Car stuggling to start up - won't fire/spark

[KitsonRis]

Basically came to start the car after a week today and it wouldn't start - it turns over fine, battery isn't flat, can hear 'poping' from the exhaust to suggest compression, but it is as if you need to give it a bit of throttle to help it (that did nothing). Cranked over for about 20seconds in total. Stopped trying for a bit. Then started first time. It did this last week as well. I got worried that it was immobiliser issues. Have also stopped for fuel and it fired up first time.
Not sure why it is starting to do this. I am not sure if it could be that it has been sat for a week. But while it has been off the road this winter it has been left for a week, maybe more, without starting and when I came to start it up to let the engine warm up it would start first time. So to why it is doing ti now is confusing me.

 

[bloke]

first guess is it's losing fuel pressure when it's standing?

 

[KitsonRis]

I didn't think of that. Any reason why it should do that? Leaky pipe? Fuel pump starting to fail?

 

[Mar172]

have a look at the relays in the fuse box under the bonnet that runs the fuel pump might need a clean

 

[bloke]

could be pump, you running a return line on the rail?

 

[KitsonRis]

could be pump, you running a return line on the rail?

I have no idea!! I havent touched anything on the engine to remove something. I will go check tomorrow in the day light.

 

[bloke]

next time it's stood for a while turn the ignition on for a couple of seconds, turn it back off and repeat a few times. if it starts ok then can help confirm it's a pressure issue. ideally you need a fuel pressure check though.

 

[da rok]

In the past i have found this to be a bad connection on the tdc sensor plug... next time it wont start try giving this a wiggle... a bit of corrosion can cause lots of problems...

 

[KitsonRis]

In the past i have found this to be a bad connection on the tdc sensor plug... next time it wont start try giving this a wiggle... a bit of corrosion can cause lots of problems...

Which sensor is this?

 

[da rok]

tdc sensor, crank sensor, if theres a bad connection it wont fire, but after a while of cranking the engine shaking around sometimes moves the plug around enough to sort it out, can be fine for a few weeks... give it a clean and try...

 

[Rubicon_]

It's the plug that sits above the bellhousing and the block where the flywheel is. It's 2x 10mm bolts to remove, worth taking it out and cleaning up with some brake cleaner as the sensor can get covered in sh*t.

 

[KitsonRis]

Not had a proper chance to look at this yet, but the EML was flashing after I started it the other day after struggling to start. Solved that by turning the car off and on again! Then I thought it could be injector issue. I did have a problem back in August where it was sat for a week in heavy rain and decided to be a three cylinder for 5 minutes. Then it came back to life. Presumed it was a wet connection and was waiting to see if it did it again before I took the car apart.
Will get the error code read when I take it back to my parent (have an OBD reader there).
But once it starts up it is fine, pull well, doesn't sound like a three cylinder, responsive and I even got 47mpg on the motorway yesterday (I know it isn't a proper diagnostic but if it wasn't working properly I would thought it would be very inefficient). Because if the TDC sensor was going surely the spark timing would be slightly out?? Isn't that was the sensor does, determines crank position to send a spark at the right time?

 

[da rok]

mine runs rough after left for a while sometimes, put it down to sticky injectors, pull the plugs out and look for signs of over fueling or under fueling, you will be able to tell if the injectors are working properly from that, could be a bad connection in a plug or some damage somewhere in the loom.

yes tdc is used for ignition timing, it sends pulses as particular spots on the flywheel go past it, so if a sensor is on the way out the timing wont go out, itll either work or it wont. sometimes the magnet in the sensors loose their magnetism, this seems to be more common on the new blue top sensors although the old ones are as well known for problems, cant do any harm in puling it out and giving it a clean, test it to see if the magnet is still strong... can test the resistance as well, I think it should be somewhere between 200 and 250 ohms

 

[KitsonRis]

Done a bit of poking around. No error codes were recorded when the EML came on, which is annoying. I am just going to replace the crank sensor as a precaution anyway. Step dad thinks the "popping" noise from the exhaust when it doesn't start but turns over could be timing issues as it is firing at the wrong point. I just thought it was a sign there is compression!

next time it's stood for a while turn the ignition on for a couple of seconds, turn it back off and repeat a few times. if it starts ok then can help confirm it's a pressure issue. ideally you need a fuel pressure check though.

I've been doing this and it seems to work. But when you turn the ignition on the fuel pump makes one of two noises. Sometimes it is an electrical buzz (presume the pump is priming) and the other is the same noise but what sound like a mechanical noise too and that the pump is pushing fuel around. It's a little random of what noise it makes. But doing this a few times seems to work. Car is now going to be left a week so I can give it a go then.

 

[sharkaroo]

Done a bit of poking around. No error codes were recorded when the EML came on, which is annoying. I am just going to replace the crank sensor as a precaution anyway. Step dad thinks the "popping" noise from the exhaust when it doesn't start but turns over could be timing issues as it is firing at the wrong point. I just thought it was a sign there is compression! I've been doing this and it seems to work. But when you turn the ignition on the fuel pump makes one of two noises. Sometimes it is an electrical buzz (presume the pump is priming) and the other is the same noise but what sound like a mechanical noise too and that the pump is pushing fuel around. It's a little random of what noise it makes. But doing this a few times seems to work. Car is now going to be left a week so I can give it a go then.

Any updates on this, I'm having issues starting mine with similar issues

 

[KitsonRis]

Any updates on this, I'm having issues starting mine with similar issues

It hasn't done it for a few weeks, even after being left standing for a week. I also had to change the injector recently, not sure if that is related. But when I was diagnosing this I unplaugged the crank sensor and gave that a clean up, although it wasn't really dirty. So in a way no! I haven't changed anything/done anything to "fix" it, it has seemed to have stopped. But if it does it again I am changing the crank sensor.

 

[sharkaroo]

I had just fitted an exhaust, fired it up and the Rev counter died, after that it would turn over but not fire. So it's pointing towards the crank sensor which I have cleaned, but it's still the same. I'll order one up to eliminate it.