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Best practices/tips for removing knock sensor?

mk2davis

Well-known member
Joined
Mar 1, 2015
Messages
191
Location
Ventura, CA
The car has been showing odd hesitation and slow acceleration under boost. I sent my ECU to ECMTuning to rule out an ECU error, and they report that the ECU is in good shape, although they did replace problematic caps and are socketing the EPROM. They suggested that my symptoms are consistent with a bad knock sensor.

As you well know, the knock sensor is a pain to get to. I can barely reach it from the driver's side. I do still have AC. It does feel like the goo (technical term) hasn't run out of my existing sensor, but I'm replacing it anyways. Ohm reading on the 2 pin is 560,000 ohm, and I've read its supposed to be around 2.

Can someone verify that it is 24mm?

Can it be reached from underneath? I've read a stubby 24mm is the best way to do it, but I'm open to new ideas.

How tight do I screw the new one in? I've read (on a DSM forum) that slightly more than finger tight. I'd like a more specific instruction if it exists. I'm thinking that I may have overtightened it when I screwed it in while the motor was out.

Any and all guidance is appreciated. New sensor comes in tomorrow, the ECU likely on Saturday.

Thanks all.
 

gvr4ever

Well-known member
Joined
Aug 6, 2002
Messages
6,190
Location
central Indiana
Search is still busted.

I had to manually find this.

click
 
Last edited:

mk2davis

Well-known member
Joined
Mar 1, 2015
Messages
191
Location
Ventura, CA
I was hoping not to remove the intake manifold, and it doesn't say how much to tighten it. Hopefully with my small hands, I'll figure something out.
 

mk2davis

Well-known member
Joined
Mar 1, 2015
Messages
191
Location
Ventura, CA
Mission accomplished. At least I hope. I was able to get to it by removing the cruise control bracket, then reaching very deep from the passenger side. I used a credent wrench and after feeling around for a few minutes, got on the head. Feet didn't necessarily stay on the ground.

Before I installed it I compared the two with multimeter, and the results weren't too different. Pin 2 to the body of the sensor we both 570000 ohmish, although when I'd shake them the old one seemed to go to open circuit easier? Not the most scientific method, but time will tell when I get the ECU back.

If symptoms continue, I'll get some 100 octane gas and see if there's a difference.
 

FlyingEagle

Staff member
Joined
Mar 5, 2005
Messages
1,635
Location
THE Ottawa
Not that it is super accessible but torquing the sensor to exact spec is pretty crucial to getting a reliable reading from it.

See what you can do to get it torqued with an inch lb torque wrench combination.
 

mk2davis

Well-known member
Joined
Mar 1, 2015
Messages
191
Location
Ventura, CA
Finally got the car started, and it idles as it should. Haven't been able to drive it yet, as it is currently blocked in. It actually seemed to start more readily, but that could just be wishful thinking.

If it doesn't drive as it should, I'll put some 100 octane in it.
 

mk2davis

Well-known member
Joined
Mar 1, 2015
Messages
191
Location
Ventura, CA
This doesn't feel like the same car to me. Hesitations and loss of power are GONE. Still won't pass smog, but that's another thread.
 
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