non-starter hints? SORTED

[hankino]

Any ideas on this non-starter, please?

320i 1990 auto touring

New bits:
dizzy and rotor, plugs, air intake hose, air filter, water pump, cambelt and tensioner.

Symptoms:
Originally the problem was a slightly high idle, and slightly hard starting (hunting, and needing the pedal applied to overcome a misfire and get the revs to 1500 or so; half a minute of this and it could be left to a 1200 stone-cold idle, dropping to just under 1000).

But now, car turns over, tries to fire, sometimes catches a bit, engine shaking, but doesn't take - try this half a dozen times or so, under ten secs each, and battery noticeably drains. Had to get AA twice now - first time they applied battery booster, floored the pedal, and it eventually fired up (diagnosis: dizzy/rotor, so changed them, they were very worn).
Second time, batteyr booster didn't work, so AA bod took out the crank position sensor, gave it a rub with some sand paper, popped it back and it eventually started (diagnosis: crank sensor).

When running the car is fine, sprightly even, with the new dizzy. If I was being picky, I'd say there was a very very slight hesitation on pick-up off the line when still coldish; a very slight murmering misfire at idle (barely noticeable and the idle is still only just under 1000 in neutral (800 when in gear), though on a restart when warm it sometimes sits at 800 in neutral.

I don't see how the CPS can be shot if it runs so well when actually going - but should this be my first suspect?

I've noticed two other things: The car starts easier if it's been parked in a garage. The inside of one of the plug caps looks white (stained, almost like a coolant stain) compared to the others, though the plug was no different when I swapped it.

any clues would be appreciated
thanks
Alex

[DaveD]

have you had your battery and alternator checked?

[Heyho]

I take it that the battery dying is a result of all the cranking, and not the main problem?

It sounds to me like your engine is overfueling from cold - something my old E34 520i used to suffer from. It's possible that the engine temperature sensor is faulty, but Motronic M20s have always suffered from this to an extent.

There used to be a factory mod to cure this in extreme cases - it involved energizing a relay during cranking only, which introduced a resistance in parallel with the engine temp sensor, therefore fooling the DME into thinking that the engine was actually warmer than it was, and injecting a little less fuel. Once the starter is released, the relay opens, and the DME sees only the temp sensor again.

Why this problem seems to get worse withn age, I don't know, but it certainly seems to!

[hankino]

thanks for the replies.
The 1st AA fella checked the battery, and while it was down a little bit on its various measures, it was within tolerance, and taking charge, alternator working etc. No question that recent events won't have done it any good, though I've always stopped short of killing it completely...
I figured that if it was just the battery (not offering enough start-up charge or not recharging properly), then applying a booster would immediately overcome that, even allowing that the engine was flooded from the unhappy cranking.

Heyho, when you say 'engine temp sensor' do you mean the BLUE sensor? because that's new, and was professionally fitted and tested as OK. I hope I can rule that out.

Any thoughts on the CPS - would I be right in thinking that if it was shot the engine wouldn't run properly even when started? As it seems to start fine when warm (or at least not stone cold), could the 'gap' on the CPS be an issue - I've read about it, but don't see how you'd alter it or even measure it, as the thing just sort of plugs in...

Could a dirty/dodgy ICV cause the starting problem, or would that only come into play when actually running?

sorry for the long posts!

[Brianmoooore]

Thoroughly check out the connector for the injector loom under the middle of the inlet manifold, including under the lower rubber boot.
Don't take ANYTHING the AA man says as definite! (Why was he sanding the CPS???)
CPS faults usually develop as a car warms up. Check whether the fuel pump runs while cranking. If it does, the CPS is feeding signals to the ECU.

[hankino]

I'm always happy to see the AA man, Brian, but long ago realised that it's a lonely job, and understandably some of them like to chat and show off a bit, even when fairly clueless. I'm grateful for the help so am always ready to just listen (as long as it's not actually raining....) - but take it all with a pinch.

The CPS 'fix' looked dubious to me - we had cranked the engine so much it had probably warmed up a bit anyway!

Not sure how to act on your advice though Mr Moooore:
How would I check if the fuel pump runs on cranking? it certainly acts like it floods, which suggests it's getting fuel.

when you say check 'the connector for the injector loom' am I just looking to give it a spray, look for obvious breaks in wire etc or is it multimeter time (as in time to buy one and learn how to use it)

thanks
Alex


OT The second AA chap was so helpful and knowledgable that he even wanted to recommend a local garage. I popped in there out of curiosity as I was passing and in five minutes unacknowledged wait I got to hear the manager fielding two angry calls ("Well it was working when it left us" etc), then a mechanic came in and said that a bit of MOT testing equipment was fcuked, kept returning a fail when it shouldn't. All the boss said was: "He'll still have to pay".
That made me chuckle, so for a laff I told him I needed a new CPS for my E30 "Who told you that then? [you muppet]" before telling me I'd have to go to an AUDI dealer!
Classic stuff.
A less than expert steer from the man in yellow there...

[Brianmoooore]

Check the fuel pump while cranking, either by getting someone to get their ear near the fuel tank and listen for its whine, or better, take off the fuel hose that goes directly to the fuel rail (NOT the pressure regulator), and place it into a container.
Check the pins in the socket for obvious corrosion, and check for wires under the boot that are corroded through.

[hankino]

right, will do the visual checks tomorrow morning, and test for fuel coming through on cranking, and take it from there.
I'll also try cleaning the CPS itself if it's covered in crud - anything I should/shouldn't use to clean it: WD40? petrol? MucOff or similar degreaser?

[hankino]

UPDATE
did a quick visual check of the connections beneath the inlet manifold, and everything seemed in order (no multi-metering), so without checking the fuel for now, I strapped on the battery booster....
she fired up after a few cranks, and a full depression of the pedal, with now-typical brief cloud of 'flooded' smoke. Had to be held to 1500 or so for ten seconds, but then assumed normal (slightly high) stone-cold idle, and eventually settled just under the 1000.
Went for a 10-mile spin, (all battery-draining items off. Slight hesitation on pick-up from idle until warmed, but otherwise great).
Turned off and started again, a couple of times, no problems.
Had checked the ICV for 'buzzing' in the pipes with key in position 2, not running - and fine to that extent.

It seems the problem is entirely connected to starting from stone cold, with a lingering sympton (slight hesitation on pick-up) until temp guage reads normal - does that help me rule anything out?

I'm thinking TPS or ICV??

[Nelly]

Not trying to teach egg sucking but, have you checked the plugs for corrosion and nasty Black deposits also, the main engine earth strap from the sump to the n/s chassis rail?

Neil.

[hankino]

thanks for the reply Nelly
the plugs are new, ditto dizzy/rotor
I'll check that sump strap thing, but that would make it entirely battery related wouldn't it? and the problem exists even with a booster taking the strain, so....
still, you never know, and I'm ready to try anything
Alex

[Heyho]

It still sounds to me like classic cold start overfuelling. Just because the temp sensor is known to be good, it doesn't mean that the DME won't overinject during cranking.

I'd consider making up a relay and loom to counter this problem. IIRC, the way to get exactly the right resistor is to use a potentiometer, and adjust the setting every cold start, until it fires up cleanly - then simply measure the pot, and replace it with a normal resistor. I may be able to dig out the approximate resistance required, and a simple wiring diagram if you like.

[hankino]

blimey, Heyho, sounds complex!
I'd be wary of bolting something on to cure/mask the problem - assuming that if everything's in order the BMW boys will have got it right - but have you tried this before?
If it ever stops raining, I'll try the strap test - running a jump cable from the negative battery terminal to a good earth on the engine, and see what happens.
Wouldn't overfueling be a pointer to the ICV being dirty/knackered or the AFM or the TPS likewise? Though I don't know how that would explain the success when warm.

BTW what's IIRC stand for?
Alex

[Brianmoooore]

If a booster battery makes any noticeable difference, then either your battery is faulty or it's not being charged.
What is the voltage across the battery terminals, with and without the engine running?
If I Recall Correctly.

[TheDutch]

Symptoms:
Originally the problem was a slightly high idle, and slightly hard starting (hunting, and needing the pedal applied to overcome a misfire and get the revs to 1500 or so; half a minute of this and it could be left to a 1200 stone-cold idle, dropping to just under 1000).

But now, car turns over, tries to fire, sometimes catches a bit, engine shaking, but doesn't take - try this half a dozen times or so, under ten secs each, and battery noticeably drains. Had to get AA twice now - first time they applied battery booster, floored the pedal, and it eventually fired up (diagnosis: dizzy/rotor, so changed them, they were very worn).
Second time, batteyr booster didn't work, so AA bod took out the crank position sensor, gave it a rub with some sand paper, popped it back and it eventually started (diagnosis: crank sensor).

When running the car is fine, sprightly even, with the new dizzy. If I was being picky, I'd say there was a very very slight hesitation on pick-up off the line when still coldish; a very slight murmering misfire at idle (barely noticeable and the idle is still only just under 1000 in neutral (800 when in gear), though on a restart when warm it sometimes sits at 800 in neutral.

I have had precisely the same problems as you today on a 318is. Arguably mine has always idled like a pig, but the no start condition I had was exactly as you've described here. Swapping the ICV over for a spare one brought it back to life; back to its former pig like glory.

Do you know of anyone who has an ICV you could borrow to check it?

[hankino]

Thanks for the replies.

The time has obviously come to buy a multimeter....

When the battery was checked by AA a couple of weeks back, it was ok, slightly down on its numbers, but passing the tests for the charging system. I'm using the booster to make up for the excessive drain of constant pointless cranking.

It's possible that I've knackered the battery since then though - but the booster doesn't make starting perfect, far from it, so I suspect there's something else going on.

Still chucking it down here so haven't been out to check earth straps and fuel delivery; the ICV is on my list for cleaning/replacement. Ant has put one by for me.

[Morat]

It would be interesting if the aftermarket one was calibrated.....

[hankino]

aftermarket one, Morat?

[Heyho]

blimey, Heyho, sounds complex!
I'd be wary of bolting something on to cure/mask the problem - assuming that if everything's in order the BMW boys will have got it right - but have you tried this before?
Alex

Not only have I done this before, it was an official BMW mod - my E34 had the proper factory-made loom which I managed to salvage from a scrapper.

If I didn't have the correct loom, I'd have made one up. It doesn't mask the problem, it cures an otherwise incurable problem. The only other way to prevent cold start overfuelling would be a re-mapped DME, and I know which of the 2 options I'm able to do at home!

Maybe if you are able to remedy your battery problem, the overfuelling may be less of an issue, but the above method is most definitely an effective fix.

[hankino]

nice one, Heyho, could be just the job then.
I'll work through the easy bits still on the list, and then have a go with this loom thing if no joy. Do you have a diagram or something that you could let me have?
Alex

[Heyho]

Hankino - managed to locate a little more info regarding the mod. The resistor to start with is 3k (3000 ohms), but sometimes it needs to be higher, sometimes lower.

If I get a chance, I'll attempt a circuit diagram, and post up later tonight.

[hankino]

cheers Heyho
I expect quite a few other people with cold-start/over-fueling prob will want to try it too

[Heyho]

Ok, here goes!

All this mod does is to present an additional resistance in parallel to the existing engine coolant temp sensor when the engine is cranking. This has the effect of the DME seeing a slightly lower resistance than it usually would at a given temperature, therefore making it think that it is slightly warmer than it actually is. Warmer = less cold start enrichment. As soon as the key is released, everything is back to normal.

The energizing coil of the relay is connected to earth on one side, and terminal 50 of the starter on the other. This switches the relay on whilst cranking.

The switched contacts are connected to the temp sensor wires, with the 3k resistor inline on one side. It doesn't matter which wire goes to which, as long as they go either side of the sensor.



If you are not confident, then don't attempt this - you don't want to be sticking 12v up the DME where it doesn't want it, and I don't want to be held responsible for any damage!

As stated, the 3k resistor is only a basic starting point - you may need to experiment with different values - ie 2.5k, 3.5k etc...You may find that the cold start is lovely, but hot starting is compromised. The alternative is a variable resistor that can be adjusted until you find the value that suits your car best.

Hope this makes sense, and is of some use!

[hankino]

thanks Heyho
Looks a bit of a stretch for my level of experience at the moment, but good to have the information for later use.
nice one!
Alex

[hankino]

UPDATE
Did the strap test - no difference - so that rules out a bad sump earth.

I checked the TPS this morning and there was no click when moving the throttle from its rest point. Figuring that someone might have adjusted the stop position at some point (could explain the 1000 idle) I unscrewed the position screw half a turn, and now you can hear a click when moving from rest. The throttle screw is still opening the throttle slightly, and there seemed to still be a small internal gap at rest.
Rechecked continuity - left-centre continuity at rest until click; right-centre no continuity at rest, coming in when fully open. So that seems fine.

BUT it won't start, in the same way as before.
I'm guessing it would have been more correct to adjust the TPS position to get that click-from-rest, but I'd have to take the throttle body off, and get a new gasket - is that right?

I also followed the wiring from the ICV and found a 'spare' smaller block connector at the other end. Can't see anywhere to plug it in, so would this be related to something not on this model, like aircon?
While rooting around I also noticed a completely severed wire end among the three that come out from around the dizzy area too... any ideas what that might be?

All that's left on my list is AFM and ICV (got spare).
Can I check the AFM by just unplugging it?

[hankino]

further along, but no solution....here's what I've done:

new dizzy cap and rotor, plugs
TPS now adjusted
ICV now changed
new blue temp
no rotting in the connector under the inlet manifold, all other plugs/connections look clean and tidy
passes the sump earth test
battery good enough (problem exists with or without booster)
'spare wires' discounted

Still starts fine hot/warm, struggles (or refuses to) start cold when it's been outside overnigght (though fine if left in a garage)

Too thick to try the 'factory loom bodge' suggested above - all that's left is the AFM...any ideas what to do with it??

[Heyho]

Too thick to try the 'factory loom bodge' suggested above - all that's left is the AFM...any ideas what to do with it??

I'll say it once more.

IT'S OVERFUELLING FROM COLD - YOU WON'T FIX IT!

Unless you do something to make it think it's warmer.

Would you be interested if I told you that the cold start mod loom was still available from BMW for about £50? Some of the different resistors are no longer listed, but you can get them from any electronics shop or supplier.

[hankino]

SOLD
I'll go to the dealer and ask for a cold start mod loom for a 1990 320i. £50??? small price to pay because this thing is driving me la-la and all the time it's not working I'm having to keep another car on the road.
cheers heyho

[Brianmoooore]

Try wiring a 2.2 k ohm resistor in place of the blue temp sensor to see if that helps it start, first.
A 1p resistor's a lot less than £50!

[hankino]

Turns out the dealer says 'no longer available' anyway - so before I start ringing round the whole country, I'll give this resistor thing a go.

Just wire it between the two pins of the plug that goes into the sensor, so that the sensor is plugged into nothing?

will update later...

[Brianmoooore]

Just wire it between the two pins of the plug that goes into the sensor, so that the sensor is plugged into nothing?.

That's all you need to do. With a 2.2k ohm resistor the engine will think that the engine is at about 22 degrees and reduce fueling accordingly.
As soon as the engine rises above this temperature the engine will overfuel, and begin to run rough.
If you connect a 330 ohm resistor in series with a 4.7 k ohm variable resistor you can track the fuelling across the engines full temperature range.

[Heyho]

Turns out the dealer says 'no longer available' anyway - so before I start ringing round the whole country, I'll give this resistor thing a go.

Just wire it between the two pins of the plug that goes into the sensor, so that the sensor is plugged into nothing?

will update later...

Well, I think it is still possible to get them - they probably didn't want the grief. I'll check it out for you.

Try the resistor in place of the sensor, but telling the DME it's 22 degrees c if it's actually near to 0 may be a little too much - but it may confirm that you're going in the right direction.

£50 may be cheaper than a 1p resistor, but I bet it's less than you've spent so far...

[Brianmoooore]

Try the resistor in place of the sensor, but telling the DME it's 22 degrees c if it's actually near to 0 may be a little too much

Try a 2.7k or 3.3k resistor as well then.
The BMW loom is very easy to make up yourself, apart from you won't be easily able to get the connectors to make it completely plug in. It's just an ordinary orange relay and a resistor. (The same as the ebay 'Sport Mode' device being discussed on an E30 chat thread, although wired slightly differently)!

[hankino]

thanks chaps
BTW my spend so far: about £150 (but I suppose the plugs, dizzy, rotor, intake rubber, were overdue...), and MANY hours of sadness.

I'll get a 2k2 from Maplins - they have several, what other ratings should it have, 5V?? - and give it a go. If it works, I'm looming.

[Brianmoooore]

Other rating for resistors is its wattage. The smallest available will do, but they will probably be in packs of 10 or some other large quantity. Higher wattage ones may be available singly, and might work out cheaper.