over fuel/no idle
Discussion
My 1985 350i has been sat in the garage for a few months as too busy for it 
Now when I came to start it, it's telling me something.
Initial problems look likely to be over fuelling symptoms, couldn't start it - suspect flooding due to smell of petrol! Black sooty plugs so cleaned them up and waited a day
Next day, got it started first time and went for a run. All seemed good and now up to normal running temperature but on coming to rest, there was no idle. Usually sits a bit high over 1000rpm but just went to 0 and cut out. Didn't restart straight away but did after half an hour or so and idle still not there - no hunting, just not there so cuts out unless I manually input some throttle.
I'm optimistic it's a simple fix and probably the ECU connector needing cleaning/disconnecting/reconnecting.
I'll try again tomorrow but as I believe it's due to standing for some time (battery on trickle) is there a likely suspect component that degrades due to inactivity?
Now when I came to start it, it's telling me something.
Initial problems look likely to be over fuelling symptoms, couldn't start it - suspect flooding due to smell of petrol! Black sooty plugs so cleaned them up and waited a day
Next day, got it started first time and went for a run. All seemed good and now up to normal running temperature but on coming to rest, there was no idle. Usually sits a bit high over 1000rpm but just went to 0 and cut out. Didn't restart straight away but did after half an hour or so and idle still not there - no hunting, just not there so cuts out unless I manually input some throttle.
I'm optimistic it's a simple fix and probably the ECU connector needing cleaning/disconnecting/reconnecting.
I'll try again tomorrow but as I believe it's due to standing for some time (battery on trickle) is there a likely suspect component that degrades due to inactivity?
Experienced something like it, but worse (wasn't able to drive at all and after a period was just able to start, but due to overfuelling cut out very quickly) and turned out to be the coolant temperature sensor. Taking the connector of and shorting it (better with resistor but this will do temporarily as well) is my check to rule this sensor out.
Rob
Rob
On a hotwire I had the throttle pot set too high. It had drifted, this caused over fuelling for me. Not saying its the same for you but easy to check and free if indeed it does the same on a flapper.
When I had plugs mucked up for another issue I found the best way to clean them was to bake them on a low heat after the usual scrubbing. The fuel leaves a deposit on the plug. There was an article on the NGK site about fouled plugs and how to deal with it (??? I think it was NGK) but cannot find it.
Edit. Wedg1e has the low down on flappers methinks?
When I had plugs mucked up for another issue I found the best way to clean them was to bake them on a low heat after the usual scrubbing. The fuel leaves a deposit on the plug. There was an article on the NGK site about fouled plugs and how to deal with it (??? I think it was NGK) but cannot find it.
Edit. Wedg1e has the low down on flappers methinks?
1000rpm is very high, even for a lumpy-cammed V8.
Might be worth checking that the airflow meter flap swings freely across its range with no sticking points, should be an even amount of resistance throughout.
I'm at work so will have to have a think, meanwhile I'm starting a countdown until honesthingy comes along with a list of links
5... 4.... 3...
Might be worth checking that the airflow meter flap swings freely across its range with no sticking points, should be an even amount of resistance throughout.
I'm at work so will have to have a think, meanwhile I'm starting a countdown until honesthingy comes along with a list of links
5... 4.... 3...
It's a standard '85 350i V8 and idle has always been around 1200rpm ever since the days I had it serviced at HarrogateHC. I got it from them in 1989!
...and another thing, instead of normal pops and bangs on the over-run, it sounds like a boxer engine. Maybe not on all 8 cylinders??
...and another thing, instead of normal pops and bangs on the over-run, it sounds like a boxer engine. Maybe not on all 8 cylinders??
Edited by mark387mw on Friday 8th April 10:03
mark387mw said:
It's a standard '85 350i V8 and idle has always been around 1200rpm ever since the days I had it serviced at HarrogateHC. I got it from them in 1989!
...and another thing, instead of normal pops and bangs on the over-run, it sounds like a boxer engine. Maybe not on all 8 cylinders??
Quite possibly, which in itself may explain why the idle has to be higher in order to maintain momentum. One bank of injectors off would definitely make it sound like that, I has exactly that problem on an ECU I bought from Ebay; needed a new transistor but an easy enough fix....and another thing, instead of normal pops and bangs on the over-run, it sounds like a boxer engine. Maybe not on all 8 cylinders??
If it's been parked for a while one or more injectors could stick, that'd also make it sound uneven.
My car idles around 600rpm once it's warm.
dixiebabes said:
My car idles around 600rpm once it's warm.
Mine too i thought that was a bit low? but the lower the more petrol i save eh
Dix
As long as it's not clattering away and has some oil pressure it should be OK. I always think it's a sign of a well-balanced and set-up engine if it can idle at low speed Mine too i thought that was a bit low? but the lower the more petrol i save eh
Dix
Wedg1e said:
As long as it's not clattering away and has some oil pressure it should be OK. I always think it's a sign of a well-balanced and set-up engine if it can idle at low speed
My 1980 280i must be running very well (most of the time) as it seems to want to tick over at 500 rpm when warm and the MOT guy said it almost passed the emissions test for a car with a CAT fitted! It does seem to go "lumpy" when hot though esp in stop/start traffic, still got to sus what that one is.Once it starts to be lumpy it will play up all the way through the rev range and won't settle till its been on the move for quite a distance (cooling air through the rad/charge going back into the battery??) then it will settle down again. It will (mostly) still tick over in lumpy mode but sounds like its about to die and occasionally will stop, but usually starts ok and returns to lumpy running, until its had a run as above. Never a problem with a cold engine.
wedgeinald said:
My 1980 280i must be running very well (most of the time) as it seems to want to tick over at 500 rpm when warm and the MOT guy said it almost passed the emissions test for a car with a CAT fitted! It does seem to go "lumpy" when hot though esp in stop/start traffic, still got to sus what that one is.
Once it starts to be lumpy it will play up all the way through the rev range and won't settle till its been on the move for quite a distance (cooling air through the rad/charge going back into the battery??) then it will settle down again. It will (mostly) still tick over in lumpy mode but sounds like its about to die and occasionally will stop, but usually starts ok and returns to lumpy running, until its had a run as above. Never a problem with a cold engine.
I used to drive a 2.8i Granada hearse for the Co-op and that was entertaining; idle speed when cold was so high it would drive off by itself if you put it in Drive.Once it starts to be lumpy it will play up all the way through the rev range and won't settle till its been on the move for quite a distance (cooling air through the rad/charge going back into the battery??) then it will settle down again. It will (mostly) still tick over in lumpy mode but sounds like its about to die and occasionally will stop, but usually starts ok and returns to lumpy running, until its had a run as above. Never a problem with a cold engine.
Once it warmed-up it would hunt like a barsteward, so in Drive it would propel itself forward in little spurts. I almost ran Directors over a few times in it
Having fried my starter motor trying to start the car, it's now got a new starter and my local garage has looked into the overfuelling and can confirm it. He says loads of petrol in the oil .
ECU suspect? As originally thought, could be poor ECU connection. If not and it needs work, any quick fixes or is this an opportunity to look for a more efficient
, yet more 'sporty' ECU?
.ECU suspect? As originally thought, could be poor ECU connection. If not and it needs work, any quick fixes or is this an opportunity to look for a more efficient
, yet more 'sporty' ECU?Start with the coolant sensor first - short it out and try again. It's a 2-minute test.
Yes check the ECU connector - plug and unplug 5 times should clean it up.
Going down the list the ECU might need "reflowing" - going over all the PCB with a soldering iron and some fresh solder - takes about an hour to do. Leave this till last.
Onve you have fixed it time for an oil change...
Yes check the ECU connector - plug and unplug 5 times should clean it up.
Going down the list the ECU might need "reflowing" - going over all the PCB with a soldering iron and some fresh solder - takes about an hour to do. Leave this till last.
Onve you have fixed it time for an oil change...
Interesting read. My 450 is rich on a cold start up. You can smell it and it hunts and threatens to stall for the first 10 seconds or so unless you tickle the throttle. Once warm it ticks over around 1000rpm. Never had a problem starting unless I've stalled it when still cold. Eventually starts after turning over a few times. Fitting a new coolant sensor tomorrow. Only 9 quid from Rimmer Brothers so figured may as well, otherwise it can go in the spares box.
Jimbo
Jimbo
JMF894 said:
Fitting a new coolant sensor tomorrow.
Please post the result - I'm hoping for a straightforward fix, don't want to be messing with the ECU and dis/reconnecting didn't fix it. Maybe a fibreglass pencil on the connector. (Can you still get fibreglass pencils or were they outlawed due to Health & Safety?)mark387mw said:
Please post the result - I'm hoping for a straightforward fix, don't want to be messing with the ECU and dis/reconnecting didn't fix it. Maybe a fibreglass pencil on the connector. (Can you still get fibreglass pencils or were they outlawed due to Health & Safety?)
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