N

nisbeam

Active Member
After changing numerous components I thought I had cured the misfire until the final straw cracked the head. Well head is now replaced & this morning it ran fine until.... yes the misfire started again.
Wondering id it could be the RF reciever mis-sending signals to the Becm because this started this morning after my wife tried to unlock using her key rather than mine.
Any ideas?:doh:
 
Yes, I don't think it is a misfire as such, but rather an electrical problem like something shorting out - the engine cuts out momentarily, but on occasion will actually stop completely. Also occasionally will not start (turn over) although all lights on dash look OK. BUT it can run perfectly OK for 50-100 miles then will start this 'misfiring' again. So I am looking for something electrical on the basis that components don't fix themselves then break again. So far I have done the following: Complete service & all new filters, checked fuel filter and fuel lines - no bubbles or crap to be seen. New battery, new fuse box, all new relays, new fuses, new fuel pump, new starter ignition switch, alternator removed & checked, ECU check (by the ECU Doctor), new crankshaft sensor (twice & also calibrated by Swindon 4x4). It has been diagnosed by three garages & I also bought a Faultmate, only fault found is engine speed sensor invalid value - but this has been replaced & double checked. Swindon 4x4 gave it back after a week as they could not find the fault. Oh yes nearly forgot now new head, cam, valves etc all new gaskets (of course). Runs beautifully smoothly when it doesn't 'cough' :mad: Only done just 122,000 miles & generally in excellent condition - it hasn't been thrashed or off-roaded.
 
Sounds like fuel shut off solenoid. PM Wills, he had this issue and is good on diesel all round.
 
Datatek - yes I have fitted a new pump just in case, the fuelling looks fine.
SpudH - thanks I have PMd Wills - hope he can help or it's going to have to go :(
 
nisbeam said:
Yes, I don't think it is a misfire as such, but rather an electrical problem like something shorting out - the engine cuts out momentarily, but on occasion will actually stop completely. Also occasionally will not start (turn over) although all lights on dash look OK. BUT it can run perfectly OK for 50-100 miles then will start this 'misfiring' again. So I am looking for something electrical on the basis that components don't fix themselves then break again. So far I have done the following: Complete service & all new filters, checked fuel filter and fuel lines - no bubbles or crap to be seen. New battery, new fuse box, all new relays, new fuses, new fuel pump, new starter ignition switch, alternator removed & checked, ECU check (by the ECU Doctor), new crankshaft sensor (twice & also calibrated by Swindon 4x4). It has been diagnosed by three garages & I also bought a Faultmate, only fault found is engine speed sensor invalid value - but this has been replaced & double checked. Swindon 4x4 gave it back after a week as they could not find the fault. Oh yes nearly forgot now new head, cam, valves etc all new gaskets (of course). Runs beautifully smoothly when it doesn't 'cough' :mad: Only done just 122,000 miles & generally in excellent condition - it hasn't been thrashed or off-roaded.
Click to expand...

burn it! put it back into the trade,check for mice,put the cat in it:)
check for signs it has been under water,sue the bastards:p
 
I've just re-read your initial post.
Are you saying that occasionaly you turn the key, the dash lights come up but the engine won't turn over?
Have you thought of the ignition switch? Could it be that your 'mis-fire' is actually the ignition being momentarily switched off?
 
Dogsbody - yes thanks, I have replaced with a new ignition switch, probably forgot to mention as I have lost track. Swindon 4x4 had it on Test book for a week including live data monitoring and gave up in the end. I think that the problem is all these monitoring tools look for faulty components, and in fact there are none. Remember the old days with dodgy wiring and a fault could occur? It seems to be the same thing. This has now gone on for 3 months and I have had occasions with no fault for 100 miles so I though it cured but it came back. That does not sound like a faulty component, more like environemntal such as dampness causing a short etc. One thing I have notice is there seems to be a lot of vacuum when I take the fuel cap off - could it be too much for the (new) fuel pump to handle. Any thoughts welcome.. :(
 
I don't think there should be vacuum in the tank - perhaps its stopping fuel flow?
You could try drilling a v small hole in the fuel cap. (or find where the air return is meant to be and ensure its not blocked!)
 
jonbill said:
I don't think there should be vacuum in the tank - perhaps its stopping fuel flow?
You could try drilling a v small hole in the fuel cap. (or find where the air return is meant to be and ensure its not blocked!)
Click to expand...

Or just drive it without a fuel cap for a day or two.

Otherwise I've got the pad and pencil out and I'm working my way through the system.

The one horrible thought that I've had is that you've got a faulty wire somewhere, inside the insulation.
 
Sorry mate, me back again with a couple more questions.

You say that 'occasionaly' you turn the key, the dash lights up but the engine won't turn over.
How frequent is 'occasionaly'?
How is this frequency compared to the frequency of the bouts of coughing?
When this happens what do you then do?

The coughing. Is there any logic to it such as;
engine hot or cold?
Travelling slowly or at speed?
On back roads or motorways?
Fuel tank full, half or nearly empty?
Driver only or vehicle fully loaded?
Day or night?

Is there ANYTHING else weird, unusual or unexpected that the car does or ANYTHING else that's playing up or failed.

Does your locking fuel cap lock properly?

Sorry about all this but I love a good puzzle, that's why I drive Rangie diesel!!
:D
 
UPDATE :doh: All rebuilt I went out for about 15 miles - ran beautifully. Left for 1 hr my wife got in to move it and splutter cough etc.:mad: So I decided it must be the vacuum in the tank. After being left it sucked fuel backwards & introduced air bubbles. So...... Today I removed the filler cap. I have just done 60 miles of smooth driving, all speeds up & down hill, pushed it occasionally. Then.... It coughed again, probably 6 or 7 times over a mile or two. Eased off as much as possible so as not to have this occur under load. After a mile or two put my foot down again & all running fine :confused:
So it is almost cured - but not quite. I still have to replace leak off pipe that goes to injector 1 (from pump I think). Also still suspicious about injector 4 as the wire has been squashed at some point. But I still have the feeling it is something really simple - a loose wire etc.
The story continues...........
 
So when I fix the bonnet switch (see other thread) I will get it MOT'd, taxed then sell it I think. I don't know where to go now as most of the car has been replaced. Anyone interested PM me & I will give you a list of all the things that have been done - it's a lovely car and only 123,000 miles.
 

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