amm203 Posted July 12, 2017 Share Posted July 12, 2017 Random question/concern; at normal operating temperature when I'm stopped at a red light (in gear) the engine revs sound like they are very slightly jumping every second. The tach doesn't show any change in RPM but you can definitely hear the engine lightly "pulsating". Am I crazy and this is normal? I'm curious if it is related to the A/C clicking issue behind the dash - like a bad relay causing a load on the engine to repeatedly happen. Link to comment Share on other sites More sharing options...
Max Capacity Posted July 12, 2017 Share Posted July 12, 2017 When was the last time you had the A/C serviced. I wonder if it's low on R134...and the clutch is cycling on the compressor... My 05 wagon 5mt, will have a bouncy idle sometimes after I back into the parking spot at work. I just give it a quick rev to 2000 rpm or so and its gone. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
compsurge Posted July 12, 2017 Share Posted July 12, 2017 A/C doesn't need servicing until it fails to cool. Then you need to find and repair the leak. Is the clicking occuering after you shutdown and is it coming from the passenger center console area? If you turn off the A/C, does the pulsation resolve itself? The idle sounds pretty normal to me. The clicking does not, unless it is coming from the aforementioned area, in which case it is likely the vent actuator that needs grease or replacement. Link to comment Share on other sites More sharing options...
amm203 Posted July 12, 2017 Author Share Posted July 12, 2017 Haven't serviced the AC since I bought the car back in Dec. 2014. It puts out moderately cold air on the outside air setting and good cold air when on the recirculation setting. It is pretty mediocre if the vehicle is not moving, though. Clicking occurs randomly and yes, it will also occur after the vehicle is shut down for a few seconds and sounds like it is coming from the area you described. I also hear it when first turning the car on right before cranking it (at the Accessory position). Pulsation seems to be pretty consistent regardless of the AC setting. I thought I read turning on the defrost setting would stop the clicking but I don't think it does. Link to comment Share on other sites More sharing options...
amm203 Posted July 12, 2017 Author Share Posted July 12, 2017 The more I think about this the more it makes sense it is that damn servo. Changing the temperature on the digital HVAC system generally doesn't change the air temp. In the winter 85° down to 72° was essentially the same air temperature. It required taking it down to 65° to actually get the air to be cold. Might try to get to that servo and grease it up - found a quick guide posted here. I assume this location is identical to the '08 since the part is the same. Appreciate the feedback on the idle issue! Edit: compsurge I noticed you are to thank for that post I came across so thank you again! Link to comment Share on other sites More sharing options...
JmP6889928 Posted July 12, 2017 Share Posted July 12, 2017 Check your front 02 sensor as that can easily cause surging at idle (STFT bounces all over the place). Even when they go bad, they don't generally cause a CEL. Link to comment Share on other sites More sharing options...
amm203 Posted July 13, 2017 Author Share Posted July 13, 2017 That could be an issue. I replaced it not long ago but I have heard of failures with new ones shortly after installation. Another thing I noticed is LTFT usually jumps to ~8-9+ after letting off throttle & idling. It only comes back down when I get back on throttle. Link to comment Share on other sites More sharing options...
amm203 Posted July 13, 2017 Author Share Posted July 13, 2017 Another thing to note. During my e-tune last winter I was repeatedly getting the P0420 code. After informing my tuner I guess he chalked it up to the new turbo/high-flow cat & just set the AP to make the code "disappear" because it never came back. I haven't changed the rear o2 since I bought the car. Does the rear impact any of these values at all or cause drops in gas mileage? I went ahead and bought a denso rear o2 considering how cheap they are for the hell of it. Link to comment Share on other sites More sharing options...
Max Capacity Posted July 13, 2017 Share Posted July 13, 2017 I believe the tune deletes the rear O2. But I'm sure someone who knows for sure will chime in soon. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
amm203 Posted July 13, 2017 Author Share Posted July 13, 2017 Monitored a couple things on the way home from work today. A/F Sensor #1 Current (Front o2): This was measured in mA and normally it moved around a bit directly correlating with A/F ratio. This makes sense. During throttle lift-off the A/F ratio maxed out and mA was pegged at about 1.74. At idle & normal cruising there was not too much change (mA were hovering around 0) and the A/F ratio was usually around 14.7 A/F Sensor #3 Voltage (Rear o2): This jumped around like crazy and did not seem too affected by throttle response. Sometimes it would hover around .7-.8 volts consistently. Other times it would randomly jump down to 0 or .1 and back up to .8 quickly and repeat. I was reading A/F Correction #3 as well and it was jumping around between -2.xx and +2.xx. Link to comment Share on other sites More sharing options...
amm203 Posted July 18, 2017 Author Share Posted July 18, 2017 Update: engine pulsing sound was being caused by the stuck vent servos. On Saturday evening I noticed with each click of the stuck servo the engine revs jumped audibly. Could only really hear it with the door open and parked in a garage. So the next day I took out the glovebox, located & lubed up the servos, problem gone. Now I just gotta find a pre-turbo leak to fix this high A/F learning @ idle. Link to comment Share on other sites More sharing options...
compsurge Posted July 18, 2017 Share Posted July 18, 2017 Weird. I guess the vent was causing the load to change somehow and requiring fluctuations in power extraction from the engine? Link to comment Share on other sites More sharing options...
amm203 Posted July 19, 2017 Author Share Posted July 19, 2017 That is what I'm guessing. This just confirms the grounding in these cars is crap. Rolling down two windows drastically slows them down. Perhaps a new alternator is necessary considering I replaced some of the under-engine grounds recently. Link to comment Share on other sites More sharing options...
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