I just bought my first e30 yesterday! A red 1991 318is and when I start it, the revs go to 1500 and then as low as 300 and then sudenly goes up to 1500 and back down then up then to normal idle speed around 800-1000.
I will put a link to a youtube video so that you can see it happening. What could this be? The oxygen sensor? Mass airflow? Idle control valve or sensor?
Also, when I start rolling in first I need to up the revs to 1500 or more before declutching if not the car rocks front to back many times.
I cant thank you enough! Martin
Idle problem with my new e30!!!
Moderator: martauto
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m_jermyn
- E30 Zone Team Member
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- Joined: Sat Mar 14, 2009 11:00 pm
- Location: Sydney Australia Mate
Hey Martin,
Congratulations on your first e30 matey.
Sounds to me that you have a vacuum leak, they are typically in the big rubber hose from the airbox to the throttle body, check this for splits or cracks. If that all looks ok then it's time to look at the other smaller hoses. Pretty much any hose that's linked to the inlet manifold or throttle body. Sometimes the hose clamps are lose and other times the hose has torn or split...
The rubber hose that goes to the brake booster also needs looking at.
Look very carefully as it only needs a very small hole. By the sounds of it yours is a big one though
Good luck and report back
Mike
Congratulations on your first e30 matey.
Sounds to me that you have a vacuum leak, they are typically in the big rubber hose from the airbox to the throttle body, check this for splits or cracks. If that all looks ok then it's time to look at the other smaller hoses. Pretty much any hose that's linked to the inlet manifold or throttle body. Sometimes the hose clamps are lose and other times the hose has torn or split...
The rubber hose that goes to the brake booster also needs looking at.
Look very carefully as it only needs a very small hole. By the sounds of it yours is a big one though
Good luck and report back
Mike
Yeah, that's a fairly big "swing" - the big rubber boot, luckily, is a very common culprit.
"Also, when I start rolling in first I need to up the revs to 1500 or more before declutching if not the car rocks front to back many times. "
Mine would do this a little bit if you lugged it really low in 1st or 2nd. No idea if this is actually kosher, but while I was doing the thermostat last weekend, I removed part 6 below (e: camshaft position sensor) for better access to the housing and carefully cleaned it with contact cleaner and a soft cloth before reinsertion, basically just to keep any crap out of the head. However, doing this appears to have dramatically reduced that problem - I can now lug it down to stalling speeds without having to clutch it or add throttle.
Worth a try unless someone says different.
http://www.realoem.com/bmw/showparts.do ... g=11&fg=10
"Also, when I start rolling in first I need to up the revs to 1500 or more before declutching if not the car rocks front to back many times. "
Mine would do this a little bit if you lugged it really low in 1st or 2nd. No idea if this is actually kosher, but while I was doing the thermostat last weekend, I removed part 6 below (e: camshaft position sensor) for better access to the housing and carefully cleaned it with contact cleaner and a soft cloth before reinsertion, basically just to keep any crap out of the head. However, doing this appears to have dramatically reduced that problem - I can now lug it down to stalling speeds without having to clutch it or add throttle.
Worth a try unless someone says different.
http://www.realoem.com/bmw/showparts.do ... g=11&fg=10
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MrBenn
- E30 Zone Regular
- Posts: 672
- Joined: Sun Jan 20, 2008 11:00 pm
- Location: Bradford-on-Avon, Wiltshire
I just picked up a 318is on Saturday and it does exactly the same thing! I am going to be investigating it today along with a load of other little problems that these cars suffer from (central locking, mirrors not working, etc etc). Mine seems to only do it when cold and the rubber boots are all looking fairly new so I think its the engine temperature sensor thats at fault. Will let you know if I come up with anything.
Alex
Alex
You haven't said whether you've checked the boot and vacuum hoses, idle control valve and temp sensor yet. As far as the intake boot, you need to look over it fairly carefully - a small tear or pinhole can be hidden until you flex it.
The fact that you have a "racing" idle @1500 rpm (normal is what, 800 rpm?) strongly suggests you have an air leak, as your friendly neighborhood mod said back on the 18th, above.
You can try to trace the source using propane or spray carb cleaner, although at the very least obviously do this from cold. If you've visually inspected the likely culprits and can't find a problem, it may be worth paying a shop with a smoke machine to try to find it, though obviously you'd want to check out the sensors before spending the money.
The fact that you have a "racing" idle @1500 rpm (normal is what, 800 rpm?) strongly suggests you have an air leak, as your friendly neighborhood mod said back on the 18th, above.
You can try to trace the source using propane or spray carb cleaner, although at the very least obviously do this from cold. If you've visually inspected the likely culprits and can't find a problem, it may be worth paying a shop with a smoke machine to try to find it, though obviously you'd want to check out the sensors before spending the money.
m_jermyn wrote:Hey Martin,
Congratulations on your first e30 matey.
Sounds to me that you have a vacuum leak, they are typically in the big rubber hose from the airbox to the throttle body, check this for splits or cracks. If that all looks ok then it's time to look at the other smaller hoses. Pretty much any hose that's linked to the inlet manifold or throttle body. Sometimes the hose clamps are lose and other times the hose has torn or split...
The rubber hose that goes to the brake booster also needs looking at.
Look very carefully as it only needs a very small hole. By the sounds of it yours is a big one though
Good luck and report back
Mike
This was exactly what was wrong woth my car. It was bouncing revs and when parked seemd to be boucning teh whole car!
Mechanic diod few chescks, and the big rubber boot/pipe going in to the idle valve had massive tear in it !
Got another one from cotswolds for around £27 so hopefully that will sort it. I will find out tomorrow for definite when he has finished with it.
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Bakedbean100
- E30 Zone Regular
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- Joined: Tue Apr 06, 2010 11:00 pm
- Location: Suffolk/Cambridgeshire
sorry to hijack thread but my car does similar when turned on from warm. the revsgo from 1,000-500 like three time before settling into a normal idle.....any ideas?
I didn't change anything yet, hehe. Wanted to let you guys see the problem before going for anything. I think the big hose near the throttle body has tears, of course, having had my e30 for 2 days now I am still learning and will make a video of the engine (in the day) to show you which hoses im talking about 
Thank all of you for helping me out with this, means a lot! I'll be buying parts after my next video when you guys confirm Can't wait until I know this car inside out 
Thank all of you for helping me out with this, means a lot! I'll be buying parts after my next video when you guys confirm
Can't wait until I know this car inside out 
It seems to run fine once warmed up (most of the time) but then when getting to a light I put it in neutral and it sometimes stalls.magpie wrote:does it run ok when the it's warm ?
i know a little bit about these motors
When started from cold these days its been going way down in revs then up to 2500 and back down to about 400. Any ideas? Posting a vid showing my engine and some torn hoses right now.
it's all down to the torn hoses as said above.
do these first,there are some more tucked away under the inlet manifold that you may need to check.
it's easier to check these ones by removing the full inlet to investigate.
do these first,there are some more tucked away under the inlet manifold that you may need to check.
it's easier to check these ones by removing the full inlet to investigate.
m52 b30 stroker 6-speed 318is Galvanizer
m42 touring
+ a yard full of scrap turds
the radiator hose is full of water re your vid and nothing to do with air intake.
this is a throttle body ,the part in the middle.
this is a throttle body ,the part in the middle.
m52 b30 stroker 6-speed 318is Galvanizer
m42 touring
+ a yard full of scrap turds
The big boot between the throttle body and the sensor is definitely dead - that's probably 90% of your problem right there.
The little hose attached to the valve cover is a vent hose:
http://bmwfans.info/parts/catalog/E30/2 ... ead_cover/
So shouldn't be your problem.
That radiator top hose equally won't be the problem, as Magpie has already said, but if I were you I'd replace the top and bottom hoses - the ones that go to the same thermostat housing on the engine - when you next change your coolant.
Given that it's just about February in Quebec, you probably want to wait until warmer weather to do any major work on the cooling system, but I'd keep an eye on coolant level periodically to make sure a bad hose doesn't start slowly emptying the system once it's pressurised.
Then replace both the top and bottom hoses and flush out the cooling system. If the previous owner left that hose on rather than spend CN$20 or whatever on replacing it, I doubt they did much maintenance!
The little hose attached to the valve cover is a vent hose:
http://bmwfans.info/parts/catalog/E30/2 ... ead_cover/
So shouldn't be your problem.
That radiator top hose equally won't be the problem, as Magpie has already said, but if I were you I'd replace the top and bottom hoses - the ones that go to the same thermostat housing on the engine - when you next change your coolant.
Given that it's just about February in Quebec, you probably want to wait until warmer weather to do any major work on the cooling system, but I'd keep an eye on coolant level periodically to make sure a bad hose doesn't start slowly emptying the system once it's pressurised.
Then replace both the top and bottom hoses and flush out the cooling system. If the previous owner left that hose on rather than spend CN$20 or whatever on replacing it, I doubt they did much maintenance! Bump
I'm going to change the hose circled in orange, should the red circled hose be a problem? and why is there oil on the fan (circled in white)? Last but very important question, is the intake hose (orange) easy to change as to do it myself?
I'm going to change the hose circled in orange, should the red circled hose be a problem? and why is there oil on the fan (circled in white)? Last but very important question, is the intake hose (orange) easy to change as to do it myself?
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E30_Crazy
- E30 Zone Regular
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- Joined: Fri Mar 05, 2010 11:00 pm
- Location: Alaska, USA (Lived in Brandon, Suffolk)
Should be almost a no brainer to swap out the intake boot (orange hose). Two clamps, one on each end of the hose (at the throttle body and at the sensor). You might need to take the filter box out to fit the new one without damaging it. Oh, and there might be the idle control valve, ICV, on the boot too. Magpie?? I'm not as keen on M40/42 engines 
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The oil on the fan cover may just be from a small oil leak down on the fronside of the engine dripping/running onto the fan or fan clutch and being thrown back up on the cover.
. The oil on the fan cover may just be from a small oil leak down on the fronside of the engine dripping/running onto the fan or fan clutch and being thrown back up on the cover.