316i spluttering

Thu Jul 21, 2011 11:11 pm

Hello,
Just wanted to ask for some help and advice on something wrong with my e30 316i.

The car will drive perfectly for 10 minutes

After this time, between 1000-2000 revs under acceleration, the car will not accelerate and will hesitate and "hiccup/splutter". After about 10 seconds of spluttering and "non acceleration", the engine will eventually climb above 2000 revs, and then will be fine...the car will accelerate like normal.
^^ I hope this makes sense It's hard to describe

Anyways, a short time before the engine starts its hesitation and spluttering the MPG/Fuel economy gauge will simply shoot to 50 (right to the left), and stay there.
Also, when I'm driving along, i will quickly turn the ignition off, and then turn it back on again, and the MPG gauge will start to work normally again --- Although about 2 minutes later it will shoot to 50mpg, and the engine will start spluttering in between 1000-2000 revs.

As well as this, on the odd occasion, when i pull up at traffic lights of a roundabout, the car will drop revs and the engine will just stall. Then after much cranking, it will eventually start.

Also, it will sometimes misfire and i will hear a loud bang (probably unburnt fuel coming from the exhaust)

Any help on this topic will be greatly appreciated as it's really really driving me nuts!
Thanks a lot,
Harjun.

Fri Jul 22, 2011 8:26 am

check your intake pipe for splits, plugs, leads and dizzy. for starters.

Fri Jul 22, 2011 8:49 am

Thanks for the reply, have checked the intake pipe for splits (none there), and the plugs and leads are all fairly new so i wouldn't have thought that they have gone bad. Also, what is the dizzy?

I'm thinking it may be the TPS, or the coolant temperature sensor, will check them both today

Fri Jul 22, 2011 10:23 am

distributer and rotor arm, check for wear and clean up the contacts, that can make a huge difference.

Possibly the blue sensor although it does tend to just mean it runs a bit rich and rough normally, not cut out.

Best bet is get the opinion of Brianmoooore- E30 Guru.

Fri Jul 22, 2011 1:32 pm

Ok thanks a lot for the help, i will do that

Also, i checked the TPS switch and its fine.
However, i checked the air flow meter following the "Haynes" manual and the air flow meter seems buggered. It doesn't give a consistant increase in resistance as the flap is opened (as the Haynes manual says it should) In fact, there are even flatspots in it where it will just return straight to the 0.5 resistance.

Basically this is what mine does

Flap closed - 0.5
now we open it slightly, it goes like this....
0.6
0.6
0.5
0.8
0.9
then still opening it (we're at about half way now)
0.6
0.6

This isn't right is it?
May buy a working AFM and put it on the car

Fri Jul 22, 2011 2:31 pm

That would give a loss in performance when it drops from 0.9 to 0.6 Could well be your AFM, test will a known working one, should be cheap enough to get hold of.

Fri Jul 22, 2011 3:43 pm

ok cheers mate,
will try get hold of one

Fri Jul 22, 2011 3:48 pm

there maybe a zoner nearby who has one you can test. where abouts are you?

Fri Jul 22, 2011 4:59 pm

Hertfordshire mate
I think I can get hold of one for £15 so I'll let you know
Thanks a lot for the help though

Fri Jul 22, 2011 11:16 pm

You can't test an AFM properly following the Haynes method!
You need to connect a six or nine volt battery across the AFM potentiometer track, and connect a meter, preferably analogue, between one of the battery terminals and the AFM wiper.
Open the AFM flap slowly by hand, and check that the meter reading rises all the time, and especially that it never drops.
Terminals 1 and 5 are the track, and 3 is the wiper.
Before you get too involved with AFMs, try a replacement DME relay (white one under the bulkhead wiring cover, fusebox side) or just pull it out and temporarily use a couple of wire links to connect both pins 87 to pin 30 or the relay's socket.

Sat Jul 23, 2011 12:57 am

Hi thanks a lot for the reply Brian.
I will do what you said with the DME relay, but i can't seem to find it. Is it in the fusebox itself?
I will also check the AFM properly.

Thanks

Sat Jul 23, 2011 9:29 am

FYI
http://homepage.ntlworld.com/lemmingsdi ... Repair.pdf

Sat Jul 23, 2011 9:44 am

redcar wrote:Hi thanks a lot for the reply Brian.
I will do what you said with the DME relay, but i can't seem to find it. Is it in the fusebox itself?

It's about 200mm from the fusebox, towards the centre of the car, under the wiring cover.
Five pin relay, usually white.

Sat Jul 23, 2011 11:12 am

Alright thanks mate
Very informative link aswelll

Sat Jul 23, 2011 7:29 pm

Tested AFM, coolant temp sensor, TPS all are fine
Dme relay is also fine as bypassed relay and the problems persist.

Checked the rotor arm and distributor cap and leads are all absolutely worn and messed up.
Getting new ones on Monday so will update then

Thanks

Mon Jul 25, 2011 10:29 am

hopefully the dizzy and rotor arm will sort you out so will be a nice easy and cheap fix...... cross fingers.

Tue Jul 26, 2011 5:21 pm

One thing I would say is NEVER clean corrosion off the rotor arm and cap contacts. All you do is widen the gap that the spark has to jump, which increases the KV's needs and puts a strain on the coil.

FWIW, I had similar symptoms on an E32 years ago - ran fine when warming up and the muixture was richer, but once warm and the mixturew leaned out it really acted up. The original 17 year old 240'000 mile cap and rotor were shagged.

Thu Aug 11, 2011 2:02 pm

thanks for the help guys,

turned out to be all the leads which cracked and broke when i pulled them out, so replaced rotor, dizzy cap and the leads with brand new ones.
Fixed the problem, engine is a lot smoother now and mpg gauge always works.

I was told all these were replaced recently when i purchased the car.