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Is it the crankshaft position sensor?

4K views 15 replies 4 participants last post by  thefarmer 
#1 ·
Afternoon all,

On Friday, I was driving home from work and the EML came on on my 400. Seemed to lose a little power (but has a split intercooler hose atm, so not much to lose), but still seemed to be running OK. However, when I did stop and rev the engine it did seem a little uneven.

I went to try and start it this morning and it does the usual thing of turning over for a long time before it finally starts. But when it does start it only runs for about 5s and then cuts out? The EML is still on.

I have noted the EML flash codes - they are:
27 - MAF related
29 - MAF related
37 - Brake Pedal Switch Plausability
81 - Needle Lift Sensor No Signal

I've had a look at the needle lift sensor wiring and it all looks OKish - even if it wasn't it wouldn't cause the start/stop issue would it?

Any thoughts? TIA :)
 
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#2 ·
A split inter-cooler hose would bypass the air filter and very quickly foul up the MAF sensor with dirt.

If the ECU can not read a correct MAF reading relevant to the true air flow into the intake you would most likely go into limp mode, bad performance due to a rich condition. If nor dealt with you would burn out your CAT amongst other things.

The Brake pedal switch would only be a drive-ability concern if you have an automatic-semi-automatic as it used this switch to know when to engage the gears.

Needle lift sensor is a sensor within the injectors. Could have failed but you need to check wiring and use a multimeter to check if you have a signal. More advanced analysis tools can be used to be certain the injectors needle sensor has in fact failed.

A bad MAF will cause seriously hot temperatures to build up in the exhaust manifold which has been known to melt wires and plastic connectors.

All in all you need to do more investigation and inspection and report back with your findings, A bad MAF is not always a bad MAF it could be related to it's electrical connections, melted wires, bad grounds and so on.

Seen as you had a split inter cooler that would indicate a cause to the MAF reading wrong air flow, becoming dirty or even failing, all due to a split hose.
Fix that split hose ASAP, get some MAF cleaner to clean MAF and retest your system.
 
#5 ·
An intercoler leak will NOT foul the MAF sensor (as that is upstream of the leak). If you think about it logically you'll see why that is impossible.

MAF sensor on the 400 only controls the EGR anyhow so you can unplug it if in any doubt. (no engine management light but will show codes).

Brake pedal switch will massively affect drivability as in extreme cases it'll limit the rpm to 1300 and no more!. Double check the correct tail lamp bulbs are fitted and that they brake lights work as they should. (The wiring uses a seperate switch to do this so this isn't 100% accurate but the switch is shared with the brake lights.

Needle lift sensor is almost always the wiring to it rather than the sensor. If in doubt measure the resistance by unplugging it at the pump and reading the resitance of the sensor (there is only one!). If I recall it should be around 100 ohms. Zero or infinate would indicate a problem.
This may well cause running issues particularly if the fault is intermittant.

Crank sensor causes a code to be logged so unlikely to be that, although I have had that before once after a gearbox change.

Try pumping the priming bulb till it goes hard and see if that improves things. (I'm thinking air getting into the fuel).

When the engine stops does it stop dead, or cough and splutter first.
If the latter then could be air (or water) in the fuel. Try draining the fuel filter to see if any water comes out. Again a rare issue but can sometimes happen if there is a fuel tank leak or contaminated fuel is used.

Whilst I do applaud people for trying to help, please don't send the opening poster on a wild goose chase without good reason.
 
#4 ·
Thanks for the replies!

I'm aware that the MAF does very little on the 400 other than control the EGR valve. The EGR valve has been removed and the MAF disconnected for about 2 years on my 400 with no apparent ill effects so far.

I'm aware that the system uses the brake pedal switch to cut the fuelling when the brakes are applied. I'll check it, though wouldn't have thought that it would cause a non-start?

I should say that I say 'split intercooler hose' quite loosely. The issue is due to one of the hoses which I have used for my FMIC. It is slipping off one of the pipes as soon as the car is driven. Will sort it out over Christmas, but need to get the car home first.

Will have in investigation on Thursday afternoon and report back...

Cheers. :)
 
#7 ·
Thanks for the quick replies again! :)

ETV,

I agree with your comments about the MAF not being affected by an intercooler leak as it is upstream of the leak. As I say it's been running perfectly OK with it disconnected for a good while (albeit while logging a fault code or two).

It did rev OK when stationary, so can't imagine that the brake light switch would be seriously amiss. Will check the bulbs just in case.

Will check the needle lift sensor for continuity/resistance. Although I think that it should still run (albeit badly) even if it is faulty/disconnected? The wire running from it has been taped up though so will check it.

I have a new crank sensor on order as it was about £25, so thought it would be worth having just in case. Would it be possible for it to fail in such a way that it didn't register a fault code? Or since I presume they are a hall-effect type, either work or don't?

Did try pumping the priming bulb, was the first thing I thought lol. Sadly it made no difference. The engine stops dead, with no coughing or spluttering.

I've had the car for 6 1/2 years so like to think that I know most L-series issues and the things that aren't generally a problem. Have had most of it apart lol.

Minesarover,

Ah ha, we may have found the issue. I have a TU1 fitted down there (soldered), but perhaps there is a dodgy joint?

Will have a look on Thursday afternoon and see what's what, hopefully able to fix it for leaving early Friday morning. If I can't I'll just take the Vitesse lol.

Cheers :)
 
#8 ·
Crank sensors usually play up either when the wiring is disturbed as the connections need to be very clean for them to work properly (as it is such a low voltage used). Or they can breakdown and stop working when hot which gives is more usually what happens. The ecu will log a fault code very quickly though and turn the management light on if it is faulty so I doubt this is the issue to be honest.

Brake light plausibility won't stop the engine running, but it will stop if revving properly. When the motor is running properly try raising the revs to say 3k then depress the brake pedal with your left foot and note what happens to the revs. On the 600 at least it'll drop slowly to 1300 and stay there and the throttle becomes less and less responsive to prodding. Eventually it will realise there is an issue and restore throttle pedal signal again but its very weird until it does!
 
#9 ·
It will start now!

OK, looks like it's the needle lift sensor then.

It's open circuit, i.e. no continuity across the pins.

The strange thing is, the timing seems to be massively retarded - i.e. clouds of grey/white smoke. I didn't notice this when it was dark.

The idle/revving is also very uneven.

I've checked the wiring back to the injector as far as I can for continuity. The wiring seems OK, looks like it's the sensor itself.

Anyone know where I can get one from? Can I just replace the sensor or do I have to replace the entire injector?

The car is driveable - just...

Anyone know anywhere in Lincs or between Herefordshire that will have one on the shelf - and that are open tomorrow??

Cheers
 
#11 ·
Right then.


I finally got somewhere with it Replaced the injectors with a set of Freelander ones as SDis are £100/set+ these days.


It seems a bit down on power, I guess that the Freelander injectors don't flow as much fuel?


I might get my original set reconditioned I think and keep the Freelander ones as a spare set. Does anyone know of a company who is able to recondition them and replace the needle lift sensor in no. 1?


Is it just the nozzles which are different between Freelander injectors and SDis? If so, are they simple to swap over?


TIA :)
 
#13 ·
Just a quick update.

Swapped the nozzles over the other weekend and all was back to normal-ish. Was quite simple actually, was just careful to make sure everything was clean and I didn't drop anything.

Although when refitting the inlet charge pipe the gasket gave up the ghost. Fitted a new one and no more boost leaks there - hopefully.

Think that I have an issue with the Tu1 wiring still though, as the EML is on and it's only boosting to about 8 PSI. Bugger.

I've found that the wires on my Tu1 seem to be corroded, I cut about 4 inches of wire back and they are still corroded. Guess that the wire isn't the best quality and it's a harsh environment in the engine bay. The corroded wire caused some major issues trying to solder the Tu1/FIP wires together!

So, I think that what I might do is to replace the entire run of Tu1 wires, right back to the box itself if needed. The unit looks well sealed, is it possible to get inside it without chopping it up?

Anyway, we're making some progress :) Just some gearbox issues to consider on the Vitesse as well lol...
 
#15 ·
I've found that the wires on my Tu1 seem to be corroded, I cut about 4 inches of wire back and they are still corroded. Guess that the wire isn't the best quality and it's a harsh environment in the engine bay. The corroded wire caused some major issues trying to solder the Tu1/FIP wires together!

So, I think that what I might do is to replace the entire run of Tu1 wires, right back to the box itself if needed. The unit looks well sealed, is it possible to get inside it without chopping it up?
The water will have penetrated up the wire. If you cut it back far enough you'll get back to proper copper. Make sure you heatshrink the joints to prevent water ingress in the future..
 
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