IACV idle problems - low speed lurch
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Joined: Dec 2005
Posts: 299
IACV idle problems - low speed lurch
It all started with a knock sensor code. I put a new KS on my VQ30DE and was blown away by the improvement in power. The only problem was the low idle <400rpm, it even stalled on me a couple of times. More reading on the forum suggested that I needed to clean the IACV which I did the next weekend. After that I had a fast idle >1300rpm that would slowly drop down to spec (700rpm) after about 10 seconds even when hot. I don’t want to turn the idle speed down because then it would stall out after 10secs.
I would almost be content to live with this if it wasn’t that the car has become really lurchy at low speeds e.g. 2000rpm in 2nd (you know - the commuter shuffle.) Trying to smoothly control the car when holding the gas at the threshold between accelerate/decelerate, the car would lurch forward then fall back. Makes me look like a learner who’s kangarooing the clutch!
I noticed the small hole on the intake side of the butterfly valve. I think Clive made comments about this too. Anyone know where this goes? It comes out the bottom of the throttle body and has a rubber hose connecting to a vacuum harness that disappears off into the abyss. I squirted a bunch of carb cleaner down there and now I’m wondering if I’ve blocked it off and disabled some critical component. Then again, I’d have thought that any solvent should have evaporated off quickly and/or been sucked out by the intake vacuum.
I was able to check the operation of the 2 solenoid valves on the IACV (this is regular idle and fast idle right?) But the big one in the middle with 6 contacts had me confused. It ohmed out like a pair of potentiometers (56ohms end to end with a center tap) Anyone know what this does and how to test it?
Appreciate any suggestions. I really miss my smooth V6 – it’s driving like an old 4 banger right now.
I would almost be content to live with this if it wasn’t that the car has become really lurchy at low speeds e.g. 2000rpm in 2nd (you know - the commuter shuffle.) Trying to smoothly control the car when holding the gas at the threshold between accelerate/decelerate, the car would lurch forward then fall back. Makes me look like a learner who’s kangarooing the clutch!
I noticed the small hole on the intake side of the butterfly valve. I think Clive made comments about this too. Anyone know where this goes? It comes out the bottom of the throttle body and has a rubber hose connecting to a vacuum harness that disappears off into the abyss. I squirted a bunch of carb cleaner down there and now I’m wondering if I’ve blocked it off and disabled some critical component. Then again, I’d have thought that any solvent should have evaporated off quickly and/or been sucked out by the intake vacuum.
I was able to check the operation of the 2 solenoid valves on the IACV (this is regular idle and fast idle right?) But the big one in the middle with 6 contacts had me confused. It ohmed out like a pair of potentiometers (56ohms end to end with a center tap) Anyone know what this does and how to test it?
Appreciate any suggestions. I really miss my smooth V6 – it’s driving like an old 4 banger right now.
Junior Member
Joined: Sep 2003
Posts: 26
OK, the middle on is the step motor that actually adjusts the air, the two hexagonal cylinders on the side are solenoids of AC and power steering. those two solenoid send signal to ECU to trigger Step motor in case AC is turned on or there is a load on Power steering, and adjusts the idle air.
Have you figured out what the little hole in TB for and what happens if it gets clogged? I cleaned my TB as well and wonder if I clogged it?
Have you figured out what the little hole in TB for and what happens if it gets clogged? I cleaned my TB as well and wonder if I clogged it?
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trungg86
4th Generation Maxima (1995-1999)
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Sep 4, 2015 04:58 AM