Rotary Car Club - View Single Post - 1993 RX-7 Idle Quick Rev Engine Rough

jamesg302 · 01-21-2011, 06:31 PM

Hello and thank you all for the suggestions. We have tested some things and still have more to test. However, I have more specific details on the problem and wanted to share them here for some suggestions.

1/21/2011

== At Cold Start ==
Idle: 1500-1700 (low probably due to accelerated warm up (AWS) solenoid, its probably bad, resistance tested on car at 16 outside of 9.3 to 11.3 spec.)

== At Warm Start ==
Idle: 750-775rpm

The car's idle both cold and warm is still rough. We tested adding different loads both cold and warm to try and narrow in on the cause of the significant drop in rpm and knocking. The following loads were tested.

HVAC Fan (speeds 1 & 3), AC (On/Off with fan speeds 1 & 3), Headlights with high beams (On/Off), Radio (On/Off), P/S (load), Clutch (In/Out), Read window defroster (On/Off), Brake pedal (depressed)

Of the above loads mentioned the computer raised the rpm to accommodate all loads. However, when the AC was turned on the engine immediately went from the rough idle to very rough engine shake with knocking. Turning the AC on while depressing the Brake pedal would cause the rpm to drop around/below 500rpm and the knocking. The knocking persists when the AC load is removed but disappears if the car is turned off and back on. Combining other loads to create a heavier electric load (i.e. radio, high beams, and defroster) had no effect.

I mentioned before that using the turbos seemed to have an effect on the knocking and rough engine. We retested and found that turbo usage has no noticeable effect on the knocking or idle. The problem seems to be linked to engine load at idle (800-1500 depending on load).

Is it possible that this symptom is being caused by a lean fuel condition? Many sites mention that a certain amount of modifications require the computer to be re-programmed. This car's only modifications are a down pipe (eliminated pre-cat) and an after-market exhaust single outlet muffler (installed by previous owner).

Also, the clutch switch, stoplight switch, and knock sensor were tested and are OK.

Please let me know your thoughts. Thanks.

Regards,
James

01-21-2011, 06:31 PM	#9
jamesg302 The Newbie Join Date: Aug 2010 Posts: 7 Rep Power: 0	More Specific Symptoms Hello and thank you all for the suggestions. We have tested some things and still have more to test. However, I have more specific details on the problem and wanted to share them here for some suggestions. 1/21/2011 == At Cold Start == Idle: 1500-1700 (low probably due to accelerated warm up (AWS) solenoid, its probably bad, resistance tested on car at 16 outside of 9.3 to 11.3 spec.) == At Warm Start == Idle: 750-775rpm The car's idle both cold and warm is still rough. We tested adding different loads both cold and warm to try and narrow in on the cause of the significant drop in rpm and knocking. The following loads were tested. HVAC Fan (speeds 1 & 3), AC (On/Off with fan speeds 1 & 3), Headlights with high beams (On/Off), Radio (On/Off), P/S (load), Clutch (In/Out), Read window defroster (On/Off), Brake pedal (depressed) Of the above loads mentioned the computer raised the rpm to accommodate all loads. However, when the AC was turned on the engine immediately went from the rough idle to very rough engine shake with knocking. Turning the AC on while depressing the Brake pedal would cause the rpm to drop around/below 500rpm and the knocking. The knocking persists when the AC load is removed but disappears if the car is turned off and back on. Combining other loads to create a heavier electric load (i.e. radio, high beams, and defroster) had no effect. I mentioned before that using the turbos seemed to have an effect on the knocking and rough engine. We retested and found that turbo usage has no noticeable effect on the knocking or idle. The problem seems to be linked to engine load at idle (800-1500 depending on load). Is it possible that this symptom is being caused by a lean fuel condition? Many sites mention that a certain amount of modifications require the computer to be re-programmed. This car's only modifications are a down pipe (eliminated pre-cat) and an after-market exhaust single outlet muffler (installed by previous owner). Also, the clutch switch, stoplight switch, and knock sensor were tested and are OK. Please let me know your thoughts. Thanks. Regards, James