cold start trouble E30 M3
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Category: Technical & Model Specific Forums
Forum Name: BMW ///M Power
Forum Discription: Ask your BMW M Power Technical Questions here (M1, M2 hybrids, M3, M5 & M6)
URL: http://www.bavarian-board.co.uk/forum_posts.asp?TID=4274
Printed Date: 29-April-2024 at 14:34
Topic: cold start trouble E30 M3
Posted By: M3Nally
Subject: cold start trouble E30 M3
Date Posted: 26-November-2003 at 11:35
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Bloody car wouldn't start last night 100 miles from home.
Had to call the AA man out, he put foor flat to the floor then feathered the throttle to get it going. Apparently foot to the floor cuts off the injectors and allows the engine to get rid of excess fuel as it was flooded. Tries starting it again this morning and it went but runs like a pig until up to normal operating temp with an uneven hunting idle and need to rev it to get going. I was reading a thread where a chap with E36 M3 had same cold start problem and some people said it could be coolant sensor as the injection won't know if it's hot or cold. Any ideas? Could it just be damp in the rotor cap etc? |
Replies:
Posted By: lancelotII
Date Posted: 26-November-2003 at 15:48
| Inlet gaskets could be your problem. As they warm they expand, sealing of the vacuum leaks thereby producing better runnuing conditions. Hunting idle is normally a pretty good sign of intake gasket problems. Also the small plenum support could be shafted, which pulls the plenum away from the intakes. |
Posted By: David 87M3
Date Posted: 26-November-2003 at 17:44
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Could be intake gaskets, But I'd expect the car to "splutter" ( ie attempt to start whilst being cranked by the starter).
I'd reccomend replacing the coolant sensor. There are 2 of them on our cars. To find out the DME one next time the engine is running unplug them 1 at a time and the engine revs will rise (Plug it strait back in) thats the one to replace, the other is for the temp gauge on the instrument cluster. (Someone here will know what one is what but I cant remember) |
Posted By: M3Nally
Date Posted: 26-November-2003 at 19:55
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David
Thanks for the info,I don't think it is the inlet gaskets. Can anyone tell me me where the coolant sensors are then? |
Posted By: grant w
Date Posted: 26-November-2003 at 20:04
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get your self a can of carb cleaner , start the car and spray all around the inlet manifold , give it a good old spray and if the engine note changes you'll know the inlet blocks need changing .. ------------- 
www.redevom3.co.uk 1989 e30 m3 2.5 1996 e36 m3 evo , sold 2002 e46 m3 smg . 1991 Daihatsu 2.8 TD Work Horse Rust Never Sleeps . Tattooed Lady - Bearded Baby - there my family .. |
Posted By: BMG M3
Date Posted: 26-November-2003 at 20:14
Have a look here http://www.e30m3therealm3.com/tech/engine-electric-layout.html - This maybe helpfull, then again maybe not |
M3Nally wrote:Posted By: UweM3
Date Posted: 26-November-2003 at 21:15
|
here some notes from the US board: (it's the blue sensor)
...on the coolant pipe. It should read 300 to 360 ohms at operating temperature (temp gauge centered). Any higher reading is telling the ECU that the engine is cold, enriching the mixture. Also check the wiring to the sensor. Terminal 13 of the harness connector to the ECU is the correct one. Resistance from terminal 13 to ground should match the resistance of the blue sensor (with the wires plugged to the sensor, of course). Another common cause of rich running is a sticking injector. Check the plugs. If one of them is more fouled than the rest, you may have found the faulty injector. Tap on the suspected injector with the engine running and see if the engine smooths out. John 88 ///M3 Cinnabar ------------- E61 520d, slow and buzzy but my wallet likes the mpg..... |
Posted By: M3Nally
Date Posted: 27-November-2003 at 09:52
|
Uwe,
Is the default reading to tell the ECU that the engine is hot or cold. If the default is hot then the ECU won't richen up when cold, which may be the problem. If the default is cold then it can't be the coolant sensor. You may remember me posting that I have a cracked exhaust (across one of the crossover pipes) which is patched up temporarily. If this is blowing would that affect cold starting? I'll have a spray with carb cleaner, check the plugs, rotor cap and arm and get a multimeter out. Then I'll go down the pub which is a much better thing to do on a Saturday afternoon. Thanks lads |
Posted By: David 87M3
Date Posted: 27-November-2003 at 10:55
| I'd reckon the lower the resistance the colder the engine. When I unplugged my temp sensor the engine revvs rise. |
Posted By: Eamo
Date Posted: 27-November-2003 at 11:54
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m3nally
you probably already know this but dont crank the car over too much as it can burn out the plugs! ------------- |
Posted By: M3Nally
Date Posted: 27-November-2003 at 13:49
|
Eamo
I am still learning all the foibles of the E30 M3 and until I have had everything blow up on me (touch a huge piece of wood) and had to rebuild it I will continue learning. This forum really is superb when you get grief, even if it is only minor. I didn't know about the plugs. Cheers |
Posted By: M3Nally
Date Posted: 27-November-2003 at 13:52
|
Chaps
I'm pretty sure the idle air valve needs looking at aswell cos it idles at 1000 rpm. Is there an owmners repair manual anywhere about to buy, like the Haynes jobbies for E30 M3? |
Posted By: ROB ROSS
Date Posted: 27-November-2003 at 18:58
| If it has a air leak it will run faster. And you will find that if the engine is getting more air than what the mass air flow sensor is telling the ecu it will not run correct. I would go with the carb cleaner. Hope it might be some help. |
Posted By: PJSM3
Date Posted: 27-November-2003 at 19:58
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Is there an owmners repair manual anywhere about to buy, like the Haynes jobbies for E30 M3?
You could try Chilton's Repair Manual (No. 8427). This is for the American market but it does cover the E30 M3. I can't remember the price - maybe about £15? |
Posted By: David 87M3
Date Posted: 28-November-2003 at 09:27
| I'd say this forum is the best manual in the UK. |
Posted By: adwo
Date Posted: 28-November-2003 at 13:33
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Hmm, why do you think it's not the inlet gaskets. A hunting and rough idle is THE syptom of the gaskets going. Check that out also. Other problems can be a sticking injector or the AFM going south. This wouldn't be as temperature related as you describe however... Or maybe it's the ICV, or... So please do the carb cleaner thing and report back... HTH, Adwo |
Posted By: adwo
Date Posted: 28-November-2003 at 13:35
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did he tell you that? What a load of BS... Think about it: put the pedal to the metal and the injectors will be cut off? How would you ever accelerate that way? Adwo |
Posted By: David 87M3
Date Posted: 28-November-2003 at 14:44
| Fully opening the throttle on a flooded engine is the way to get it going. I guess it allwos max air into the engine. |
Posted By: Sohlman
Date Posted: 28-November-2003 at 14:54
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It could be leaking fuel injectors. Have had a poor running problem on my car after starting that clears itself after it has been running for about 5 seconds, or the revs have been raised to about 2000rpm. Was diagnosed by ML who state that the injectors trickle fuel into the piston and slowly flood the engine. If they leak a little bit like mine it is not to much to worry about, but they have told me that if the starting of the car deteriorates i need to invest in a new set of injectors. They cost about £50 each and the fitting is about 1.5 hours on a 635. So about £400 on my car and i would emagine £300 on a four cylinder M3. Worth having it checked out by someone mind you.
-------------  Sunday 10th July Brooklands Sharkfest and Big Coupe Day. http://635csi.mysite.wanadoo-members.co.uk/ - Coupe Events
|
Posted By: adwo
Date Posted: 28-November-2003 at 16:26
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At WOT the car will also receive the biggest amount of fuel. Once an E30 M3 is flooded the only solution is removing the plugs and drying them. So keep an extra set in your car... Regards, Adwo |
Posted By: M3Nally
Date Posted: 28-November-2003 at 16:53
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Adwo,
His theory may be bo~~ocks but it started the car, that was all I cared about. He said it was damp and had alot of cars that day with the same starting trouble. I have not had any trouble starting since but it is still a bit rough until it's warmed up. I am now armed with carb cleaner, and multimeter and will have a look tomorrow morning before the rain comes down again. Good weekend all |
Posted By: ROB ROSS
Date Posted: 28-November-2003 at 18:08
| There is a thing called flood clear mode on injection cars. Engine off, full throttle and crank the engine. That is how you would do a dry compression test with out disconecting your fuel. It works. |
Posted By: adwo
Date Posted: 28-November-2003 at 21:06
|
How can you crank the engine without it turning on? Pull fuse 11 or the fuel relay is the only method I know (or the code feature on the OBC).. Repeat: the only way to bring the S14 back to life is to install fresh spark plugs or hang em out to dry.. Or this is an undocumented Bosch feature: do you have any proof of this IRL? Adwo |
Posted By: adwo
Date Posted: 28-November-2003 at 21:09
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I can surely understand that!
I am betting on a injector not sealing intermittently combined with the gaskets leaking...
Same to you, let us know what you find... Adwo |
Posted By: M3Nally
Date Posted: 29-November-2003 at 12:02
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Well,
I have checked the plugs, all ok Checked the rotor cap, the contacts are a bit pitted but nothing to write home about Checked the coolant sensor ,reading seemed to be ok Sprayed the inlet manifold with carb cleaner and the revs rose! Sound familiar to anyone. Will leaking inlet gaskets get much worse quickly or can I leave it a while? Anyone got any instructions on changing them? Ta for all your help |
Posted By: grant w
Date Posted: 29-November-2003 at 12:46
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the simple solutions are often the best ,its your inlet blocks that need changing , it depends on how your going to drive your car , if it's a every day car and you like to give it some stick then i would change them straight away it won't do your valves or pistons any good running that weak on one or two cylinders .
you'll need to find out what size throttle bodies you have 46mm or 48mm , early cars had 46mm and later cars had 48mm . munich legands have both in stock , £49.17 each + vat and fitting .. munich legends 01825 740456 -------------
www.redevom3.co.uk 1989 e30 m3 2.5 1996 e36 m3 evo , sold 2002 e46 m3 smg . 1991 Daihatsu 2.8 TD Work Horse Rust Never Sleeps . Tattooed Lady - Bearded Baby - there my family .. |
Posted By: ROB ROSS
Date Posted: 29-November-2003 at 13:43
Leaking inlet gaskets. At least you have found the fault.You should really do them as soon as poss.
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Posted By: M3Nally
Date Posted: 01-December-2003 at 10:27
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Cheers chaps,
If I have an air leak, why do the plugs still look alright? I suspect it's because once it gets warm the leaks seal up and it then runs the right mixture. I had a look at Gustaves site where he uses paper gaskets from E28/E34 M5 to seal inlet leaks, has anyone done this? |
Posted By: grant w
Date Posted: 01-December-2003 at 11:55
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if your going to bodge the job why go to the trouble to import paper gaskets why not use some silicon sealer just as good if not better or just do the job properly .. -------------
www.redevom3.co.uk 1989 e30 m3 2.5 1996 e36 m3 evo , sold 2002 e46 m3 smg . 1991 Daihatsu 2.8 TD Work Horse Rust Never Sleeps . Tattooed Lady - Bearded Baby - there my family .. |
Posted By: adwo
Date Posted: 01-December-2003 at 13:35
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The S14 is very sensitive to intake leaks, you should tend to them immediately. Running lean at 7000 rpm is not something you want to do. Regarding the M5 gaskets: I tried them but they only work with the 46 mm throttle bodies, otherwise the shape is totally different.
Don't use silicon on the cylinderhead, you will regret it dearly when changing the gaskets the next time.. You can use it between the gasket and the throttle body though. Sparingly!! Regards, Adwo |
Posted By: 215DMX
Date Posted: 01-December-2003 at 13:45
| I believe BMW had a service update for this problem some years ago which was to use sealant and NOT to replace the intake blocks - anybody? |
Posted By: grant w
Date Posted: 01-December-2003 at 13:49
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i'm not endorsing the use of silicon i would'nt use it my self , i'd have new inlet blocks fitted straight away , as i found out to my cost on my old engine that had a air leak on a allready lean running engine and it destroyed one of the pistons , the use of silicon is a trick used by racing teams so that they don't have to keep fitting new inlet blocks ... -------------
www.redevom3.co.uk 1989 e30 m3 2.5 1996 e36 m3 evo , sold 2002 e46 m3 smg . 1991 Daihatsu 2.8 TD Work Horse Rust Never Sleeps . Tattooed Lady - Bearded Baby - there my family .. |
Posted By: M3Nally
Date Posted: 01-December-2003 at 14:52
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I never bodge anything, so do i need any special BMW tools to take the inlet manifold off?
How long to do this job? |
Posted By: David 87M3
Date Posted: 01-December-2003 at 16:28
BMW replaced my intake gaskets |
Posted By: M3Nally
Date Posted: 01-December-2003 at 17:14
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So if I phone my friendly local dealer they will kindly change mine gratis???!!!
That would be nice for Christmas. |