completely trashed ISC

[tsiAWD91x]

(finanly got in the mood to troubleshoot my idel) looks like it got left in the rain for a week WTF WTF.....time for another trip the the yard

 

[tsiAWD91x]

another

 

[kicknurass4fun]

Wow!!! Looks pretty healthy Did you pull the car out of a lake or something? Ive had 3 iscs go bad on me and not one ever even looked close to that. Check to see if you have antifreeze leeking threw the TB and into the ISC.

 

[tsiAWD91x]

nah man i did a block for the TB coolant lines.... its just shitty never been replaced in 160k maybe from before hand when all the emmisoins where hooked up

 

[steve]

You had to have a leak of the seal between the halfs of the throttle body to soak the ISC like that. Or the outer seal failed and it's been pressure washed a few times.

Steve

 

[lil corb]

would a bad ISC click aswell and idle at 2000rpms and surge?

 

[tstkl]

i cant figure out how to get mine opend... i have a bad one i thought i might as well take apart and figure out what went wrong with it, since they all go bad sooo often... maybe theres a cheaper fix...

 

[steve]

The "cheap" fix is to find two with one good coil each and swap a good coil over.
Here's how they come apart. http://www.stealth316.com/2-isc-iac.htm

Steve

 

[tstkl]

The "cheap" fix is to find two with one good coil each and swap a good coil over.
Here's how they come apart. http://www.stealth316.com/2-isc-iac.htm

Steve

it looks like in that pic the fiav allows air into the throttle body, but i know that isnt true,... what does the faiv do with the coolant? and if you re route the coolant likes so they dont go to the throttle body, do you have to block of the ports at the throttle body?

im guessing the isc acts like another throttle body and just allows more or less air in to control the idle speed.. am i right? then you would want 100%tps and 100% isc at wot, wouldnt you?

edit: and that site shows the thing open after the person took the three screws out of the back of the motor... the three screws that do not exist on my motor...how do you open a dsm isc?

 

[ilikespeeding]

I dont think I would have known what that is if you hadn't told me. Then again, I dont alot about cars either...

 

[steve]

it looks like in that pic the fiav allows air into the throttle body, but i know that isnt true,... what does the faiv do with the coolant? and if you re route the coolant likes so they dont go to the throttle body, do you have to block of the ports at the throttle body?

The FIAV is another air bypass in the throttle body. It's used to provide additional air during the warm up of the engine. The coolant circulates around a wax pellet and as the coolant warms up the wax expands? and causes the bypass to close off.
People who just remove the coolant lines to the throttle body without blocking off the FIAV are running with it open all the time.

im guessing the isc acts like another throttle body and just allows more or less air in to control the idle speed.. am i right? then you would want 100%tps and 100% isc at wot, wouldnt you?

If you want to use that analogy, then the FIAV, ISC and BISS are little throttle bodys. They're actually air bypasses around the throttle plate allowing a certain amount of air to reach the cylinders. The ISC is a stepper motor that the ECU uses primarly to manage the idle speed but it does open with the throttle plate so that when the plate closes the ECU can slowly close the ISC and keep the engine from dieing. This is called dashpot emulation.

edit: and that site shows the thing open after the person took the three screws out of the back of the motor... the three screws that do not exist on my motor...how do you open a dsm isc?

I haven't looked at a '90 ISC in a while, the the rest of them before they came out with the new black version were all just like the one in the picture. It's the same part on a 4G63 as it is on a 6G72.

Post a picture of yours.

You guys would really benefit from reading the 1G technical manual that is included on the Manual CD.

Steve

Steve

 

[tstkl]

you mean youve never seen this? your in for a treat... this thing looks like its indistructable, theres no screws or anything... my guess is you have to pry it open, but i havent been successful at that...