Very rough pulsing idle after sitting in garage for 2 yrs

ihaveaquestion · Jan 17, 2017

98 Honda Accord LX-V6.

So about 2 years ago, I got a job in the bay area and had to leave my car in DC. Now I got a chance to relocate back, the first thing I tried to do is to fire up the car. Well, the battery is dead which is expected. But once the car started, the idling has a big pulsing...+-500RPM I would say.

I changed out the MAP sensor and initially the problem went away, but it came back the next day...so, I am not positive what I need to do now. Clean the Idle valve? Throttle body? But the car hasn't been driven for 2 years...how can there be carbon/dirt built up during this time? I actually cleaned them up pretty well before leaving for the bay area. Any suggestion on what else I need to look into?

I also notice black smoke coming out of the back of the engine, which I think requires a replacement of head cover gasket on the rear of the engine. 3 years ago, I had replaced the head cover gasket: https://www.amazon.com/Genuine-Honda-12030-P8A-A00-Cover-Gasket/dp/B00E5O57T6 but this only covers the front of the engine, can someone tell me the part number for the rear of the engine?

FNCONE · Jan 17, 2017

When I Started my j32 auto swap it rev'd and had a terrible idle I let it run for an hour and took a slow spin around and it eventually fixed itself. (The engine was from a totaled car and by the time I started it it was about a year and half)
I'm not saying it will fix itself but that's my experience with a motor that sat for a long time. I'll try find my video it was revving from 1 to 4k like if it was angry

604ACCORD · Jan 18, 2017

I'm pretty sure its the same part for both valve covers.

dawg316 · Jan 18, 2017

The gas is gonna be bad which will make it run bad. Thtow in some new gas. And just let it idle and run for a while.

ihaveaquestion · Jan 20, 2017

Unfortunately, I cannot let the car idle for too long. The black smoke comes out from the back of engine, which suggests perhaps a bad head cover gasket.

Any suggestion on how to fix the pulsing? Do you think the gasket would fix the pulsing? or is it more of throttle body, idle valve kind of thing?

The tranny is on its last leg too, could it be a cause for pulsing idle? We are talking not just rough idle, but big pulse +- 500 RPM while idling.

Thanks!