ISC really at fault?

[Aikouka]

I ran the test that the Haynes manual lists for the ISC motor (I actually used a battery charger set to 6v since I have no 6v batteries) on a extra motor that I had in some 1g NA intake manifold. Well, the motor hummed and sometimes the small gold-colored part would twist a little bit (I really wasn't making a great connection to the negative pins.) But, then I used the same test on the ISC in my car and it didn't make any noises.

Now, that says to me "pull the little bastard out and put in the one that makes the humming noise." But, my idle surge is very minimal. It will go up to ~1.25k and then go down to 1k and back up again, so would a bad ISC create a problem this small? I was thinking about just taking the ISC out of my car, and running another test on it when it's out of the car, so I have an easier time making the connections. I've never noticed any vacuum leaks, but the idle switch connector's wire looks like it's going to break off soon, so that might need to be replaced too. The throttle body also moves normally, and doesn't stick. Any thoughts?

 

[temfate]

Pull it out and check each coil per the vfaq... www.vfaq.com hit DSM, intake, something about ISC test...

Sometimes a bouncing idle is because the ISC can no longer adjust fully for the mods you've done to the car. It's a good idea to reset the BISS... That can also be found at the vfaq. Basically you ground two connectors, then adjust the idle set screw until you're at 750rpm (preferrably measured by a electronic gauge than the stock one)...

 

[Aikouka]

I ran those tests, because it's practically the same test that's in the Haynes manual (except Haynes only has you test one set of pins on the top and one set on the bottom (i.e. 1-2 or 2-3)) I have an extra one so I guess I'll swap it in tommorow. I really don't have any mods on the car, so I doubt it's a problem with that. And I've had the car Idle at 750rpm before.

I noticed something, in the VFAQ for adjusting the BISS ... the highlighted prong on the diagnostic port ... isn't that actually terminal 8 and terminal 10 is one down?

 

[Rick4g63]

Aikouka, If that motor has more than 100k miles on it I would replace the ISC motor:
http://www.machv.com/1gdsmidspcom.html

and the BISS:
http://www.machv.com/newbasidsets.html

Reset the ECU, set to 750 rpm and drive it around to see if the problem persists.

Good luck

 

[Aikouka]

Hmmm I took out my car's ISC motor and I noticed something weird in my ISC housing ... I took a picture to show you. It looks like a seed. Could this have been messing up my idle? Also, I checked my ISC motor when I took it out and it does actually work, but it doesn't seem to work as well as the NA ISC motor that I tested last night. Also, I read that you can use an NA motor in a turbo, but I noticed that the NA ISC motor has fins on the part that moves and the turbo is flat. Does that matter?

Also, just one quick thing, in my picture at the bottom, there's a weird bell-shaped part on the Intake Manifold. Could anyone tell me what that is and what it does? My NA intake manifold has one, but it has an electrical connector on it, and my turbo one does not. So I've always wondered what it was, but could never find it in the manual.

 

[Rick4g63]

Aikouka:

1. The haynes manuals are not explicit and concise as the Mitsu shop manual.

2. The Turbo ISC and N/A ISC are different. The values for checking the operation of the turbo ISC are different. (I will post the procedure to do a operational check on an ISC motor per mitsu technical service letter).

3. The "bell" shaped housing next to the ISC is the EGR valve which is controlled by the EGR solenoid.
This is from the mitsubishi service manual:"The EGR system reduces oxides of NOx in engine exhaust and helps prevent detonation (engine knock). The system allows a predetermined amount of hot exhaust gas to recirculate and dilute the incomng air/fuel mixture. The diluted air/fuel mixture reduces peak flame temparature during combustion."

THIS DOES NOT AID IN ENGINE EFFICENCY PERFORMANCE. You can make a plate and install it to prevent the EGR from introducing air into the intake. Or purchase one from dejon for $10: http://www.dejontool.com/images/DSM-Tools & Misc/EGR1.JPG

 

[Aikouka]

But I'm still not sure what those weird seed-like things were in my ISC "port". If they were some foreign object, how in the world would they have gotten in there. I cleaned them out, so should I just put my original ISC back in?

 

[Thomas91169]

perhaps your car was previously owned by a drug dealer?

take them and plant them and see what happens.

and put in your old one, perhaps those seeds got into the intake somhow and were blocking the isc from working right.

 

[Rick4g63]

Aikouka save those "seed" and take it to a mitsu dealer and ask to speak with a tech/mech that have experience with that problem.

Clean that area and carefully re-install the ISC and try it.....

Good luck

 

[temfate]

If they were keeping your isc from seating flushly it could in fact have been causing your problems...

The ISC's are technically about identical, I opened a NA one and my Turbo one, and merged the two good coils into one working unit that measures identical to a brand new one. I'd say whichever is in better shape you should use. But that choice is up to you. Just remember after pulling and replacing the ISC you really need to reset the BISS in order to get it aligned right.

 

[Aikouka]

I put the ISC motor back, and asked my dad if he knew anything about it. He said it was just a seed that got in the intake, probably because the car sat for a long time (Like I said in some other thread, the inspection sticker was dated back in 2002 before I got it reinspected.)

And by resetting the BISS, do you mean properly setting the idle while grounding those two connections?

 

[temfate]

Yes, grounding the connection behind the battery, and on the debug port cause the ECU to put the ISC into the middle position. Thus your base idle gets set with the ISC having maximum travel in both directions.

 

[Aikouka]

Okay, I put the ISC back in, and hooked up the proper connectors to adjust the BISS. Now I idle around 750rpm with very slight fluctuation. I hear a clacking noise when I turn the car to on, which is the ICS, but before I took it out, the noise was just a slight click. Did I do something wrong or is it back to normal?