Unofficialbmw.com Forum Index Unofficialbmw.com
The UnofficialBMW BB, answers for your BMW questions.
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Weird Uncontrollable Revving

 
Post new topic   Reply to topic    Unofficialbmw.com Forum Index -> E30 - 3 Series Forum

Support Unofficialbmw.com :: Download Free Healthy Habits iPhone app!

View previous topic :: View next topic  
Author Message
MarkE



Joined: 17 Jan 2006
Posts: 49
Location: Covington, Ky

PostPosted: Tue Sep 27, 2011 3:29 pm    Post subject: Weird Uncontrollable Revving Reply with quote

OK, when I first got the car years ago, it did this odd revving thing for a minute, and then stopped. Like rev up to 3000rpms, then off, then up to 3000rpm then off, etc. It has happened a couple times since then to no ill effect. I gathered it was some sort of recalibration with the chip or some such.

Well, the other day, it started it again, while I was driving. That wasn't good, but it wasn't the end of the world. I was close to home and pulled it into my spot and let it do it's thing. I let it do it's thing for a bout 3 minutes. It wouldn't stop.

I turned it off, then back on and then it just revved high, no let off. I turned it off and let it cool. Started it again, and it went back to the on-off revving. I tried driving it and it never stopped, which was no fun on the little trip I took.

So, what the heck is this and what do I do about it? TIA

Mark

P.S. I've missed you guys. Smile
Back to top
View user's profile Send private message
85-325e



Joined: 30 Jun 2002
Posts: 4711
Location: Southampton, NY

PostPosted: Tue Sep 27, 2011 6:18 pm    Post subject: Reply with quote

Hay Mark... Welcome back Wink!

You know, I was having reverse problems recently with the idle dying off. Dale suggested cleaning the ICV (Idle Control Valve). When I did, I realized that this was an original part in my original car, and I had never cleaned it, So I popped it off, and cleaned it with carb cleaner, sprayed in there etc. It was amazing how dirty it was. Now, my idle is stable.

Don't know if that would help you out but that and the AFM (Air Flow Meter) could be sticking... I cleaned that too. They both helped I guess.

Not only is my idle stable, but when I come to a stop, the idle doesn't surge down, but gently drops.

Don't know if this will solve your problem, but they're simple, cheap things to try first. Dale did say that "idle" is always happening somehow.
_________________
Cosmo - 1985 BMW 325e, Single Owner, 235,000+ ORIGINAL miles and still going strong!

Back to top
View user's profile Send private message
polyrhythmic



Joined: 01 Sep 2006
Posts: 60

PostPosted: Wed Sep 28, 2011 1:38 pm    Post subject: Reply with quote

Sounds very much like your ICV. Your ICV could be sticking or the connection could be loose. Try unplugging it while the engine is running and see if you get the same effect. It's also worthwhile to clean the ICV with throttle body cleaner. I'm about to do mine as well as the TB while I'm at it.
_________________
Charles
1984 318i 5spd 3.91 LSD
Original UnofficialBMW BMW (Unofficially)
Pushing 300,000 and going strong Smile
Back to top
View user's profile Send private message
MarkE



Joined: 17 Jan 2006
Posts: 49
Location: Covington, Ky

PostPosted: Thu Sep 29, 2011 5:00 pm    Post subject: Reply with quote

polyrhythmic wrote:
Sounds very much like your ICV. Your ICV could be sticking or the connection could be loose. Try unplugging it while the engine is running and see if you get the same effect. It's also worthwhile to clean the ICV with throttle body cleaner. I'm about to do mine as well as the TB while I'm at it.


If you guys say so. I'll try it. You get that its like rev, then idle, rev, then idle, then rev, then idle, right?

So, can you guide me to to the ICV? The Bentley is less than clear. Also, anybody know about the Idle and Full Throttle Switch?

Thanks again,

Mark
Back to top
View user's profile Send private message
85-325e



Joined: 30 Jun 2002
Posts: 4711
Location: Southampton, NY

PostPosted: Thu Sep 29, 2011 8:38 pm    Post subject: Reply with quote

Hi again Mark...

OK, the Throttle Position Switch is under the throttle body. I have to be honest... I've never taken mine out but I did fiddle with one that I got with a head. They tend to fill with oil... they need to be drained by drilling a tiny weep hole in the bottom of the body of the sensor so it drains on a regular basis.

The ICV is on the exhaust side of the intake manifold... It's long and round (cylindrical), with a connector at one end and two hoses coming into it. You remove the two hoses and the connector, and you have the ICV valve in your hand. Then just spray it inside with carb cleaner until it's clean. Shouldn't take more than a few minutes.

Also, check ALL of your hoses, even the big ones, for open areas or cracks. Air can wreak havoc with your idle.
_________________
Cosmo - 1985 BMW 325e, Single Owner, 235,000+ ORIGINAL miles and still going strong!

Back to top
View user's profile Send private message
idanity



Joined: 21 May 2005
Posts: 3097
Location: N.W.U.S.A.

PostPosted: Fri Sep 30, 2011 7:49 pm    Post subject: Reply with quote

yup...what he said...^^

sounds like a full tuneup is in order, maybe a quick check on all the vacuum hoses too (at .88cents a foot, replace any cracked ones).

i had my TPS full of varnish, and i clipped a corner off with a drill or a 4" cutoff wheel (don't remember which) and it did drop some water/ fuel / >? dont know but i do know i sprayed that sealed black unit with electronics cleaner, until it emptied out clear (it started brown, like coffee)...never needed to replace it, but since then, i haven't had an issue with it.


my cold start valve was checked at the beginning of the summer and it is still sparkling clean. (that lasted 5 years now w/no need to re-clean since the rebuild).

most components are very bulletproof, but luckily (depends on how you look at it) our bmws are temperamental.

at least it still drives...however terrible, it does start, so you at least have a basis to work with..its so tough to work with a car that shuts down with every failure and leaves you (or me) guessing on too many fronts.


hope that helps.
_________________
..........
Back to top
View user's profile Send private message
m78



Joined: 14 Nov 2001
Posts: 2807
Location: In the great midwest

PostPosted: Fri Sep 30, 2011 10:08 pm    Post subject: Reply with quote

If after you clean the ICV and you get no appreciable improvement, you may check the infamous c191 plug (that is if your car has one).

The symptoms sound suspiciously like what happens when the c191 plug begins to fail.
_________________
Lachssilber Metallic 203 1988 325i sedan with 200,xxx miles

Top Speed 220 km/h

(OO=00=OO)
Back to top
View user's profile Send private message
85-325e



Joined: 30 Jun 2002
Posts: 4711
Location: Southampton, NY

PostPosted: Sat Oct 01, 2011 12:47 am    Post subject: Reply with quote

Yeah, Mark... it would help to know what car you have as there are differences between the ETA, the Super ETA, and the "i" series cars.
_________________
Cosmo - 1985 BMW 325e, Single Owner, 235,000+ ORIGINAL miles and still going strong!

Back to top
View user's profile Send private message
dale



Joined: 22 Aug 1999
Posts: 3087
Location: Seattle, WA USA

PostPosted: Sun Oct 02, 2011 12:33 am    Post subject: Reply with quote

Based on MarkE's post here from a few years ago, he has a 12/84 build date 1985 325e
http://www.unofficialbmw.com/phpBB/viewtopic.php?t=27313

Let us know when you clean the ICV and how the affects your idle. If you have a multimeter, you can try adjusting the ICV as well if you want to change the idle speed.

I was helping a friend get his 325i going and it was idling at 1800rpm, turns out his TPU (throttle position switch) was flooded with oil leakage from the throttle body. When that lower seal goes out, the oil leaks down into the TPU.

One safety tip for your ETA, change out the factory plastic T fitting for a new brass T fitting. The plastic gets brittle with age and heat and if it cracks it'll spray fuel all over your exhaust, not good.
_________________
http://www.unofficialbmw.com
UnofficialBMW.com Webmaster
dale@unofficialbmw.com
sold in 2016
87 325 5spd eta
Back to top
View user's profile Send private message
85-325e



Joined: 30 Jun 2002
Posts: 4711
Location: Southampton, NY

PostPosted: Sun Oct 02, 2011 12:00 pm    Post subject: Reply with quote

Gee Dale... I forgot all about that plastic fitting... just ordered the set of 3 assorted ones from Amazon... Thanks for the heads up...
_________________
Cosmo - 1985 BMW 325e, Single Owner, 235,000+ ORIGINAL miles and still going strong!

Back to top
View user's profile Send private message
MarkE



Joined: 17 Jan 2006
Posts: 49
Location: Covington, Ky

PostPosted: Mon Oct 24, 2011 4:01 pm    Post subject: Reply with quote

dale wrote:
Based on MarkE's post here from a few years ago, he has a 12/84 build date 1985 325e
http://www.unofficialbmw.com/phpBB/viewtopic.php?t=27313

Let us know when you clean the ICV and how the affects your idle. If you have a multimeter, you can try adjusting the ICV as well if you want to change the idle speed.

I was helping a friend get his 325i going and it was idling at 1800rpm, turns out his TPU (throttle position switch) was flooded with oil leakage from the throttle body. When that lower seal goes out, the oil leaks down into the TPU.

One safety tip for your ETA, change out the factory plastic T fitting for a new brass T fitting. The plastic gets brittle with age and heat and if it cracks it'll spray fuel all over your exhaust, not good.


Hi guys. Thanks for the help so far. I got busy and back burnered this issue for a bit and just drove my wife's car. BUT, I'm back on it. I cleaned the pretty dirty ICV and it revved just a bit lower and smoother, but it revved. It starts as a very high idle when cold and then, when I depress and let out the clutch, it goes to Rev-idle-rev-idle-rev-idle still. Every time.

I thought I'd diddle around with TPS next. The date of build obviates the C191 thing. Any other suggestions?

Thanks, again. You guys rock.

Mark
Back to top
View user's profile Send private message
85-325e



Joined: 30 Jun 2002
Posts: 4711
Location: Southampton, NY

PostPosted: Mon Oct 24, 2011 8:03 pm    Post subject: Reply with quote

Mark...

The car SHOULD idle hi when cold. In fact, when you start the car, you shouldn't touch the accelerator, but just turn the key. The engine will automatically rev high and will lower when you hit the accelerator.

I don't think that's your roblem, but it's just the way you're supposed to start the car.

I think you need to chak all hoses for leaks or cracks. Air leaks can really create huge issues...
_________________
Cosmo - 1985 BMW 325e, Single Owner, 235,000+ ORIGINAL miles and still going strong!

Back to top
View user's profile Send private message
MarkE



Joined: 17 Jan 2006
Posts: 49
Location: Covington, Ky

PostPosted: Tue Apr 16, 2013 6:11 pm    Post subject: Reply with quote

FOLLOWING UP (sorry for the delay). I finally broke down and took it to the mech. Turns out it WAS the ICV. It was shot. Replaced and had me going fast. Of course, I thought it wasn't that so I didn't bother replacing, but that's the breaks.

Thanks for the help.

Mark
Back to top
View user's profile Send private message
85-325e



Joined: 30 Jun 2002
Posts: 4711
Location: Southampton, NY

PostPosted: Tue Apr 16, 2013 9:05 pm    Post subject: Reply with quote

Well, at least it's working for you now, and that's the most important. Congrats on the nice fix!
_________________
Cosmo - 1985 BMW 325e, Single Owner, 235,000+ ORIGINAL miles and still going strong!

Back to top
View user's profile Send private message
MarkE



Joined: 17 Jan 2006
Posts: 49
Location: Covington, Ky

PostPosted: Tue Apr 16, 2013 10:46 pm    Post subject: Reply with quote

Let me tell you, I had visions of being the master of all my BMW repairs.

Well, it's easy if you have a garage and it's easy if you've got the time, but I've found that when I'm busy I'm like every other schmuck out there who lets his car deteriorate around him. Sure I've done a lot, but I've let my car down too. I'm here, before you guys taking ownership for my failings.

Of course, I'm still in love with the car and the build. I've got two and we're going for more. But it's not so easy to stay up on things. You guys help, a LOT.

Mark
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Unofficialbmw.com Forum Index -> E30 - 3 Series Forum All times are GMT - 5 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum



Powered by phpBB © 2001, 2005 phpBB Group