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· Registered
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87 Posts
Discussion Starter · #1 ·
my car has a significantly lower idle in park and neutral approx.(400-500rpm) than in drive approx. (800). In Drive sometimes it gets unsteady, but never stalls.

P1250
P1622....im pretty sure these first 2 are the wheel speed sensors
P0150 Bank2 sensor1
P0505 IAC
P0173 Fuel Trim bank1
P0170 Fuel Trim Bank2
P1188 DTC

now i dont have a clue what DTC is and im assuming the fuel trims are clogged fuel injectors? so i put fuel injector cleaner in.

getting my car running right is my top priority right now. i have cleaned the IAC but the code still comes up for it.

Things i have cleaned/repaired:
-VCG
-cleaned maf
-cleaned IAC
-misc. vacuum leaks (it has been tested)
-replaced air filter
-cleaned throttle body
-replaced both intake boots
-spark plugs
-replaced both pre-cat o2's


Help would be greatly appreciated! thank you.
 

· Noone Special
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700 Posts
in my experience it has been a maf with faults p1188. Have you car scaned by a bmw diag tool to verify before you spend afew hundred on a maf. or swap with someone else you know with a bimmer.

Besides that I would smoke out the intake system, verify that there are no leaks in the system. If you find a leak that was your problem.
check the ccv system for hoses for any cracks or breaks. make sure the vacuum line on the ccv is either connected to the vacuum source or has the plug in it.
 

· Registered
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87 Posts
Discussion Starter · #4 ·
Look for an air intake leak. Check your boots from the air filter to the throttle body. They dry rot and crack. Check for bad vacuum lines.

Sent from my C771 using Bimmer App
yeah i replaced both boots already and i know for a fact i do not have any vacuum leaks.

engine code for the IAC came up im thinking i have to replace it and does anyone know what DTC is?
 

· Registered
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87 Posts
Discussion Starter · #5 · (Edited)
in my experience it has been a maf with faults p1188. Have you car scaned by a bmw diag tool to verify before you spend afew hundred on a maf. or swap with someone else you know with a bimmer.

Besides that I would smoke out the intake system, verify that there are no leaks in the system. If you find a leak that was your problem.
check the ccv system for hoses for any cracks or breaks. make sure the vacuum line on the ccv is either connected to the vacuum source or has the plug in it.
I have a feeling you are right about the maf i have been doing research on other peoples cars that threw the P1188 and a bad maf causes the fuel trim codes as well because it is maxing out the amount of fuel injected into the motor. the maf isnt telling the computer how rich/lean to run and messing up the air/fuel ratio which is causing a weird idle once in a while. i am going to find out exactly whats going on when i recieve my obdII cable and software in the mail aug 13th. for now i am just going to drive the car as is.

Also DTC is an abbreviation for "Diagnostic Trouble Codes" so that doesn't explain anything on the P1188 specifically.
 

· Seek to understand,^Value
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25,378 Posts
a website that tells you about the codes
Bear in mind that the codes are computer specific ...

Most are the same but some are different depending on what engine computer you have.

Complete details here:
- All OBDII codes, including BMW-specific P1xxx DTCs specific to the engine computer of each BMW (1) (2)
 
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