seal is bad? The car is manageable to drive and the $4,500 engine re-build cost is difficult to accept at this time. Thank you again for taking the time to read this post and offer your advice. Regards, James