Rough idle & running

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Jordy
Joined: Thu 24 Apr, 2014 20:49
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Rough idle & running

Post by Jordy »

Hi all,
I have a 2.0 Z3 1999 and am having trouble with it actually running.
It starts up fine, then after a minute or so the /!\ light and CEL or EML comes on and it goes all lumpy & rough.
Trying to rev it just results in nothing. If I turn off the engine and try to restart it straightaway it's still rough, but if I wait five minutes, it'll start fine for a minute then go rough again. I can't even drive it to a garage.
I've changed the following without any success: Air filter, oil, oil filter, fuel filter & spark plugs. I've now got to the Cam Position Sensor & Lambda sensor but thought I'd post on here first to try and get an insight as to what may be the issue before removing them. I don't know anyone with a code reader so I'm just going down the long road of elimination, which is becoming costly! Any help would be good. Cheers guys.
Del
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Re: Rough idle & running

Post by Del »

If you have all the engine warning lights coming on, it is almost certain that your ECU will have recorded an error code(s). Knowing what these codes are, can be extremely useful. I only use a cheap OBD II code reader (about £20 from ebay) and a converter cable to plug into the circular, under bonnet diagnostic port (£4). It's "worth it's weight in gold" as I have used it on various cars for friends and family to successfully pinpoint problems. An independent garage would only use something similar.

Edit - for a quick initial check I would also get a torch on the rubber bellows downstream from your MAF sensor - I think there is an upper and lower bellows on your engine? This is a very common problem with old perished rubber causing a large, unmetered vacuum leak so that the combustion mixture is too weak to start and run the engine.
therealdb1
Joined: Tue 25 Jun, 2013 21:47
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Re: Rough idle & running

Post by therealdb1 »

Welcome Jordy,
You really need to stop there and get the codes read. It is a needle in a haystack otherwise and you will spend a fortune on replacement parts that you don't need.
Buying your own code reader is not expensive these days, considerably less than a cam or lambda sensor anyway, and it will be worth its weight in gold as Del says if you intend keeping the Z for any length of time.
To get you running again I'm sure someone on here could read the codes for you if you tell us which area of the country you are in. In fact there is a thread by Robert T at the top of the list on the Z3 specific forum that lists those with code readers that are willing to help others locally.
Best of luck
Chris
Jordy
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Re: Rough idle & running

Post by Jordy »

Thanks for the quick responses - very Much appreciated.
I spoke to a friend who knows someone with a code reader and he asked him to come over which he said he would.
I decided now to stop replacing bits as, like you say, is the old needle&haystack thing.
At least I get to know a bit more about the mechanics though! I will look to see about the vacuum leak thing though as that does seem plausible, plus I've been told about that twice but don't actually know how to test it,
Thanks again!
Jordy
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Re: Rough idle & running

Post by Jordy »

I forgot to mention that when it's chugging away it smell of unburnt fuel.
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janijoeli
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Re: Rough idle & running

Post by janijoeli »

Hi Jordy, as others have said, check intake side between MAF and engine for any air leaks. If you cannot see anything obvious, take bits off one by one and inspect them thoroughly. I remember seeing a photo somewhere on this forum of a vacuum hose with a barely visible hole, which caused the engine to run rough.

One easy thing you could try is to disconnect MAF. Engine should then use the default fuel maps, as it doesn't know how much air goes in. If it runs fine, the fault is likely either an air leak (common), or MAF itself (less common). If it still runs rough, could be the lambda. Engine might think that it is constantly running very lean, even on default fuel maps, and is basically choking itself with fuel.

Also if you have an aftermarket oiled air filter, MAF could have got oily and dirty and is now giving incorrect readings (although I know this whole "MAF vs. K&N" topic is very controversial on teh interwebs :D).

Best of all, these tests don't cost anything. ;)
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Mint
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Re: Rough idle & running

Post by Mint »

Jordy wrote: I will look to see about the vacuum leak thing though as that does seem plausible, plus I've been told about that twice but don't actually know how to test it.
This is what a split hose looked like on mine. Its the hose which connects to the throttle body with a small hose branched of it:

Image

In my case though, it made no difference to idling or running, I just noticed it whilst I was doing a bit of engine bay cleaning :)

HTH
Jordy
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Re: Rough idle & running

Post by Jordy »

A quick update:
I had a diagnostic tool (DT) put on it and it showed all oxygen levels were even and acceptable, but it was pointing towards the fuel delivery as the most likely cause of trouble. The mechanic said the DT rarely points to the cause directly, instead it will merely give an indication of where the problem lies. Getting at all the vacuum hoses looks a bit more challenging, so I got a genuine Fuel Pressure Regulator from BMW today and will fit that later and see if that's sorted it. If not, I'll get under the car and look at the hoses.
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Re: Rough idle & running

Post by Jordy »

I've just fitted the new FPR & it has made no difference. Boo.
Before I go down the fuel pump road, could anyone tell me how to go about checking the vacuum hoses, & their locations please?
Any pictures would come in handy!
Thanks.
Del
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Re: Rough idle & running

Post by Del »

See attached link
The possible parts are 13541705209 & 13541435627 - the latter seems to cause most problems to forum members with your engine (or similar).
If you could disclose what error codes were produced, it may help forum members with suggestions.

http://realoem.com/bmw/showparts.do?mod ... g=13&fg=15
Jordy
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Re: Rough idle & running

Post by Jordy »

Sorry, I didn't see the codes as the machanic was dealing with it and I assumed it would be sorted out there and then.
I saw there was a hose from the FPR which ran down between the engine. Where does this go and is there a possibility that could have ruptured?
Cabrioot
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Re: Rough idle & running

Post by Cabrioot »

I had a simular problem.
Took al the enginecovers off, engine runs and sprayed brakeclaenig bit by bit in all corners (not on exhaust) and see if the idle speed changes when spray in the enginebaycorners and on the hoses
Good luck
Jordy
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Re: Rough idle & running

Post by Jordy »

I've taken the parts off just after the MAF and checked them for holes and found none.
Only thing left is the fuel pump. Please God let this end!!
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Re: Rough idle & running

Post by Jordy »

I know I'm clutching at straws to an extent now, but before I get the fuel pump done, is there any chance it could be to do with the fuel injectors at all? Another guy was supposed to be coming up this morning with a code reader but he didn't turn up.
Del
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Re: Rough idle & running

Post by Del »

Hi Jordy

Sorry to hear you are still having problems.

The injectors on the Z3 are not likely to be so bad that they would cause bad running problems. The type of old-fashioned fuel injection system on these cars is very reliable compared to the new cars with more complex "direct injection". Furthermore, the fuel pump is either likely to be working of not working. The error codes would be very helpful in this case to give you some guidance to the problem.
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Southernboy
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Re: Rough idle & running

Post by Southernboy »

.... Have a look at this item... if it's plastic casing is cracked, it will have an effect on the idling and smooth running of your motor... It's the crancase ventilation and oil separation valve.
Try googling the item if nobody else here has any experience with replacing it. It is found below the MAF area... and it may not look identical to what is shown in this drawing. It has a couple of hoses which attach to the intake and engine...
Perhaps if you google the item, you will have a clear idea of it's functions etc... really hope this helps you...
It's Item # 1.
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Also check the connections of all the hoses and the hoses themselves...
"Normal is overrated"
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Southernboy
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Re: Rough idle & running

Post by Southernboy »

..... please have a look at this youtube vid.... also, take note of the guy who posted the vid... he may be contactable and useful... He certainly has offered to help >>>
http://www.youtube.com/watch?v=JLDo7Jk78ac
"Normal is overrated"
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Jordy
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Re: Rough idle & running

Post by Jordy »

Wow, thanks for the info Southernboy. I'll take a look and see if I can find anything.
I would've taken it straight to the garage but as the RAC towed me once, they won't tow me to the garage for the same problem! I'll update as soon as I've had a look.
Jordy
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Re: Rough idle & running

Post by Jordy »

Thanks Del.
I know the error codes pointed towards fuel delivery (that's what the mechanic said), and as I'd already changed the FPR, I was kind of hoping it was the fuel pump just so it'd just get fixed!
After I've looked at the area that Southernboy suggested, I think I might try and limp it to the garage, or try and get it towed there.
Del
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Re: Rough idle & running

Post by Del »

Common OBD II error codes "that point to fuel delivery" might be ones like P0171 & P0174 (fuel too lean) for example. On the face of it, one could conclude that not enough petrol is getting into the combustion mixture, however, in most cases these error codes are caused by 1) perished vacuum pipework letting in "unmetered" air and/or 2) a failing MAF sensor.
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Re: Rough idle & running

Post by Jordy »

Would perished hoses allow the engine to start and run fine for a minute or so before going rough?
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janijoeli
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Re: Rough idle & running

Post by janijoeli »

Could be. I believe the lambda sensor needs to be warmed up before it can be used for measuring a/f ratio, although I don't know how long it takes. In the meanwhile, engine is probably running on default fuel maps. So maybe when the lambda is warm and ecu starts actually measuring a/f ratio, which is off for whatever reason, you get the rough running. Purely guesses though, maybe someone with actual real technical knowledge will chip in shortly. :)

Btw have you tried unplugging the wire to the MAF sensor yet, as I suggested a couple posts up? If engine runs fine with no MAF signal, at least you'd know that changing the fuel pump won't fix anything.
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Southernboy
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Re: Rough idle & running

Post by Southernboy »

.......... and just to add to the confusion, you may want to check the cam position sensors are functioning correctly... for that you will need to hook up the car to a diagnostics though.
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cn55
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Re: Rough idle & running

Post by cn55 »

Not sure if this is of any use, not used them myself but prices look good and appear to be genuine Bosch.

http://www.maf-shop.com/
Tilly
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Re: Rough idle & running

Post by Tilly »

Jordy wrote:Hi all,
I have a 2.0 Z3 1999 and am having trouble with it actually running.
It starts up fine, then after a minute or so the /!\ light and CEL or EML comes on and it goes all lumpy & rough.
Trying to rev it just results in nothing. If I turn off the engine and try to restart it straightaway it's still rough, but if I wait five minutes, it'll start fine for a minute then go rough again. I can't even drive it to a garage.
I've changed the following without any success: Air filter, oil, oil filter, fuel filter & spark plugs. I've now got to the Cam Position Sensor & Lambda sensor but thought I'd post on here first to try and get an insight as to what may be the issue before removing them. I don't know anyone with a code reader so I'm just going down the long road of elimination, which is becoming costly! Any help would be good. Cheers guys.

Sorry to hear about the problems and all the possible fixes.
I had a similar problem which started on the M about four months after a replacement vanos was fitted from Dr Vanos in the states. Once warm. lumpy idle and very poor low rev pickup.

This is what was done. New vanos seals replaced. New MAF, new cam sensors, New Lambda sensors, new throttle switch, valve shims adjusted, New idle speed control valve, fuel pump pressure test, breather systems checked and finally another new vanos and vanos gears.

The lesson I learnt was you need somebody with some good diagnostic and code reading equipment. Faults sometimes don't register. Occasionally you just have to replace a part with a donor part and see if it cures the problem. You have to be systematic in the approach to solving the issue once you have conducted a full diagnostic test. You need time and in my case, since the work was carried out by specialist independents or a BMW main dealership, deep pockets. If fact in the end the BMW main dealership finally cured the problem but the car was in the garage for over a month. The total time to finally fix the problem was well over a year.

I wish you luck. Once fixed the end result is well worth it.
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Re: Rough idle & running

Post by Jordy »

Hi janijoeli,
I tried unplugging the MAF as it was running, and before starting engine with no joy.
Thanks anyway.
Jordy
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Re: Rough idle & running

Post by Jordy »

I can't wait to get it sorted out!
Just to know what the problem is would be good.
I've got a day off Saturday so I'll spend some time underneath checking all the hoses etc.
I'll google that box that was suggested further up the post as well.
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Re: Rough idle & running

Post by Jordy »

Hi Tilly,
What was the fault on your car in the end?
Tilly
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Re: Rough idle & running

Post by Tilly »

Jordy wrote:Hi Tilly,
What was the fault on your car in the end?
It was the Vanos. When the Vanos was stripped down the pushrod on the exhaust side had sheared so when the exhaust Vanos solenoid actuated nothing happened as the rod was not attached. Diagnostic checking had indicated that there may have been a problem on the exhaust side but it needed very careful and expert evaluation and even then it was only confirmed when everything was dismantled. That is the reason why I suggested that to save time, and in the end money, expert diagnostic testing with the correct equipment is vitally important.
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Re: Rough idle & running

Post by Jordy »

Would it be safe to disconnect the Lambda sensors then start the engine?
Just a thought of what Janijoeli mentioned, about the Lambda sensors.
I mean, if they aren't active until they get warm and the engine runs ok when cold, maybe then the car will still run off default setting? Then I'll know to replace the sensors. I think there's six, or is it two?
Tilly
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Re: Rough idle & running

Post by Tilly »

Jordy wrote:Would it be safe to disconnect the Lambda sensors then start the engine?
Just a thought of what Janijoeli mentioned, about the Lambda sensors.
I mean, if they aren't active until they get warm and the engine runs ok when cold, maybe then the car will still run off default setting? Then I'll know to replace the sensors. I think there's six, or is it two?
If a lambda sensor is faulty then a fault code will appear on diagnostics. If it is borderline then you may not get a fault code but I do not think that you will get the relative symptoms that you described. They are recommended to be replaced after about 100,000 miles. On my car there are 4 probes, 2 on the manifold and 2 on catalytic converters. I am not sure what just disconnecting the sensor from cold will reveal. I would, not try and disconnect when hot.
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Re: Rough idle & running

Post by Jordy »

Update:

I eventually found someone with a diagnostic tool who works for Audi & used to work for BMW to see what the problem was.
He said it would be the Lambda sensors pre-cat that did this as the after-cat sensors would think that not enough fuel was getting through and effectively choke the engine.
(Or something similar).
The code that came up said just that.
Hooray!
However, the tool doesn't say which pre-cat sensor was faulty so I'm just gonna buy one and fit it anyway.
Possible closure?
I really hope so!
Cooper01
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Re: Rough idle & running

Post by Cooper01 »

Hi Jordy, please give us an update on how you went and what was eventually done to fix the issue. Thanks. Cooper01 :rtm:
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Re: Rough idle & running

Post by Jordy »

Yes of course!
Just got to wait til Monday lunchtime when the sensor gets delivered then I can replace it.
Here's hoping that'll finally fix it!
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Re: Rough idle & running

Post by Jordy »

Update:

I've changed one Lambda sensor and it was still no good. I then swapped them around i case I'd inadvertently replaced on good one instead of the bad one but still no joy.
I've had another sensor delivered and I'm just about to change the other one.

Standby.....
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Re: Rough idle & running

Post by Jordy »

Both pre-cat Lambda sensors replaced and still no good.
We cut the exhaust before the cat to see if there was a problem there and we can now rule that out, so we welded it back together.
It's just becoming too much now. Really can't be bothered as every diagnostic tool points to different places.
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Re: Rough idle & running

Post by Jordy »

I've finally given up trying to fix the problem now.
I decided to take the only option left.

The car goes in to the garage on Tuesday to finally get fixed.
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motco
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Re: Rough idle & running

Post by motco »

My 2.2 had these symptoms and it was the throttle body sticking. I don't know if yours is a fly-by-wire but if it is, this is a distinct possibility.
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Re: Rough idle & running

Post by Jordy »

motco wrote:My 2.2 had these symptoms and it was the throttle body sticking. I don't know if yours is a fly-by-wire but if it is, this is a distinct possibility.
I had the car booked in the garage today but it wouldn't even drive off the forecourt so I rang and cancelled the garage.
Taking what you said, I bought some carb/intake cleaner from Halfords (of all places, I think they're crap), I took the MAF off and sprayed directly into the throttle body and waited a few mins then started the engine.
No engine light!
I repeated this three times.

Now the car runs fine!

I can't believe I spent all that money on sensors, filters and whatnot and all it needed was a can of spray from Halfords for £6.99!

Thanks everyone for trying to help though, as at the very least, I've got to know a bit more about the mechanics of a car.
Now all I need is a bit of sun so I can have the roof down!!
Bi11
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Re: Rough idle & running

Post by Bi11 »

Great news, hope that's is sorted now!
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Tilly
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Re: Rough idle & running

Post by Tilly »

Great news. Hope the weather now improves so you can really enjoy your car.
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motco
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Re: Rough idle & running

Post by motco »

Jordy wrote:
motco wrote:My 2.2 had these symptoms and it was the throttle body sticking. I don't know if yours is a fly-by-wire but if it is, this is a distinct possibility.
I had the car booked in the garage today but it wouldn't even drive off the forecourt so I rang and cancelled the garage.
Taking what you said, I bought some carb/intake cleaner from Halfords (of all places, I think they're crap), I took the MAF off and sprayed directly into the throttle body and waited a few mins then started the engine.
No engine light!
I repeated this three times.

Now the car runs fine!

I can't believe I spent all that money on sensors, filters and whatnot and all it needed was a can of spray from Halfords for £6.99!

Thanks everyone for trying to help though, as at the very least, I've got to know a bit more about the mechanics of a car.
Now all I need is a bit of sun so I can have the roof down!!
Good to hear Jordy! 8-) Mine was fixed with a second hand throttle body as it had let me down once before. £20 for the part and £48 to fit it - I didn't fancy the knuckle barking, back breaking grovel over the wing into the bowels of the engine. :oops:
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Re: Rough idle & running

Post by Jordy »

I started the car this morning and it was bad again!
So I sprayed it and waited for a while and tried again - no light!
I let it idle for five minutes and all looked good, so I revved it and the light came on.

Never mind, at least I know where the problem lies now.
I'll change the throttle body and enjoy the sun!
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motco
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Re: Rough idle & running

Post by motco »

Error code P0121 was returned on mine - "Throttle Position Sensor/Switch A Circuit Range/Performance Problem". Good idea to get a fault code check to confirm.
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Re: Rough idle & running

Post by Jordy »

motco wrote:Error code P0121 was returned on mine - "Throttle Position Sensor/Switch A Circuit Range/Performance Problem". Good idea to get a fault code check to confirm.
Yes, I managed to get it going again and drove to the garage, where the guy said that different code readers could give different codes.
I told him the things I'd done and that the car did run after spraying carb cleaner in the intake and he said that he'd connect it up and see what shows up.
Just a case of waiting to hear now.
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Re: Rough idle & running

Post by Jordy »

I've finally got the car back on the road!
The garage called my this morning to say they had cleaned the throttle body as it wasn't that bad, and that they had also found a small hole in the vacuum hose (as was suggested higher up in this thread by other members). He said the hole was very missable. It was a combination of the hole and the dirty throttle body that caused the problem, and this is probably why the different code readers gave different results.
He only charged me £90 as well which was good.
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Southernboy
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Re: Rough idle & running

Post by Southernboy »

......... Congrats ! at last you have the issue sorted and can enjoy a drive in the rain.... :sunny
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Cabrioot
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Re: Rough idle & running

Post by Cabrioot »

Well done and enjoy your rides
Del
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Re: Rough idle & running

Post by Del »

Glad you got it sorted in the end - I bet the car runs great now. I've never known a dirty throttle body cause such severe problems - but you learn something new every day :)
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motco
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Re: Rough idle & running

Post by motco »

Del wrote:Glad you got it sorted in the end - I bet the car runs great now. I've never known a dirty throttle body cause such severe problems - but you learn something new every day :)
The first time mine failed it was a total failure. The engine would idle only, and it had to be recovered to the specialist I use. Unfortunately, on mine at least, it is inaccessible without losing knuckle skin as it's buried down the side of the engine underneath the large diameter induction hoses and airflow meter housing. The second time it only caused a bit of rough running and a dashboard like Blackpool illuminations without the drunks walking past. :wink:
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