E30 Zone

Again with my M40 around. Idle when engine is cold is bad, like it tries to set the same idle speed as when hot, around 750rpm. And when really cold, if you blip the throttle it seems like its going to stall about a second and the goes up, and when rpm's go down, they go down the idle speed and then back to 750rpm.

When cold I started the engine and then unplugged the ICV (it is new, 2 pin style). For about two seconds it screwed a bit and then it went up to about 1200rpm steady and without any hesitations, so smooth. You could blip the throttle and the response was like never before, instantaneously.

Checked that the ICV Works and the wiring to it too, I took the ECU off and checked for signals on the connector. With engine at about 30-35ºC (sitting for 4 hours after using it) the coolant sensor said 1.87 kOhm, which I suspect is in range as I saw in the BMW Repair manual.

Then I checked continuity for the TPS at idle position, and it Works (it is new but now I am sure the ECU is getting it).

So, I don't know what more to check. It seems that the ECU is closing the ICV even if the engine is cold. Any suggestions? I'd appreciate!

Thanks!

This is an interesting one!

I have the same symptoms on my car, have done for ages...have you checked for vacuum leaks? The most suggested method is to spray carb cleaner around the intake side of the engine block and the intake manifold and all vacuum hoses.

I have checked everything I can, where abouts do you live?

Do you have a 316i or 318i?

I think to entirely eliminate the coolant temp sensor, test it before you drive it in the day, should be around 350ohms with the current uk temps I believe, then again when hot...but then again, mine still stutters anywhere until just over the mid range of the blue part of the temp gauge, what about yours?

Don't suppose you have access to a spare ECU to try as thats the only thing that I haven't been able to change! Of course our problems could be different!

ECU can't reduce the airflow below what's getting to the engine by means other than through the ICV, so check for air leaks after the throttle and that the throttle butterfly stop hasn't been tampered with.

Brianmoooore wrote:ECU can't reduce the airflow below what's getting to the engine by means other than through the ICV, so check for air leaks after the throttle and that the throttle butterfly stop hasn't been tampered with.

I read about ECU's being burnt because of bad ICV valves, could that make the ECU work as it shouldn´t?

http://www.bemarim3ex.com/demos/repair- ... oting.html

I checked for vacuum leaks many times with carb cleaner on throttle, brake booster, vacuum lines etc with no result.
When I replace TPS i put new gasket on throttle body. One thing is that when I removed the butterfly, it was loose and there was a leak in one of the vacuum ports, and it was repaired. Before repairing this, the idle speed would increase as the engine gets warmer (typical if vacuum leak I suspect).
How can I know if the stop screw was moved?

Soul4t I was reading your thread before you answered and saw your videos Mine is a 318i without catalyst. It Works the same manner as yours when I leave the car on the street with low temps. Think we are on the same boat

EDIT: my ECU remains on 157

Hmm, yea we may be...lets get the oars in!

That M3 ICV page is interesting!...It seems to refer to a 3 pin ICV, but I suppose it is possible that our ICV's could work in a similar way, causing the same damage to the ECU.

Brianmoooore of course is correct, we should ensure that the whole intake system (and indeed anything else that may be of fault) is checked through first, before we shoot blindly at things which I'm sure is a gripe of Brian's...

So continue with the systematic analysing until we get to that stage...I believe I am at that stage!

I would like to add that my problem I am sure has become progressively worse over the years...I might actualy connect up the known good ICV and leave it for a while as one time I did find it seemed to work correctly during a test...it didn't last to be fair but I should try it.

Have you tried the 2nd test that link describes, checking resistance between pins, then slowly moving the valve to look for a spot of continuity? I might give it a bash when I can!

Regarding the Throttle stop screw controling the Throttle plate gap to the side of the TB, Brian will probably have the definite acurate info on this, If I can remember, the gap is only 1mm?

My ICV valve is new from the dealer, and if you apply voltage it closes. The thing is, ICV valve is normally open I think. So when we start the engine, the ECU is sending a signal and closing the ICV; that's because when we unplug it, idle goes up (ICV opens again)
So I think the thing is the ECU is closing the ICV, why? My thoughts:
-ECU thinks engine is warm (coolant sensor), so it closes the ICV.
-throttle screw is messed and the butterfly is open above specifications, so the engine sucks more air, then the AFM is seeing too much air and tells ECU that ICV doesn't need to be open.

Any more thoughts? I checked for leaks without luck and I think that would make non-steady idle rpm (unmetered air). And for electrical problems, when we changed TPS and ICV to correct this without luck, they made a check with the computer and no errors were stored on the ECU. Maybe when TPS and ICV were bad, previous owner fiddled with stop screw to allow the car idle and now with good parts we get this problem? Before changing TPS and ICV car would run 800rpm when cold, 1100 when hot.

Hmm Yea, when you crank, the ICV opens right up, then it appears to snap shut, Yup, idle definitely rises, smooths and idle response is mint when unplugging opening the gap in the ICV to around 3/4mm (relaxed position). What I observed, was when the idle went below 500rpm or so, the ICV did open up trying to stop it from stalling...so there does seem to be some communication...

Have you left the ICV unplugged for the whole warm up process before? My engine begins hunting with the ICV disconnected at around the end of the blue area on the temp gauge, like a rythmic hunting, and it's perfectly smooth before the end of the blue area...

DaniTD wrote: -ECU thinks engine is warm (coolant sensor), so it closes the ICV.

Yup, that might make sense, I've got a new blue sensor in, tested at the ECU I don't know how many times, cold, warm and inbetween.

DaniTD wrote: -throttle screw is messed and the butterfly is open above specifications, so the engine sucks more air, then the AFM is seeing too much air and tells ECU that ICV doesn't need to be open.

Yup, that also would make some sense, though wouldn't the idle just be high, no cold start hesitation as the ECU would still know how much air is getting in and adjust fuel accordingly.

DaniTD wrote: Any more thoughts?

Well, from what I think I know, there is either

1. Unmetered air there somewhere resulting in super lean mixture.

2. ECU is telling ICV to open according to the lack of air being metered, and engine speed, but ICV isn't responding enough or ECU thinks it's sending a signal but ECU actually isn't, resulting in over rich mixture.

3. There is something a miss in the ECU fuel map

4. The CTS or TPS signal is not actually reaching the ECU...We know it's getting to the ECU loom plug, but the pins might not be making contact, but surely we'd have problems at warm temps and mpg. My MPG last fill was 35, the one before was 39, so probably not...the 39 was driving as economicaly as possible, mostly motorway!

What would be good to know is the effect of heat as the car warms up on either a lean condition or a rich condition, or does heat make both easier?

Whatever is happening, surely the ECU knows that it's not right as it recieves the rpm from the pulse sensor, so it must be trying!

My stumbly Idle has imporoved a bit since richening up the CO idle adjustment screw, bringing the CO mix from around 0.5 to 3...it's supposed to be around 1 I believe, however these measurements were made when the car was warm (at MOT). Doing this kind of blind adjustment isn't recommended as you might fix the problem without knowing it!

My ECU definitely logs a code (04 I think) when the ICV is disconnected...

Yea, the previous owner may have fiddled the Throttle stop screw, so it's definitely worth checking!...If the top of the adjustment screw and nut have a brush of paint accross them it's probably the origional factory setting.

Where does your idle typically sit when cold and hot?

Sorry there's so much here!

soul4t wrote:Sorry there's so much here!

Hey, no problem, I´m from Spain and I had to read a british board to know someone with the same problem! At least we are not crazy

My car sits on a garage at about 18-20ºC all year. When I start the car on the morning, it goes to about 2000rpm (coolant sensor may be telling hey bro coolant is cold, full ICV) and inmediatly sits on 750rpm (maybe air flow meter saying hey too much air, close the ICV)(that can be why you see the ICV open and then closing when you start the engine and not closing inmediatly when cranking)

Although it seems to idle well, you could notice a delay when you touch the gas, and when rpm are dropping below 1000 you touch the gas again, it hunts for a second below idle rpm and then will accelerate. This is real annoying when you are taking off and want to engage second gear at low rpm, because while clutch pedal is pressed rpm go down and when you release the engine don't react and the starts kangarooing.

If I restart the car at operating temperature, it goes to about 1200 and inmediatly to 750rpm (sure the ICV closes as you crank). Engine has better response.

The big problem is when I go to the university on Winter, with 0 to 5ºC and the car parked all day. When you start it, it gets worse. It hunts like in your video and shifting from 1st to 2nd is somewhat embarassing. When you press the accelerator when engine is slowing down under 1000rpm it can hunt at aprox 500rpm and even the oil light would light up.

I didn't tried to unplug the ICV with engine out of blue zone. Have you tried to unplug the AFM while engine hot and running? It's supposed that the car would hunt a Little bit but it would stay running, mine stalls (my theory of too much air from throttle for the quantity of fuel on the ECU map can gain some force here)

Were you complaining about your text?

DaniTD wrote: Hey, no problem, I´m from Spain and I had to read a british board to know someone with the same problem! At least we are not crazy Mad

Ha, yea I don't think we're completely mad!...try telling the Mrs that!

Yup I get the same kangarooing if I don't ensure I have my foot on the accelerator a bit before I bring the clutch out to ensure the rpm is steady...to be honest when it's cold I'm leaving loads of room before the car in front and left foot braking to keep my foot on the accelerator!...certainly not advised!

My car stalls if I unplug the AFM when it's hot and running, logs a code (07 I think)....hmm interesting theory about the air not enought fuel...I sniff at the exhaust to see if I can smell petrol strongly, but no, it doesn't smell of petrol at all...when I first really started to work it all out, I had low rpm idle...stuttering etc until warm, then tiny missfires when holding rpm. I took it to a garage and they hooked it up to a CO meter in the tail pipe, it was running lean, so we might both have lean conditions!

DaniTD wrote: Were you complaining about your text? cool

Don't follow this one...

Did your car have this problem since you bought it?

Tomorrow with cold engine I will mark the current position of the throttle stop screw and move it to try to close it a little bit, and see how the car starts. Will try to close as much as possible so it wouldn't stick inside and give it a try. Fingers crossed...
I will tell you the results when done

soul4t wrote:Sorry there's so much here! Razz

DaniTD wrote: Were you complaining about your text? cool

Don't follow this one...

I wrote a lot, too

Ha,

Yea great, try that and let us know how it went, if I get time I might stick the other ICV I have in mine...

I've had the car about 6 years, 1st noticed a problem about 5 years ago!!!!!!!

Started really trying to fix it about 3 years ago!

Oh Yea,

Worth mentioning for mine...when I drive and the temp gets above the blue and I stop, maybe grab some milk...bread, whatever, then come back to the car, when I start it it's worse than when it's stone cold...missing, spluttering...then within about 5-10 seconds it sorts itself out...ECU must sense the low rpm and pop the ICV open a tad more/ a tad. Either way the lean machine must be lean for a reason!...1st thing is vac leak....AHHHH!...sorry

No luck, tried to close the throttle a Little bit but it won't go further. Don't know if it's fully closed or the TPS is hanging the throttle on place. Maybe I have to loose the TPS first... oh my... to do that I have to disassembly the throttle butterfly from the intake... for something that I don't know if it would make any better

Well, if you re adjust the throttle stop screw, you should re adjust the TPS so that it clicks just as it moves off the stop screw.

Taking the Throttle body off is not bad really, the hardest bit is not dropping the nuts down the side of the block! Just take your time and all will be fine...

Remove the large the large air intake hose, I then take off the top part of the Air filter housing, undoing the electrical connector of course... it looks like you have to undo all the vac hoses to the bottom of the Throttle body, but there are 2 nuts about half way down the Throttle opening (if I remember correctly) that release the lower crankcase breather part which free's that bit up...also the accelerator cable is held with a black plastic thing, you can easilly prise the outer parts and push it forwards away from the TB. You can then undo the 2 8mm (I think...might be 10mm actually) nuts holding the accelerator part to the top of the TB, then you just have the 4 nuts holding it to the intake manifold.

Once you have it off you can set the Throttle plate stop screw, then adjust the TPS using the 2 screws that hold it on...I don't think I've forgotten anything...actually, didn't you say that you changed the TPS, so you must of had it off before! Ha!

Was there actually much of a gap past the Throttle plate? You might be best to leave it as it was unless you know and can set the gap correctly (not sure of the gap still...I had a look, but couldn't find the link...I'll have another look!)

http://www.mediafire.com/view/?52m0nzzl2cgtmk2

On page 9 of this document, it describes the throttle plate setup...you will need to remove the TB...

Hope the link works!

Yes, I had changed the TPS and it's a real pity. But I´m going to try to loosen the two TPS bolts with a tiny torque wrench only removing the intake boot. The thing is, now thinking, the throttle bolt is surely messed up. When I place the new TPS, it was a real pain in the ass to get it click with the throttle released. The TPS has 2 screw so it can be rotated to align it with the throttle. But when I put mine, it had to be forced to one of the sides to get the clicking, like you need more adjusting clearance, instead of getting it in the middle. This can be a sign of throttle bolt messed up.

Mine was pretty much all the way one way too, I think that might be normal though as my TB is in good condition compared to others I've seen!

Did you try to close the throttle?

Yea, I was naughty and changed the throttle stop screw, the idle was about 550rpm when cold then 700rpm when warm before...it's just more drivable as it is now with is slightly more open than it should be, but I had the problem before I changed it...I will probably change it back when I fit the replacement ICV I have...but I changed/checked pretty much everything before I changed mine...to be fair I think I adjusted it as that pdf document stated and it was even more open, so I closed it...either way, when I adjust it closed fully it just lowers the idle back to around 550rpm. Though it's not a fair test until I set it properly!

Great, I was searching for a document telling how to adjust the throttle body (BMW has no info on his manual because the throttle is intended to not mess with it) and you pdf does, thank you! Tomorrow I'll try to loose the TS and adjust things like your pdf says! Thanks!

I had the same problem on my 325i replaced everything and I mean everything could not solve the problem. After 6 years of living with it I finally fixed the problem by resetting the adaptation values using carsoft. Now everyone will tell that you simply disconnect the battery for a while and that'll reset the DME, WRONG.

My battery went flat a little while after resetting the adaptation values and after charging the battery and reinstalling I was back to the same old idle fault. Reset with carsoft once again and perfect.

Previous to this I replaced the entire ignition system with new BMW parts all new sensors CPS, CTS, ICV, TPS, and tried 2 afms and 4 DME's also checked and repaired all earths and wiring connectors (c191).

So clearly in the 1980's BMW wanted to keep all work in house because if you didn't pay for the diagnostics the car idled like cr*p.

Woh, I haven't heard of this one...makes sense though as I can't help thinking that it seems like a fuel map issue. So carsoft works with our older BMW's...thats good to know, I bought an EDIBIAS (I think) software kit which was supposed to work with Motronic, but it went from 1.7 upwards! I think I might definitely look into this one! Did you need an old laptop with a seriel port as apposed to using USB? Or did it work fine through USB?

abelai wrote: So clearly in the 1980's BMW wanted to keep all work in house because if you didn't pay for the diagnostics the car idled like cr*p.

Makes sense!

Thanks mate!

Carsoft 6.5 which will do motronic 1.3, just a cheap ebay thing running on an old laptop with a serial port.

I have also used carsoft on e36's and e34's running m50's and m52's handy bit of kit for those cars as it can give you live data but for the e30 I use an old skool sun diagnostics oscilloscope SST1500.

If you look for posts on idle faults with e30's it's pretty clear it's a very common fault so it's got to make you wonder.

Excellent mate!

I'm definitely going to look into that!

Well, throttle body adjusted to spec (loose TPS, unscrew throttle screw until flap gets stuck, then half turn the screw to make sure the flap doesn't bind).
Reassembled all, checked for leaks once again with carb cleaner, still the damn Idle Air Valve closed.
Anyway, it sounds like when cold engine is too rich (fuel smell, engine hunts below idle speed when rpm are going down from taking of the foot from the pedal). At least the car seems to be not so jerky when shifting like before.
Maybe need some AFM adjusting? Dunno...
Bad DME? Dunno...

Hmm,

Nice one for setting it all back to spec.

I think mine might smell a bit of fuel from the tailpipe when cold and misfiring, but I put it down to unburnt fuel from lack of sufficient fuel for combustion...rather than the combusted mix being rich if you follow...

Good about the jerking being less!

I don't know about the AFM...it's only adjustment (for our engines) is the idle CO mix...I would have thought that wouldn't lead to such a severe misfiring...do I remember you saying that you've had the CO set to within spec? Thats all you can do with that adjustment. I think it's between 0.5 and 0.7ppm. I think mines at around 3 (within permissable limits for our authority, so passes MOT) and it runs better, but still not perfect...and clearly it is masking the real problem!

The DME should be able to ensure the optimum combustion is acheived by all it's inputs, the AFM mainly...it could be a faulty AFM, but these are apparently rare. I have tried 2 known good ones and reset the carbon track on mine (not really recommended), no change.

There do seem to be quite a few idle problems in general with e30's so abelai's suggestion might be feasable...unfortunately alot of the threads that people have started haven't been concluded!

The vast majority of problems like this will be solved by eliminating air leaks and investing £6 each in a set of reconditioned injectors, as long as no one has played around with adjustments that never need adjusting.

Brianmoooore wrote:as long as no one has played around with adjustments that never need adjusting.

The thing is that most of them have been messed about with by people who know no better.

How do you set it back to factory spec?

Ben

Brianmoooore wrote:The vast majority of problems like this will be solved by eliminating air leaks and investing £6 each in a set of reconditioned injectors, as long as no one has played around with adjustments that never need adjusting.

The problem is, Brianmoore, previous owners of our cars were playing with that adjustments to mask other faults. For example, mine had the ICV valve damaged. We cleaned and tested it with no result. So, we put a new one, and the car was always idling high (900 when cold, 1100 when hot). So, the TPS was not set correctly. Why? It seems like previous owner, because the ICV failed and surely the engine stalled when cold, messed with the throttle screw to let more air into the engine and get better idle. But this way, TPS was not working when throttle released and then my new ICV was open all the time. We readjusted the throttle and the TPS, changed the throttle gasket and fixed properly the throttle to the intake, because when we disassembled it, the four nuts that fix it were loose.
After doing this, idle was being rough (650-700 when cold, 1000 when hot). I discovered an air leak on the left vacuum por of the intake (blanked on non-cat engines) It has a piece of rubber hose and a cap at the end to prevent air going through. That rubber hose was cracked and changed it.

Now idle is steady at aprox. 750rpm cold-hot. The problem is, when cold 750 seems low and sometimes it gets rough, with por throttle response and hunting below idle when blipping the throttle (and smelling rich, even somedays I had to change the car of place being cold with engine running 1 or 2 minutes you could see some unburnt petrol on the tailpipe).
When warm, engine seems to idle fine except from some strange vibration from the engine when revving to 1200rpm in neutral. Engine seems to run best when being warming up, after blue zone and before first line)

DaniTD wrote: Engine seems to run best when being warming up, after blue zone and before first line)

Does sound as though Brian is right about the injectors being worn.

Ben

BenHar wrote:

DaniTD wrote: Engine seems to run best when being warming up, after blue zone and before first line)

Does sound as though Brian is right about the injectors being worn.

Ben

Maybe but I don't understand what worn injectors have in common with ICV not opening when cold
If I don't get a fix for this, maybe I'll install a potentiometer on the dashboard to adjust manually the ICV like Choke on carburetor engines

AFAIK, the only correct way to set up the throttle stop is to replace the ICV, on an otherwise healthy engine, with a special BMW tool (basically an ICV with a fixed opening in it), then adjust the stop for a specific idle RPM.
The method I use is to remove the ICV, then either block both hoses or block one of the ICV ports and replace it, and then adjust the throttle screw so that the idle is excessively low with the engine threatening to tear itself of of its mounts.

The problem is, I adjusted the throttle stop as specified on Hayne's: unscrew stop screw until throttle flap gets stuck, then half turn forward. I don't think I can get throttle plate more closed (maybe I am wrong).

The procedure you describe (an always open ICV) and adjust throttle screw for an specific idle speed, is done hot or cold? I suppose cold, right? Because to do that, you need to move the throttle screw but with the TPS always in idle position right? And to adjust TPS on M40, you have to take full throttle out! How can you make live adjusting of the throttle screw with engine running and making TPS always in idle position?

Procedure is done hot. TPS can be dealt with (if it goes out of idle position), by unplugging it and shorting together the appropriate two pins of the plug.
If multiple adjustments have been got at, then you'll end up setting different things in turn more than once, gradually getting close to where they originally were.