2.5 diesel warm starting - I hesitate to raise this issue again, but....

OK I know the issue is well documented and various bodge fixes are available e.g. via eBay.

However, despite having trawled this site and done various google searches, I cannot find a single post where somebody has fixed the root cause of this problem, rather than bodging around it by fooling the engine into thinking it is cold for a few seconds.

I have no problem with this bodge fix, it is a good pragmatic solution - however, I would love to know what really causes the problem in the first place...

Does anybody know?

I have heard and read various theories, including:

1) worn injector pump means when it is hot, the injection pump cannot pump the fuel properly. But if this is true, why is there a cloud of black smoke when the engine does finally fire?? Surely this means lots of unburnt fuel has found its way into the engine?

2) worn timing chain throws the injection timing out. If this is the case, why can't you just reset the timing? OK I accept this needs special tools, but surely this would be better than the eBay bodge, as it should improve not only hot starting but also general running throughout the rev range?

One thing that does seem really odd to me, is that even though sometimes I may have to crank the engine for up to 30 seconds to start it, when it does fire it appears to start evenly on all 6 cylinders and run perfectly straight away. Surely if it was a wear issue, you would expect some cylinders to kick in for a second or two before the others came in - it is surely unlikely that the wear is perfectly even across all 6 cylinders, is it not? In which case, the root cause must surely be something that affects all 6 cylinders equally (timing would fit this, worn pump or injectors IMO would not).

I discussed the issue briefly with the guys at Emmets of Colne when I was picking up a few used spares for my P38. They say it is worn timing chain, and that it can be fixed for £150, but would not tell me what they actually do (fair enough I suppose!). Does anybody know how they cure the problem?? Has anybody had this fix done by Emmets?

Has anybody taken their P38 to a diesel engine tuning specialist and got the problem sorted that way?


It just seems amazing to me that this problem exists on all installations of the 2.5 BMW engine (BMW/RR/Omega) yet nowhere can I find a definitive statement of what causes it, and how to fix the root cause of the problem...

Any thoughts gratefully received - or even better, if you have solved this problem WITHOUT the eBay bodge, please tell us how!!

Cheers

Jerry

Worn pump

nathan5346 said:

Worn pump

Click to expand...

Having this problem on mine and using a hot start fix, I too would like to know which parts are the issue?

dean68uk said:

Having this problem on mine and using a hot start fix, I too would like to know which parts are the issue?

Click to expand...

No idea exactly what parts but the worn pump was the one i kept seeing and being told when i looked in to it. So new pump would suggest no more hot fix

I also have heard that the fault is in the pump. But you're quite correct I have no proof. I would like to do away with the hot start unit that I fitted and would be willing to spend a few beer tokens, I like things to work correctly.

I've just thought, what do the Beemer drivers do?

Well I had my hot fix problem from the first summer i got it with only 5k on the clock, so I don't think its a worn pump, I think its simply a sensor of some kind...... but then again I do talk out of my ass a lot

Interesting responses so far, many thanks...

I did spend a bit of time looking on the BMW forums but to no avail. Most of the threads ended up pointing to the Range Rover P38 hot start fix kit on eBay

Has anybody just taken their car to a diesel injection specialist and asked to have the timing checked and adjusted if necessary?? This would seem the most obvious thing to do first, I would be surprised if nobody has done it!

It is also worth noting that Land Rover do specify different timing for engines over a certain mileage, has anybody set theirs up to the 'high mileage' value and, if so, did it make any difference to the hot start issue??


Cheers,

Jerry

The cost of the diagnosis coud amount to a few ££££££ as nobody can pin point the excact problem. My 1998, 2.5 DSE was the same, she had 15000 miles and was a pig when hot. Call me a cop out but I went for the fle-bay option and since fitting it have never had a problem, first piston up and she fires. I guess it's down to each owner on what decision they make.

Interesting input again, thanks

It seem that some relatively low mileage P38s have the problem too - I did not expect to hear this! - which does suggest that wear is not the only problem here.

I have done a bit more reading around, seems like the Bosch pump on the P38 (VP37) is also fitted to lots of other cars. If the cause of the problem lay within the pump itself (wear or not), surely we would be hearing of problems with hot starting on cars other than those fitted with the BMW 6 cyl engine? I think the pump may even have been used in some VAG TDI cars, and there are an awful lot of those about!!

This is all starting to point towards saying 'sod it, nobody knows!' and buying the hot start fix....

Cheers

Jerry

Hi

I had a 2.5 with 148k and I didn't have the hot start problem I have just replace the fip due to a fault with actuator it was bench tested and it was fubar lets say drop off is 600 mine was 300 and had no internal pressure at all it was total gone it cnt even be refurbed so I dnt think it is the pump and I have also set the chains to the higher mileage by usin said tool to be spaced by 4.6mm and I must say it makes a different it is so quiet

BMW had the ECU programmed to give little or no mixture enrichment and no glow plug cycle when hot for reasons best known to themselves. This has previously been documented. As far as I can see, the only proper fix would be to re-program the ECU to enrich the mixture and/or cycle the glowplugs. given that the problem occurs even on low mileage engines it cannot IMO be FIP wear. The hot start fix simply fools the ECU into giving a rich mixture to start and also cycle the glow plugs. I'm pretty sure the glow plugs are not needed, just the rich mixture.

It could be its simply a sensor on the glow plug side of things, not reconsigning too hot or cold, that's why the fix simply works, the whole thing is Bosh.... you don't expect them to admit there equipment is fubar do you? I have heard of some people taking the problem to BMW as well as Land Rover and it was a case of denial to them and it must be another problem (and of course a more expensive one that didn't fix the problem)

I suggest everybody reads. Land Rover Tech bulletin. 0023 Issue 2. Dated 07-06-2000.

Any chance of posting it on here?

The TB The Wammer Mentioned.....

Many Thanks

I completely cured my starting problems back in January by adjusting the static timing of the pump.

Mine took a lot of cranking when hot and if it was real cold needed two goes of the glow plugs to get it going. I mistakenly replaced the glow plugs with spurious ones and was blaming them for the cold start problems but they've been just fine since I sorted it. Now it starts a dream hot or cold. It'll even start withou a full go of the glow plugs from cold. Transformed!!


I've 144k on the clock, bought it with 70k so I've watched the hot (and cold for that matter) start issues develop over its life. I even bought the hot start 'fix' off ebay in preparation for the time it was going to be required but held out due to misgivings about the side effects. Also had the benefit of advice from a maestro called 'Chas' on the Blackbox-Solutions support forum who regularly chastises people to fix known faults before trying to deal with symptoms. Smart advice that has stood to me over 4 years of P38 ownership.

I've got faultmate so had the benefit of being able to observe a readout called 'timing modulation' from the EDC and observe that it was out of spec. From what I've gleaned this will be related to stretch in the timing chain or a pump that has been out and not timed exactly right on refitting.

Anyway, mine was out of spec and I sorted it by the simple procedure of physically rotating the whole pump where it sat just by loosening the retaining bolts. Doing this does not require any special tools (I thought it did, and had the tool for retaining the timing sprocket but this is not actually required). Getting at the bolts is awkward and you must remove the inlet manifold but that's about it.

Its an iterative process of looseneing the pump, rotating slightly, tightening back up, start it up, check the reading from the ECU with faultmate (read at a warm idle), shutting it off loosen bolts rotate another bit or back as required until the timing modulation reads in spec. Tighten everything up, put manifold back on (the p38 will start and idle just fine with the manifold removed so no need to put this back on everytime) and hopefully it will start as good as mine.

I don't know if this is a cure-all or if there is another type of hot start issue related to actual wear in the pump (the one that adding vegetable oil su[pposedly cures - low pump pressure) rather than the timing chain but this procedure has turned mine from a poor starter to great starter in one January afternoon.

HTH Spudh

SpudH said:

I completely cured my starting problems back in January by adjusting the static timing of the pump.

Mine took a lot of cranking when hot and if it was real cold needed two goes of the glow plugs to get it going. I mistakenly replaced the glow plugs with spurious ones and was blaming them for the cold start problems but they've been just fine since I sorted it. Now it starts a dream hot or cold. It'll even start withou a full go of the glow plugs from cold. Transformed!!


I've 144k on the clock, bought it with 70k so I've watched the hot (and cold for that matter) start issues develop over its life. I even bought the hot start 'fix' off ebay in preparation for the time it was going to be required but held out due to misgivings about the side effects. Also had the benefit of advice from a maestro called 'Chas' on the Blackbox-Solutions support forum who regularly chastises people to fix known faults before trying to deal with symptoms. Smart advice that has stood to me over 4 years of P38 ownership.

I've got faultmate so had the benefit of being able to observe a readout called 'timing modulation' from the EDC and observe that it was out of spec. From what I've gleaned this will be related to stretch in the timing chain or a pump that has been out and not timed exactly right on refitting.

Anyway, mine was out of spec and I sorted it by the simple procedure of physically rotating the whole pump where it sat just by loosening the retaining bolts. Doing this does not require any special tools (I thought it did, and had the tool for retaining the timing sprocket but this is not actually required). Getting at the bolts is awkward and you must remove the inlet manifold but that's about it.

Its an iterative process of looseneing the pump, rotating slightly, tightening back up, start it up, check the reading from the ECU with faultmate (read at a warm idle), shutting it off loosen bolts rotate another bit or back as required until the timing modulation reads in spec. Tighten everything up, put manifold back on (the p38 will start and idle just fine with the manifold removed so no need to put this back on everytime) and hopefully it will start as good as mine.

I don't know if this is a cure-all or if there is another type of hot start issue related to actual wear in the pump (the one that adding vegetable oil su[pposedly cures - low pump pressure) rather than the timing chain but this procedure has turned mine from a poor starter to great starter in one January afternoon.

HTH Spudh

Click to expand...

That maybe ok for people with a full fat Faultmate. But for those who do not have one several special tools are needed to set static timing.

So the TB is basically saying (1) fuel pump, if not that try (2) leak off pipes, if not that then.... erm... no idea, give us a ring ;-)

Would be great to get hold of the questionnaire data, sort it so it only covers hot start issues, and see what the fixes were.

Wammers - any idea how much it would cost to get somebody with the correct tools (presumably a Bosch diesel injection specialist) to check and if necessary adjust timing? Spud's post suggests this could be a fix for some of us at least... the problem with this, though, is that we have no idea what his pump is now set to, other than whatever the setting is, it works and gives good readings on Faultmate! It is of course quite possible that the pump has to be set outside the recommended spec to achieve this.......

So, we need somebody with full fat Faultmate AND the injection timing tools, then we can get to the bottom of this. Any volunteers?


Cheers,

Jerry

Also it wouldn't be that hard to find out if it is rich mixture, glowplugs, or both that are needed to treat the hot start symptoms - with the eBay bodge kit fitted, is there a relay that can be removed to disable the glowplugs? If so, anybody care to remove it and see if the car still starts fine when hot??

And the other way round - can the glowplugs be manually forced on easily? If so, I will happily try this as I don't have the eBay bodge fitted (yet) and see if it starts properly when hot just with glowplugs (no extra fuel)

Tests like this can sometimes help to get to the bottom of the issue.....


Cheers,

Jerry