worzel

Hi and premature seasonal greetings! Can report I eventually fixed the idling fault- now it no longer surges. Field lane service station (long established independents for BMW) suggested a few simple fixes (I admit to being sceptical about their offerings)- but seems to have worked- Advice was- Only use premium grade juice- apparently these cars don't relish the supermarket stuff Switch the box into sport (I haven't tried this as I haven't needed to). Run it for about a 100 miles or so on the better fuel. Seems to have worked. Two last points- As I was told, relocating the icv next to the throttle body hasn't affected its operation so thanks for that info and a question- Should the revs drop when engaging drive- the Bentley bible says no but what do others think. Revs drop only slightly but I suppose it would make sense if they were unaltered or even rose as on modern autos. Any offerings? Regards John

Hi Mr D Thanks for reply. I agree that air leaks are pretty common but I'm pretty sure there aren't any in this case- here's why- Every hose on the intake system has been removed and pressure tested- I've replaced some that were marginal The servo pick up hose has been replaced as a precaution and the servo is holding vacuum The throttle body has been removed and cleaned/ditto the idle valve All the above I did myself so I'm not taking another's word that they've been completed. plus- when I removed the inlet manifold (for the second time) I relocated the idle control valve so it sits right next to the throttle body (for convenience) I modified the hose system for this using new silicone hoses with the pick up that clips under the manifold properly fitted with silicon instant gasket. Additionally, I'm now venting the head breather direct to atmosphere (rather than into the intake system) and I've blanked off where these hoses normally feed into the engine. In effect the only air feeding into the engine comes through the filter and MAF plus any going thru the idle valve. The pick up for the fuel pressure valve has also been properly silconed into place. I admit to little experience of fuel injected cars with this number of intake hoses and sensors but I do have a lot of experience with twin double choke sidedraught dellorto carburettors which in themselves are fairly complex devices and (my experience only) I've found that air leaks and the symptoms they cause at slow running speeds tend to be present (and sometimes worse) when engines are cold- unless the air leak is being caused by something expanding as the engine heats up. However, I take your point so as a double check my next job will be to spray carb cleaner over all hose joints whilst the engine is hot to see if the revs alter- I'll report back. Regards and thanks John

Hi-again Following on from Daz's reply- am I correct in thinking that cats became compulsory in the UK post 1992 and- I'm getting confusing messages on this- the Bentley manual indicates that the revs shouldn't drop when engaging a gear but I've read posts from other owners who report that this isn't so. Bentley do suggest that a fall-off in revs might indicate problems with the ICV/ICV wiring circuit- which is correct/ Incidentally, since accessing the ICV is such a pain as I previously mentioned I've relocated it next to the throttle body and it does seem,as somebody pointed out, the orientation of the valve is irrelevant to its operation (mine sits vertically rather than sideways). Makes replacement a 10 minute job at most although not quite as neat as BMW would prefer. Regards John

Hi Daz Thanks for that useful bit of info. I recall that when I recently had the inlet manifold off the car I noticed that there was a plug not being used. On the basis of where the Bentley manual identifies the usual location of the sensor (by the starter/under it) I'm guessing that on my car there was provision for one in the original specification but it wasn't fitted. Does that sound a reasonable assumption? Regards John

Hi As a newcomer I don't think I can add/input anything useful and if I seem to be asking questions the answer to which might seem b*******g obvious I apologise. Sorry- here's another one but first some background info. In Jan this year I bought a really nice 91 525i auto. Inevitably though I met a few problems- mainly concerned with low speed running. Symptoms- coming to a dead stop, once up to normal running temp inevitably the engine would be surging between about 600-800 revs for a few seconds then settle down until the next stop. Cold starts- no problem and no other issues during warm up. Additionally- if in slow moving traffic and just using idle speed to inch forward the surging would recur. What I've done- the simplest things first- Change plugs, air filter, fuel filter. Drained/flushed gearbox and changed filter. Fitted new TPS Fitted new Bosch MAF after original was diagnosed as having an intermittent internal short Fitted a (reportedly) known working Bosch ICV Result- clearly improved- surging when stopping pretty much cured with only occasional surging when crawling in traffic. However (always an however) I notice that occasionally during warm up when engaging drive depressing the throttle induces a momentary jerk that feels like the engine is trying to stall. Once at normal temp this doesn't occur. Thinking it might be an idea to change the oxygen sensor (as I suspected it might be linked to the problem of surging when hot when the O2 sensor kicks in) I booked it in to the MoT station I've used for the past 15 years or so. Good garage, knowledgeable sensible staff so definitely not cowboys. Here's my question- they informed me that actually it doesn't have an oxygen sensor fitted and it appears never to have had one. There are no loose wires/cut wires etc and as he said if somebody had just deleted the sensor you'd expect this to show up as a fault code. So- can anybody confirm that it's possible that a Feb 1991 car might well not have been fitted with one of these? Regrds and thanks John

Hi Apologies if this seems a question with an obvious answer but is there any reason why Organic Acid antifreeze shouldn't be used in a 91 525i? According to the "label on the tin" it indicates suitable for all petrol/diesel engines- is it? Regards John

Hi Thanks for that info- google shows a fair few of these units in the USA. Regards John

Hi I feel like I'm looking for the Holy Grail! I've contacted countless suppliers (both BMW franchise outlets and various independents but seem to be coming up against a brick wall. I'm looking for an idle control valve for a 1991 525i auto. Post September 1992 valves for the later E34 's seem fairly easy to get hold of but not the one I need. Additionally, there seems to be some confusion on the parts of some suppliers about just what fits what. Currently the valve on my car is a Bosch 0280 140 524 but a few sellers have indicated this is incorrect and the part number that fits is 0280 140 574. Other suppliers however say that the 574 unit superseded the 524 one. Slightly confused on this. Any ideas as to which is correct and- where I might get hold of one- preferably new, Bosch or equivalent quality or anybody got any better thoughts on this one? Regards John

Hi A quick update. False alarm- the "unattached" fitting actually connects to the fuel pressure regulator on the fuel rail- must get my eyes re-tested! I've nearly finished relocating the idle control valve and am 100% (not 110%) confident there are no air intake leaks. just need to secure the valve using a custom made bracket and connect the last few hoses. Might not be quite as decorative an installation as BMW intended but it'll be a whole lot easier to replace the valve should the need arise. incidentally, does any owner know if the orientation of the valve matters ie does it need to be on its side as per the original or is that irrelevant. I assume the rubber mount is to minimise vibration- although being originally bolted close to the block must create some internal vibration surely? I'll let you know the results- probably this week Regards John

Hi Thanks for all of the info posted. Something puzzling me- I've taken the inlet manifold off- again- and noticed something I've overlooked before. On the underside of the manifold at the bulkhead end there is a small, clipped in plastic hose take off point that fits a hose of about one tenth inch internal diameter. I don't see any loose hose lying around in the engine bay so could anybody tell me what this is for and to where it is connected or is it something that is only used for certain auxiliary devices that use vacuum. The fitting itself clips to the manifold using the same sort of plastic clip used for the idle control valve hose. It's fitted with an "O" ring so it must be powering/affecting something or maybe it should be blanked off. Might explain the idle speed problems I'm having. Regards and thanks John

Hi Thanks for the info and the possible places to look for repairs plus the suppliers of MAFS on ebay. Unfortunately ACTRONICS don't currently repair MAFS and funnily enough neither do one of the major German Bosch outlets- I'd have thought this unusual in this day and age. I've not yet approached ATP which I've used in the past to source parts direct rather than pay Lotus's inflated prices (a Lucas Constant energy Module from Lotus- £140, the exact same module new from ATP- £23). I do know from a conversation I had with one of their staff a few months ago (unfortunately I can't remember his name) that they can definitely repair idle control valves- they charge £50 to test them but will deduct this £50 from the final bill. This guy I spoke to said I was fortunate to get hold of him as apparently he personally provided a lot of the input in designing the fuel injection system for the E34 series. As for the aftermarket ones- so far I've tried two, both from the same supplier in Spain (Origin I think they're called- they're on ebay)) at £69 each. Very nice seller as took them back without any quibble when I said that they made the engine run far worse. He was pretty adamant that they were equivalent to the 0280 213011 Maf but I suspect they might be specced for another model in the E34 series as they both exhibited a rhythmic misfire rather than an erratic one which made me suspect they were causing under-fuelling. My local PARTCO store in Liverpool (just before Partco went belly up) reckoned they could still get hold of new Bosch Mafs despite no longer being made but at a price- £700 plus a £75 surcharge pending my current one in part-ex. Delivery in about 4 working days. Where do they get these prices from exactly? Incidentally, for fellow owners, I'm relocating the idle control valve to a more convenient ie accessible location to the right of the throttle body. Some clever routing of new silicon hoses plus an extension to the plug connector and it'll mean that the valve will take no more than 30 minutes to remove- and without any skinned knuckles! I'll report how it works although I don't see why it should raise any issues in its new spot as it's only an air bleed valve in effect. Regards John

Hi thanks for that info- I'll post their response to my enquiry regards John

Hi Has anyone any experience of having a MAF repaired? The 91 525i I own apparently uses a Bosch item that is no longer listed (0280 213011) so in case this proves to be the cause of the idling problem I'm trying to find out in advance who might be able to deal with it. Any ideas- I was thinking of trying an outfit like ATP industries in Cannock who re-manufacture various electronic sensors. Regards John

Hi Can anyone think of a reason why the Idle Control Valve couldn't be moved to a more convenient location away from underneath the inlet manifold on a 91 525i? This would mean a bit of hose modification and fabricating a new mounting point - possibly adjacent to the MAF but doesn't look overly problematic or are there any technical reasons why the airpaths for the attachment hoses to the ICV have to be a certain length? Regards John

Hi All I'm new to BMW but not to classic cars- I've mainly owner Lotus Elans which by their design are simpler (cruder some might justifiably say)- but easier to fix certainly. However, to the point. In Jan this year I bought a 91 525i auto which was advertised as one of those (Timewarp) cars. As it turns out it was pretty accurate description, the body is totally rustfree (even inside the doors) and the blue leather interior is factory fresh. As usual there are though one or two "issues"- I reckon probably due to minor causes but I'm not sure where to start. Problem one- I drove it back to Liverpool from Buckinghamshire without any problems (or maybe I didn't notice them) but now I've noticed that when coming to a full stop when the engine is at normal temp there is a momentary surge/hunting for about one or two seconds then the idle steadies. I've eliminated air leaks as a cause, removed and cleaned the idle control valve, cleaned the MAF and changed the air filter but the problem remains. An un-named garage suggested that at 66000 miles carbon build up was probably causing it but I reckon that's a red herring. the idle control valve was slightly gummed up before cleaning incidentally. No fault codes are showing- but then again I wouldn't take that to indicate much on its own. Cold starts are no problem and it idles fine when cold. Related to this- just how evenly do these engines idle- this is a non Vanos engine that is factory std ie unmodified but it's not quite as sewing machine smooth as I would have thought. Problem two- are these cars notorious for following the camber? I've had it correctly tracked but it still seems to pull slightly rightwards although at other times it runs arrow straight. No sticking of brakes, tyres are same make, facing the right way (they're directional), pressures are correct, wheel bearings and bushes are ok. Problem three- this might not actually be a problem. Engaging reverse when at normal running temp produces a noticeable "jolt" in the drivetrain. Have had this looked at but no evidence of worn bushes or prop joints. Gearbox is ZF and oil level is correct, oil spec is correct and oil is about 2 weeks old. I know some auto boxes do have a tendency to produce this kind of noise when selecting reverse but is it normal on these? Last question- not really a problem but can somebody explain how the heating system works? The auxiliary electric water pump I imagine boosts the flow straight from the rear of the block and pumps this into the heater valve. When hot is selected I can understand how this works but what about when cold is selected- does this pump work continuously while the engine runs or does selecting cold throw a switch somewhere that shuts off the current to the pump because surely if the pump does run continuously even when cold is selected it is still collecting hot water from the block- or have I got this completely wrong? Regards John