1996 1.9 idle issues related to charging issue?

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Jdog1woof
Joined: Sat 12 Sep, 2015 01:20
Posts: 4

  Z3 roadster 1.9

1996 1.9 idle issues related to charging issue?

Post by Jdog1woof »

(Disclaimer- if I am posting this to the wrong area I throw myself down on my knees to the mercy of the site admins to help me re locate the post- sorry and thanks for your help!)
Hi,
new Z3 owner (96 with 1.9, 5 speed), life long auto enthusiast (all American muscle/pony and sports cars), always turned my own wrenches, and I have been BLOWN away with the community that surrounds this vehicle- I have never seen a more knowledgeable and helpful community around a car.

To be honest, I fell into this car (short money, "had to have it" sort of deal...) it's got 96k miles, came into my garage as a sort of basket case, but has come together quickly. I have been chasing a rough idle issue (which i will describe momentarily) and was looking for someone to sanity check me. The issue presents as follows:
When cold, the engine starts, runs and idles fine- as it warms, it develops a rev. dive symptom (a prime example of how this issue manifests is, going from 2-3k RPM and cruising you will approach a light. as you downshift there is no issue. As you finally coast to a stop and disengage the drive train the engine will dive from whatever RPM it was at to say.. 2-300 maybe... about stall speed... then recover to 1000, then dive and recover again, 2-3 times then stabilize. I have replaced plugs, coil, cleaned MAF, replaced 02, all basic tune up stuff... starting to think it is electrical in nature. the car had a dead battery when it rolled into my garage, i popped it down the drive way, and have had occasion to drive it daily since (side bar- i never thought i would own a 4 cylinder car that i CANNOT WAIT to drive... what a killer car!) so the battery has yet to die, I wonder if a sick battery or sick alternator could cause this issue... thoughts from the experts?
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: 1996 1.9 idle issues related to charging issue?

Post by Del »

I would suspect a sensor and I would plug it into a code reader - a simple OBD one should work OK. I would suspect the camshaft position sensor.
Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
Posts: 2093

  Z3 roadster 2.8
Location: Daglan, France

Re: 1996 1.9 idle issues related to charging issue?

Post by Mike Fishwick »

More likely to be a sticky idle control valve - take it off and clean it before suspecting naything else.
A Z3 is not just for Christmas - it's for life!
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colb
Joined: Sat 05 May, 2012 22:46
Posts: 690

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: 1996 1.9 idle issues related to charging issue?

Post by colb »

Go for Mikes suggestion first, the idle control valve can get gummed up and can be fixed with a good clean, spray some carb cleaner in it and wash it out well.

Colb
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
Jdog1woof
Joined: Sat 12 Sep, 2015 01:20
Posts: 4

  Z3 roadster 1.9

Re: 1996 1.9 idle issues related to charging issue?

Post by Jdog1woof »

Thanks folks. I will do the idle control valve next, found a pretty good step by step with pictures on removing the intake to get at it... Does anyone know of any resources to locate replacement hoses (large diameter rubber, pre bent hoses) fr these cars? I'll bet when I start taking stuff off the motor These 20 year old horses will show their age.

Thanks also @del for the suggestion on the cam position sensor. I haven't seen a clear cut description of what the failure mode of this sensor is, but have you seen any clear cut step by steps of its replacement? I have a lot of experience with older GM small blocks (built a few from scratch) but none with these motors.
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: 1996 1.9 idle issues related to charging issue?

Post by Del »

Jdog1woof wrote:Thanks also @del for the suggestion on the cam position sensor. I haven't seen a clear cut description of what the failure mode of this sensor is, but have you seen any clear cut step by steps of its replacement? I have a lot of experience with older GM small blocks (built a few from scratch) but none with these motors.
I'd be surprised if the later Bosch type idle control valve was causing such major issues - see photo. The earlier type of idle control valve fitted to some earlier BMW engines such as the M42 was however known to be troublesome. However, no harm in giving it a clean as suggested above.
Image

Youtube link to the cam position sensor (only one on the M44 engine) being changed. However, before spending money I would check for error codes. I read many US forums where cleaning an old MAF sensor (as you have done) is recommended. Personally, I have found that once "they fail, they fail" and that no amount of cleaning with solvent mends them.
https://www.youtube.com/watch?v=nz7RdAL4ARE
Jdog1woof
Joined: Sat 12 Sep, 2015 01:20
Posts: 4

  Z3 roadster 1.9

Re: 1996 1.9 idle issues related to charging issue?

Post by Jdog1woof »

Update. Finally got around to checking out the idle air control valve, wicked gunned up. I cleaned it but after thinking it over I just ordered a new one. Will update once installed. Thanks again for the support. If not this next will be del's cam sensor suggestion.
Jdog1woof
Joined: Sat 12 Sep, 2015 01:20
Posts: 4

  Z3 roadster 1.9

Re: 1996 1.9 idle issues related to charging issue?

Post by Jdog1woof »

Annnnd the winner is..... IDLE CONTROL VALVE!

Installed and bam, idle smoothed right out! Thanks everyone for the support
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