voltage on lamdas when cranking
Discussion
Double, triple and checked again ,I put everything back where it should be, Bit of a strange one it seems to try to fire but just wont quite catch very unlike it.
(The engine has been out and not been ran for best part of 11 months now) Think i will double check the crank sensor to see if it is clean.
(The engine has been out and not been ran for best part of 11 months now) Think i will double check the crank sensor to see if it is clean.
slinky said:
I've no idea whether the Cerb is different, but I doubt it'll be going anywhere near lambas during cranking..
It'll be open loop and using stored values.
I agree not lamda problems. Have you got access to the mbe ecu with your laptop. Could be lots of things but if you can connect to the ecu then it becomes easier. without the laptop its back to basics.It'll be open loop and using stored values.
So
Have you checked you have a spark from each coil packs.
Fuel, are the plugs wet after prolonged cranking.
a1rak said:
I agree not lamda problems. Have you got access to the mbe ecu with your laptop. Could be lots of things but if you can connect to the ecu then it becomes easier. without the laptop its back to basics.
So
Have you checked you have a spark from each coil packs.
Fuel, are the plugs wet after prolonged cranking.
All hooked up and all seems fine it is trying to fire but not catching plenty of fuel and a spark.So
Have you checked you have a spark from each coil packs.
Fuel, are the plugs wet after prolonged cranking.
I was just wondering about the lamdas as i was not seeing them move on the lap top when i was cranking over just making sure all is ok from that side, Starting to think crank sensor mine is sitting at 27.5 degrees and shoots to 60 when cranking ? this cant be right???
Edited by scotty_d on Saturday 30th November 17:07
I have removed the sensor and going to leave it on the radiator over night, it is reading a little low on the resistance side, Spec says 290 ohms mine is 270 ohm might be on its way out.
Will get a new one on order Monday if it does the same tomorrow.
After reading ignition timing should be 17-22 degrees Before i cleaned it up it was 30 Degrees it was sound a little more willing at 27.5 so think i am on the right track.
Will get a new one on order Monday if it does the same tomorrow.
After reading ignition timing should be 17-22 degrees Before i cleaned it up it was 30 Degrees it was sound a little more willing at 27.5 so think i am on the right track.
scotty_d said:
a1rak said:
I agree not lamda problems. Have you got access to the mbe ecu with your laptop. Could be lots of things but if you can connect to the ecu then it becomes easier. without the laptop its back to basics.
So
Have you checked you have a spark from each coil packs.
Fuel, are the plugs wet after prolonged cranking.
All hooked up and all seems fine it is trying to fire but not catching plenty of fuel and a spark.So
Have you checked you have a spark from each coil packs.
Fuel, are the plugs wet after prolonged cranking.
I was just wondering about the lamdas as i was not seeing them move on the lap top when i was cranking over just making sure all is ok from that side, Starting to think crank sensor mine is sitting at 27.5 degrees and shoots to 60 when cranking ? this cant be right???
Edited by scotty_d on Saturday 30th November 17:07
Is the cold start enrichment working? if it fires then stops maybe its not putting the extra fuel in required for cold starting. check the feedback from the temp sensors on the ecu. When I had this problem in the past on older cars I have given them a tow start from another car.
I went back out this morning re fitted the crank sensor hooked the lap top up, it was sitting at 30 degrees again with the ignition on. I tried cranking and the same as yesterday.
One observation is if i apply light throttle the ignition moves to 15 degrees and stays right through the throttle travel???? Going to pick up a new sensor and go from there i think before going it to anything else.
One observation is if i apply light throttle the ignition moves to 15 degrees and stays right through the throttle travel???? Going to pick up a new sensor and go from there i think before going it to anything else.
The lambdas wont have any bearing on the starting problem. They will remain static until the exhaust gases are hot enough to wake them up.
If the car has not run for 11 months, has the petrol degraded or has condensation in the tank dropped to the bottom and you are getting some water in the fuel?
On the laptop screen you can see the engine speed. This will give some idea if the crank sensor is doing anything. The figure should rise up to maybe near 250 rpm and not fall back to 0 during the cranking. If you have a 'scope it should be a perfect square wave pattern.
With the engine having been stood, there may be a slight loss in compression. If you have fuel, if you have a spark, the third thing you need is compression combined with the correct timing.
The symptoms you describe are those you get - tries to start but not quite - in engines that are flooded or in engines with poor compression.
To address the first, remove the plugs and heat the tips up on your gas cooker if you don't have gas bottles, and refit them and try again.
To address the second, remove the plugs and squirt a little engine oil into each cylinder - 2 teaspoons is enough - refit the plugs and turn the engine over , with the injectors disconnected or the fuel pump fuse removed, a good few times. This allows the oil to sit on top of the upper compression ring. Then remove the plugs, clean and dry out, heat as before then refit and try again.
If the car has not run for 11 months, has the petrol degraded or has condensation in the tank dropped to the bottom and you are getting some water in the fuel?
On the laptop screen you can see the engine speed. This will give some idea if the crank sensor is doing anything. The figure should rise up to maybe near 250 rpm and not fall back to 0 during the cranking. If you have a 'scope it should be a perfect square wave pattern.
With the engine having been stood, there may be a slight loss in compression. If you have fuel, if you have a spark, the third thing you need is compression combined with the correct timing.
The symptoms you describe are those you get - tries to start but not quite - in engines that are flooded or in engines with poor compression.
To address the first, remove the plugs and heat the tips up on your gas cooker if you don't have gas bottles, and refit them and try again.
To address the second, remove the plugs and squirt a little engine oil into each cylinder - 2 teaspoons is enough - refit the plugs and turn the engine over , with the injectors disconnected or the fuel pump fuse removed, a good few times. This allows the oil to sit on top of the upper compression ring. Then remove the plugs, clean and dry out, heat as before then refit and try again.
I don't know why the compression would drop from lying for a few months as it was fine before I removed, it running well starting no problem. I will change out the sensor first the drop in its resistance is making me think its not 100% so I am going with my normal fault finding mentality 
scotty_d said:
I have removed the sensor and going to leave it on the radiator over night
Hmmm.... any magnet that you heat up starts to lose its magnetic field so in the case of a crank sensor there is less chance of it working.As for losing compression - any engine left stood for a while can result in the piston rings sticking in the grooves.
A someone else has said, towing it may be the best way as this will cause enough engine speed to raise compressions and overcome any flooding that may have occurred.
And towing it will raise the engine speed high enough to ignore the cranking signal of the sensor too.
I'd give the following a go if you haven't already.
- Check your battery is fully charged.
- Check grounds on the battery, chassis and block
- Verify the ECU voltage is over 12V
- Confirm throttle movement and values match and replicate blade angle.
- Have someone hold one of the fuel lines from the fuel cooler into a 2 litre coke bottle to check for fuel flow.
- If so, connect back up and prime the fuel system. Key on and off a few times and listen for the pump starting to strain.
- Pop a spark plug and have someone turn the engine over whilst watching for a good blue spark (not yellow).
- Confirm you have fuel vapour mix coming out the plug hole (smell)
- If so put it back together
- Crank again and monitor engine speed when cranking needs to be 150 revs/min +
- If your laptop loses connection then you have bad ECU voltage so check the ECU ground in the passenger footwell near the bottom of the door hinge.
- Do not crank for too long 10 seconds tops with 10-15 seconds between.
- After the 4th crank with no start push the throttle to the floor while cranking This will clear out any unburnt fuel if you have any.
Thank you Ridds nice and comprehensive. A few thing in that list I have not checked and my lap top has been losing connection on cranking so wil, I will check all earths in the door way.
I have been running 2 battery's so plenty of go to turn it over.
Will check to see how strong the spark is, I did try my spare coil packs but no change.
I have been running 2 battery's so plenty of go to turn it over.
Will check to see how strong the spark is, I did try my spare coil packs but no change.
Couple of other things, how did you get the engine out, loom off the engine or loom off the car? If it was off the engine then...
I'd go through the coil pack connections and the same with the injectors and throttle pots. Pots can be confirmed as they turn opposite ways on a 4.2 and the same on a 4.5 so it they read OK then they're OK.
There were differences in coil wire locations on certain years and you need to ensure you have the correct coil connectors on the correct packs. The Injectors are not quite as critical as just getting fuel in is enough and the batch firing will aid this but ensuring they the right way round will help!
I'd go through the coil pack connections and the same with the injectors and throttle pots. Pots can be confirmed as they turn opposite ways on a 4.2 and the same on a 4.5 so it they read OK then they're OK.
There were differences in coil wire locations on certain years and you need to ensure you have the correct coil connectors on the correct packs. The Injectors are not quite as critical as just getting fuel in is enough and the batch firing will aid this but ensuring they the right way round will help!
Made some progress but not great, Killed the starter off so not too happy at that, did crank in small bursts but i must have roasted it still..... 
patience is something i need to work on ........
Never mind a few observations.
Strong spark from each lead.
only 2 plugs were wet and fouled cylinders 1&2 the other 6 were dry , still as new???? Not sure what is going on with that now????? could not see or smell fuel in the other 6
I tested the fuel flow from the cooler and plenty flowing out when running the fuel pump and plenty pressure when i crack the fitting on the back of the fuel rail.
So it does sound like only 2 cylinders are trying to fire so why no fuel in the 6 others?
Any ideas are much appreciated.
Cheers Scotty
patience is something i need to work on ........Never mind a few observations.
Strong spark from each lead.
only 2 plugs were wet and fouled cylinders 1&2 the other 6 were dry , still as new???? Not sure what is going on with that now????? could not see or smell fuel in the other 6
I tested the fuel flow from the cooler and plenty flowing out when running the fuel pump and plenty pressure when i crack the fitting on the back of the fuel rail.
So it does sound like only 2 cylinders are trying to fire so why no fuel in the 6 others?
Any ideas are much appreciated.
Cheers Scotty
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