Very bad idle after cleaning IVC and TB.

[Fappas]

Hi. I recently cleaned the IVC and TB on my 1995 E36 316i with brake cleaner.

After putting everything back together the car has a very rough idle. When I start up it idles at 1500 – 2000rpm. The idling changes during driving. Sometimes it idles as low as 500rpm and feels like it wants to cut out and sometimes it just cuts out when I take my foot off the accelerator (not very often though). Sometimes it actually idle at the correct 1000rpm but then when i switch the car off and start again its back to 2000rpm. The idling also jumps up and down sometimes.

I’ve checked all the hoses and there doesn’t seem to be any air leaks.

Any ideas what the problem might be? Any help is appreciated.

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Hi. I recently cleaned the IVC and TB on my 1995 E36 316i with brake cleaner.

After putting everything back together the car has a very rough idle. When I start up it idles at 1500 – 2000rpm. The idling changes during driving. Sometimes it idles as low as 500rpm and feels like it wants to cut out and sometimes it just cuts out when I take my foot off the accelerator (not very often though). Sometimes it actually idle at the correct 1000rpm but then when i switch the car off and start again its back to 2000rpm. The idling also jumps up and down sometimes.

I’ve checked all the hoses and there doesn’t seem to be any air leaks.

Any ideas what the problem might be? Any help is appreciated.

Sorry I meant to say "ICV"

 

[GPGrobler]

If the idle jumps up and down, there has to be an air leak. Any other members know how far advanced the E36 ECU is where "learning" new settings are concerned? Someone tampered with the screw on my E30's TB keeping the car idling with air passing through the TB instead of the ICV, after I corrected the settings, the car took a day or two to adjust itself and idle normally again.

This makes me think that the old Bosch ECU's does have a limited "learning" ability.

 

[Spiro]

Brake Cleaner is a NO NO... u supposed to use Throttle Body Cleaner

 

[GPGrobler]

1995 E36, Please let me know if it is the M40 8 valve engine?

 

[Fappas]

Brake Cleaner is a NO NO... u supposed to use Throttle Body Cleaner

Thanks. I looked for throttle body cleaner but couldn't find any shops that sell it. I was told and read on other forums that brake cleaner is safe. Is it the brake cleaner that causes this rough idle? If what can be done to fix it?

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1995 E36, Please let me know if it is the M40 8 valve engine?

Hi, Its the M43 8 valve

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Could the O2 sensor have anything to do with this?

 

[VeNoM_Ct]

Brake Cleaner is a NO NO... u supposed to use Throttle Body Cleaner

Thanks. I looked for throttle body cleaner but couldn't find any shops that sell it. I was told and read on other forums that brake cleaner is safe. Is it the brake cleaner that causes this rough idle? If what can be done to fix it?

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1995 E36, Please let me know if it is the M40 8 valve engine?

Hi, Its the M43 8 valve

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Could the O2 sensor have anything to do with this?

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My e36 M has the exact same issue... All pipes (except one very short pipe below the TB) were replaced a year or so ago... cleaned all sensors and its been 100s since then until now.

I think the Idle control valve dirty again (perhaps MAF too) but its such effort to remove everything...

I used very good brake cleaner through the air filter box but that only worked for about 3 days...

 

[Luis Malhou]

I recently did my brothers e36 325, stipped down MAF, etc. He also complained of roughly idling and surging. After cleaning with Carb Cleaner its 100%, feels like a new car.

No matter what people say, brake fluid is only good to help release stuck bolts or rusted stuff, but its corrosive properties is not a good thing. Buy a good carb cleaner and spray everything clean again, should come right.

Make sure all the plugs are dry and clean too.
GL

 

[Fappas]

Brake Cleaner is a NO NO... u supposed to use Throttle Body Cleaner

Thanks. I looked for throttle body cleaner but couldn't find any shops that sell it. I was told and read on other forums that brake cleaner is safe. Is it the brake cleaner that causes this rough idle? If what can be done to fix it?

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1995 E36, Please let me know if it is the M40 8 valve engine?

Hi, Its the M43 8 valve

---

Could the O2 sensor have anything to do with this?

---

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My e36 M has the exact same issue... All pipes (except one very short pipe below the TB) were replaced a year or so ago... cleaned all sensors and its been 100s since then until now.

I think the Idle control valve dirty again (perhaps MAF too) but its such effort to remove everything...

I used very good brake cleaner through the air filter box but that only worked for about 3 days...

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What did you use to clean the sensors? And which sensors did you clean?

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I recently did my brothers e36 325, stipped down MAF, etc. He also complained of roughly idling and surging. After cleaning with Carb Cleaner its 100%, feels like a new car.

No matter what people say, brake fluid is only good to help release stuck bolts or rusted stuff, but its corrosive properties is not a good thing. Buy a good carb cleaner and spray everything clean again, should come right.

Make sure all the plugs are dry and clean too.
GL

Maybe I must try Carb cleaner cause I cant seem to find throttle body cleaner anywhere.

 

[boost3d]

The Maf on these cars are also highly sensitive...an easy test to perform is, disconnect the maf and go around the block. reconnect the maf and go around the block. the car shouldnt behave the same

 

[Sankekur]

Did you unplug the ICV and TPS when you cleaned the throttle body and ICV? If you did there is a chance than you might have mixed up the plugs, not sure about e36's but I know e34's of this era use the same plugs for the TPS as ICV so it is pretty easy to mix them up.

 

[Gizmo]

BRAKE CLEANER! Eish!
You were supposed to use carb cleaner, you may have killed the ICV. Time to buy a new one.

 

[Fappas]

Did you unplug the ICV and TPS when you cleaned the throttle body and ICV? If you did there is a chance than you might have mixed up the plugs, not sure about e36's but I know e34's of this era use the same plugs for the TPS as ICV so it is pretty easy to mix them up.

The plugs can't be mixed as its at totally different locations.

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BRAKE CLEANER! Eish!
You were supposed to use carb cleaner, you may have killed the ICV. Time to buy a new one.

I was afraid that someone would tell me that.

 

[ver328i]

not discounting any of the above but check for vacuum leaks man. The m43 is notorious for leaky pvc valves. My Dad had this bad idling issue after engine cleaning once and it had us guessing for days.

Turned out to be this goodie

 

[Gizmo]

As above, remove and inspect the crank case vent valve for leaks, common problem area.

 

[Fappas]

So i came home tonight and disconected the ICV and then the car was idling properly. How is it that the car is idling with ICV disconnected? When i connected it again the high and low idle was back again. So i disconnected again. So can i keep driving with ICV disconnected? Does this confirm that ICV is finished? Shouldnt the car be stalling with disconnected ICV?

Sorry for all the questions but im really puzzled right now.

 

[Gizmo]

Its dead. The vacuum created by the motor will hold it open enough for the car to idle. Best you replace it or it will stall when you turn the AC on or idle higher or lower on cold starts or cold days ect.