Engine STILL occasionally reving up on its own 'FIXED'

[liquid079]

I posted a couple of months ago about this problem which seemed to be caused by water in the airflow meter. After fitting a few second hand afm's and finally a Miller MAF my car is still doing it.

First time it happened today, I pulled off the road into a petrol station and after idling for a minute the revs started going up to 2000rpm and then back to normal repeatedly before the engine decided to stall. After waiting 30 seconds I turned the key and all was fine.

I'm wondering if a faulty ICV or fuel pressure gauge would cause this problem?

[abelai]

So this is an intermitant idle problem right there are 2 main things you can check one unplug the tps and check the switch for continuety as it sounds like your losing the signal and when i dissconnected mine the idle sits at 2000rpm. The other thing is a bad connection under the inlet manifold wiggle the wires and see what it does. I think most likely the tps though.

[march109]

have you checked the rubber pipe that runs from the AFM (or now maf in your case) to the throttle body via the ICV?? if it has a split or hole even slight it will expand as the engine draws air (as it has positive pressure) and expose and stetch or open the split (however you want to think of it) which will allow air in that is not accounted for by the MAF. When the pressure equalises the pipe has equal pressure to the atmosphere and shrinks back down to size (and thus your revs fall), and then it happens all over again.

[liquid079]

Ok I will check these things when I get back from work and report back.

Thanks, Dan.

[abelai]

Good man keep us informed as I'm becoming tired of reading idle posts where we never here if the problem is fixed or what fixed it. I'm trying to make check list guide for idle problems as it is a big issue with m20 engines.
Doesn't help when people don't describe the idle problem very well as there are 4 different idle problems I've had them all and now got one left to fix:
Rough Idle
High Idle
Low Idle
Hunting Idle
All can be caused by many things but there is a process of elimination.

[e30-320i]

i had a similar problem on my old 320 it turned out to be a load of crud had built up on the throttle stop so sometimes the throttle wouldn't go back enough to click the tps to idle.def sounds like tps or airleak

[liquid079]

Ok.

Had a tinkle today.

Checked for airleaks on the rubber elbow and there wasn't any.

Using my limited knowledge with a multimeter I checked the TPS, I got:

0 ohms between middle and left pin on closed throttle.
0 ohms between middle pin and right pin, between nearly full throttle, and full throttle.
Infinite resistance between middle and right at all other positions.

I haven't checked for voltage at the TPS harness connector, but this seems to suggest the switch is working correctly if I'm correct?

I had time to take a quick look at the ICV as well. It buzzed away with the ignition on, but the valve didn't seem to close /open when I disconnected the plug, except for when the plug was almost disconnected and the valve made an attempt to open slightly and buzzed at a slightly different tone.

Again I didn't have time to do the checks my bently manual states but this shows something is not quite right with the ICV if I'm right.

I shall probe further when I get some daylight free.

[abelai]

OK thats good it sounds like the TPS works fine. Now when the idle is rising up and down if you disconnect the ICV does the idle stay exactly where it was, so if you disconnect at 1200rpm does it stay there solid? If so then you ICV is getting mixed signals from the ECU (DME), now that could be because the signal from the TPS to DME is being intermitant flicking from idle map throttle on map so check the condition of the wires to the TPS behind the rubber boot on the connector you can also check they have voltages to them with ignition on. If this all checks good try the wires under the inlet manifold the round connector try moving them about while the car is idling and see if the idle changes.

Your idle control valve might not be 100% but something is telling to open then snap shut which means the DME must be getting duff signals somewhere along the line.

More out of interest to me than anything else what does it idle at if you disconnect the tps and start the car?

[liquid079]

Thanks for your reply abelai, you seem to know your stuff.

Tested the tps plug today and got 10 volts between centre terminal and the outer pins which seems about right, I also checked the wires behind the rubber boot and they were okay although there was a bit of oil on them.

Tested the ICV plug:

12 volts to the centre pin
4 volts between centre and right(1)
9 volts between centre and left(3)

My bible says there should be roughly 10 volts between the centre pin and either of the outer ones, so pin no. 1 seems to be getting insufficient current .

I went for a drive and after 20minutes the car started 'kangeroing' whenever I gave it some gas( so this is not just an idle problem) I pulled over and the revs were rising and falling between 1700rpm and 2000rpm, I disconnected the ICV and the revs returned to normal again.

Driving on, after about 10 minutes this happened again( this was with the ICV disconnected) putting the plug back on and it settled down again , this had me puzzled. Pulling the plug on and then putting it back on had no noticable affect on the idle at normal idle.

The connector under the manifold is okay, pulling wires didn't seem to do much.

If I start the car with the TPS disconnected it revs at 1900rpm.

If anyone can enlighten me on this one it would be much appreciated.






The DME relay is fairly new.

If I start the car with the TPS disconnected it idles at 1900rpm.

[liquid079]

I have also noticed that when I take the oil cap off it makes no difference to the idle speed, it did before.

[abelai]

The voltages at the ICV connector are what everybody gets no one gets 10volts. I still think something is stoping the TPS signal getting to the DME because when you disconnected it the revs were 1900 and thats what they bounce up to when your idle problem happens. TPS problems can also effect normal driving as it tells the DME which map to use and what to do with the ICV. I think pin 2 on the TPS should be ground not sure of the voltages for the other two I'll try too find out for you.

[Martinaston]

Take the throttle body off and clean the inside and the butterfly, then turn it upside down and drill a 1mm hole into the switch just below the word bosch and turn it back up the right way and let the oil drain out.
Check for the click just as you start to open the throttle, if thats ok re-fit it and then give the ICV a blast with carb claener and then see what happens.

[abelai]

The odd thing here is that disconnecting the icv should not have resulted in the revs dropping to 800rpm, as when you disconnect the icv the valve should stay in exactly the same position as it was just before you pulled the plug. As for the revs going back up to 1700-1900 with the icv disconnected thats very odd. As Martinaston said it is possible that tps is only just closed when the throttle is, which could be a dirty TB or a tight throttle cable. You could get some contact clean (halfords sell it) disconnect all the connectors (TPS, ICV, loom under inlet manifold, and temp sensor) just to clean all these up and make sure there is a good connection.

[Martinaston]

The ICV is fed by a pulsed signal through pins 1+3 so it just depends which one recieved the last signal as you pull the plug off, that then sets the ICV valve nearer the open or closed position as the power is cut off, leading to a different result each time you do it.
The 7 pin connector under the manifold has nothing to do with the ICV wiring, it only handles the injector and temp sensor wires. Messing with that before you sort the ICV will probably just introduce more problems.

[liquid079]

Ok, thanks for your suggestions guys.

When I changed the engine over christmas I replaced many parts for new including:
Blue temp sensor
Brown sensor(whatever that is.
Dizzy cap
Rotor

I've also recently checked all the connections on the wiring loom for signs of corrosion and found none.

Took the throttle body off today and checked the butterfly etc, this was fine. I cleaned out the tps and checked the adjustment and all the contacts, there was a small amount of oil inside but nothing I would have thought that would effect its operation. There was already a hole drilled in the base of the tps.

I pulled out the old ICV off of my 320i engine and put that on, this seemed to not make much of a difference whilst connected, but strangely did with the plug off. Either way whenever the idle jumps around if I pull the plug off/connect it back up it seems to stop doing it, at least for a minute.

I noticed a fuel smell whilst driving, The fuel lines are under a year old but I checked them anyway and could not find any cracking. I checked the vacum pipe going from the preasure regulator to the inlet manifold and found a hole in the end of it, so I snipped the end off it. I noticed the preasure regulator had slight damage on it so I pulled out the one off of my 320i engine although its lower preasure I thought this wouldn't matter at the low to mid rev range. Doing all this has seemed to lessen the symtons quite a lot, although it still does it, it seems to stutter more than kangeroo whilst driving.

Also can anybody tell me what the socket below the diagnostic plug nearest the thermostat does, as the wire coming from this has been snipped??

I think I'm going to order a new ICV anyway, any more suggestions would be much appreciated.

Dan.

[320iAN]

i'm keeping an eye on this thread to, mine is doing something the same .. except it idles fine then starts hunting but the rev's drop (some times it stalls) .. but the revs don't go any higher than normal idel rev's (750/800 rpm)
i thought i had a spare IVC but after hunting for about an hour i can't find it!

good luck with your fault and fingers crossed you get a result from the new valve

[Martinaston]

The plugs under the diagnostic socket are for the crank position sensor (it wouldn't run at all without that one). The other is for the sensor on the HT lead that just runs back to the diagnostic socket and is not used by the ECU, so no problem with that being cut.
Did you check the stop screw on the throttle butterfly ? it should stop the butterfly from completly closing so you can just see a slither of light around the edge.
If everything else seems ok then maybe getting a spare ECU and give that a go.

[Templ8e30]

Having a similar problem with my touring, TPS is working well, I've got my hands on a spare ICV but if this doesn't work I'll be swapping ecu's.

Cheers,

Iain T

[liquid079]

I think I have checked everything I can to do with the throttlebody/tps, including the .0015in clearance between the butterfly and the throttle body, so I'm pretty sure everything in this area is pukka. I have ordered a new gasket as well, as the current one has seen too much action.

I'm going to order a new ICV later, although BMW want £107 for one so I might try GSF, does anybody know if these are ok?

I have a spare ECU so I'll try that, although I'm not hopefull on that making a difference. I'll test the temp sensor and some other stuff as well and see if I find anything interesting.

Thanks, Dan.

[320iAN]

strange??
tonight while i left my 320 ticking over i un-plugged the ICV and the idle evened out and reved better (no flat spot) then when i reconnected the ICV it went lumpy again?
ive not drove it though with the ICV un-plugged .. my car is boxed in at the moment .. could it be the ICV thats up with my car?

[siddiqi1]

keep us updated fella, this is a productive thread!!!!

[320iAN]

strange??
tonight while i left my 320 ticking over i un-plugged the ICV and the idle evened out and reved better (no flat spot) then when i reconnected the ICV it went lumpy again?
ive not drove it though with the ICV un-plugged .. my car is boxed in at the moment .. could it be the ICV thats up with my car?

i took my E30 out last night and i disconnected the ICV plug .. the car just stalled when i tried to drive it, but it did idle just the same with the plug connected as it did disconnected? .. makes me think the ICV is not working 100%

[abelai]

Have a look at this post. It seems you can have an idle control valve that passes all the normal tests but is still buggered. It happened to Brianmoooore so it can happen to us mortals too

http://www.e30zone.net/modules.php?name ... hlight=icv

[abelai]

liquid079, have you replaced your icv yet if so whats the outcome?

[liquid079]

yep abelai, I swapped it yesterday.

I got my new ICV on, I also put a new throttle body gasket on, and replaced the stud on my rocker cover that was rounded off, just to eliminate any air leaks.

While I was doing this I also noticed a rather large crack in the end of the breather hose, I must have done this myself as the hose is only 6 months old. I cut the end of this off and it still fitted on nicely.

After doing this I got my multimeter out and done voltage and continuity tests on the ECU connector as described in my bently manual, I was pleased to see everything was spot on. I then swapped my ECU over just to be sure.

After correcting all these possible air leak problems I was expecting to have solved the problem...

But NO It's still doing it, and I'm almost really stuck with this about where to go next.

Anyway moving on, I took it for a long drive just to make sure the ECU was happy with it's new settings etc. The more I drive it the more it seems like a TPS problem, even though this tested fine. Over the 40 odd miles I drove it today I'd say that:

20% of the time the car was driving fine- perfect idle, smooth throttle response and nice acceleration .

60% of the time the car was perfectly driveable but not right- Idle constant but a too high(1100rpm-1200rpm), throttle respose very jerky on and off, and definately down on power( not much better than my old 320i engine) .

20% of the time bloody awfull- Idle up and down between 1500rpm and 2100rpm, throttle response... slight throttle you can just about nurse it along, very jumpy at half throttle and at full throttle the revs drop right down towards idle speed eventually stalling .

Also the economy gauge sometimes drops down dramatically, although I am keeping the throttle steady, and then goes back up to normal. I'm talking cruising at 70mph on level ground and it will drop from around 30mpg to below 15mpg . I'm guessing the eco gauge may get some of its information from throttle position, and this might be an indication that the TPS is giving off funny signals sometimes... or no??

So I'm tempted just to buy a new TPS and see what happens.

Any suggestions welcome, Dan.

[Martinaston]

Are you sure the crank position sensor/wire is ok ?
Its more of a running problem if its that bad and your looking in the wrong place, was it like this before or was it just an idle problem ?

[liquid079]

I have checked the crank position sensor as best as I can, and can't see any wear on the housing. AFAIK there is no way of testing this??

The car was running perfectly fine until one VERY wet day in july, when it first started to show the symptons. It was then I found water in the airflow meter, I got through two second hand airflow meters and a miller MAF before I decided it was something else.

I have checked every wiring connector in the engine bay bar the fuse box and can not find any corrosion.

No this has never just been an idle problem, its very intermittant, I've driven the car for over 20 miles before its done it, but then I,ve driven it up the road a couple of miles and it has done it all the time.

Seems to happen maybe a bit more when the car is properly warmed up, although it still does it sometimes when the engine is cold.

[Martinaston]

Housing ? your sure its not rubbing the water pump pully ?
If thats ok try cleaning and copper greese the battery terminals and remove the engine earth and give the contact points a clean with a wire brush.
Try that and if its still playing up i'd start checking the dash earth points.

[siddiqi1]

could be your fuel pump playing up?!have you tried a new fuel pump relay,or evn a fuel press. rugalator.

If you were getting insuficient press. then would these not be the symtoms.

Keep us up to date,very good thread


Saboor

[abelai]

Sorry to here the ICV hasn't fixed your problem.

The ECO gauge gets its signal from the ecu pin 32 "fuel rate output". Now the interesting thing here is that your saying at steady throttle the ECO gauage drops which has to mean more fuel is being dumped in, if the TPS sent a signal that you had reached WOT thats exactly what would happen. Also the fact you say somebody has already drilled a hole in the bottom of TPS means there has been a problem with it in the past but also check the wires from the TPS to the ECU. Disconnect the ECU and on the loom connector find the wires for the TPS 52 & 53 bridge these go to the connector on the TPS and check for continuity between the outer pins if all is good then all I can think of is your TPS is poo!

When you do find the problem it'll run like a dream with everything being new on the damn thing

[320iAN]

liquid079 .. have tried a new coil?, your coil may be "breaking up"

i still think my cars fault is with the ICV. ive not got another one yet butive a mate who says i can take the one from his 320 and try it

[320iAN]

now today my 320 has started ticking over eradicaly?
the rev's jump up and down, the fuel use read out is flickering from 10-50 mpg while on idle and the temp gauge is flickering to??
could it be my ECU thats playing up?
the car drives spot on, accelaration is responsive

[liquid079]

Martinaston-sorry didn't mean to confuse matters I meant the crank sensor cable is not rubbing on the pulley. I have tested the five main ground points and they came up fine. The dash earth points, good idea, I will check those. The battery terminals are good, I think my battery is getting a bit tired as its turning the engine over a little slow these days and its only a little fella.


Saboor- I might try the fuel pump as I have a spare. The preasure regulator is next on my shopping list, although with my 320i fpr on the symptons were still there, although it is only a 2.5 bar so I'm not sure. The relay tested fine on the ecu connector tests.

abelai- The eco gauge was exactly what brought me back to the tps as well as the jerking under on off throttle, and a slight fuel smell sometimes. I'll see if I can test it when the idles playing up, I shall do those tests and report back. Yep when this is sorted out it should drive really nicely with almost every part on the engine/drivetrain that has potential to wear replaced... I think they call it 'preventative maintainence' .


320iAN-A bad ground point somewhere maybe?

[320iAN]

320iAN-A bad ground point somewhere maybe?

this is something i was going to check .. i usualy give the main live and earths a clean when i buy an older car

[abelai]

Look at Page 40 of the pdf file:
http://shark.armchair.mb.ca/~dave/BMW/e30/e30_89.pdf
That explains the wiring for the TPS
Page 39 shows the wiring for ICV

You can also check here for BMW workshop tests but they much the same as you have already tried:
http://ee1394.com/bmw/docs/factory/repair/en/index1.htm
Main Groups, section 13 (fuel system)

One of the biggest problems with your issue is its not always there almost like a loose connection to the TPS. Only other idear is to have the rubber boot to the TPS pulled back exposing the wires so when the car is actually acting up you can check for continuity between pins 1 and 2. You can also check the pin 2 on the TPS connector has good ground.

We're not stopping till its fixed