Misfire diagnosis nightmare
Discussion
Honda civic 1.8 vtec, sudden limp mode, flashing EML, misfiring.
Located to cylinder 3, changed ignition coil, no change, spark plugs all fine.
No smell of fuel from 3rd cylinder when starting so no fuel getting in cylinder.
Swapped injectors round and put cylinder 2 in cylinder 3 and vice versa. Started car, now BOTH 2 and 3 cylinders not firing, car still firing on 2 weirdly.
Fault code points to faulty vtec solenoid BUT would that make any sense why only one cylinder wasent firing initially and then 2 stopped firing once injectors were swapped with each other??
Located to cylinder 3, changed ignition coil, no change, spark plugs all fine.
No smell of fuel from 3rd cylinder when starting so no fuel getting in cylinder.
Swapped injectors round and put cylinder 2 in cylinder 3 and vice versa. Started car, now BOTH 2 and 3 cylinders not firing, car still firing on 2 weirdly.
Fault code points to faulty vtec solenoid BUT would that make any sense why only one cylinder wasent firing initially and then 2 stopped firing once injectors were swapped with each other??
Rozzers said:
You’ll need a scanner with an oscilloscope function to see what pulses are at the plugs to the injectors.
Seems like a wiring fault to me too. A set of NOID lamps can provide a very quick and easy way to check which injectors are being driven electrically. A mechanics stethoscope will reveal which ones are responding mechanically.Apparently all electrical connections are fine and its basically 2 injectors that have gone.
Mechanic is relatively good but seems odd how only 1 went then as soon as one moved another 1 went.
Can this happen once one has gone? Having a nightmare sourcing injectors so dont want to go through all this hassle to find it wasent even them (although everything else has been checked as far as i know)
Mechanic is relatively good but seems odd how only 1 went then as soon as one moved another 1 went.
Can this happen once one has gone? Having a nightmare sourcing injectors so dont want to go through all this hassle to find it wasent even them (although everything else has been checked as far as i know)
Polly Grigora said:
Polly Grigora said:
Dodgy injectors
or
Short on injector caused a problem and then caused another problem when moved
Check injectors that don't work with multimeter set to Ohms before getting more involved
As commented earlier, use a multimeter to check if the injectors are open circuitor
Short on injector caused a problem and then caused another problem when moved
Check injectors that don't work with multimeter set to Ohms before getting more involved
Is there anyway one injector can knock another one out especially if it was just pulled out and then put back in, can that cause any issues in itself as i know they are supposed to be sealed etc.
If there is no chance at all that 2 injectors would go one after the other and swapping them will fix it then i will have to question him, but only want to question him if its needed, he is the person with 12 years experience after all.
He was showing me the pulsing of the power on each of the faulty injector wiring, i.e you could see the light pulsing with when the fuel injector would be spraying, like a fast pulse.
Edited by inline6bmwfan on Friday 16th September 19:25
inline6bmwfan said:
I assume mechanically as the electrical supply to them is pulsing as it should be.
That indicates the supply is OK and the injector isn't shorted. It doesn't tell you whether the injector is open circuit. But a short circuit in the injector is really the only way for the injector to damage the ECU, and if the NOID light shows the injector is being driven electrically when it's in the circuit that proves it isn't a short circuit.So i pulled the fuel rail out to see the part number on the injectors, then put it back in, didnt detach the injectors from the rail, just straight in and out basically.
Now the car cant even kick in anymore, it tries to start but sounds like its not getting enough fuel anymore so cant even get the engine idling.
Almost as if a third injector has gone down, there must be another explanation this is bizarre.
Now the car cant even kick in anymore, it tries to start but sounds like its not getting enough fuel anymore so cant even get the engine idling.
Almost as if a third injector has gone down, there must be another explanation this is bizarre.
This can go nowhere.
It sounds like you are tampering with the car, and also the mechanic ?
If you had the rail out with the injectors clipped into it, as most OEM's are, the obvious test would be to crank and get a visual on actual injector spray.
On refitting, you may have disturbed something, or damaged an o-ring leading to further problems now.
Really it sounds as if minimal actual diagnostic testing has been done. You are unable to fully question or understand any tests the mechanic with only 12 years experience has done, and unwilling to challenge him. Which if you do not understand is quite reasonable.
But any information coming this way is also then like Chinese whispers, with undoubtedly some errors or misunderstandings coming through.
it's very easy to confirm spark...so does each cylinder have a good spark at all times ? You say spark plugs are fine, how do you know this ? there is no mention that you have confirmed good spark ? No guesses, evidence.
It's very easy to do a compression test, or more detailed running compression test with suitable test equipment...has either of these even been done ? What were the results ?
If injectors are thought to be an issue they can be tested either visually as already mentioned, or sent for testing for a relatively small fee. Or in some cases new OEM injectors can be quite cheap. But injector failures are rare, even more so two or more without some sort of causation.. Or just swap injectors to different cylinders to see if the problem moves. Has this been done ? Has fuel pressure been tested ?
Noid lights...I rarely trust, they're just too slow and intermittent to ever be truly reliable to get a real picture of injector triggers ( plus our eyes are not fast enough ). Really you need a scope to properly get a visual on signals to the likes of an injector.
Does your car use regular high impedance injectors, or low's with an external resistor pack ? Resistor packs can sometimes fail causing problems on vehicles that use them. Not often, but possible.
Also....how exactly are you/whoever "smelling" for fuel in the cylinders when starting ? to suggest there is no fuel at cyl 3 as in your first post ?
And really, with now 2 dead cylinders as you suggest, finding the source of the problem should be even easier....unless of course part of the problem is simply fouled/flooded plugs from all the poor running in the interim. Never make an assumption "plugs are all fine". Assumptions without actual testing will have you running round in circles.
It sounds like you are tampering with the car, and also the mechanic ?
If you had the rail out with the injectors clipped into it, as most OEM's are, the obvious test would be to crank and get a visual on actual injector spray.
On refitting, you may have disturbed something, or damaged an o-ring leading to further problems now.
Really it sounds as if minimal actual diagnostic testing has been done. You are unable to fully question or understand any tests the mechanic with only 12 years experience has done, and unwilling to challenge him. Which if you do not understand is quite reasonable.
But any information coming this way is also then like Chinese whispers, with undoubtedly some errors or misunderstandings coming through.
it's very easy to confirm spark...so does each cylinder have a good spark at all times ? You say spark plugs are fine, how do you know this ? there is no mention that you have confirmed good spark ? No guesses, evidence.
It's very easy to do a compression test, or more detailed running compression test with suitable test equipment...has either of these even been done ? What were the results ?
If injectors are thought to be an issue they can be tested either visually as already mentioned, or sent for testing for a relatively small fee. Or in some cases new OEM injectors can be quite cheap. But injector failures are rare, even more so two or more without some sort of causation.. Or just swap injectors to different cylinders to see if the problem moves. Has this been done ? Has fuel pressure been tested ?
Noid lights...I rarely trust, they're just too slow and intermittent to ever be truly reliable to get a real picture of injector triggers ( plus our eyes are not fast enough ). Really you need a scope to properly get a visual on signals to the likes of an injector.
Does your car use regular high impedance injectors, or low's with an external resistor pack ? Resistor packs can sometimes fail causing problems on vehicles that use them. Not often, but possible.
Also....how exactly are you/whoever "smelling" for fuel in the cylinders when starting ? to suggest there is no fuel at cyl 3 as in your first post ?
And really, with now 2 dead cylinders as you suggest, finding the source of the problem should be even easier....unless of course part of the problem is simply fouled/flooded plugs from all the poor running in the interim. Never make an assumption "plugs are all fine". Assumptions without actual testing will have you running round in circles.
stevieturbo said:
This can go nowhere.
It sounds like you are tampering with the car, and also the mechanic ?
If you had the rail out with the injectors clipped into it, as most OEM's are, the obvious test would be to crank and get a visual on actual injector spray.
On refitting, you may have disturbed something, or damaged an o-ring leading to further problems now.
Really it sounds as if minimal actual diagnostic testing has been done. You are unable to fully question or understand any tests the mechanic with only 12 years experience has done, and unwilling to challenge him. Which if you do not understand is quite reasonable.
But any information coming this way is also then like Chinese whispers, with undoubtedly some errors or misunderstandings coming through.
it's very easy to confirm spark...so does each cylinder have a good spark at all times ? You say spark plugs are fine, how do you know this ? there is no mention that you have confirmed good spark ? No guesses, evidence.
It's very easy to do a compression test, or more detailed running compression test with suitable test equipment...has either of these even been done ? What were the results ?
If injectors are thought to be an issue they can be tested either visually as already mentioned, or sent for testing for a relatively small fee. Or in some cases new OEM injectors can be quite cheap. But injector failures are rare, even more so two or more without some sort of causation.. Or just swap injectors to different cylinders to see if the problem moves. Has this been done ? Has fuel pressure been tested ?
Noid lights...I rarely trust, they're just too slow and intermittent to ever be truly reliable to get a real picture of injector triggers ( plus our eyes are not fast enough ). Really you need a scope to properly get a visual on signals to the likes of an injector.
Does your car use regular high impedance injectors, or low's with an external resistor pack ? Resistor packs can sometimes fail causing problems on vehicles that use them. Not often, but possible.
Also....how exactly are you/whoever "smelling" for fuel in the cylinders when starting ? to suggest there is no fuel at cyl 3 as in your first post ?
And really, with now 2 dead cylinders as you suggest, finding the source of the problem should be even easier....unless of course part of the problem is simply fouled/flooded plugs from all the poor running in the interim. Never make an assumption "plugs are all fine". Assumptions without actual testing will have you running round in circles.
So mechanic is off today so ill try explain some of what i have said.It sounds like you are tampering with the car, and also the mechanic ?
If you had the rail out with the injectors clipped into it, as most OEM's are, the obvious test would be to crank and get a visual on actual injector spray.
On refitting, you may have disturbed something, or damaged an o-ring leading to further problems now.
Really it sounds as if minimal actual diagnostic testing has been done. You are unable to fully question or understand any tests the mechanic with only 12 years experience has done, and unwilling to challenge him. Which if you do not understand is quite reasonable.
But any information coming this way is also then like Chinese whispers, with undoubtedly some errors or misunderstandings coming through.
it's very easy to confirm spark...so does each cylinder have a good spark at all times ? You say spark plugs are fine, how do you know this ? there is no mention that you have confirmed good spark ? No guesses, evidence.
It's very easy to do a compression test, or more detailed running compression test with suitable test equipment...has either of these even been done ? What were the results ?
If injectors are thought to be an issue they can be tested either visually as already mentioned, or sent for testing for a relatively small fee. Or in some cases new OEM injectors can be quite cheap. But injector failures are rare, even more so two or more without some sort of causation.. Or just swap injectors to different cylinders to see if the problem moves. Has this been done ? Has fuel pressure been tested ?
Noid lights...I rarely trust, they're just too slow and intermittent to ever be truly reliable to get a real picture of injector triggers ( plus our eyes are not fast enough ). Really you need a scope to properly get a visual on signals to the likes of an injector.
Does your car use regular high impedance injectors, or low's with an external resistor pack ? Resistor packs can sometimes fail causing problems on vehicles that use them. Not often, but possible.
Also....how exactly are you/whoever "smelling" for fuel in the cylinders when starting ? to suggest there is no fuel at cyl 3 as in your first post ?
And really, with now 2 dead cylinders as you suggest, finding the source of the problem should be even easier....unless of course part of the problem is simply fouled/flooded plugs from all the poor running in the interim. Never make an assumption "plugs are all fine". Assumptions without actual testing will have you running round in circles.
So spark wise they have been checked for gap and checked to ensure there is no burn marks or anything else on them, all look good, they were also changed just 8000 miles ago.
So the 'faulty injector' was initially in cylinder 3, it was moved to cylinder 2 and the fault followed, it was then moved to cylinder 1 for confirmation, then BOTH cylinder 1 and cylinder 3 stopped firing. Regarding the smell, the way it was tested was the coil pack and spark plug were removed from each cylinder one at a time and the car was cranked, with the working cylinders you could smell the fuel instantly as it was dumped into the cylinder, with the non working ones there was zero smell, it was noticeable straight away.
inline6bmwfan said:
So i pulled the fuel rail out to see the part number on the injectors, then put it back in, didnt detach the injectors from the rail, just straight in and out basically.
Now the car cant even kick in anymore, it tries to start but sounds like its not getting enough fuel anymore so cant even get the engine idling.
Almost as if a third injector has gone down, there must be another explanation this is bizarre.
Yes another 1,2,3 or 4 injectors could have gone open circuit, they could be beaking when disconnected, moved or removedNow the car cant even kick in anymore, it tries to start but sounds like its not getting enough fuel anymore so cant even get the engine idling.
Almost as if a third injector has gone down, there must be another explanation this is bizarre.
As mentioned previously, use a multimeter set to ohms to test the injectors as they could well be open circuit
oakdale said:
I think you need to check the fuel pressure on this.
Will mention this, out of curiosity the error code that comes up points to an oil control solenoid valve having high voltage.But that doesent add up to whats going on, is it possible codes are completely wrong sometimes?
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff