This is a tricky one...My Rover 620SLDi some months back developed an annoying habit, which I'm having a great deal of difficulty fixing. Once the engine has warmed up, I cannot get the engine speed past about 3100 RPM (usually good for 80-85mph in 5th). What happens is that the engine management light comes on and no further power is available (quite abruptly), although I can continue at the same speed OK. If I lift my foot off the accelerator and press down again straight away, I can sometimes get a bit more, so it's not an absolute thing. It has the feel of some vacuum related problem to me, but I can't see where.

Anyway, it's been into the local Bosch diesel specialists who have so far replaced the air flow sensor and a heat sensor (located up by the injectors), without any success. Annoyingly, I cannot recall the actual error code recorded in the ECU, but it was certainly not specific enough for the diesel specialists to go straight to the problem.

Any ideas? This business of replacing parts one after the other gets a bit pricy, not to mention tedious, after a while, and I'd be glad to get some more focussed ideas as to where to look.


[Edited by Johnny2R on 11-06-2002 at 11:11 PM GMT]

Your car has "Drive by wire". Basically the throttle cable is attached to an electronic control unit which inturn controls the engine, maybe it could have something to do with this. My mum has a 420SDi and I know that when you press the brakes and try and accelerate at the same time there is absolutely no power available.

If the orange check engine light is on, there WILL be a stored fault code contained in the Bosch EDC ECM. It would appear (from my experience...) that Bosch Diesel Specialists themselves cannot read all of these fault codes - T4 is the only tool to do it.

The ECM remembers the fault codes (within 20 ignition switch cycles, anyway) so best get it into an MGR dealer for a checkup from the neckup.

Sounds as though you've spent a small fortune already!

Why didn't you take it to a dealer in the first place? We're not as expensive as you all think!

Dr Dave wrote:Why didn't you take it to a dealer in the first place? We're not as expensive as you all think!

Well, you've convinced me! It's just that the Rover dealership in Norwich has recently changed to a company I've had bad experiences with in the past and I was keen to avoid them. Price was not the issue - I don't mind spending the money if it solves the problem. My previous experience with this company was of spending the money and not solving the problem. But if they're the only people with the right equipment, I guess I should bite the bullet.

I don't think you have much choice Johnny - go for it :)

Let us know how you get on, OK?

Dr Dave wrote:
I don't think you have much choice Johnny - go for it :)

Let us know how you get on, OK?

Well, I wen this morning to the Rover dealers in Bury St Edmunds, Ames, to get a diagnostic check done and it doesn't exactly give me the answer, unfortunately. The fault code stored was 'Injection Timing Deviation', which the guy elaborated upon as 'Injector Timing Actuator Circuit Fault'. I don't really know what to do with this information next, though. To remind you of the problem, it was that whenever the engine has warmed up and is under load the engine management light comes on at around 3050-3100rpm and there is an effect like a slight dab on the brakes and no further acceleration is possible, although the existing speed can be held.

The guy at Ames was making vague suggestions that the Superchip replacement chip might be responsible, but this strikes me as dubious, as I had it fitted 2 years ago and the problem only cropped up about 3 months ago. The only thing that does concern me is whether it might be confusing the Rover diagnostic tool.

How does this all hang together to you?

this could just be me being stupid, but do you still have the original Rover chip? in which case, does replacing the Superchip with it solve the problem?

One of the company Astras had a very similar problem happen to it. YOu would be driving along, minding your own business, and then things would get a bit lumpy, and the the engine-chekc light came on, and the car seemed to loose power and not go higher than about 70mph.

My mark 3 200 had a problem which the diagnostic machine couldn't find, whereby the moment the engine warmed up, the car would behave erratically, and sometimes the revs would lock, or just fly up and down. Turned out to be the "crank sensor".

steve wrote:
this could just be me being stupid, but do you still have the original Rover chip? in which case, does replacing the Superchip with it solve the problem?


Yes I do. I haven't tried replacing it yet (it's a rather fiddly job) because it is so unlikely to be the cause of the problem. My main concern was that it might somehow be causing the Rover diagnostic computer to be reporting the wrong error, rather than actually causing an error itself. A technical support guy from Superchips assured me that this was most unlikely, the chip is going to be invisible to the diagnostics computer. In any case, I can't really test this without booking it in for yet another £40 diagnostic test.

This whole business is getting tedious and expensive.

Check the wiring that passes over the top of the cam belt cover for chafing and shorting. This was a problem with the early 6oo diesels

Yeah - thanks free - the engine wiring loom is/was a weak area on early L series Diesels - it chafes on the acoustic engine cover. Check on the cam cover and also around the front of the engine near to the fuel injection pump for signs of chafed wires. I bet thats your problem 8)

Reading your post more - the more confident I am about this. The ECM needs two signals engine RPM-wise - one from the crank sensor and the other from No1 fuel injector - it has a needle lift sensor on it. From these inputs, the ECU can then tell what position the engine is at - if the needle lift sensor is faulty or the wiring is open circuit, it will flag up a Deviation Fault.

Just an idea, that's all :)

Dr Dave wrote:
Yeah - thanks free - the engine wiring loom is/was a weak area on early L series Diesels - it chafes on the acoustic engine cover.

Will do. I feel like I'm homing in, if the aberrant behaviour matches up with the reported problem area.

One curious thing is that there is a wire dangling loose from the wiring loom which looks as if it should be significant but I cannot work out where it should plug in, if at all - and neither can my local garage or even a guy from the local Bosh diesel specialist. It comes off the wiring loom about 6" before the fuel pump, and is a single red wire ending in a spade connector encased in a round white plastic plug (about 10mm across) with a black sealing ring round it. It looks like it belongs to some kind of sensor, but for the life of me I cannot work out where it should go - there are no obvious gaping sockets within reach of it. It may be a red herring, something standard to the wiring loom which isn't actually used on this engine, but it's a puzzle. Any ideas?

J2R

freeroverk wrote:
Check the wiring that passes over the top of the cam belt cover for chafing and shorting. This was a problem with the early 6oo diesels

Thanks! Will it be obvious to me when I see it? I.e., what will a chafed wire look like? Are you talking about one where the insulation has worn through, or something like that?

J2R

Yes, the insulation will be worn through and the wire possibly broken.
You won't miss it but you mau have to look carefully.

The 'spare' wiring terminal is just that - I remember thinking the same back in '96 when the 600 Diesel came out. Quite what it is, I don't know 8)

This problem was up to VIN 223718 after this VIN the loom was modified and held in place by two metal clips. According to the technical bulletin the wire chafing can cause numerous other problems. The red wire with the single large terminal maybe the air con compressor feed. Unless you have air con already fitted

Yeah, the cam cover wiring mod was clear after that VIN but the other wiring was still suspect

freeroverk wrote:
This problem was up to VIN 223718 after this VIN the loom was modified and held in place by two metal clips. According to the technical bulletin the wire chafing can cause numerous other problems. The red wire with the single large terminal maybe the air con compressor feed. Unless you have air con already fitted

Well, I've looked at the wiring and see no obvious signs of damage. Over the crank case the wiring is enclosed within a kind of sheath of some plastic fabric, and this sheath was slightly split in one place. Having opened it up a bit further, though, it was apparent that the wiring enclosed was all in a good state and unchafed. Any ideas where to look next? There's a hell of a lot of wire in these cars...

The air con compressor thing sounds very likely to me, as I haven't got air con.

Dr Dave wrote:
The ECM needs two signals engine RPM-wise - one from the crank sensor and the other from No1 fuel injector

Is it easy to give me a quick indication of where the crank sensor is on this engine, so I could check there? One problem is that there is no Haynes manual for this car and engine. I have the one for the 200 and 400 series diesel, but the engine seems to be mounted somewhat differently and not everything is in the position indicated in the manual.

3 months after i bought my 220sdi the cam belt snapped at 70 mph i had the hole head replaced. when i got the car back i had the same sort of problem cruising at 50 60 put your foot down no increase of speed and the engin manage light was on flick your foot of the accelurator and slam it down it would pick up as norm. took it to rover and the cam belt was set up wrong it wasn't sitting on the cogs propaly. Dodgey machanic replaced the head and belt which resulted in the prob.

Sounds interesting, Hussey.......

Make sure any wiring is checked near to the fuel injection pump - that's the favourite area

I haven't got a car nearby to take a pic:(

The crank sensor is on the back of the engine on the alloy gearbox adaptor plate. Has a 2-pin wiring plug going to it

HTH Dave

Well, now I'm getting desperate! I took the car into my local Bosch diesel specialists again, who checked out the wiring (OK), the needle lift sensor again (OK), replaced the fuel pump with a spare one (didn't fix the problem). I'm running out of things it could be, aren't I? Where to look next???

Have you every considered that the ECU could be faulty or needs replacing?

Personally, I would replace the Superchips chip, if only to rule that out of the equation.

SteveChilds wrote:
Personally, I would replace the Superchips chip, if only to rule that out of the equation.

I'm going to do that as soon as I get the car back from the workshop.

cjreilly wrote:
Have you every considered that the ECU could be faulty or needs replacing?

How easy is this to test? Certainly this is not what the Rover diagnostic test suggested. And what does a replacement cost? (It's OK, I'm sitting down and have a stiff drink at the ready...)

EDC ECU failure is unheard of....

About £375 for a new unit

I doubt it very much that it would be the ECU - more likely to be a fault in the FIP than the ECU :( and that's bloody expensive, believe me.

Four-figure territory>=(

I doubt it very much that it would be the ECU - more likely to be a fault in the FIP than the ECU :( and that's bloody expensive, believe me.

If the FIP is the fuel injection pump, they tested that out already - they temporarily replaced it with another one, to no avail. I just heard from the guy now - they replaced the speed sensor, and that didn't do the job either, and they checked out the turbo wastegate (which could have caused the symptoms, apparently, if not the diagnostics fault). No joy.

So far, then, he's checked the wiring, the mass air flow meter, the needle lift sensor, the coolant temperature sensor, the fuel pump, and the turbo wastegate. I may have forgotten a couple of things as this saga has been going on for some time now.
>=(

What to do next? I'm going to try swapping over the Superchips chip but I don't hold out much hope of success there.

Well, yeah - there ain't a lot more you can do!

Perhaps removing the chip will be the next logical step:(

OK, make sense of this if you can. The problem has gone away. Of its own accord. After four months of absolutely predictable fault behaviour (c.3100 RPM, engine management light comes on and no more power is available), I was bombing down the M40 the other day when the problem simply stopped occurring. I could go right on through up to whatever revs I liked (well, within reason), and no CEL! Also, the performance was definitely nippier throughout the whole rev range, suggesting that the fault had been affecting performance before, even at revs below 3100, altough this had been overshadowed by the gross problem above 3100.

The problem occurred again briefly once I pulled off on to the A40, but then went away again and has not come back since.

The only thing of any significance I can think of is that it was a very hot day, and I was pretty well caning the engine, which probably meant that it was running hotter than usual. It was as if some blockage had been removed when the problem stopped occurring. Does this make any kind of sense? Could there be some problem which sheer engine heat could have sorted out?

In any case, I'm VERY glad to see the back of it...

J2R

Could have been a 'stuck' EGR valve, perhaps, that was freed off by the long hot run :D

Dr Dave wrote:
Could have been a 'stuck' EGR valve, perhaps, that was freed off by the long hot run :D

Sounds plausible, but...I actually had the EGR stuff disabled for a while a couple of montsh ago, and the problem was still there. Actually, it wasn't me who disabled this but my local garage (I had accidentally broken a part), and I'm interested to know how to do this again, just to test how it affects performance. What do I do to disable it? Is simply pulling off the red pipe sufficient?

I would love to know what this was, just in case it comes back. But maybe we will never know!

J2R


[Edited by Johnny2R on 05-08-2002 at 10:55 PM GMT]

Yes, pull the red vacuum pipe off and plug it.

But, if the valve had stuck open [like I think it may have done] then pulling the vacuum pipe would have no effect ??? woudl it?

Fingers x'd huh? :)

Dr Dave wrote:
Yes, pull the red vacuum pipe off and plug it.

But, if the valve had stuck open [like I think it may have done] then pulling the vacuum pipe would have no effect ??? woudl it?

Fingers x'd huh? :)

Well, you da man, I know nothing! I'll give it a go and see.

J2R

Dr Dave wrote:
Yes, pull the red vacuum pipe off and plug it.

But, if the valve had stuck open [like I think it may have done] then pulling the vacuum pipe would have no effect ??? woudl it?



So, how would I unstick the valve, if that is what my problem is? (It is conceivable that it has stuck again, of course).

J2R

Difficult, if not impossible.

Saoking it in petrol and freeing it off would be the best way methinks 8)