325i spluttering and revving on its own

[jimf]

Hi folks,

My car starts and idles perfectly from cold but a couple of minutes into a journey it will lose power and splutter, then it will rev up 2500rpm a few times on its own then settles and runs fine again. It seems to only do this when the engine is halfway between cold and normal temp.

The ICV doesn't seem to be sticking and all pipes have been checked for leaks.

Anyone had these symptoms that can point me in the right direction please.

[aimlessrock]

could be possible injector leakage- ie leaking fuel and on start up burning off the excess.

Have the injectors been overhauled recently?

[Satan]

Did you take the intake boot off at all and do check it for any splits VOE

[jimf]

I've checked the intake boot and it is in good order.

If it were a leaking injector I'd imagine it would be all to cock from startup but the car doesn't splutter until a few minutes on the road. Saying that, there is quite a fuely smell from the exhaust.

[arrisbmw]

what colour are the spark plugs ?. sounds like your running rich

[arrisbmw]

if you stop the car when fully warm. wait 2 mins is it hard to start then ?

[jimf]

I agree that it is running rich, what would be the cause of it, how do you rectify it and would it be linked to this daily short episode of spluttering and surging issue? It starts perfectly no mater what temperature.

[arrisbmw]

could be a few things worth checking . blue temp sensor. ICV MALFUNCTION. WIRING TO INJECTORS CONNECTOR under inlet manifold corrodes.

b,t,s tell the ecu the temp of the engine and richen the mixture when cold.
icv try swap out of a know good one.
the electrical connector to the injectors is prone to corrode inside.

I<m thinking electrical issue somewhere/ as the car is warming up.

I suppose it could be as simple as a spark plug breaking down, or a knackered plug lead.
or bear#k down inside dizzy cap/ rotor arm . basic thing all worth checking over.

[Steve]

http://www.e30zone.net/e30zonewiki/inde ... ch_Running

[arrisbmw]

if it start well even when hot. don,t think its injection issue.

[arrisbmw]

once it has done it once , is it fine for the rest of the day ?

[jimf]

Yes, exactly that, it runs perfectly for the rest of the day, even from cold on the way home from work.

The spark plugs, distributor cap and rotor arm are all only a couple of hundred miles old.

[arrisbmw]

did the problem start after fitting them . ? the only reason i ask is a fitted a duff new plug recently . resistance was show zero.
or have you had any work done on it lately
you didn,t mention the .............
are the plug leads o.k

[jimf]

I have been driving the car daily with the new parts fitted for 2 months. The problem has only been going for a week now. I have not replaced the leads although I checked them for security. But surely if it was a duff plug or lead the problem would be present all the time rather than just at this particular time. I can see how a faulty ignition system would cause the lack of power and spluttering but not the engine revving up on it's own.

[jimf]

Good news, I found the fault. It's the blue temp sensor. I was having a prod around with the engine running and barely touched it and the car revved up. Switched off and had a fiddle with it then the car struggled to start. I can actually rev the engine up and down by wiggling it. Looks like this is the cause of the fuely smell as well.

[arrisbmw]

good stuff, one of my prediction was right bts. now you gotta figure out if wiring fault or the actual sensor
get the multi meter out.


to check the sensor completly cold = 2100 to 2900 ohms
hot ( 270 - 400 ohms ) quoted from haynes manual.

you can also test at the ecu plug . best way, as it confirms all the wiring is o.k to. but not as easy there is a post on here.
depends what engine management sys is in your car on what pins to check.
when i check mine at ecu multi plug, was 2633 cold 198 hot , apparently hot a little low.
DO SO AT YOUR OWN RISK !!!!!!!!!!!!!!!!!!!!

[jimf]

with the plug removed the plastic bit on the sensor feels a bit wobbly so I'm quite certain that's the issue and not the plug or wiring. I'll just fit a new one and I'll soon know if I need to look at wiring. It's only £15 for a Bosch item.