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1984 633 CSi Erratical idling

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Mitsos
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1984 633 CSi Erratical idling

Post by Mitsos » Mon Mar 07, 2016 2:52 am

This is my first post so First I want to say hello to all the members . I enjoyed navigating through the forum and I'm very impressed with the information and passion for the E24.

I purchased my shark from Florida as my Christmas gift . The car is a 1984 633CSI 5 speed . Everything is there and has no rust . It has some electrical gremlins that due to winter temps here in NY couldn't spend a lot of time diagnosing yet. With some warm weather coming our way this week and your help, I hope to bring her in excellent running condition.

She has idling issue that PO described me and I confirmed when she was shipped to me . She starts right up when cold . When coolant temp hits around 150F (when cold start valve closes) rpms start to jump up and down . She runs and drives a bit rich too. Check out the video .
https://www.youtube.com/watch?v=RHAvSjB5Rq0
After checking vacuum lines for leaks ? replacing an ICV hose and cleaning ICV nothing changed . I disconnected the coolant temp sensor and rpms settle but still idles a bit high .No rpm hunting though. When I connect back the coolant temp sensor plug ,idling is up and down again .
I was hoping that sensor was the issue and replaced it . Didn't change anything :(

The O2 light is ON on the OBC check board .
I'm registering her tomorrow and start driving local , also throwing a new bosh O2 sensor

I look forward for your advise to the idling haunting.
Thank you in advance !
Dimitris
1984 BMW 633 CSi

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sansouci
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Re: 1984 633 CSi Erratical idling

Post by sansouci » Mon Mar 07, 2016 11:19 am

Dimitris,
IIRC, NY doesn't do an emission test on over 25 y.o. cars, but a glowing check engine light may fail you. Change out the sensor and be sure it is connected in the engine compartment. There is a two part orange connector on the passenger side firewall. Let us know if that fixes your problem.
Update your profile to add vehicle and location.
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Brucey
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Re: 1984 633 CSi Erratical idling

Post by Brucey » Mon Mar 07, 2016 7:56 pm

FWIW the CSV closes as soon as the key is turned from 'start' to 'run'.

If the O2 sensor has failed then you will be onto 'open loop' running which means that any minor fault (eg an air leak) will cause the engine to run badly, especially when hot ( the engine runs super-rich when cold, so bad air leaks are often tolerated on cold starts).

If you unplug the CTS and a hot engine runs better, this is pretty much a sure-fire sign that the engine is running lean otherwise.

A typical cause for a 'hunting' or 'surging' idle is a bad air leak (or a badly set throttle body). Once the oil is hot and runny, the amount of air that lets an engine barely run when cold (which can be 'mostly air leak') is enough to make it do over 1000rpm when hot. Surging can then occur, since at about 1200rpm on a closed throttle, the fuel is automatically cut. It doesn't cut back in again until the rpms drop to around 750rpm.

hth

cheers
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Re: 1984 633 CSi Erratical idling

Post by Mitsos » Wed Mar 09, 2016 12:15 am

I replaced the O2 sensor today with a Bosch one. The O2 light didn't turned off . Disconnected the battery for a few mins but light didn't reset. That means I'm still in open loop ?
I also replaced the temp switch sensor . The coolant temp sensor was replaced 3 days ago. Neither 3 of those sensors fixed the problem. It only occurs when the coolant temp reaches 140-150 degrees. Is that the temp that CSV stop keeping the engine running rich ?
1984 BMW 633 CSi

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Re: 1984 633 CSi Erratical idling

Post by tschultz » Wed Mar 09, 2016 2:31 am

O2 Light? The check panel light doesn't relate to condition of the actual sensor.

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Brucey
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Re: 1984 633 CSi Erratical idling

Post by Brucey » Wed Mar 09, 2016 8:49 am

Mitsos wrote: I also replaced the temp switch sensor . The coolant temp sensor was replaced 3 days ago. Neither.... of those sensors fixed the problem.
hang on, you are playing 'parts change bingo' here; there is no need for that, (Jeez, there are a lot of parts you might replace too... :roll:) you can tell if these parts are functional or not by using a voltmeter, so why not do that....?
It only occurs when the coolant temp reaches 140-150 degrees. Is that the temp that CSV stop keeping the engine running rich ?
No. Read my earlier post.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Re: 1984 633 CSi Erratical idling

Post by Mitsos » Wed Mar 09, 2016 2:54 pm

Brucey wrote:
Mitsos wrote: I also replaced the temp switch sensor . The coolant temp sensor was replaced 3 days ago. Neither.... of those sensors fixed the problem.
hang on, you are playing 'parts change bingo' here; there is no need for that, (Jeez, there are a lot of parts you might replace too... :roll:) you can tell if these parts are functional or not by using a voltmeter, so why not do that....?
It only occurs when the coolant temp reaches 140-150 degrees. Is that the temp that CSV stop keeping the engine running rich ?
No. Read my earlier post.

cheers
I didnt know the CSV doesnt stay on longer. Please watch the youtube video on my first post.It is really haunting and only starts at 140-150 degrees . when CTS is unplugged . she idles a bit high but steady
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Re: 1984 633 CSi Erratical idling

Post by Mitsos » Fri Mar 11, 2016 5:43 pm

Brucey wrote:
Mitsos wrote: I also replaced the temp switch sensor . The coolant temp sensor was replaced 3 days ago. Neither.... of those sensors fixed the problem.
hang on, you are playing 'parts change bingo' here; there is no need for that, (Jeez, there are a lot of parts you might replace too... :roll:) you can tell if these parts are functional or not by using a voltmeter, so why not do that....?
It only occurs when the coolant temp reaches 140-150 degrees. Is that the temp that CSV stop keeping the engine running rich ?
No. Read my earlier post.

cheers

I did some testing today and the connector of the ICV doesnt get any power. Next is to figure out where it is getting power from . Any help is greatly appreciated
1984 BMW 633 CSi

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Ralph in Socal
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Re: 1984 633 CSi Erratical idling

Post by Ralph in Socal » Fri Mar 11, 2016 6:29 pm

Didn't the earlier cars (82/83/84 e28 base) have an idle control module separate from the ecu? I know some of the e28 cars had them so look for a small (3 inches by 3 inches by 1 inch thick) green plastic electrical box near the ecu in the glove box. Those are known to go bad.

I may very well be mistaken with this!!!


Ralph
There is a very fine line between "Hobby" and Mental Illness.

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Brucey
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Re: 1984 633 CSi Erratical idling

Post by Brucey » Fri Mar 11, 2016 6:44 pm

the ICV only gets power if the control circuitry is working correctly i.e. it is holding the idle speed down AND the idle contact is made in the TPS.

That your idle is 'high and steady' with the CTS unplugged means that you have enough air getting into the engine at idle, presumably without intervention of the ICV. This probably means that the throttle body is set wrongly, or (more likely) you have a catastrophic air leak of some kind.

If you have not yet downloaded it, you can download the correct ETM for your car which at least will tell you where the wires go and what is connected to what. [If you have an 008 ECU this does have a separate idle control module but NB if this fails it is difficult to see how this could make the idle speed too fast.]

However the ETM won't tell you how the system works.

You would be amazed how many people start out with a sticky ICV, and to 'cure' that they reset the throttle body (and thus the TPS never goes into the 'idle' position), and then spend ages trying to 'cure' the knock ons from that.

Or (as is normal) through wear of the throttle body linkage the throttle closes slightly and then it won't allow a cold idle even with the ICV fully open. They then reset the throttle body (without resetting the TPS) and lose all idle function.

If you have an O2 sensor problem (or again an air leak) the ECU's attempts to hold the mixture ratio correct can add to a load of other symptoms and also make the idle surge up and down. That could be why the 'problems' get worse when the engine warms up.

However there is no way you can have an idle that is too high (not under any circumstances) unless there is a load of air getting into the engine somewhere. If this happens when the ICV is shut (i.e. without power) then you have a badly set TB and/or inlet air leaks.

So my advice is to

- check for air leaks
- check for air leaks again
- reset the throttle body (as per the manual)
- reset the TPS

then report back.

cheers
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Re: 1984 633 CSi Erratical idling

Post by songzunhuang » Wed Sep 27, 2017 7:55 pm

Brucey, etc all - my 84 633 has begun to idle rather poorly. Cold or warm, the idle is extremely rough until I drive around a bit - then it smooths out. Also the idle has creeped up to about 1000 rpm. It was lower before.

From all the banter, it sounds like a vacuum leak, but I’ve inspected the hoses from the intake, valve cover, ICV and they all look good.

Also when I unplug the ICV the rpm goes up quite a bit, plugging it in lowers it. I’m guessing that means the ICV is doing it’s job.

I’ll look into the TPS adjustment, but if it was off, wouldn’t the idle be bad all the time and not just at start?

I’m going to poke around this weekend and was wondering if you had any other suggestions based on the symptoms described. Thanks in advance.
-----
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1984 633CSi
Last 7 of VIN: 6997383

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tschultz
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Re: 1984 633 CSi Erratical idling

Post by tschultz » Thu Sep 28, 2017 2:08 pm

songzunhuang wrote:
Wed Sep 27, 2017 7:55 pm
Brucey, etc all - my 84 633 has begun to idle rather poorly. Cold or warm, the idle is extremely rough until I drive around a bit - then it smooths out. Also the idle has creeped up to about 1000 rpm. It was lower before.

From all the banter, it sounds like a vacuum leak, but I’ve inspected the hoses from the intake, valve cover, ICV and they all look good.

Also when I unplug the ICV the rpm goes up quite a bit, plugging it in lowers it. I’m guessing that means the ICV is doing it’s job.

I’ll look into the TPS adjustment, but if it was off, wouldn’t the idle be bad all the time and not just at start?

I’m going to poke around this weekend and was wondering if you had any other suggestions based on the symptoms described. Thanks in advance.
I'd start by removing the ICV and cleaning it out with some carb cleaner to make sureno oil or gunk is preventing it from opening properly when cold. This should improve idle also. If that doesn't fix it, your ICM (green box in glove box) could be going bad...

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Re: 1984 633 CSi Erratical idling

Post by songzunhuang » Fri Sep 29, 2017 4:44 am

tschultz wrote:
Thu Sep 28, 2017 2:08 pm
songzunhuang wrote:
Wed Sep 27, 2017 7:55 pm
Brucey, etc all - my 84 633 has begun to idle rather poorly. Cold or warm, the idle is extremely rough until I drive around a bit - then it smooths out. Also the idle has creeped up to about 1000 rpm. It was lower before.

From all the banter, it sounds like a vacuum leak, but I’ve inspected the hoses from the intake, valve cover, ICV and they all look good.

Also when I unplug the ICV the rpm goes up quite a bit, plugging it in lowers it. I’m guessing that means the ICV is doing it’s job.

I’ll look into the TPS adjustment, but if it was off, wouldn’t the idle be bad all the time and not just at start?

I’m going to poke around this weekend and was wondering if you had any other suggestions based on the symptoms described. Thanks in advance.
I'd start by removing the ICV and cleaning it out with some carb cleaner to make sureno oil or gunk is preventing it from opening properly when cold. This should improve idle also. If that doesn't fix it, your ICM (green box in glove box) could be going bad...
Thanks for the ideas. I think I am going to buy a new ICV. They are not so expensive and it couldn’t hurt. As for the ICM, I will have to look into that. It hasn’t come up in my inquiries yet.
-----
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Re: 1984 633 CSi Erratical idling

Post by tschultz » Fri Sep 29, 2017 2:46 pm

Usually the ICV doesn't go bad... Cleaning them up makes a big difference. It is easy too. The rotating 'door' should move freely with a flick of the wrist if you have it out of the car.

It is vibrates with the key on, it is working. It is really just a stepper motor and the ICM tells it what position to move the door to. Since it works when warm, I'd suspect the valve first...

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Re: 1984 633 CSi Erratical idling

Post by Brucey » Fri Sep 29, 2017 10:46 pm

yep, often a sticky ICV only works when it is warm.

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Re: 1984 633 CSi Erratical idling

Post by songzunhuang » Mon Oct 02, 2017 5:45 am

tschultz wrote:
Fri Sep 29, 2017 2:46 pm
Usually the ICV doesn't go bad... Cleaning them up makes a big difference. It is easy too. The rotating 'door' should move freely with a flick of the wrist if you have it out of the car.

It is vibrates with the key on, it is working. It is really just a stepper motor and the ICM tells it what position to move the door to. Since it works when warm, I'd suspect the valve first...
Thanks guys. Today I took out the IAC and cleaned it well. I did notice that I could flick it and hear something moving. I believe it was that door you mentioned. As it turns out, in doing all this I discovered a split hose! That was the real culprit. Luckily, I actually had a spare. I ordered it once and didn't want to deal with replacing it since it was way down there. Well, today I had a reason to go way down there.

If you look at my post in my project, I recorded it all. Here's a quick pic of what I saw when I removed the IAC.
Screen Shot 2017-10-01 at 10.38.30 PM.png
Yup, split hose not good for idle.
Screen Shot 2017-10-01 at 10.38.30 PM.png (579.08 KiB) Viewed 5828 times
-----
Song Huang
1984 633CSi
Last 7 of VIN: 6997383

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Re: 1984 633 CSi Erratical idling

Post by songzunhuang » Mon Oct 23, 2017 11:39 pm

songzunhuang wrote:
Mon Oct 02, 2017 5:45 am
tschultz wrote:
Fri Sep 29, 2017 2:46 pm
Usually the ICV doesn't go bad... Cleaning them up makes a big difference. It is easy too. The rotating 'door' should move freely with a flick of the wrist if you have it out of the car.

It is vibrates with the key on, it is working. It is really just a stepper motor and the ICM tells it what position to move the door to. Since it works when warm, I'd suspect the valve first...
Thanks guys. Today I took out the IAC and cleaned it well. I did notice that I could flick it and hear something moving. I believe it was that door you mentioned. As it turns out, in doing all this I discovered a split hose! That was the real culprit. Luckily, I actually had a spare. I ordered it once and didn't want to deal with replacing it since it was way down there. Well, today I had a reason to go way down there.

If you look at my post in my project, I recorded it all. Here's a quick pic of what I saw when I removed the IAC.
Screen Shot 2017-10-01 at 10.38.30 PM.png
Just following up. I replaced the split hose and it's not better. Still the same really. Then I had a cooling issue again and got distracted. I recently fixed the cooling system (again) and now it's back to this idling issue.
-----
Song Huang
1984 633CSi
Last 7 of VIN: 6997383

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Re: 1984 633 CSi Erratical idling

Post by bpoliakoff » Tue Oct 24, 2017 2:18 am

Thanks guys. Today I took out the IAC and cleaned it well. I did notice that I could flick it and hear something moving. I believe it was that door you mentioned. As it turns out, in doing all this I discovered a split hose! That was the real culprit. Luckily, I actually had a spare. I ordered it once and didn't want to deal with replacing it since it was way down there. Well, today I had a reason to go way down there. If you look at my post in my project, I recorded it all. Here's a quick pic of what I saw when I removed the IAC.Screen Shot 2017-10-01 at 10.38.30 PM.png[/quote]

I have the same valve on my 81 with first year Motronic. However yours appears to have electrics while mine is purely mechanical. It is called an idle regulator and has a screw in fitting that can be used to "tune" the airflow. My car is a Euro and as far as I know never had an ICV
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.

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Re: 1984 633 CSi Erratical idling

Post by songzunhuang » Sat Nov 10, 2018 3:00 am

It's back!!!

Like a bad dream, my rough idle is back with a vengeance. In the last 3 days, the car has died in traffic 3-4 times and once in a parking lot. Most times I just have to start it up again and continue on. Sometimes, I have to do it several times. The weird thing is that once I am on the road, it appears to be mostly fine. It's just I'm am super paranoid when I see traffic because it means I have to sit there idling.

I was poking around under the hood to see if I had a loose ground again for the injectors. That seems to make things better last time so I took off the injector wire ground (brown wires fasten to the fuel rail with a 10mm bolt) and cleaned it with electronics cleaner and a wire brush. Next day, it died again. So that wasn't it.

Today, I was poking around again and noticed that the main ground from the firewall to one of the valve cover bolts was really loose. So I tightened that up a few hours ago. I am getting ready to drive home (about 42 miles) and I hope I make it without incident. It's really dark right now at 7pm. I may give up and take it to the shop, but then again I always say that and it seems to get better! It's a haunted car.
-----
Song Huang
1984 633CSi
Last 7 of VIN: 6997383

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Re: 1984 633 CSi Erratical idling

Post by hornhospital » Sat Nov 10, 2018 3:50 am

When that same ground strap was accidentally left loose after a valve adjustment on my 633, it wouldn't run. The nut was finger tight. After tightening with a 10mm wrench, it ran as it did before the adjustment. That ground is more critical than most realize.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann";'87 325is "Odette"; '93 325is "Elvira"; '95 M3 "Ashlyn"; '95 318is "Bebe"

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Re: 1984 633 CSi Erratical idling

Post by songzunhuang » Sun Nov 11, 2018 1:59 am

hornhospital wrote:
Sat Nov 10, 2018 3:50 am
When that same ground strap was accidentally left loose after a valve adjustment on my 633, it wouldn't run. The nut was finger tight. After tightening with a 10mm wrench, it ran as it did before the adjustment. That ground is more critical than most realize.
Made it home without incident. Today (Sat) I took everything apart and cleaned it well with a wire brush and contact cleaner. Reassembled everything tight. I really hope this was the problem.

Why am I still not sure? Just for kicks I started the car and while idling, I completely disconnected the ground to the valve cover to see if it would die. It didn’t. So now I’m not certain that was the issue. I’ll need to do some more poking around another day. Meanwhile, I’ll keep on driving!
-----
Song Huang
1984 633CSi
Last 7 of VIN: 6997383

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