Jerky Acceleration

[dreman77]

With the problems I have now, my acceleration had to join in as well.

I was going uphill quite slowly and all of a sudden the car started to jerk and the revs kept going up and down. I stopped at the traffic light and the car died. AArrrggghhh!!!!! I started it again and it started right up but now the idling is erratic. It moves up and down from 1000 rpm to 500 rpm. It normally sits at about the 700 mark. Driving it back slowly and it was still jerky all the way back. When I accelerated harder, about 2500 - 3000 rpm, the jerkiness went away.

I dont even know where to start looking as I have not ordered the bentley manual.

Please help....... thanks

[Morgenster]

Check the elbow hose from idle valve to intake manifold (it's right under the intake manifold and not so easy to reach). Most likely vacuum leak.

[bmwrp8]

check The Elbow Hose From Idle Valve To Intake Manifold (it's Right Under The Intake Manifold And Not So Easy To Reach). Most Likely Vacuum Leak.

+1

[dreman77]

+1

ok... i have looked at the intake manifold, under it, around it and i see alot of hoses but do not know which one is the vacuum hose. I really must be stupid. I ave had a look at realoem and am still lost. Could anyone point me in the right direction please while i am still searching for a bently here in oz.

thanks

[bmwrp8]

ok... i have looked at the intake manifold, under it, around it and i see alot of hoses but do not know which one is the vacuum hose. I really must be stupid. I ave had a look at realoem and am still lost. Could anyone point me in the right direction please while i am still searching for a bently here in oz.

thanks

here, it's for an e36 but m50 motor hope this helps http://www.bimmermania.com/viewtopic.php?t=180

[dreman77]

here, it's for an e36 but m50 motor hope this helps http://www.bimmermania.com/viewtopic.php?t=180

Thanks alot. its alot clearer now. In the photo of the ICV, where does the suspect leaking elbow connect to? Left or right of the picture shown?

[bmwrp8]

Thanks alot. its alot clearer now. In the photo of the ICV, where does the suspect leaking elbow connect to? Left or right of the picture shown?

just check both or not all your vacuum hose including the intake boot. does not matter where the leak is.. vacuum leak = bad idle

[dreman77]

just check both or not all your vacuum hose including the intake boot. does not matter where the leak is.. vacuum leak = bad idle

Hi all,

I removed the ICV today with both hoses. I checked the hoses and the elbow which connects to the intake boot. I also checked all the lines that connected to the intake boot in one way or another. While some of the hoses were cracked, they were not cracked right through. Could they still have caused the bad idle. I did notice what I believe to be engine oil in the breather tube. At least thats what I think the tube is. There was oil in the intake boot and a bit around the throttle. Is this normal?

I will clean the ICV but I also want to clean the throttle. Should I do it still attached to the intake manifold or take it off. By looking at it, i think ist only being held by 4 hex bolt and the switch.

[Morgenster]

Hi all,

I removed the ICV today with both hoses. I checked the hoses and the elbow which connects to the intake boot. I also checked all the lines that connected to the intake boot in one way or another. While some of the hoses were cracked, they were not cracked right through. Could they still have caused the bad idle. I did notice what I believe to be engine oil in the breather tube. At least thats what I think the tube is. There was oil in the intake boot and a bit around the throttle. Is this normal?

I will clean the ICV but I also want to clean the throttle. Should I do it still attached to the intake manifold or take it off. By looking at it, i think ist only being held by 4 hex bolt and the switch.

I don't think it hurts to take it off, but I don't think it's necessary.
Cracks are a bad sign, but chances are that after disassembling - cleaning - and reassembling averything will work normally again, just because something was not attached properly or clean enough before.
The breather hose carries crankcase fumes into the manifold and it should be slightly oily but not too much. Unless you're not talking about the crankcase ventilation hose connected to front of the engine.
See how everything works after cleaning and reassembling. It's a good introduction to your engine and if it solves the problem you're saved.
If it doesn't solve the problem you can move on to more difficult stuff.

[russiankid]

If you have an M50 engine the hose coming from the ICV to the intake boot is on the right side standing from the drivers side. The U-hose or as some refer to as " crooked penis hose" runs from the ICV to the intake manifold. This one is fairly hard to see.

[dreman77]

With the problems I have now, my acceleration had to join in as well.

I was going uphill quite slowly and all of a sudden the car started to jerk and the revs kept going up and down. I stopped at the traffic light and the car died. AArrrggghhh!!!!! I started it again and it started right up but now the idling is erratic. It moves up and down from 1000 rpm to 500 rpm. It normally sits at about the 700 mark. Driving it back slowly and it was still jerky all the way back. When I accelerated harder, about 2500 - 3000 rpm, the jerkiness went away.

I dont even know where to start looking as I have not ordered the bentley manual.

Please help....... thanks

Thank everyone for your help. Pulled the ICV and hoses out and put them back after cleaning the ICV and the idling is alright now. However I did not find any major cracks that contributed to this. I did find that my o-ring on the connector into the intake manifold is worn and will replace once I get the part. Hopefully this doesnt happen again.

However now the rpms sit a bit higher and I noticed that the rpm takes a second or two longer to return to idle when coming to a stop after releasing the accelerator. I hope it will work itself out. :D

Thanks again.

[bmwrp8]

However now the rpms sit a bit higher and I noticed that the rpm takes a second or two longer to return to idle when coming to a stop after releasing the accelerator. I hope it will work itself out. :D



mine's also like that after i cleaned my ICV but yup after a few days it goes back to normal

[Morgenster]

Thank everyone for your help. Pulled the ICV and hoses out and put them back after cleaning the ICV and the idling is alright now. However I did not find any major cracks that contributed to this. I did find that my o-ring on the connector into the intake manifold is worn and will replace once I get the part. Hopefully this doesnt happen again.

However now the rpms sit a bit higher and I noticed that the rpm takes a second or two longer to return to idle when coming to a stop after releasing the accelerator. I hope it will work itself out. :D

Thanks again.

If you disconnected the battery before starting work and reconnected afterwards then that is to be expeced and it will settle to a more normal tune after a few drives.

[paanta]

If you've got minor cracks, I'd replace as many vacuum lines as possible. That stuff is cheap enough that it makes sense to do it before you have problems, IMO.

[dreman77]

If you've got minor cracks, I'd replace as many vacuum lines as possible. That stuff is cheap enough that it makes sense to do it before you have problems, IMO.

I will. I have to order the parts from overseas though as the want an arm and a leg for it here. I also just realised that the temperature sensor in the air filter box is broken. There are no wires running from it into anywhere. I tried looking in realoem but i cant seem to find the part. will this be a major issue if the car doesnt know what temp is coming in?

[Morgenster]

I will. I have to order the parts from overseas though as the want an arm and a leg for it here. I also just realised that the temperature sensor in the air filter box is broken. There are no wires running from it into anywhere. I tried looking in realoem but i cant seem to find the part. will this be a major issue if the car doesnt know what temp is coming in?

Broken how?
Iirc it is not related to motor management itself but to some valve for warming the throttle body or something.

[dreman77]

Broken how?
Iirc it is not related to motor management itself but to some valve for warming the throttle body or something.

its broken as in there are no wires attached to it and i can see the spring inside. ;(