1G Revs Dropping off?

[xxShaneOmac]

Revs Dropping off?
After driving for 10 mins and once my car is fully warmed up I get trouble.

I can stop and rev to 3k and hold it there and then it will just drop to 1000 and then 1200 and then 2k and just drop and come back up. Its really spratic will do it once then good for 10 seconds. Will do it 5 times back to back.

This all happens when im driving, starting from a stop and out of no where my rpms will just drop super low Ill about to die. If im bearing giving it gas and trying to keep a constant speed I start to jerk back and forth. And at a stop my rpms start to fluxuate 200 rpms lower then bounce back up..

Replace plugs / wires / fuel fitler / oil / coolent flush and check my throttle plate it moved freely.

What else could I do?
MAF TPS ISC FIAV ??


1993 NT Talon 4G63

 

[brassc2007]

Does it do it when you are just sitting there idling?# The idle speed control is a known problem for the 4g63 motor.# Test it and see what you get for a reading.

 

[xxShaneOmac]

After the car is warm key point. When its cold it runs PERFECT

But after its fully warmed, When I stop and just idle, It bounces a few hundered down and the jumps back up.

O2 Sensor going out?

 

[91TsiTalon]

Check the ECU. And does it change when the A/C is on or off?

 

[brassc2007]

Remove the connector to the ISC There are six pins on the ISC. They are labeled 1 2 3 across the top and 4 5 6 across the bottom. (see left)

Measure the Resistance between pin's 1-2, 2-3, 4-5, and 5-6
Each pair of pins measured should read 28-33 Ohms
Note: The values should measured with the car off and cool!
If any of the "coils" (which is what you're testing) are bad then your ISC needs to be replaced
If all the coils were good there's one other thing to check on the ISC


Use a 6volt battery (lantern or camera battery) and apply 6 volts to the ISC motor.
Use jumper wires to connect the positive (+) terminal of the battery to terminals 2 and 5 of the ISC and the negative battery terminal to terminals 3 and 6 of the ISC.
If there is no movement or vibration from the motor, then it is bad
Note: The use of a 12volt battery will destroy the ISC motor!!



I assume no credit or ownership for these instructions and picture.

 

[xxShaneOmac]

Everytime I touch some sort of power my rpms drop.

Lights
AC
Heater
Break
Cd Player turns on

My rpms drop 50 or so each thing I do
Whats this?!

 

[brassc2007]

It sounds like your running short on power. Start the car then disconnect the negative battery terminal, the car should stay running if the alternator is putting out full amperage to recharge the battery. If the car dies replace your alternator.

 

[crimsondragon]

VFAQ Site - Visual Frequently Answered Questions -->intake --->anything on idle surge and ISC

 

[xxShaneOmac]

I unplugged my ISC while my car was doing its little iddle surge drop to were it starts to die then jumps back up.

And nothing, nothing happens to RPMs when the ISC is unpluged.

 

[tqmx1]

What are you trying to run for your idle speed? The idle speed should be 750 +/-100. The high idle speed of 1200 the ECU will fuel cut it and drop it back to 1000 where the fuel cuts back in and back to 1200. If thats the case run your BISS in a turn or two and try it again.

 

[xxShaneOmac]

I want 750 +/- 100 and When the car is cold its right on the dot of 800.

Once it warms up it Drops, Dosnt surge cause it wont go past 800 just drops down to 500 chokes and comes back up.

When I unplug my ISC. the cars Revs do not change one bit. Is that normal? shouldnt they go up when I unplug my ISC

 

[crimsondragon]

Did you bother checking the ISC if it's gone bad? I would look into that.

 

[xxShaneOmac]

I dont have a OHM meter.
Not very electronicly wire gifted.

Should this be the time I start to take this up?
Could an ISC be my problem,
Would I have to test it when the car is warm or would it show problems at cold temp 2?

 

[crimsondragon]

Go back to Vfaqs, look under intake and find the ISC test article. Also read the article Idle Surge by Terry. Read all of it to gain a better understanding of your throttlebody, ISC, FIAV, and EGR. Yes your ISC could be a problem otherwise I wouldn't sugest it in the first place.

 

[tqmx1]

I want 750 +/- 100 and When the car is cold its right on the dot of 800.

Once it warms up it Drops, Dosnt surge cause it wont go past 800 just drops down to 500 chokes and comes back up.

When I unplug my ISC. the cars Revs do not change one bit. Is that normal? shouldnt they go up when I unplug my ISC

OK in that case the Oring on the BISS screw has shrunk and let the ajuster screw it self in. The cold idle should be up about about 1200RPMs and then when warmed up should drop back to the 750 range.

Just to check unscrew the BISS a couple of turns and try it.

 

[xxShaneOmac]

OK in that case the Oring on the BISS screw has shrunk and let the ajuster screw it self in. The cold idle should be up about about 1200RPMs and then when warmed up should drop back to the 750 range.

Just to check unscrew the BISS a couple of turns and try it.

So your saying If I unplug my ISC when the Car is warm it should idle at the 750 area? Should It be dropping revs at all?

And If I unplyg my ISC when the car is Cold I will jump up to 1200.

Correct?


And I just tested the ISC, Wierd I got a reading of like 1.8 ohms for them.
I followed DmTaLoN's Idle Speed Control Test/Fix Page! What??
If I touched 1 and 4 It wouldnt register but when I touched 1-2 I got 1.8 ohms etc though all 6 coils.

 

[tqmx1]

No I am saying leave the ICS alone and reajust the BISS. Lefty loosey back it out a few turns and it should rase the idle. If it does go down to your local and pick up a new Oring and reset the idle.

 

[xxShaneOmac]

Pulled the ECU, Looks good to me besides one little part, it looks like glue on a cap thingy and its hard but Im not sure. Picture one

http://img167.imageshack.us/img167/4676/img1170fh5.jpg
http://img352.imageshack.us/img352/2879/img1171gi1.jpg
http://img168.imageshack.us/img168/9281/img1172xg7.jpg
http://img168.imageshack.us/img168/2760/img1173nt0.jpg
http://img168.imageshack.us/img168/5884/img1174bh0.jpg
http://img352.imageshack.us/img352/3503/img1175ty9.jpg
http://img352.imageshack.us/img352/4886/img1176hk4.jpg

Everything look ok on the ECU?

This is the OHM Reader I was useing and the settings.
Was registrying to the right of 2 appx 1.8.
This is 1.8 ohms not 1800 correct?
BTW ECU was out of the car, would this have any effect on the reading?

http://img301.imageshack.us/img301/638/img1179uz9.jpg
http://img183.imageshack.us/img183/2139/img1177mc9.jpg

 

[xxShaneOmac]

No I am saying leave the ICS alone and reajust the BISS. Lefty loosey back it out a few turns and it should rase the idle. If it does go down to your local and pick up a new Oring and reset the idle.

Just to go over
From a cold start I started the car it landed at about 1100 rpms and I pulled the ISC and nothing happend. OK.

Then I attached the ISC back on and I lefty the biss out appx 4 turns. Each time the RPMs climbed for 2 seconds then went back down to 1100 rpms.

I could not get it to climb rpms and stay at that rpm.

And
Retested ISC w/ the ECU in, Same results.

 

[tqmx1]

OK now let it come up to temp and let the FAIV close and the idle should come back down. Once every thing has stabelized at normal opperating temp then check the RPMs.

 

[crimsondragon]

So your saying If I unplug my ISC when the Car is warm it should idle at the 750 area? Should It be dropping revs at all?

And If I unplyg my ISC when the car is Cold I will jump up to 1200.

Correct?


And I just tested the ISC, Wierd I got a reading of like 1.8 ohms for them.
I followed DmTaLoN's Idle Speed Control Test/Fix Page! What??
If I touched 1 and 4 It wouldnt register but when I touched 1-2 I got 1.8 ohms etc though all 6 coils.

You're not supposed to touch pin 1 and 4 together. it's 1-2, 2-3, 3-4, 4-5, and 5-6. Either you did it wrong or your ISC is totally FUBARed. Should get a reading of 28-30 ohms as state in the guide. Do it again just to be sure.

 

[xxShaneOmac]

Ive tested the ISC 4 or 5 times. Im thinking its FUBAR, when I unplug it, my idle dosnt change, Acording to the link you gave me it should go up to 1200 ish rpms and hold steady.

If you can look at the pictures and verify that Im reading it right with the right settings.

And once my car was fully warmed I idle at 1200 now surging up to 1500 after I backed out my BISS.
So this means I need a new one correct tqmx1?

 

[tqmx1]

If it's up to 1200+ with the engine up to normal opperating temp slowly screw the BISS back in. Go one turn let the engine stabelize for at least 30sec. and then take it in another turn until you get it in the 750rpm range. When you get close your ajustments will be down to 1/2turn or less.

The factory way to check the idle speed is.

Run the engine for more than 5sec. at a engine speed of 2000/3000RPMs

Run the engine at idle for 2 min.

At that point check the idle speed ( it should be between 750 +- 100RPMs)

 

[xxShaneOmac]

If it's up to 1200+ with the engine up to normal opperating temp slowly screw the BISS back in. Go one turn let the engine stabelize for at least 30sec. and then take it in another turn until you get it in the 750rpm range. When you get close your ajustments will be down to 1/2turn or less.

The factory way to check the idle speed is.

Run the engine for more than 5sec. at a engine speed of 2000/3000RPMs

Run the engine at idle for 2 min.

At that point check the idle speed ( it should be between 750 +- 100RPMs)

Ok Ill do this
My idle is fine untill It gets Hott then it drops 150 rpms and back up to normal.
Ill def order an new biss and oring.

Back to the bucking and my ISC ohm readings
What else can I do to figure this all out?

 

[crimsondragon]

Go to the junkyard and find a spare ISC. Test it to be sure it's working and put it on your car. Brand new ones from Satan are too pricey.