Idle Trouble

[SpoolinTalon2]

So I had some idling issues. I had been told about the ICS and TCS (I think thats what they are called). But I didn't know how to check if those were trully bad or not. So there's a screw right by the throttle body and I messed around with that turning it clockwise and counter clockwise, while turning it counterclockwise my idle increased and turning it clockwise it decreased, so i turned it clockwise. But turning a screw clockwise means that its tightening, so my questions are: What exactly is happeniing when I tighten the screw? and was it a bad thing that I did this? Thanks.

 

[kspharris]

What type of idle issues are you haveing? Turning the BISS screw is not a bad. It is there for you to set your Base Idle. Let us know what type of problems you are having. Turning the screw clockwise slowly blocks an opening in the throttle body that lets air pass through to the motor so that it stays running properly. The more you turn it clockwise the more air it blocks, causing the car to idle down. If your car is reving on it's own then it is MOST likely your ISC. Let us know and hope this helps.

 

[SpoolinTalon2]

Well the idle was too high (1-3k rpms) and then that's when i decided to turn the screw. But if it's blocking air wouldn't that effect my cars performance then? Thanks.

 

[Siral3x]

The BISS sets/adjusts the idle on your car , and it won't affect the performance.
If you are sure that the ISC is bad then turning the BISS it's not the gratest thing to do because your not adjusting the idle your compensating your air/fuel mixture.
Most likely your air/fuel mixture is RICH at the moment, and the gas millage will drop when you have a bad ISC..so I would recomend having the ISC and TPS checked and double checked.
High Idle is common to DSMs and is called "idle surge", do a quick search on the forum and you'll find a lot of info about it.
You can test the ISC the "Fyourself...just look it up under uel" section in a Chiltons or Haynes. With a multimiter you are supposed to chk the ISC resistance and get something like 30 ohm for the 6 pins..chk 1 pair at a time...just look it up in a book.

Let me know if you need a ISC....I got a couple used working ones.
Best of luck to you.

 

[steve]

If you are sure that the ISC is bad then turning the BISS it's not the gratest thing to do because your not adjusting the idle your compensating your air/fuel mixture.
Most likely your air/fuel mixture is RICH at the moment, and the gas millage will drop when you have a bad ISC..so I would recomend having the ISC and TPS checked and double checked.

The BISS has nothing to do with the A/F ratio. Where did you pull that from?

If the ISC is working correctly then the idle speed won't change untill you force the ISC out of range and it can't correct anymore. While the ISC si working and in range the changes you make to the BISS iwll cause a matching change to the ISC so as the BISS lets in more air the ISC will let in less to maintain the idle speed.

The A/F is controled at idle and cruise by the feedback from the O2 sensor.

Steve

 

[SpoolinTalon2]

I have heard that the gas mileage is effected from your o2 sensor being bad but not from your ISC being bad. Which right now I do need an o2 sensor and my gas mileage does suck. So I'm gonna try to find how to check your ISc and TPS ( i think thats the other one) to try to find out if they are bad or not. If anyone has a link or knows where this is at I would appreciate it. Thanks.

 

[steve]

You can check half of the ISC system by measuring the resistance of the coil windings and making sure than they are between 20 and 40 ohms. There are four winding to check. On the connector there are six pins, two rows of three pins. Each of the center pins in a row is the common power input fo a coil and the outside pins the windings. measure the resistance from the center pin to each of the outer pins in both rows (2 to 1) (2 to 3) (5 to 4) (3 to 6). The other half of the ISC system is the ECU and wires.

The TPS on a 2G is adjusted differently than on a 1G but most of the testing is the same.
Your interested in the total resistance and that the output changes smoothly as the throttle moves without dropouts or spikes. In addition the IPS is part of the 2G TPS and needs to open and close.

Steve

 

[SinaiTSi]

I was having problems with high idle as well and I noticed it once it started getting hot out, since it was fine all winter. What fixed my problem was slightly loosening the throttle cable so it wasn't quite as tight. This did away with high idle alltogether.

 

[Siral3x]

The BISS has nothing to do with the A/F ratio. Where did you pull that from?
The A/F is controled at idle and cruise by the feedback from the O2 sensor.

I know that the O2 sensors feedback to the ECU controls the A/F , but after my ISC died, chk engine light came on, and I took the car(95 GST) to the dealership. They said that the ISC was bad for months and told me that the ECU was going out because I drove it like that for 2 months. I didn't got an explanation why it would affect the ECU? anybody else knows why?
My gas milage dropped incredibly 17-18MPG only from 22+mpg right after the ISC died, and the guy at the Mitsu dealer said that the ISC also compensates the PS pump, and that is pretty important.
I mentioned that I was running rich because my exhaust was smelling like pure 93 octane gas. I was really worried that I have a gas leak.
No such thing, they didn't find anything wrong with the car at the dealership except the bad ISC, and a bad ball joint.
I changed the ISC with a new one- my gas millage came back to normal , and my exhaust did not smell like gas anymore . weired..
Never had a problem with the car, but I wanted a awd so I sold it.

 

[steve]

my ISC died, chk engine light came on, and I took the car(95 GST) to the dealership. They said that the ISC was bad for months and told me that the ECU was going out because I drove it like that for 2 months. I didn't got an explanation why it would affect the ECU? anybody else knows why?

If the ISC coil windings short, it blows the ISC drivers on the ECU.

Steve