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[al brown]

In addition to the above, I'd be checking the coolant temperature sensor.

My code reader showed it at 8 degrees, that was my first thought. I know there is more than one sender, and I'm assuming the reader is showing the one the ecu sees.

Sorry. I'd missed that.

I have an oscilloscope (or two ) by the way, but if the ECU is reporting stable RPM while cranking I think it knows all it needs to. I wonder if the fuel pump is taking a while to prime. You say there's pressure at the rail, but maybe not enough?

It's not exactly a stable rpm figure as the car tries to fire, it feels like no fuel to me but equally it could be a poor spark and then wet plugs as mentioned above. I've tried running the pump for 20 seconds first and it makes no difference so maybe fuel isn't the problem. I've ordered a fuel pressure tester (good excuse to buy one) so I'll check when it arrives as there is no pressure reading I can see on my computer.

As for air temp, it's it does although I don't remember what it was reading, I didn't think that would have to much of an impact on the fuel delivery unless it was way off, there is certainly no code though

[al brown]

Inlet air and coolant both were reading 8 degrees.
With ignition on there is 3 bar fuel pressure and the pump can be heard running.
MAF reads 0 with ignition on.
Crank sensor has been swapped with one from a working car.
Coil pack swapped with one from a working car.

Car still struggles to start but as before runs perfectly once started and can be restarted within an hour or so without problem, occasionally starts from dead cold also still and smells of fuel during cracking when it fails to start.

Only thing I haven't changed that I can think of is the cam sensor (different on the donor car I have), I am assuming the cam sensor is involved in the ignition timing.

Any ideas before I buy a cam sensor?

[zirk]

Inlet air and coolant both were reading 8 degrees.
With ignition on there is 3 bar fuel pressure and the pump can be heard running.
MAF reads 0 with ignition on.
Crank sensor has been swapped with one from a working car.
Coil pack swapped with one from a working car.

Car still struggles to start but as before runs perfectly once started and can be restarted within an hour or so without problem, occasionally starts from dead cold also still and smells of fuel during cracking when it fails to start.

Only thing I haven't changed that I can think of is the cam sensor (different on the donor car I have), I am assuming the cam sensor is involved in the ignition timing.

Any ideas before I buy a cam sensor?

From the Car or the Engine bay, or unburnt fuel perhaps, go back to basics, is each plug sparking?, pull them out one by one or if its an inline one piece pack pull them all out and test each plug spark by earthing using a jump lead or something. Even if its only firing on 2 it should still catch and fire up, so either all or nothing on the sparks

[al brown]

After a minute or so of cranking it smells of fuel from the exhaust.
Was struggling to find a way to check the actual spark as its a one piece pack which doesn't lock onto the plugs, the contacts are sprung loaded. It does try to fire, just doesn't catch. Will try and check the actual spark.

[zirk]

After a minute or so of cranking it smells of fuel from the exhaust.
Was struggling to find a way to check the actual spark as its a one piece pack which doesn't lock onto the plugs, the contacts are sprung loaded. It does try to fire, just doesn't catch. Will try and check the actual spark.

Yea its tricky, but pull the whole pack off then check each spring output by touching with a earthed spark plug, your probably throw more fault codes doing this be the way

[al brown]

Will give it a try when I can get a second pair of hands. If it's not sparking, or not sparking well at least what is the likely culprit? I've already tried a working coil pack.

[al brown]

Would it not give a code of the was no spark, or is a poor spark enough to stop a code registering while still not letting it start.

[X30XE]

Just be very careful with the coil. It produces quite enough voltage & current to be lethal.

[X30XE]

Have you checked the integrity of the engine block earth?

Try unplugging MAF, Coolant temp sensor, air temp sensor and see if that makes a difference. In the absence of a signal the ECU should substitute a "safe" guess-timate value. 

Does this engine have idle air control or an electronic throttle body?

[zirk]

Would it not give a code of the was no spark, or is a poor spark enough to stop a code registering while still not letting it start.

It should throw a Miss fire Code, Multi or Cyl blah Blah, assuming the ECU is not telling it not to spark or inject fuel for what ever reason.

I always start with the sparking on any missfires, plugs, plug holes, leads, Pack etc, its normally the easiest and cheapest fix, if Im convinced thats doing what it should be doing then move on the something else. In your case you just want to prove its sparking correctly on cranking.

Yes, obviously watch out for the high Volts when messing around.

Also, as said, dont rule out Cam Sensor or Temp Sensor

[al brown]

Well after some clever clamping of plugs etc it seems to me there is a good spark, but then again when I put the plugs back in it started straight away so I think I'll check again when it won't start.
I was thinking cam sensor as its about the only bit that hasn't been swapped for a known working part, or at least been checked, coolant temp and air temp both read fine add does the maf. Would be nice to work it out before I buy parts, but I'm running out of ideas.

Cheers for all the help.

[Kevin Wood]

I would expect a fault code if the cam sensor is dodgy, and it should still have a strategy to start with that sensor failed.

You have a coil pack for each cylinder and individual coil drivers in the ECU, so checking for a spark doesn't really tell you much other than that the ECU is seeing the engine crank over. Any ignition fault would only affect a single cylinder.

[andrew38]

Had this on a Corsa 1.2 Twinport it was the crank sensor and it does not throw up a fault code a lot of the time, I changed both the crank and the cam sensors as they were cheap anyway and were 10 years old, ours was a 2005 Corsa with about 70k on the clock at the time. Easy fix.

[al brown]

Well, it seems the car is running now. I had it where it was not starting and then straight away swapped the crank sensor, which didn't seem to help as it was still coughing and not starting. Later that night I pulled all the plugs and checked the spark, without trying to start it first. When I put the plus back in it started straight away and now has done several times over the last couple of days.
My thoughts are it was the crank sensor, as many have suggested, and the train it didn't start straight away after I changed it was because I had flooded the plugs trying to start it before I swapped the sensor.

Thanks everyone for the help and advice, if it turns out to not be fixed I'll be back for more help, but it seems like it was a faulty crank sensor that didn't throw a code.

Cheers again, Al

[Kevin Wood]

Sounds like a plausible explanation.