ISC Test Results

[Liger Zero]

OK, I received a link on how to test the resistance in my ISC and did so following it step-by-step and here are the readings I got. I tested both my tan cover and my new black cover one. Here are the Results for each:

The Link: DmTaLoN's Idle Speed Control Test/Fix Page!

Tan Cover

Pins 1-2= 29.8 Ohms
Pins 2-3= 29.8 Ohms
Pins 4-5= 29.8 Ohms
Pins 5-6= 29.8 Ohms

---------------------------

Black Cover

Pins 1-2= 38.5 Ohms
Pins 2-3= 38.5 Ohms
Pins 4-5= 39.0 Ohms
Pins 5-6= 39.0 Ohms

Is the ISC with the black cover supposed to read higher like that? And if so will that mess things up with my ECU reading more Ohms than it was supposed to from factory? Thanks!

 

[illeffekt vr-4]

You should of posted that info in this thread http://www.dsmtuners.com/forums/newbie-forum/314392-isc-issues.html so others on here can help you out better.

Going by the numbers the tan one should work better but you can give the black one a try and see how it goes. Remember to adjust the idle/biss again.

 

[Liger Zero]

Wow, I re-installed the tan one again and boy does it run better! Idles pretty much perfect and where its supposed to be, still gotta redo the BISS, but im guessing I just wasted my money on the black ISC...

 

[nongthep]

i just do mine. NO CEL in my dash, Idles likes it should be, no stall

 

[toddevo]

Wow, I re-installed the tan one again and boy does it run better! Idles pretty much perfect and where its supposed to be, still gotta redo the BISS, but im guessing I just wasted my money on the black ISC...

You should never have to touch the BISS screw ,you mean the SAS or speed adjustment screw .

 

[joyfil2001]

You should never have to touch the BISS screw ,you mean the SAS or speed adjustment screw .

Please don't post false information. The BISS screw needs to be adjusted in conjunction with the ISC to set base idle correctly.

 

[Liger Zero]

Does it take a little while for the ECU to stabilize the idle to where you have the BISS adjusted at? Because when I disable the ECU's control over the idle it idles almost perfect around 800rpm and when I take the ground wires off it jumps up to 1300rpm with the tan ISC and 1500 with the black ISC, am I doing something wrong or does the ECU need time to adjust properly? Thanks!

 

[nongthep]

^^ same question first startup was fine after driving and stop at the redlight samethings happen rpm raise up to 1200-1400 and go down to 700-800rpm. and CEL is on again.. but idle a lot better than before

 

[Liger Zero]

For some reason my CEL doesnt even come on period. Ive unplugged sensors, stalled many times, bought the car with practically no vacuum lines, and still no CEL. My concern is that a 90 ECU which was put in my car from a junkyard isnt the same as what a 92 ECU should be, even after the 2 wires that need switched in the harness.

 

[nongthep]

i did change spark plug 7es and ngk wire and new isc today. will come back and tell the result tomorrow.

 

[SnowBird]

Was the tan one messed up to begin with or was it giving you that same problem of pulling the ground wires and jumping back up? I have the same problem also, Ive been running with my ISC and Idle switch unplugged without any problems, but it bugs me It doesnt work, and Ive also tried 2 different tan ISC's that both test out good. My FIAV is gone also so that cant be a factor. Good luck with it tomorrow, keep us updated.

 

[Liger Zero]

I changed my plugs and wires too, before I even tried this. Good luck for your attempt at this! Things that I found out after I did this was that I have a 1990 ECU and I had to change 2 wires.

Oh, and snowbird, my tan ISC wasnt giving me the same problem, it was actually idle surging very bad and stalling most of the time. When I crossed the 2 ECU wires that solved that problem but now it idles pretty HIGH as stated.^^^

One other thing that I think may be affecting things is that my BOV is striiped out. Its recirculated though. But the screw is stripped out and now I just have a rubber stopper plugging in the hole so there isnt a vacuum leak. Think that may affect my problem???

 

[SnowBird]

I changed my plugs and wires too, before I even tried this. Good luck for your attempt at this! Things that I found out after I did this was that I have a 1990 ECU and I had to change 2 wires.

Oh, and snowbird, my tan ISC wasnt giving me the same problem, it was actually idle surging very bad and stalling most of the time. When I crossed the 2 ECU wires that solved that problem but now it idles pretty HIGH as stated.^^^

One other thing that I think may be affecting things is that my BOV is striiped out. Its recirculated though. But the screw is stripped out and now I just have a rubber stopper plugging in the hole so there isnt a vacuum leak. Think that may affect my problem???

I dont think the BOV is causing it, the leak would be a mechanical problem, and when you unground and have the idle jump up that is electrical. PLUS, I just had my BOV flange on my intercooler pipe rewelded because the flange was so bent that when tightened down I could slide a dime in the gap, and that didnt really cause any idle issues.

What is stripped on your BOV? I would only think the 2 bolts that hold it down, but I dont see how you could plug that with a hose?!?! If it is one of the bolts that indeed hold it down try getting a longer bolt and put a nut at the other end pulling the BOV and flange together, you follow? I would fix that problem because it can only be giving you problems.

Again, if you are ungrounding when setting the BISS and then getting jumpy idle is sounds electrical. I feel ya man, I dicked around with my ISC's for awhile but they got the best of me, that and because I am no wiseman by any means and electrical problems frustrate me. Thats why I just unplugged the damn thing Being here in FL you can always count on the temp being warm, so an idle adjusted straight off the BISS hangs in there pretty good. Best of luck, you are tackling a problem that in the DSM world is, well,

 

[DSM "BISH"]

yes i have also found this out as well. i am in the processs of figuring out what happend to my ecu and one of my isc chips burned out as well as a big round cylinder on my bread board. they told me i need to peplace my isc mostl ikely before getting a new ecu so what happend to my current one dosent happen again. but i have a few questions regarding some of the post in here? i did not know that there was two diffent colors of isc's what is the tan one and what is the black one? like what does the color differnce mean? and what dose CEL mean? sorry for all the questions but i am new to the computer tuning world and would like to figure out what i am looking at .

 

[yokotabrat]

i did not know that there was two diffent colors of isc's what is the tan one and what is the black one? like what does the color differnce mean? and what dose CEL mean? sorry for all the questions but i am new to the computer tuning world and would like to figure out what i am looking at .

There are pictures of both iscs here: DSMISC pictures

The tan one is the older ones found on many DSMs, whereas the new black housing ones are the new ones that Mitsu sells. The coil resistances are different between the two (30 ohms for the tan ones and 40 ohms for the black ones). The thought is that the black ones are more robust and have less of a chance of killing the drivers in the ecu. I've personally seen a few dead black iscs and their coil resistances measured 10 ohms instead of the near 0 that the tan ones tend to measure. This means less of a chance of blowing up the drivers in the ecu, which is always a good thing.

CEL means check engine light.

Hope this helps.

 

[Liger Zero]

I dont think the BOV is causing it, the leak would be a mechanical problem, and when you unground and have the idle jump up that is electrical. PLUS, I just had my BOV flange on my intercooler pipe rewelded because the flange was so bent that when tightened down I could slide a dime in the gap, and that didnt really cause any idle issues.

What is stripped on your BOV? I would only think the 2 bolts that hold it down, but I dont see how you could plug that with a hose?!?! If it is one of the bolts that indeed hold it down try getting a longer bolt and put a nut at the other end pulling the BOV and flange together, you follow? I would fix that problem because it can only be giving you problems.

Again, if you are ungrounding when setting the BISS and then getting jumpy idle is sounds electrical. I feel ya man, I dicked around with my ISC's for awhile but they got the best of me, that and because I am no wiseman by any means and electrical problems frustrate me. Thats why I just unplugged the damn thing Being here in FL you can always count on the temp being warm, so an idle adjusted straight off the BISS hangs in there pretty good. Best of luck, you are tackling a problem that in the DSM world is, well,

Dang man! I wish I lived in FL! Anyways, the screw that is stripped on my BOV which is a Greddy BTW, is the bolt that adjusts the valve, I believe. The one the tightens and loosens it thats located on the top of the BOV. That completely steipped out so the screw wont thread in to hold the valve down and you can hear a continuous hiss when you listen to the BOV on idle. I wish I were a wiseman at this, electrical problems freak me out because at that point it could be anything, bleh. But im hoping I can figure something out.

 

[DSM "BISH"]

agreed liger zero! electrical problemns are big headaches when they come about. im trying to get into them tho like figuring out terms and how to fix things its kinda fun . but anyway thank u yokota brat that did defintly help. i had all black isc drivers in my computer and yes they did burn out. so in theory are the tan ones better then?

 

[steve]

i had all black isc drivers in my computer and yes they did burn out. so in theory are the tan ones better then?

You misunderstand. The drivers are on the ECU board for controling the ISC mounted on the throttle body. All the driver chips are black. The ISC however originally was a cast body with a tan connector and the new version is black plastic.

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[Liger Zero]

agreed liger zero! electrical problemns are big headaches when they come about. im trying to get into them tho like figuring out terms and how to fix things its kinda fun . but anyway thank u yokota brat that did defintly help. i had all black isc drivers in my computer and yes they did burn out. so in theory are the tan ones better then?

Oh I agree whole-heartedly with you! I love figuring stuff out! More than anything, because when you do, you never forget it, ! BUT whats killing me is trying one thing after another and nothing is getting fixed, ! Im running out of ideas and its scaring me, because I dont know what to do next and I think my dad is about to hang me for buying this car and it costing me so much money that I dont have. I bought it under the understanding that it ran great and was reliable, etc. But its turning out to be a challenge to get it back to running "correctly" seeing that whoever the previous owners were pretty seemed like they didnt know what they were doing and screwing up the wiring harness and everything. But I bought this car becasue this is EXACTLY my favorite DSM ever, so I dont mind putting money into it, I just wish I had some, !

 

[nongthep]

we are on same boat. i feel ya pain.