Idle Surge, very bad, need help!!!

[xhypno]

Ok here is the problem. On May 6, I bought a 1994 ES Talon with the 2.0l 4g63 motor. It has 65k on it, and is in very good condition. About one week ago, the check engine light went on, and when at an idle the rpms jump about 300-700, and when the clutch is in or when not in gear (slowing down) the same surge appears.
I connected an ohm meter to the data port and came up with a code 43. Which is for the egr system. I tested the thermo valve sensors, all working. I test the vacum to it, good. I figured all that is left is the egr valve. I removed the valve, and it was fauled bad, alot of carbon deposits. I used carb cleaner and a wire brush to clean it. I then vacum checked the valve. It seemed to be working.
At this point I thought every thing should be fine. I put the valve back in and started the car. It was fine. But after a 10 min drive later that day, it started again, but this time with no check engine light.
I have checked every sensor under the hood twice with the ohm meter and still can't find another problem.

Does anyone have a suggestion?????

Any help will be appreciated!!!!! Thank you Philip

 

[nineD5_GS-T]

Originally posted by APEXiD33a
For anyone who has their throttle body coolant lines byapssed u will DEFINETELY get this idle surge if u do not block the FIAV valve. This valve is open until the car warms up, (coolant warms up) , then melts some wax in the valve and then closes the hole to let no air bypass the throttle plate. This is made for cold starts. U dont need it in warm climates, i dont drive my car in the winter so all i did was bypass the coolant lines and use rtv silicon ( u can use jb cold weld too probably will work best) on the holes indicated in the pic thats attached.

Anyone try this yet?

 

[Tal95er]

Hey guys I have been having somewhat of a different problem with my idle, but I think it may be related.

Every once in a while after driving for awhile and stopping the car, going into a store or something, I come back out start it up and the car idles irratically between 500 - 750 and sometimes lower. It like putts and sounds like it is going to die, but once I give it a little gas it is fine or once it is warmed up again. After that I don't have any other problems with the idle, until I turn the car off again and it all happens over again.

Anybody had this tyoe of problem??
Any suggestions would be apprerciated.

Mike

 

[TheLastGr8Car]

I had Idle Surge and was told to adjust the Screw that everyone is talking about. What I found when adjusting screw is it is on a funny spectrum with low idle on one end and high idle on the other (pretty simple). I would adjust it and get it narrowed down to a point where the surge was small but still there. I scratched my head and after a while of messing around I also noticed my BOV had pushed out of it's setting (because I don't have after market upper I/C piping yet) and there was a small, I mean small gap allowing free flowing air into I/C pipe. Once I tightened it back up my idle went up and steadied. That was my fix may or may not work for anyone else.

Semper Fi

 

[98autogstspyder]

Alright I have had a problem with my idle ever since i got the car. I actually took the time to read this whole entire thread. (for me and my attention span i think thats pretty impressive). Anyway... i am just going to sum it up. I have also gotten information from many other threads as well so i will be adding info that was retrieved from other spots in the forum and other forums.

Problem: Idle Surge

Suspects:
- Vacum Leak
Check both gaskets on throttle body
Check vacum line for break booster
Check for any fault that is allowing air past the throttle plate
For anything not mentioned here, doing a boost leak test is a good idea. Once all boost
leaks are eliminated then continue.
- Dirty Throttle Body- Dirt can cause the throttle plate to not close
completely.
- Replace the Fast Idle Air Valve (FIAV). Costs about $140 new.
- Check the cruise control cable to make sure it is not too tight
- Check the BISS, BISS o-ring, fuel pressure solenoid hoses, BOV return hose, egr seal;
- Unplug the Idle Surge Controller (ISC), adjust the BISS and reset the ECU
the ISC is a stepper motor, it does not provide any feedback to the ECU, so the
computer assumes it is working correctly. The ECU will never confirm a
malfunctioning ISC with a ''check engine light'' code.
- A bad exhaust leak can cause this. The mechanic I bought the car from
told me that by me fixing the exhaust leak on my car, it would fix my problem.
I dont fully understand why me fixing this would solve the problem.
- Bad O2 Sensor
- Bad Coolant Sensor
- Bad Throttle position sensor (TPS)-Now I have read in this thread that the TPS is the culprit when the idle surge starts right after you start the car.
- Bad ISC motor- Costs about $220 brand new. I have read that this is the culprit when the car starts to surge after it has been running for a while.
- Bad throttle body seals- There are two seals in the throttle body that get old and need to be replaced after time. The fix is cheap, but digging into throttle bodies isnt the easiest of things.


I have gathered my info from various threads on this site including this one, and these other two sites that are very helpful;

http://www.dsm.org/how-tos/tttt/tttt3.html
http://dmtalon.v8eaters.com/ISC.html


Now here is my situation. I also own a 1992 eagle talon awd 5 speed with 115,000 miles on it. This is the car I am having the problem with. My car will idle at 2500 - 3000 when I first start it. It does not surge then. The car will start to surge after about a minute when the idle is supposed to return to its normal idle. So according to my information listed above, do you think my TPS has gone bad, or my ISC or something else. My car surges from 1100 rpms - 1500 rpms. The car drives great, but only when I go into neutral by pushing the clutch in, or when I am stopped does the idle surge begin. My egr is blocked off, but I dont know if it was done correctly. My car has a pretty bad exhaust leak as well. Also, the four lines on my throttle body are all capped off. I was told that this wouldnt be the cause of the problem. I have alot of things to check, but given my situation what item do you think would be the cause of my particular problem.

FIXED PROBLEM: My fast idle air valve (FIAV) was not working properly. The car apparently thought that the car was always trying to warm up. I discovered this by taking off my upper intercooler piping and throttle body elbow with the car running and plugging my fingers in the holes that lead to the FIAV. The idle went right to 750 after this. I created a block off plate for the FIAV and removed it along with the ISC. I don't recommend doing this if you use your a/c.

 

[cfisher]

I've been having the same problem but I dont' get the high surge. Start up the car, idles perfect but after it warms up is where the problem starts. I will drive up to a light, put the car in neutral and the RPM's drop to 500 or so. The car sputters for a couple seconds and I can smell raw gas fumes. It will then just pop back up to 750 RPM's and everything is fine. It will do this at every stop. I have pulled a CEL recently for "P0141 - Heated Oxygen Sensor Bank 2" & "P0403 EGR which I have blocked off". I also have replaced my ISC with a new one and no change. I can actually unplug the ISC while the engine is running and nothing changes RPM wise.

 

[98autogstspyder]

yea thats a peculiar thing with mine also. i have unplugged it while the car is running and nothing seemed to change. i have even adjusted the biss too while the car is running and it doesnt do anything..... hmmm

 

[Anubis_4_99]

mine has just recently started doing this, although my car will die unless i have my steering wheel slightly turned to the left.. it fall's to about 350, bumps upto almost 1k, goes down and try's to catch and then die's.. i've gone over some of the thing's in this thread and havent found anything to help yet

 

[river]

dont buy a new TPS, just adjust the throttle position sensor using VFAQ's method. either your ISC is working, or its not. the ECU will compensate for idle one way or the other, unless your TPS is off. it cant correct that. your BISS really has almost zero effect, and if you do adjust it, make sure you ground out the appropriate pin w/ the ecu and the piece under the hood also. the ecu will always compensate unless you ground those out. adjust your TPS, you may need a new one, but its doubtful. chances are it just needs to be adjusted.

 

[cfisher]

My TPS reads 0-100% on the SAFC & 3-99% on the logger so I think my TPS is okay. I've also unhooked the ISC from the throttle body and had a friend turn the ign on and off without actually starting the car. It moves in & out like it should so I'm now steering away from an ISC problem.

 

[river]

doesnt matter what your AFC reads. whatever your TPS is adjusted to on the throttle body is going to be set to 0% by the ECU. you followin me? the basline (0) for the ECU is directly linked to where the TPS is set to on the throttle body. follow this vfaq and adjust it.
http://www.plymouthlaser.com/tps.htm
pretty much, if your TPS is adjusted off, your throttle could be 100% open and if the TPS was adjusted w/ your throttle body open at 100%, your ECU would still read it as 0% because its seeing the point at which the TPS is saying "0%" i dont know how to better explain it. replace all the seals in the throttle body too, and make sure you use new gaskets in between the intake and the IC piping. any kind of vaccum leak will cause idle surge also, so check around for those.

 

[boostedsm12684]

What if you only get idle surge when you are moving and not in a gear but coasting??? what the hell causes that????? 1.5k to 1k then back up is what mind does but only when my car is moving and not in gear. someone please e-mail me

[email protected] or PM me on here with what I should do please

 

[xantblazex]

I have a very related but slightly different situation.

My car starts two different ways. Depending how the car starts, brings two different immediate performance situations.

Sometimes i start my car and it the RPMs start high between 1.5-2000 RPM and slowly come down to slightly above 1090 RPM idle. When the car starts like this, I get perfect driving results.

Sometimes i starrt my car and the RPMS will either struggle to reach 1000 RPM or it will hit 1000 RPM and immediately drop back to zero forcing me to restart the car. Regardless, in any of these 2 conditions, my car will start moving but immediately stall as soon as i hit the clutch and put the car in neutral. The RPMs wont hold, forcing me to constantly lose my power steering and either restart the cart by forcing clutch / rolling start to reactivate the car, or by restarting it by turning ignition. Usually after 4-5 minutes of stalling, the car will jump back into groove.

I know you can understand my concern. It is not fun driving a car when it is constantly stalling out for 4-5 minutes. And I also fear I am straining the starter.

I suspect it is the vaccum lines. Anyone ever face a similar situation?

 

[98autogstspyder]

What if you only get idle surge when you are moving and not in a gear but coasting??? what the hell causes that????? 1.5k to 1k then back up is what mind does but only when my car is moving and not in gear. someone please e-mail me

[email protected] or PM me on here with what I should do please

mine does it whether i am moving or not. But when i put the clutch in when im moving it does the surging pretty bad. I tested my isc today and it read b/w 28 and 33 ohms. I am going to check for leaks and tps soon....

I think this thread has more than enough information in it. Don't ask for anymore advice unless you have tried all of the above first.

 

[EcLiPsE-BoY]

this is justa mere suggestion, On my 2.0 non turbo I encounterd idle problems. It would idle very high or way too low 1200-500. I changed plugs wires, It didn't seem to do much but make it worse...hmmm scratching my head... I called nappa picked up a new coil....to no avail it ran like new, and idled properly again all was fixed as far as the[4g63t] eagle talon idling at 2k Dsm member Intact TsI had this problem with his 95 talon tsi AWD and was discusing with me how he seem to have solved the problem. If you guys have a minute message him and get his low down on how he corrected this problem...

 

[Calmor]

I've been fighting an idle demon on a '90 Talon 2.0 non-turbo. It was surging like crazy when we bought the thing, and I figured it would be a relatively easy fix. I was quite mistaken.

Symptoms:

With the idle switch unplugged, the car idled around 2000 RPM. Since fuel cutoff happens at 1500 RPM when the idle switch is activated, the idle would surge badly.

Attempts at a cure:

I blocked off the EGR valve, to no avail.

After pulling the ISC and turning the key on/off with the ISC out, I noticed that sometimes it would just vibrate instead of move. I changed the ISC and cleaned the throttle body with a dry rag. Unfortunately, I couldn't find a '90 specific ISC, and the idle speed actually increased to about 2200. I believe this could have been caused by the cleaning because I run into this again later.

I blocked off the FIAV and disconnected the coolant lines from the TB. No change.

I changed the oring on the BISS. No change.

I cleaned the throttle body with cleaner, and the idle was up to 3000 RPM. I then readjusted the throttle plate to close more (but not completely, leaving a very small gap), and the idle is back down to 2000 RPM.

I've checked the vacuum lines over and all seems to be in order. I pulled the air intake hose and put my finger over the hole that the ISC/FIAV pulls the air from (with the BISS closed completely) and the engine dies slowly (a tiny bit of air is still entering through the butterfly). With this hole blocked off, the BISS opened up some, and the air intake hose reconnected (for the MAF sensor's sake), the engine will idle at 750 RPM all day long... but bypassing the ISC means that it'll stall every time it returns to idle.

I also put my hand over the throttle plate and the engine dies almost immediately, with a large amount of vacuum holding my hand to the plate even after the engine stalled, so I've ruled out an intake leak or large vacuum leak. The fact that it dies with my finger over the ISC air intake hole leads me to believe that the ISC is not sealing properly with the throttle body and allowing large amounts of air into the engine.

The '90 non-turbo throttle body is nothing like all of the pictures of the turbo parts I've seen or even the '91 non-turbos. It's definitely not like my '95 GSX's TB, so finding parts seems to be difficult. If I do find another TB, which ones will bolt up without much problem? Also, does anyone have any suggestions on the modification of the existing TB to restrict the air passage around the IAC?

 

[honduraneclipse]

I've been fighting an idle demon on a '90 Talon 2.0 non-turbo. It was surging like crazy when we bought the thing, and I figured it would be a relatively easy fix. I was quite mistaken.

Symptoms:

With the idle switch unplugged, the car idled around 2000 RPM. Since fuel cutoff happens at 1500 RPM when the idle switch is activated, the idle would surge badly.

Attempts at a cure:

I blocked off the EGR valve, to no avail.

After pulling the ISC and turning the key on/off with the ISC out, I noticed that sometimes it would just vibrate instead of move. I changed the ISC and cleaned the throttle body with a dry rag. Unfortunately, I couldn't find a '90 specific ISC, and the idle speed actually increased to about 2200. I believe this could have been caused by the cleaning because I run into this again later.

I blocked off the FIAV and disconnected the coolant lines from the TB. No change.

I changed the oring on the BISS. No change.

I cleaned the throttle body with cleaner, and the idle was up to 3000 RPM. I then readjusted the throttle plate to close more (but not completely, leaving a very small gap), and the idle is back down to 2000 RPM.

I've checked the vacuum lines over and all seems to be in order. I pulled the air intake hose and put my finger over the hole that the ISC/FIAV pulls the air from (with the BISS closed completely) and the engine dies slowly (a tiny bit of air is still entering through the butterfly). With this hole blocked off, the BISS opened up some, and the air intake hose reconnected (for the MAF sensor's sake), the engine will idle at 750 RPM all day long... but bypassing the ISC means that it'll stall every time it returns to idle.

I also put my hand over the throttle plate and the engine dies almost immediately, with a large amount of vacuum holding my hand to the plate even after the engine stalled, so I've ruled out an intake leak or large vacuum leak. The fact that it dies with my finger over the ISC air intake hole leads me to believe that the ISC is not sealing properly with the throttle body and allowing large amounts of air into the engine.

The '90 non-turbo throttle body is nothing like all of the pictures of the turbo parts I've seen or even the '91 non-turbos. It's definitely not like my '95 GSX's TB, so finding parts seems to be difficult. If I do find another TB, which ones will bolt up without much problem? Also, does anyone have any suggestions on the modification of the existing TB to restrict the air passage around the IAC?

I SOLVED YOUR PROBLEM ! its your ECU check for leaking caps that would cause horrible surge

 

[Calmor]

After a bit more playing with the throttle body, I finally got it to idle under 1250 (required emissions inspection limit in PA). I sealed up the ISC a little better, figuring that having the wrong model ISC in it was causing some problem with how it seals against the throttle body. I also RTV'd the rubber gasket on the bottom plate (similar to the gasket between the upper and lower halves of a later throttle body) to ensure air wasn't leaking straight over. The BISS is now backed out some (instead of all the way tight and still idling too fast) and the car idles lower.

Now the problem is that it doesn't seem to be able to pick where it wants to idle. It doesn't "surge" per se. Sometimes on a hot start, it'll barely stay running, sputtering at 500. Sometimes it'll idle at 1200. I've blocked off the FIAV, and this morning when I started it, I held my foot on the throttle to start and warm it up, and it didn't fall under 1500 even after it was warm... until the next warm start, when it ran at 750 for a while.

I probably should check the ECU and see what kind of capacitor issues it's having. My only other remaining factor is setting the TPS. I'll go search the threads to find what I'm looking for... thanks for the suggestion.

 

[graf703]

So... My surge started like this. Failed ISC motor was having car die out between shifts. Replaced it for 1/4 what I spent on the engine w/ the turbo. A few months later on a really hot/humid day it starts idling at 1500 intermittently (sp?) when its warmed up completely. It is still intermittent but it will make it up to 2500 rpms, really hard to deal with in parking ramps.

I don't hear any exhaust leaks. The ISC is less than 6 months old. I've heard somewhere else that the ISC may not be seated properly... I am in school and won't have time to do anything till the weekend, but I am going to just try resetting the ecu/reinstalling the ISC. The throttle body is pretty clean.

As long as i don't have to buy a new ISC I'm happy!

 

[graf703]

UPDATE....

I unplugged the ISC and the idle didn't change... I then drove around with the ISC unplugged and the car started to bog/almost die. At Idle with ISC unplugged it is running pretty rich (stings the eyes). Anyone able to speculate what this might mean?

In any case I'm trying the old tried and true reset the ECU! I'll let ya'll know if it works.

 

[98autogstspyder]

What makes you think your problem is related to the ISC. I would say more times than not the ISC has nothing to do with idle surge problems. Did you see the checklist I posted earlier on this thread?

 

[graf703]

Fear, and reading some other people's threads who changed the isc and it fixed the problem. Old TB is coming this weekend so i'll confirm if it was the fiav or not! Thanks!

 

[graf703]

SO I fixed mine by changing the tb to my spare.... but the spare had a monster boost leak out of a coolant hose. So I changed back... However, in the operation I realized the tb plate was actually bumping open... unplugging the cruise control helped a lot. Then I switched back to the old tb that has surge. Loosend the cruise control and wallah (sp?) good luck with yours!!!!

 

[mac 108]

Ok I just bought a 1992 Talon TSi AWD automatic with 105k miles on it. The only problem is idle surge when it is in park or neutral.

When it is in Drive or Reverse, no problem, the idle is a little high at 1000, but that can be adjusted by screwing in the idle adjustment screw. However, when the car is in park or neutral, the car idles over 1000 and surges up and down between 1000 and 2500 like I am tapping the gas pedal. Once you turn the A/C on, the problem goes away and the idle goes down to the normal 1000.

The only mod on the engine is a manual boost controller.

 

[1gnasty]

aic sensor myth be bad

 

[SomeblackGUY-RS]

I have 91 N/t laser with this this horrible surge sickness .i was wondering if someone can simply put a check list in order for me.

I think it should go...
-clean throttle body
-check TB gap
-TB sensor
-check ISC screw
-O2 sensor
-vacum leaks

would this be good for my first couple steps to fixing this.