Fixed - M88 Rough Idle, Noise, Vibration till warm.
Moderators: GRNSHRK, ron, bfons
Fixed - M88 Rough Idle, Noise, Vibration till warm.
85' M635.... Having an issue with a rough idle and lots of noise from the engine at startup, as in once it starts when cold, it will idle/sputter/miss at much lower than 850 it's set at and makes a lot of noise from the front of the engine, until it warms up, then it runs/idles fine, no noise. I typically will start it and feather the gas to get it stable after a few seconds, but the noise/shaking is a lot. At first I thought it was the ambient temp here in St. Louis as it was still cold in the morning, 30-40 degrees in my garage, but as its warmed up to spring its still occurring. M88 engine, Timing chain and guides were done along with a ton of other stuff, belts, hoses, oil pump rebuilt, water pump, new exhaust, headers, within the past 1000 miles or so, by my friend @brickwhite, who I bought the car off of this spring. Oil level is fine, no smoking or anything, no vacuum leaks, nothing is obviously loose near, above, or below where I believe the noise is coming from, but it does sound like the chain area, but then goes away once it warms up. I can see oil moving around if I open the Oil Cap while its running, so everything looks like it's doing what it should and after its warm and idles at 850 on its own, no issues at all, runs and drives great. Taking it in to my mechanic next week but curious what anyone thinks this could be.
Link to video https://youtu.be/X9GrwthJWWA
Link to video https://youtu.be/X9GrwthJWWA
Last edited by passta on Sat May 15, 2021 1:49 am, edited 1 time in total.
Saint Louis, MO
90 E32 750il
85 M635CSi
15 F10 M5 (gone)
07 E60 550 (gone)
02 E39 540 Touring (gone)
87 E28 535IS (gone)
85 E23 735 5spd(gone)
85 E24 635CSI (gone)
86 E28 535IS (gone)
90 E32 750il
85 M635CSi
15 F10 M5 (gone)
07 E60 550 (gone)
02 E39 540 Touring (gone)
87 E28 535IS (gone)
85 E23 735 5spd(gone)
85 E24 635CSI (gone)
86 E28 535IS (gone)
- Ralph in Socal
- Platinum Member
- Posts: 2748
- Joined: Tue Apr 14, 2009 3:32 am
- Location: High Desert of SoCal
Re: M88 Rough Idle, Noise, Vibration till warm.
I’m not expert on the M motors but isn’t the front crank hub a known failure point? I would check that asap as worsening can then damage the crank as well. Good luck
Ralph
Ralph
There is a very fine line between "Hobby" and Mental Illness.
85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)
85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)
Re: M88 Rough Idle, Noise, Vibration till warm.
That's been replaced same time as the chain and everything else as well.Ralph in Socal wrote: ↑Thu May 06, 2021 4:44 pm I’m not expert on the M motors but isn’t the front crank hub a known failure point? I would check that asap as worsening can then damage the crank as well. Good luck
Ralph
Saint Louis, MO
90 E32 750il
85 M635CSi
15 F10 M5 (gone)
07 E60 550 (gone)
02 E39 540 Touring (gone)
87 E28 535IS (gone)
85 E23 735 5spd(gone)
85 E24 635CSI (gone)
86 E28 535IS (gone)
90 E32 750il
85 M635CSi
15 F10 M5 (gone)
07 E60 550 (gone)
02 E39 540 Touring (gone)
87 E28 535IS (gone)
85 E23 735 5spd(gone)
85 E24 635CSI (gone)
86 E28 535IS (gone)
-
- Platinum Member
- Posts: 3320
- Joined: Thu Sep 28, 2006 9:28 pm
- Location: scottsdale, arizona
- Contact:
Re: M88 Rough Idle, Noise, Vibration till warm.
Could the noise come from a worn out chain tensioner??
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
flickr.com/photos/bertsphotos.
Re: M88 Rough Idle, Noise, Vibration till warm.
I thought the same because it sounds like it but it is new as well. Not to say it couldn't be bad or something though...
Saint Louis, MO
90 E32 750il
85 M635CSi
15 F10 M5 (gone)
07 E60 550 (gone)
02 E39 540 Touring (gone)
87 E28 535IS (gone)
85 E23 735 5spd(gone)
85 E24 635CSI (gone)
86 E28 535IS (gone)
90 E32 750il
85 M635CSi
15 F10 M5 (gone)
07 E60 550 (gone)
02 E39 540 Touring (gone)
87 E28 535IS (gone)
85 E23 735 5spd(gone)
85 E24 635CSI (gone)
86 E28 535IS (gone)
Re: M88 Rough Idle, Noise, Vibration till warm.
What about the oil pump chain tension, it needs to be shimmed properly.
Leonard
80 633 polaris
79 635 (euro) fjord
85 635 schwarz
80 633 polaris
79 635 (euro) fjord
85 635 schwarz
-
- Platinum Member
- Posts: 1659
- Joined: Mon Jul 16, 2007 2:58 pm
- Location: Cheltenham, U.K.
Re: M88 Rough Idle, Noise, Vibration till warm.
Rough idle only sorted on my M with properly balancing tbs with manometer.
That noise sounds to me like something loose after your rebuild - hopefully nothing internal, but definitely worth checking pulley to crank hub bolts, crank hub main nut, tensioner mounting nut etc. I've found fastenings that I've marked with paint that have loosened after a few thousand miles - drive shaft (or whatever you call the shafts that take drive from the diff to the rear wheels) allen-headed bolts being my most serious culprit, probably because there was oil in the threads.
Hope you get it sorted soon so you can enjoy that banshee wail as you wind it up! A glorious noise.
All the best,
Rob
That noise sounds to me like something loose after your rebuild - hopefully nothing internal, but definitely worth checking pulley to crank hub bolts, crank hub main nut, tensioner mounting nut etc. I've found fastenings that I've marked with paint that have loosened after a few thousand miles - drive shaft (or whatever you call the shafts that take drive from the diff to the rear wheels) allen-headed bolts being my most serious culprit, probably because there was oil in the threads.
Hope you get it sorted soon so you can enjoy that banshee wail as you wind it up! A glorious noise.
All the best,
Rob
"Most of it necessary; all of it enjoyable." LJKS
'84 635CSi, dogleg...itbs and supercharger????? Eaton Mess
'84 635CSi, dogleg...itbs and supercharger????? Eaton Mess
Re: M88 Rough Idle, Noise, Vibration till warm.
I wonder if the cold start injector is bad. Mine does this when its cold and I know my cold start injector isnt really doing anything. But when mine warms up its fine as well. I'm fairly certain mine has to do with the Johnson box that was installed when it was federalized in '85. I unhooked mine last weekend thinking that would help but I need to go back in and remove the wiring and repair the connection to the coolant temp sensor that the motronic uses for cold start and fuel enrichment. From what I've read the Johnson box intercepts this signal and uses an O2 sensor and potentiometers to work like a piggyback O2 sensor. Sorry for the long reply but you might be experiencing the same issue.
On cold start, disconnect the Cold Start injector and see if that makes any difference. It's the blue Bosch connector on top of the Throttle bodies.
On cold start, disconnect the Cold Start injector and see if that makes any difference. It's the blue Bosch connector on top of the Throttle bodies.
Re: M88 Rough Idle, Noise, Vibration till warm.
I've reached the limits of what I can do in my limited time and garage space and am going to have it checked out this week by the shop I use. I'll post back what the outcome is hopefully this week.
Saint Louis, MO
90 E32 750il
85 M635CSi
15 F10 M5 (gone)
07 E60 550 (gone)
02 E39 540 Touring (gone)
87 E28 535IS (gone)
85 E23 735 5spd(gone)
85 E24 635CSI (gone)
86 E28 535IS (gone)
90 E32 750il
85 M635CSi
15 F10 M5 (gone)
07 E60 550 (gone)
02 E39 540 Touring (gone)
87 E28 535IS (gone)
85 E23 735 5spd(gone)
85 E24 635CSI (gone)
86 E28 535IS (gone)
Re: M88 Rough Idle, Noise, Vibration till warm.
'Ralph in Socal' and 'Wattsmonkey' you were both right. Issue was loose, actually missing, bolts on the crank hub. 4 of the 8 were no longer there and had worked there way out. Had those put back in with thread locker & tightened to spec, and then the remaining 4 removed, checked and thread lockered those, and tightened. The hub itself which was a new hardened one from BenGerman on mye28.com was fine and no other damage done luckily.
Saint Louis, MO
90 E32 750il
85 M635CSi
15 F10 M5 (gone)
07 E60 550 (gone)
02 E39 540 Touring (gone)
87 E28 535IS (gone)
85 E23 735 5spd(gone)
85 E24 635CSI (gone)
86 E28 535IS (gone)
90 E32 750il
85 M635CSi
15 F10 M5 (gone)
07 E60 550 (gone)
02 E39 540 Touring (gone)
87 E28 535IS (gone)
85 E23 735 5spd(gone)
85 E24 635CSI (gone)
86 E28 535IS (gone)
-
- Platinum Member
- Posts: 1659
- Joined: Mon Jul 16, 2007 2:58 pm
- Location: Cheltenham, U.K.
Re: Fixed - M88 Rough Idle, Noise, Vibration till warm.
Glad you got that sorted before expensive damage!
"Most of it necessary; all of it enjoyable." LJKS
'84 635CSi, dogleg...itbs and supercharger????? Eaton Mess
'84 635CSi, dogleg...itbs and supercharger????? Eaton Mess