Idle woes .

[atsiauto]

My car has developed a horrible idle problem, I have changed TB to get a different FIAV on there I left the car with a local mitsubishi dealer and according to him the computer ( which has had caps replaced long ago) is not operating the isc .

We first tried the throttle body but now the car idles at like 4k which before was the typical idle surge up down up down etc .

I need some ideas and thoughts guys I know trhis is basic sh*t for many of you, so help me if you can I hate not being able to hop in the car and go , it has also been so long since I have had to fight the car on anything techie that I am not feeling as sharp as I used to on the DSM-esque drama

Should I be looking at the ECU ? I am not getting any good info from the mechanic at the dealer either not sure what he tested and what he didnt I just know it runs worse than it did before .

 

Biss screw?

 

[turbowop]

Are you sure the throttle body you installed has a good FIAV? Is the ISC working properly?

 

[GVR4_1057]

Check the impedence on the ISC coils. There are 6 pins.2 rows of 3 . If you have a 1G (tan )ISC it should be 3K ohms if it is a 2G(black one)it should be 4K. Check from the center to each end on each set of 3.Example illustration below check from 2 to 1, and then 2 to 3. Then go 5 to4, and then 5 to6. It you find any of them open (no value)then you need to replace the ISC.


1/2/3
4/5/6

Also if you unhooked the coolant lines to the TB and did not block the FIAV passage this will cause your car to idle too high.
If these are all good check BISS screw and o-ring, or injector seals, or some other intake manifold vacuum leak. A pressure check would be a good idea at this stage.

Also verify that your closed throttle switch and/or throttle cable are not holding your throttle plate open at idle.

 

[ktmrider]

Check the ISC coils like mentioned then get the ECU out for inspection.
If I read your post correctly the dealer says the ISC voltage is at zero or not changing. The ISC driver on the ECU is right next to the capacitors that like to leak. Also a bad ISC can take out the driver card on the ECU.
How long ago were the caps replaced? Could be time for new ones and/or the original work did not remove the acid properly.
Worst case get the ECU or pics to Terry Posten or SteveP.
Last, the VFAQ has an outstanding guide to troubleshooting idle problems.

 

[atsiauto]

The ISC I have off the car is good, the one in the car I will inspect tomorrow and do a boost leak check , probably pull the ECU and scrutinize that area around the caps I seem to remember one of those upright boards in the area around the caps controlling idle, Im hoping to have some more info by Sunday .

 

IC105 and IC107 are the 2 ISC drivers, Check both of them for any bubbling or signs of burning.

 

[atsiauto]

Boost leak test revealed injector seals are leaking on the intake side, I would say this is a boost only thing but not sure if theres enough fresh air leaking in to cause issues, I will replace them if you guys can tell me where to buy a set .

I went ahead and put my old TBI back on ( my throttle seals were newer) and my second ISC which tests out fine,but have the ECU out to photograph the board which does have some staining onthe area around a smaller replaced cap also one of the green square caps has some trace exposure on the board as well as what looks liek a previous attempt at a jumper ( see 1st pic then click to enlarge) , kind of looks like they sweated the solder on the leg of one of the round caps to get good conductivity , theres one small black chip in the vicinity of 105-7 that the board underneath looks a little irregular (has a "26" on it)

hopefully my POS nikon ebay refurbished camera will focus in enough for all to see what I am talking about .

 

[toybreaker]

There's definately been a repair there.

It also looks like the corrosion/damage in the area was extensive.

The residual acid really does a number on the board when it's not properly neutralized. /ubbthreads/images/graemlins/banghead.gif

 

[BoostedAWD91]

anyone with their FIAV blocked off having problems with idle surge? i have mine blocked off on a fresh rebuilt TB, fresh Ecu and everything and its starting to surge already

 

[GVR4_1057]

Could still be intake manifold gasket leak, injector seal leak or a vacuum hose leak somewhere. Try a pressure check. Verify that your throttle plate is closing completely /ubbthreads/images/graemlins/dunno.gif

 

[BoostedAWD91]

also at idle my tial bov is 1/4 of the way open which i found pretty strange.
why would it be open? idle switch adjusted down to far?

 

[GVR4_1057]

How much vacuum are you running? There are 4 different spring rates available from Tial that need to be matched to your idle vacuum range.

 

[atsiauto]

Oddly enough after putting my old TB back on and another ISC the car is idling normal.

My plan is to send the ECU to a board member for scrutiny and make sure that can be ruled out in the future , I need injector seals if anyone can hooke me up with who sells them would be preeshatated.