DSMTalk Forums: Mitsubishi Eclipse, Plymouth Laser, and Eagle Talon Forum banner
Cancel
Create thread New Garage Forums

FIAV - ISC block off question.

3 reading
Jump to Latest
41 - 59 of 59 Posts
Discussion starter · #41 ·
Nothing but a bit of time with a torch to warm things up if frozen. Haha, jk lol. Since this thread is about sensors... Got a stupid question. The knock sensor, what is it? Is it what I think it is? What would happen if it were to go bad? Just curious.

And well, my FIAV is blocked and haven't had any issues. Other then the ISC being old, but ya, no problems here. I'm getting ready to order a DSM link, with a few other good things
 
#42 ·
The knock sensor detects knock and ping, if it goes bad to the point where it sets a code (very uncommon) the your car will barely get out of its own way and run worse than a non turbo model, if it fails partially (like most do) the sensor will become overly sensitive and the car will run good sometimes and other times barely be able to get out of its own way.
 
Save
Reply Quote Like Like
#45 ·
Returning to the topic... My 94' Talon DL has a bad ISC and im about to make a block off plate for it... As i am 16 and dont have a job yet I cannot afford $200 to go to the devil... Also I have a headgasket and timing belts to change (All those parts dont even equal an ISC price). Now my question is, when I removed my ISC from my car I only removed it because it was broken, It appears as if it had actually broken off from the base... I think it melted but it looks very strange. Pictures included. So when I block the ISC off is there anyway to run a switch to increase the idle at cold starts such as purge silenoids and stuff? I dont mind feathering the throttle at cold starts but id rather have the simplicity of just toggling a switch to increase the RPMs +250 then bring them back down when I turn it off? I am running AC, power steering, and a possibly shorted alternator causing my car to die from the load. Because when its just sitting there it idles just find but turn the fan on and RPMs shoot down sometimes killing it. :dunno:
 

Attachments

#46 ·
The isc is what controls the idle electronically and is the only thing that controls the idle speed that way, so a switch wouldnt be able to be implemented.
 
Save
Reply Quote Like Like
Discussion starter · #48 · (Edited)
A new problem arose for me also. Changed the ISC with a new one, and before I changed it, my car was idling at a steady 2k.. And now, with the new ISC its idling at a steady 1,500 rpm... Not really sure whats causing it, might be something with my TB. Went to adjust the BISS and well, come to find out there is nothing in there but what looks to be the remains of the screw lol, good o'll DSM :) Haven't even looked at the BISS till now... The question rises though.. How was it idling at around 850 rpm before? vacuum leak?

I'm going to get a DSM link for it soon, will that also be a tool for me to use to better pin point stuff going bad, sensors?

Come to think of it, it still has the stock maft sensor, and the cone filter on it was bad, so I took it off and have no filter on it now.. could that be the issue?
 
Discussion starter · #49 ·
Also, if I was you I'd remove the AC and Power steering.

Katz said:
Returning to the topic... My 94' Talon DL has a bad ISC and im about to make a block off plate for it... As i am 16 and dont have a job yet I cannot afford $200 to go to the devil... Also I have a headgasket and timing belts to change (All those parts dont even equal an ISC price). Now my question is, when I removed my ISC from my car I only removed it because it was broken, It appears as if it had actually broken off from the base... I think it melted but it looks very strange. Pictures included. So when I block the ISC off is there anyway to run a switch to increase the idle at cold starts such as purge silenoids and stuff? I dont mind feathering the throttle at cold starts but id rather have the simplicity of just toggling a switch to increase the RPMs +250 then bring them back down when I turn it off? I am running AC, power steering, and a possibly shorted alternator causing my car to die from the load. Because when its just sitting there it idles just find but turn the fan on and RPMs shoot down sometimes killing it. :dunno:
Click to expand...
 
Discussion starter · #51 ·
BISHILVR said:
Disconnect your battery for a few minutes to reset the ecu.
Click to expand...
Tried it, didn't seem to work.. Had the battery unplugged for a good 5 - 6 minutes. When its idling, there are times where it acts like it wants to be brought down to normal idle, but just stays at a steady 1,500 rpm... I'm thinking about rebuilding my TB
 
#52 · (Edited)
Jed1991 said:
Also, if I was you I'd remove the AC and Power steering.
Click to expand...
#1 I live in Texas.
#2 Father figure thinks Power steering is a must. As he is getting older and cant drive without unassisted steering. Yet he still demands to drive my car. :confused:


Also air filter is required for proper measurments and to prevent your car from leaning out, and basically your turning your cars piston walls into sand paper with the dirt and such.

Did you verify that you set the ISC properly? Does unscrewing the throttle stop any help? Could even be a stuck throttle who knows check cable tension and verify full closing of throttle. Might even test the Throttle position sensor.

I will load how to set the ISC if you dont know how. If you replace it you have to set the computer to "sync" with the ISC.
 
Discussion starter · #53 ·
Katz said:
#1 I live in Texas.
#2 Father figure thinks Power steering is a must. As he is getting older and cant drive without unassisted steering. Yet he still demands to drive my car. :confused:


Also air filter is required for proper measurments and to prevent your car from leaning out, and basically your turning your cars piston walls into sand paper with the dirt and such.

Did you verify that you set the ISC properly? Does unscrewing the throttle stop any help? Could even be a stuck throttle who knows check cable tension and verify full closing of throttle. Might even test the Throttle position sensor.

I will load how to set the ISC if you dont know how. If you replace it you have to set the computer to "sync" with the ISC.
Click to expand...
hmm, well I think I have a combination of things going wrong. The ISC before I changed it with a new one I think is the original sensor that came with the car being built, so I'm pretty sure the sensors are needing to be changed. I'm thinking about sending my TB to be rebuilt at TMZperformance since my BISS screw is shot, I can only see what looks to be the remainders of the screw, and can see the O ring at the bottom. So with that, I'm pretty sure it wouldn't hurt to have it all rebuilt.

Not sure how to sync it though
 
#54 ·
After changing you ISC you should adjust your base idle speed as per FSM, resetting the ECU or just adjusting the screw on top of the TB just without telling your ECU you are doing it will just screw it up even more. I am talking stock conditions anyway (stock ECU and ISC). About the FIAV, when new it actually works pretty well doing what it is supposed to do, that is providing some additional air to the engine after a cold start. When the wax inside the FIAV expands it pushes a plunger sealing the additional air passage shut. What happens with time (and we are talking years) is that whatever pollutant passing through the TB (i.e. sludge from VC ventilation clogs the air passage making it impossible for the plunger to seal properly. Thus blocking the FIAV makes the idle better even though I would expect you have to increase the RPM a bit to compensate at cold start. When I had this problem I went the unconventional way, I opened the FIAV and cleaned it (not using any chemical in order not to contaminate the wax in the FIAV). After 7 years the cars still idles perfect at 750 without a glitch. Sorry for the long post. Before anybody flames at me :tat: please understand that I am talking pure stock setting meaning climbing in the car in a freezing morning in NJ, start the car, go back and have breakfast while the car is warming up without keeping my foot (or a very heavy paperweight) on the gas pedal :)
 
Discussion starter · #55 ·
serviceguy said:
After changing you ISC you should adjust your base idle speed as per FSM, resetting the ECU or just adjusting the screw on top of the TB just without telling your ECU you are doing it will just screw it up even more. I am talking stock conditions anyway (stock ECU and ISC). About the FIAV, when new it actually works pretty well doing what it is supposed to do, that is providing some additional air to the engine after a cold start. When the wax inside the FIAV expands it pushes a plunger sealing the additional air passage shut. What happens with time (and we are talking years) is that whatever pollutant passing through the TB (i.e. sludge from VC ventilation clogs the air passage making it impossible for the plunger to seal properly. Thus blocking the FIAV makes the idle better even though I would expect you have to increase the RPM a bit to compensate at cold start. When I had this problem I went the unconventional way, I opened the FIAV and cleaned it (not using any chemical in order not to contaminate the wax in the FIAV). After 7 years the cars still idles perfect at 750 without a glitch. Sorry for the long post. Before anybody flames at me :tat: please understand that I am talking pure stock setting meaning climbing in the car in a freezing morning in NJ, start the car, go back and have breakfast while the car is warming up without keeping my foot (or a very heavy paperweight) on the gas pedal :)
Click to expand...
Ya, my car is 18 years old, and well, I highly doubt my TB has been rebuilt during that time frame lol so I'm pretty sure it needs some attention. Like I said, I have a combination of things going wrong I'm sure. Once its rebuilt and everything is fixed on it, then I'm sure things will calm down for the time being. Will help a lot when I get a DSM link also
 
#56 ·
serviceguy said:
After changing you ISC you should adjust your base idle speed as per FSM, resetting the ECU or just adjusting the screw on top of the TB just without telling your ECU you are doing it will just screw it up even more. I am talking stock conditions anyway (stock ECU and ISC).
Click to expand...
That's not exactly accurate. The ECU knows what it wants to idle at, and adjusting the BISS when it's idling high becaue of improper adjustment (or it missing in this case) will allow it to reach that target idle RPM. In this case, you'd screw the BISS down until target idle was reached, and a bit more (though at that point you'd want to enter the proper BISS set mode if you hadn't already).
 
Discussion starter · #58 ·
Ya, I can tell that the ECU is wanting to bring the rpm's down, but something is keeping it from getting the job done. Will do me good to overhaul my TB, and actually have a BISS screw that works lol
 
#59 ·
Absit said:
That's not exactly accurate. The ECU knows what it wants to idle at, and adjusting the BISS when it's idling high becaue of improper adjustment (or it missing in this case) will allow it to reach that target idle RPM. In this case, you'd screw the BISS down until target idle was reached, and a bit more (though at that point you'd want to enter the proper BISS set mode if you hadn't already).
Click to expand...
What I was trying to say is that the ECU 'needs' to know when you are adjusting the BISS (I couldn't be bother to look up the name, thank you) in order to set the ISC to a specific known position. This is accomplished using a jumper on the proper connector (whose name now I don't remember, it's basic Vfq.com material or FSM anyaway). Yes you can fix it just adjusting the BISS but it will be a guesstimate because you wouldn't know exactly where the ECU wants the idle to be and where the ISC is right there and then. Kind of a moving target to use a simplified example, you can keep shooting at the same place hoping your target will go back to and get hit it :tat: or you can have somebody holding it still for you and make a sure kill!
Anyway, if your idle is erratic that means that you're out of the compensation range of your ECU or it would adjust the ISC enough to see the 750 RPM (or wathever you set the idle speed to), as the ECU knows what the RPM is and wher it wants it.

Houch, my brain is smoking now, too much thinking!
 
41 - 59 of 59 Posts
About this Discussion
58 Replies
11 Participants
Last post:
serviceguy
DSMTalk Forums: Mitsubishi Eclipse, Plymouth Laser, and Eagle Talon Forum
posts
2.3M
members
104K
Since
2000
A forum community dedicated to Mitsubishi Eclipse, Plymouth Laser and Eagle Talon owners and enthusiasts. Come join the discussion about performance, turbos, builds, modifications, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
General DSM Tech and Tuning Help! Tech Newbie Questions Forum Body Tech and Appearance Electronics Tech