Engine STILL occasionally reving up on its own 'FIXED'

[abelai]

Hi 320iAN

Well from your posts you seem to be looking hard for the answers to our idle problem which is great. I've come to the conclusion it is 100% and electrical fault and has to be linked some how to to the fact that when the car is rolling the idle is good. I'm going to try seeing if disconnecting the speed pick up on the diff makes any difference and also swap the clocks as I believe that the speed signal goes through the clocks (SI board not sure yet) then to the DME also goes to OBC. Does your car have an OBC?

I read somewhere while searching for information on motronic 1.3 that it runs a different idle for rolling and not rolling but haven't been able to confirm this and anybody out there reading this can you please let us know if your idle is higher when rolling than stationary.

[liquid079]

Ok, I'm now waiting for a crank position sensor and a new battery, wednesday should bring good things.

Whistle... whistle...

I'm now certain this problem is totally intermittent, i.e not temperature, time or speed related, driving down a bumpy road nor thrashing the car will make it happen. And it hasn't got any worse over time... infact if anything it isn't as bad as it used to be.

This means it's bloody hard to diagnose . Although I have the advantage that over an hour of driving it will do it at least once.

I've managed to test the current to the TPS while it's revving eratically, and the voltages stay the seem, so for a second time I think the TPS is all good. Blipping the throttle cause the engine to splutter, so I'm sure it is then overfueling.

I have to keep remembering that this problem first reared its ugly head on the wetest day we have had this year.

Dan.

Saboor- having the battery in the boot must be a pain in the Ass.

[320iAN]

abelai: i bought my E30 with the fault, i just put it down to the car needing a drive as it had stood still for 4 mths then after a 45 mile drive home i pulled up in my drive and the idle was as it still is now

if i blip the throttle a few times the car almost stalls when i let the throttle go and the engine struggles to settle .. sounds very same as your Dan?

Ian

[liquid079]

320iAN-Is there any sort of pattern to your crazy idle, i.e does it do it more when its warm/cold after a long drive etc?

Have you tried spraying wd40 around all the intake parts to show up a possible leak?


And have you taken the top of your AFM, to see what state it is in?

Mine tries to stall, although normally clears itself if I give it some beans, on application of throttle.

[Martinaston]

Take the air box off of the air flow meter and get someone else to start the car, while there cranking it have a look at the door of the meter and see if it holds staedy part way open or if its bouncing due to a worn spring.

liquid079
What symptoms do you have now you've vitrualy rebuilt it ?

[siddiqi1]

I know this has probably been suggested, but just wanted to give a suggestion.

Once when fiddling with my car, due to cold start issues, i started squeezing and shaking the boot under the Inlet Manifold" and then my revs starting rising up to 1500rpm.

Ill be honest, i shat myslef as i thought all hell was about ot break loose, i cut the engine immediately. I then started her up again and it rose to 1500rpm again, i cut it off again.

I then went back to the Rubber boot and wiggled it a bit more, went to start it and then it was fine.

Could you possibly hard wire in the connections there, that may solve it?

Regards

Saboor

Saboor- having the battery in the boot must be a pain in the Ass.

It is, Ill have to connect up two jump leads to reach!!!

[320iAN]

320iAN-Is there any sort of pattern to your crazy idle, i.e does it do it more when its warm/cold after a long drive etc?

Have you tried spraying wd40 around all the intake parts to show up a possible leak?


And have you taken the top of your AFM, to see what state it is in?

Mine tries to stall, although normally clears itself if I give it some beans, on application of throttle.

it's worse the warmer the engine get's, starts up "spot on" ive tried a AFM that i know works but it was from my old 320i Auto and it would not even idle with it fitted?. all the rubber air hose's look fine, when my car starts to idle rough i can rev it no prob's .. but if i just "blip" the throttle the rev's stutter and then drop right down, driving is fine just if i'm moving the car slowly (parking etc) with hardley any throttle it will stall.

[liquid079]

liquid079
What symptoms do you have now you've vitrualy rebuilt it ?

Symtoms- Yesterday started her up, she idled a little high(900rpm ish) and fairly smoothly, although not as smoothly as once was . Left her to idle for a few minutes and all seemed fine. Drove for a few miles until up to temp, pulled over in a layby, still idling normally had a fiddle under the bonnet for the umpteenth time checking wires, air hoses, crank position sensor etc anything that might set this thing off... Nothing.

Drove on round the block, seemed to be driving pretty well, although not perfect, 10 minutes later arrived back home pulled up, revs rose once then dropped back down to normal then 20 seconds later started rising and falling between 1500rpm and 2000rpm, bliping the throttle seemed to momentarily stop it but then it would start again. Holding the throttle caused it to splutter and miss but no longer seems to cause it to stall .

Never seems to do it for more than a couple of minutes, after that it is back to normal, for how long?? there is no pattern to it, sometimes it will do it regularly, sometimes hardly atall, but always at least once in a thirty minute period.

Saboor- I have checked for visible loose connections and cannot find anything through wiggling pulling pushing anything, including underneath the DME relay. Do you mean the rubber boot covering the TPS connector?

320iAN- So your problem could possibly be time/temp related?

I'm going to know my car like the back of my hand when this is finnished

[320iAN]

i don't think my cars problem is to do with temp .. i started it up tonight to try and see at how long the car idle's normaly at .. not long, only a few min's of idle/running and it started to drop it's rev's then the fuel eco needle started jumping!!
it started to stutter on idle before the temp-gauge even started to move .. i remember the night i bought it and i started (jump-leads) the car and almost straight away it was idleing rough but like i said it had stood for 4 mths so i put it down to lack of use? at the moment i can drive the car as ive strippd the rear lights and bumper of the rear end.
i'm off work this thursday and i was going to do some body work on my E30 but it look's like i'll be checking as many electrical & earth connections as i can.. this problem must be one of them really stupid easy to fix faults but takes a life time to find it!!

[Martinaston]

liquid079
Have you checked the vacuum pipes to the brake servo ? try a bit of silicon around the twin pipes that come out the side of the throttle body.

320iAN
If its just a lumpy idle the injectors probably need a clean, do you get much water from the exhaust ?

[320iAN]

no, no water from the exhaust .. in fact very strangly this is the first E30 ive owned that hasn't even got a small cloud/puff of smoke on start up (valve stem's must have been done at some point?)

[liquid079]

liquid079
Have you checked the vacuum pipes to the brake servo ? try a bit of silicon around the twin pipes that come out the side of the throttle body.

One of the pipes around the throttle body is maybe a little loose, but it always has been, do you think the miniscule amount of air possibly leaking here could cause a problem? But good idea I shall try that anyway.

I'm also going to have another good check for air leaks.

Dan.

[siddiqi1]

No buddy, i mean the rubber boot right underneath the inlet manifold. If you remove the rubber hosefrom the AFM to THROTTLE, and look straight down, you will see it.

It is in two halves, they screw together......right underneath the inlet manifold, AFM side.....you cant miss it. If you even follow the lead from the AFM you will knowwhat im talkinig about, im sure your problem lies there

Regards

Saboor

ps: 4 pages now, we have gotah to sort this out

[liquid079]

No buddy, i mean the rubber boot right underneath the inlet manifold. If you remove the rubber hosefrom the AFM to THROTTLE, and look straight down, you will see it.

It is in two halves, they screw together......right underneath the inlet manifold, AFM side.....you cant miss it. If you even follow the lead from the AFM you will knowwhat im talkinig about, im sure your problem lies there

Regards

Saboor

ps: 4 pages now, we have gotah to sort this out

Oh yea the loom connector, this was one of the first things I checked, as it made sense as it was close to the road and water could have got in there. The connections were like new under there, and I also peeled the boot back and had a look.

I also checked the c101 loom connector in the same way thanks to mr moore's advice, this was fine as well.

But I will double check.

Thanks, Dan.

P.S Got my BMW battery today, so the testing can begin again, The crank position sensor should be on it's way.

[siddiqi1]

Sorry for double suggestion, this is an odd one! Its even gotthe best of the zone scratching, i think its one of those things needed to be witnessed in person

Saboor

[liquid079]

Changed my mind now, this is definately worse once the engine is warmed up (properly warmed up).
Seems to happen more often, when cold it happens occasionally, when warm it happens more often.

Noticed today that the eco-meter bounces about with the revs. Under throttle it splutters untill about 4000rpm-5000rpm and then it seems to almost clear itself.

Also noticed that the revs start off between 1500-2000rpm, and then the range gets narrower and narrower, going up the dial untill it holds at around 2000rpm, then it will suddenly drop back to normal.

While driving along and its playing up I can take my foot off the throttle and its like having cruise control, it will hold at a certain speed, dipping the clutch and revving the engine does not stop it.

Someone PLEASE help, I think my cars gone mad!!

[320iAN]

i was talking to a mechanic tonight that i know and he say's he worked on a E30 yrs ago with what sounds like the same fault as this and he say's it was found to have been a hair-line crack on the air box ? ive got a spare AFM and box so tomorrow i'll swap over the MAF from my car on to my spare air box and see what happens

some how i doubt it was the same fault though

[liquid079]

i was talking to a mechanic tonight that i know and he say's he worked on a E30 yrs ago with what sounds like the same fault as this and he say's it was found to have been a hair-line crack on the air box ? ive got a spare AFM and box so tomorrow i'll swap over the MAF from my car on to my spare air box and see what happens

some how i doubt it was the same fault though

I don't understand how a crack on the 'fresh air side' of the air meter could cause any real running problems though??

Did I read right that you have a Mass Air Meter on your car as well?

Talking of air leaks I checked with wd40 for any, with no luck. This is strange as taking the oil cap off does not result in any change in the engine note It used to!

Dan.

[320iAN]

woops no my car and my spare airbox are both AFM types .. just my spare is from my old 320 Auto and the meter is nacked, like i says i doubt it was the same fault? but anything is worth a try

i'm almost finished the body work on my car then i'll set my sights on my car's idle issue more ive listed my cars faults just so it's easier to see and to see if anyone's car has the same fault?

my idle faults
1990 320i manual
starts fine
idle "spot on" when cold
idle "hunts" after a few min's before the temp gauge even starts to move!
rev's fine but give the throttle gentle tap's/blips and it will almost stall the engine
rev's jump up and down between 400 + 2000 rpm on idle
eco fuel gauge needle jumps from 0 to 50mpg iradicly on idle
car drives fine, pulls fine but has stalled at stop junctions.

[siddiqi1]

I don't understand how a crack on the 'fresh air side' of the air meter could cause any real running problems though??

Did I read right that you have a Mass Air Meter on your car as well?

Talking of air leaks I checked with wd40 for any, with no luck. This is strange as taking the oil cap off does not result in any change in the engine note It used to!

Dan.

Mine for a fact does hunt at idle once i take off the oil filler cap. A friends E30 doesnt do that either, it was suggested that maybe a blocked breather could be the result, though i believe there is a leak somewhere, possibly exh. manifold side?

I assume youve done the TPS?

Saboor

[liquid079]

Saboor- My engine used to drop like yours when the oil cap was released. The only air leak I can think of now is the inlet manifold gasket, or the EGR valve , or maybe fuel injectors??

320iAN-I have a TPS off a 320i tested, so I think it works fine, yours very cheap.

[liquid079]

Yea I've done the TPS, not the slightest difference

[Martinaston]

liquid079
If it makes no difference with the oil cap off then it may be down to an air leak at the top/bottom of the crank ventilation pipe, under the manifold, the O-rings may have perished.

320iAN
It sounds like you have a worn spring on the air flow meter, once it starts to run at the warmed up low idle the door in the meter is bouncing around and over reacting to the throttle input.
If your taking the air box off have a look at the door while its idling, I don't think a cracked airbox will cause a problem though because it will run just the same without one altotogether.

[feens]

liquid079
What symptoms do you have now you've vitrualy rebuilt it ?

Symtoms- Yesterday started her up, she idled a little high(900rpm ish) and fairly smoothly, although not as smoothly as once was . Left her to idle for a few minutes and all seemed fine. Drove for a few miles until up to temp, pulled over in a layby, still idling normally had a fiddle under the bonnet for the umpteenth time checking wires, air hoses, crank position sensor etc anything that might set this thing off... Nothing.

Drove on round the block, seemed to be driving pretty well, although not perfect, 10 minutes later arrived back home pulled up, revs rose once then dropped back down to normal then 20 seconds later started rising and falling between 1500rpm and 2000rpm, bliping the throttle seemed to momentarily stop it but then it would start again. Holding the throttle caused it to splutter and miss but no longer seems to cause it to stall .

Never seems to do it for more than a couple of minutes, after that it is back to normal, for how long?? there is no pattern to it, sometimes it will do it regularly, sometimes hardly atall, but always at least once in a thirty minute period.

Saboor- I have checked for visible loose connections and cannot find anything through wiggling pulling pushing anything, including underneath the DME relay. Do you mean the rubber boot covering the TPS connector?

320iAN- So your problem could possibly be time/temp related?

I'm going to know my car like the back of my hand when this is finnished

Hi Liquid ive had similar problems with my car but found the cause to be a sticking throttle peddle!!! It only barely stuck and still dont know how it would cause the car to rev up and down but one squirt of WD40 on the peddle springs and a quick free up and she was fixed!! I Know it sound very small of a thing to do concidering you have changed basicly everything you could, just thought it would be worth a shot!!

[liquid079]

Martinaston-I might get some new gasket, wip the manifold off and try that, although I did the wd40 test/wiggle test on it and it didn't make a difference.

Feens- I shall do that, although this reving happens when the tps is on its base setting and middle setting.

Thanks, Dan.

[siddiqi1]

Saboor- My engine used to drop like yours when the oil cap was released. The only air leak I can think of now is the inlet manifold gasket, or the EGR valve , or maybe fuel injectors??

Id be inclined to check that, that sounds promising, and is most likely to be there if not anywhere else. EGR, i dont think so, though i think you'll agree Dan, it could bloomen be anywhere

Lets try the inlet manifold side firstly.

[320iAN]

thanks Dan .. i have a TPS from my old Auto that worked fine, i think it's the same part No as my manual?

i'll have a look at the AFM-door later today, i did clean it all with brake cleaner and there was a heck of alot of crap came out it but that's not to say it was all of it

with the air box open and the car running am i looking for the shutter/door moving about losely or fixed in a certain position?

[liquid079]

I also have three 325i airflow-meters, I have been told on good authority that two of them work fine if anybodys interested.

My crank position sensor hasn't arrived yet, I think the royal mail strikes are causing problems.

I'll order the manifold gaskets and hopefully whip it off next week and take a look at the EGR valve and anything else that takes my fancy.

320iAN- No probs I'm here to help, I'll be putting GSF out of business when I've finnished this, the amount of parts I'll be flogging. On my AFM the flap was jumping about like mad, which it shouldn't have been doing.

PHEW... four pages and still going

[Martinaston]

You could do the gaskets as well but i was refering to the O-rings, part 9 one at the top and one at the bottom.
http://bmwfans.info/original/E30/2-T/32 ... l-11_0117/

[320iAN]

i never got the time yesterday to check my AFM but i had the car running yesterday and if i hit the top of the AFM the idle would get worse, cut out a couple times while hitting the AFM .... could it just be the shutter/butterfly???

[Martinaston]

I think they only suffer from two different problems, one is a worn out contact strip and the other is a knackered spring.
Have a look at the link if you want to tinker with it but its probably better to just replace the whole thing,
I won't put the direct link up because the home page is worth a look. Once you've got past that click on the blue bosch link and then the AFM button.
http://frwilk.com/

[320iAN]

a strange thing happened tonight which made me wonder about the answer to the car's idle problem?
when i first got in it to go a short drive i turned the key and ......... nothing, everything worked just no power to the engine, then after a few trys it started. when i got back home i switched it off and turned the key again to start it and?? nothing again .. so i got my jump leads and connected the earth lead from the battery to the engine and BROOOOM!!!!! it started and idle'd slightly better, i switched of the engine, took the jump/earth lead of and once again ? nothing .... which leads me to thinking the main engine earth needs replaced ;) i'll make up a new one and see how it go's

[siddiqi1]

320iAN,

You mention you conected the engine earth and the battery,how did you do this,seriously dont mean to ask the obv,i have my bat at the back,so would i conect the neg terminal of the bat to the susp turret in the engne?

The engine earth,now is the one from the sump to the engine?

Regards

Saboor

[Brianmoooore]

Word of caution for anyone with an oil level sensor. If you try to start an engine with one of these on an E30 with a defective engine earth strap (sump or mounting arm to chassis rail), then you will burn out a small wire in the engine loom, which will melt into other wires in the loom and cause all sorts of faults or prospective faults for the future.

[320iAN]

Saboor, my 320 has it's battery up front so is a little easier to do this, i used one jump lead and connected one end to the battery earth and the other to the inlet manifold to create an engine earth ... this might not be the cause of my idle fault but it does point out my car has a bad earth, might be the one from the engine block to the chassis? (under the Air box)

i had a earth fault on a cavalier sri i had before and it was down to a rotten earth strap, it looked fine but when i gave it a small tug it fell apart!