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rough idling M30 (rubberknees)

Printed From: Bavarian-Board.co.uk - BMW Owners Discussion Forum
Category: Technical & Model Specific Forums
Forum Name: General Motors
Forum Discription: This forum will deal with technical issues for the cars not dealt with in the other forums. These don't need to be BMWs!
URL: http://www.bavarian-board.co.uk/forum_posts.asp?TID=18917
Printed Date: 25-August-2019 at 16:25


Topic: rough idling M30 (rubberknees)
Posted By: Philip
Subject: rough idling M30 (rubberknees)
Date Posted: 15-June-2005 at 10:34

rubberknees' 528i M30 is suffering low idle speed. these comments may help courtesy of the good 'ol boys on the Bimmerboard

"Rough idle is all about vacuum. Sure you can throw some corrective actions at the problem in the form of electrical fixes, but if you do not have a good running motor to begin with, who knows how many 'fixes' will be needed.

 

Check the vacuum hoses, oil fill cap, oil dipstick, oil pan bolts, valve cover nuts, idle air hose, air intake boot, vacuum connection on the manifold for the HVAC and other stuff.

 

Adjust the valves and go over them twice, once to check and once to verify they are correct when the engine is dead cold. Maybe even check the gap at the rocker instead of the now worn valve stem-eccentric."

 



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Philip
'86 E23 735iA SE - Polaris - The Silver Surfer
'85 E23 735iA SE - Cosmos Blue - VJ
'86 E28 528iA SE - Dia Black - Helga
'86 E23 728iA SE - Polaris - The CHAV mobile



Replies:
Posted By: siscobmw
Date Posted: 16-June-2005 at 10:17

Rough or low idle speed?

Francesco from italy

 



Posted By: M3AG
Date Posted: 17-June-2005 at 10:45
I have a poor idle, and regardless of how tight I make the connections and how good the hoses etc are, it still idles badly, low (650rpm) and when you come to a halt, 9 times out of 10 it stalls!


Posted By: Philip
Date Posted: 17-June-2005 at 11:30

Ah but in your case could it be ECU related as you are currently running an Alpina lump with a stock ECU. Somehow the stock ECU is not getting the signal it needs to control the idle.

have you tried a different ICV in case yours is shot?

Did the Alpina car have the early or later type ICV? I know BMW changed the ICV during the life of the 3.5 engine.

another possibility is old/worn injectors.

there is a brand new set of injectors on ebay for 60 quid - now that is a bargain - I reckon they will go somewhat higher though



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Philip
'86 E23 735iA SE - Polaris - The Silver Surfer
'85 E23 735iA SE - Cosmos Blue - VJ
'86 E28 528iA SE - Dia Black - Helga
'86 E23 728iA SE - Polaris - The CHAV mobile


Posted By: siscobmw
Date Posted: 17-June-2005 at 11:59

Well, under the big black inlet pipe, there should be what is exactly a tap( 2,8 liters engine have not ICV, as early motronic 3,5 liter before 9/84),it has a L shape or a T shape , and has got a big screw in one side.That screw can setup the idle speed....There are also inlet pipes over there, so check them for damages(they usually get harder with hot and time....and One day they're broken without 2-3 days notice).

Other check: the aux air valve( used on  2,8, 3,0 3,2 and early 3,5 liters  till 9/84) probably has got a bad "stopair diaphragm"or a crack in this housing, causing leaks....It's not repairable.You can change it for 30-50 GBP depending from the model( it is usually bolted on the valve cover , near bulkhead side).

Hope tha this helps....

Francesco from Italy



Posted By: siscobmw
Date Posted: 17-June-2005 at 12:04

Huh I forgot to mention....

I had a similar problem when I had valve clearance on my '83 635 and I forgot to plug the connector of air flow meter....

The idle was all but sweet and right, it had 500 rpm , as I blip throttle the engine stalled.

2 chances: Your Air flow meter is gone forever,AFM wirings are chafed somewhere or cutout....

Try removing wirings from the AFM, if this makes no difference , it's the AFm, if not You have to check carefully somewhere for air leaks....

Francesco from Italy



Posted By: Philip
Date Posted: 17-June-2005 at 14:49

brilliant posts Francesco, I have to say you really know about BMW's.

are you a BMW trained mechanic?

 



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Philip
'86 E23 735iA SE - Polaris - The Silver Surfer
'85 E23 735iA SE - Cosmos Blue - VJ
'86 E28 528iA SE - Dia Black - Helga
'86 E23 728iA SE - Polaris - The CHAV mobile


Posted By: siscobmw
Date Posted: 18-June-2005 at 03:29
Originally posted by Philip Philip wrote:

are you a BMW trained mechanic?

 

Thank You for Your kind words.

I'm not a BMW trained mechanic, I 'm 1 unlucky BMW owner(it's a bit different)....

I had not all of these problems on my '83 635CSi, but I changed everything for an "initial peace of mind"....The car was ok, but I found further improvements every time I changed a bit(changed distributor rotor and cap, so the idle was very stable,I changed aux air valve and rough idle when cold diseppeared,I changed what i thought a good brake bomb was and I got better brakes, changed the fuel pressure regulator and I found a lot of lost bhp, also I have a good %CO and I pass every italian MoT without fuss...)

In early "Jetronic and Motronic" M30 engines every electronic bit depends from each other, so when something goes wrong , You can menace the health of other components...I had to change everything to discover this.

Anyway, I have a friend who knows this car like his pockets and owns a lot of BMWs(currently: BMW 2002 Cabrio Baur, 3.3Li manual E3, 3003cc CSL Batmobile,'84 635CSi, '85 M635Csi, '86 M635CSi, e23 phase 1 735i,'84 E23 735i executive with alpina engine, '86 745i, 535i E28,e36 M3 GT, recently sold a M5 touring elekta-a kind of non official version for Italy...daily driver is a MiniCooper S) ...What i know comes from the magic brain of my friend..Now i can put the hands on a lot of BMWs....(he's so good that sometimes he has a sort of " partnership" with Mobile tradition...).

I always hope to help!

Francesco from Italy



Posted By: M3AG
Date Posted: 18-June-2005 at 07:06
My problem is that we have re-shelled an Alpina B9 3.5, and put all the bits into a later e28 shell.
The engine etc when it was in the priginal shell would run and idle OK, and the same for the engine that was removed from the donor shell, but when the Alpina engine was placed into the donor shell, it tries to stall ater driving it (revs bounce from 250rpm to 850rpm before settling down to a decent stable if not low idle.

Phil suggested the problem may be linked to the car running rich, any ideas? Seems plausible to me, but then again, anything does!


Posted By: Philip
Date Posted: 18-June-2005 at 08:03

Originally posted by M3AG M3AG wrote:

Phil suggested the problem may be linked to the car running rich, any ideas? Seems plausible to me, but then again, anything does!

as you know, i'm no mechanic, so I based that observation on watching you revving the car outside AJR's place. there was a rich running/fuelly smell and I remember Andy saying it needed a good blast up the road to clean out the motor.

you have done this in 100mph Merc bashing style and yet the lumpy idle/stalling issue is still there.

as you know the motor to be in excellent health, this issue must be sortable. Time to cruise down to Tris/Roofer for a session.



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Philip
'86 E23 735iA SE - Polaris - The Silver Surfer
'85 E23 735iA SE - Cosmos Blue - VJ
'86 E28 528iA SE - Dia Black - Helga
'86 E23 728iA SE - Polaris - The CHAV mobile


Posted By: M3AG
Date Posted: 18-June-2005 at 10:05
that fuel smell was the leak it had!


Posted By: bmw1066
Date Posted: 18-June-2005 at 16:43
Have you tried the crank shaft senser

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Mark 735 se 1982
RED BARON A E23 is for life not just for x-mas
BMW e34 530 v8 Sport kit
Spelling always Bad


Posted By: siscobmw
Date Posted: 18-June-2005 at 17:01

M3 AG wrote:but when the Alpina engine was placed into the donor shell...

Are you sure  You have swapped every bit to thew shell correctly?From here it seems you have done mistakes( please, check carefully You do not have mismatched wirings of the termotime switch or gauge sender  with wires for motronic coolant sender...first of all, it's not impssible , on some model...)...

RUNNING RICH????
                            bad Air flow meter or bad temperature sender( or bad matched wires when You bolted on the stuff).... also bad valve clearance...but it is the last thing You should check....From here it's nearly impossible to diagnose...

Francesco from Italy



Posted By: M3AG
Date Posted: 19-June-2005 at 04:14
perhaps it's something that I'll have to live with? Maybe an adjustemnt of the idle will correct the problem?
Everything was done as it should, so all I can think is the temp sender (thermotime switch?) is faulty or the cold start valve is playing up?
Valve clearances are fine as the car ran perfectly before the swap.

Thanks Francesco.


Posted By: eta.
Date Posted: 19-June-2005 at 10:04

[/QUOTE]


Thank You for Your kind words.


Anyway, I have a friend who knows this car like his pockets and owns a lot of BMWs(currently: BMW 2002 Cabrio Baur, 3.3Li manual E3, 3003cc CSL Batmobile,'84 635CSi, '85 M635Csi, '86 M635CSi, e23 phase 1 735i,'84 E23 735i executive with alpina engine, '86 745i, 535i E28,e36 M3 GT, recently sold a M5 touring elekta-a kind of non official version for Italy...daily driver is a MiniCooper S) ...What i know comes from the magic brain of my friend..Now i can put the hands on a lot of BMWs....(he's so good that sometimes he has a sort of " partnership" with Mobile tradition...).


I always hope to help!


Francesco from Italy

[/QUOTE]

Francesco, can you post up pics of the e3, batmobile and the e23's please?


Posted By: siscobmw
Date Posted: 20-June-2005 at 03:55

Originally posted by M3AG M3AG wrote:

perhaps it's something that I'll have to live with? Maybe an adjustemnt of the idle will correct the problem?
Everything was done as it should, so all I can think is the temp sender (thermotime switch?) is faulty or the cold start valve is playing up?
Valve clearances are fine as the car ran perfectly before the swap.

Thanks Francesco.

I believe that these are 2 important factors....

Then a look at idle valve and one at the flap of the airflow meter , and You should have checked every possible culprit.....

For the pictures, wait a moment, I give you the links,so this post will be not so "haevy to charge"....

Francesco



Posted By: siscobmw
Date Posted: 20-June-2005 at 04:37

The site where the pics are is" under work ......"As soon as the site is on-line, I will post pictures.....

SiSco from North italy



Posted By: siscobmw
Date Posted: 20-June-2005 at 04:51

For the moment: this is my friend M635CSi, arktis blau, 46000kms, every toy except the sunroof and rear aircon( not availale in 1985, probably...)....This car was prized as the best european conserved M635...( no restoratio, no rust, nothing wrong, the rear exhaust box is the one fitted at BMW factory( no joke, this man knows very well hoew to keep the bmws in mint conditions...).

His "86 745i ( full optional except the sunroof, 181000kms ), this is perfect despite kms....:

This is the BATMOBILE( original , the engine was race specced by Conrero when the car was new...Mobile tradition gave him a a prize for the best restoration...):

Last picture( a 39000kms 2500, in chamonix white and My friend 735i executive with Alpina engine( 17 inches alloys are , logically , not original....)

Francesco from italy



Posted By: siscobmw
Date Posted: 20-June-2005 at 04:53

Ok the site is again off -line...sorry( but if You click on the right button, the select properties, you can see the URL of pictures, so ....

Francesco



Posted By: M3AG
Date Posted: 23-June-2005 at 06:15
Fran
you still after Springs for an m535i?
AG


Posted By: bmw1066
Date Posted: 23-June-2005 at 06:22
AG the adjuster on the air flow meatier seams only to adjust the mixture no the idle, did mine on gas machine, I also have a gas machine you can use if you need one.

-------------
Mark 735 se 1982
RED BARON A E23 is for life not just for x-mas
BMW e34 530 v8 Sport kit
Spelling always Bad


Posted By: M3AG
Date Posted: 23-June-2005 at 07:49
Mark
we're going down the extreme route now, the ECU for the original car is being migrated onto the loom in the car next week, this should eliminate any problems and restore the 245 pnies the engine most definatley has!
Many thanks though!

AG

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we're the Sweeney son, and we ain't had our dinner.....


Posted By: siscobmw
Date Posted: 23-June-2005 at 09:05

Originally posted by M3AG M3AG wrote:

Fran
you still after Springs for an m535i?
AG

I have to Thank God, as I found in Germany a front+rear springs set, on their M535i Bilsteins(renewed 2 years ago and used for few miles cause the car was a rust bucket)and they are also complete with top mounts, front struts with also front discs and bearigs, internal dust covers and so on....for 170 Euros(delivery included!).

I could get a pair of front springs for spares, but Part numbers have to be 31 33 1 126 904 or 31 33 1 127 662 ....

BEst regards, Francesco From Italy

 




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