DSMTalk Forums: Mitsubishi Eclipse, Plymouth Laser, and Eagle Talon Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
1,318 Posts
Discussion Starter #1
I have had idle surge for a while, here is what ive checked and what not. I checked my ISC 1-2 is 30ohm 2-3 is no connection, 4-5 is 30 and 5-6 is 30, and i have another tb laying around that has an isc that was supposed to be working fine, and it measures identical.

If i floor the car all the way up to 80-90 or so alot of the times the idle surge stops.

If i turn on my AC the surge stops and idle slowly comes back down to normal most of the time, it at least stops it from surging and will just hover at like 1800rpm or around there, every once in a while it will idle surge with AC on but only rarely.

I havent cleaned my TB and i checked alot of the vacuum lines up top and none of them seemd to impact the idle.

I was getting a p1400 which is a manifold differential presure sensor or something, i believe its like a map sensor. I dont know if this could cause it, where it is or anything about it.

Based on this anyone have any good suggestions thanks!
 

·
Honorary Administrator
Joined
·
4,869 Posts
Your open circuit between pins 2 and 3 is a dead coil in your ISC. You should have about 30 ohms for 1-2, 2-3, 4-5, 5-6. I had the same issue, one coil failed. It's also important to measure it at operating temp too, I've seen them where the ISC tests fine cold but has an open coil when the motor is up to temp.
 

·
Registered
Joined
·
30 Posts
I had the same problem whe I bought my 91. Cleaning the TB did nothing, adjusting the TPS helped a little, but getting new coils for the ISC really did the trick.

I set the idle to spec, then the damn thing nearly died every time I turned on the AC! I raised the idle to spec with the AC on, then it would surge from 1200-1500 when the AC was off.

I headed down to the local boneyard and found a 2.0 ISC. I brought my digital multimeter with me (indispenseable!), made sure I had good resistance results and tore out the little coils. The ISC as a whole would have been about $10-15, but just the 2 coils was ~$1. I got home, opened up my original ISC, made sure which leads were which and was a-soldering away.

While I was at it, I calibrated the TPS, cleaned the TB and made sure to seal the connection to the manifold well. Has been great ever since. Rock steady at 750 rpm!
:D
 

·
Registered
Joined
·
1,318 Posts
Discussion Starter #5
so could i open up the isc and pull out one of the coils and use that on the other one? could i use like a 1-2 coil on the 2-3...cuz i got 2 that both have the 2-3 dead. I cant get it off right now the screw is so tight so i ahvent had a chance to look inside and see what it looks like.
 

·
Registered
Joined
·
1,318 Posts
Discussion Starter #6
oh well i just read the vfaq on testing and he said theres 2 coils inside one for the top one for the bottom and each of those has 2 coils in it, and they are the same thing so i could take the bottom coil off the one i have and put it in as the top coil on the other and taht would make the 1-2 and 2-3 work. I just dont know how hard it is to put it in and what not.
 

·
Registered
Joined
·
1,318 Posts
Discussion Starter #7
I pulled out one coil from one isc and put it in place of the bad one in the other and did a super horrible solder job but hey it works! i tested all the pins and they are all 30 ohms and the car is running great....YAY
 
1 - 7 of 7 Posts
Top