d Ka misfiring
Discussion
My 2004 Ford Ka starting misfiring yesterday morning. I did the usual: renew plugs (no change), renew leads (no change), renew coil pack - no change. Checked all plugs: all four give a strong spark.
What now? Disconnecting injector no 2 while runing doesn't make the misfire worse - suggesting that cylinder no 2 is at fault.
done compression test: cyl 1-4 give 15.5-15-14-13.5 bar (warm engine). not ideal, but OK (engine has done 175,000 miles!!!).
What's the fault? Engine management system???
That will be expensive...
Any ideas guys?
What now? Disconnecting injector no 2 while runing doesn't make the misfire worse - suggesting that cylinder no 2 is at fault.
done compression test: cyl 1-4 give 15.5-15-14-13.5 bar (warm engine). not ideal, but OK (engine has done 175,000 miles!!!).
What's the fault? Engine management system???
That will be expensive...
Any ideas guys?
OK, now a year later, it has started misfiring again.
It varies day by day: sometimes its almost impossible to drive, sometimes it's not too bad. It's worst at low engine speed. On the motorway I can cruise at 70-80 without misfire.
I did the usual: changed plugs, leads and coil (coil was expensive, from Ford £145 + VAT!).
But it still misfires.
I checked compression: OK.
ECU gives no errors.
What can it be? I wigled the wires on the airflow meter and TDC sensor - no change.
I sprayed WD40 into the air intake (maybe loosening the flow meter) - no change.
Now I'm at a loss and the last thing I want to do is go to my local Ford dealer - who are a rip-off and technically completely useless.
HELP!!!
It varies day by day: sometimes its almost impossible to drive, sometimes it's not too bad. It's worst at low engine speed. On the motorway I can cruise at 70-80 without misfire.
I did the usual: changed plugs, leads and coil (coil was expensive, from Ford £145 + VAT!).
But it still misfires.
I checked compression: OK.
ECU gives no errors.
What can it be? I wigled the wires on the airflow meter and TDC sensor - no change.
I sprayed WD40 into the air intake (maybe loosening the flow meter) - no change.
Now I'm at a loss and the last thing I want to do is go to my local Ford dealer - who are a rip-off and technically completely useless.
HELP!!!
Yes I have:
Oxy sensor is new (few months old).
Cat: removed, don't have one.
OK now you think how....
The car is converted to LPG, so doesn't need a cat - and it passed the MOT without one.
The LPG conversion is completely ruled out as a potential cause of the misfire. Engine still misfires when LPG system is completely disabled and bypassed.
compression is OK, so are valve seats (hardened ones put in) - valve seat recession is a common problem with LPG, but again ruled out here.
Engine mileage now 190.000
Oxy sensor is new (few months old).
Cat: removed, don't have one.
OK now you think how....
The car is converted to LPG, so doesn't need a cat - and it passed the MOT without one.
The LPG conversion is completely ruled out as a potential cause of the misfire. Engine still misfires when LPG system is completely disabled and bypassed.
compression is OK, so are valve seats (hardened ones put in) - valve seat recession is a common problem with LPG, but again ruled out here.
Engine mileage now 190.000
I had all the injectors checked out by a Prins lpg installer.
How do I check for sticking valves? Will an oil change immediately rectify sticking valves?
I admit to not having changed the oil for a very long time. A very very long time, as the oil still looks yellow....Just top it up every year....It hardly burns any....
Another possiblility is the air flow meter, since the backfiring isn't strong, and not into the back of the exhaust, which indicates an insufficient fuel supply. Are airflow meters easy to check out?
How do I check for sticking valves? Will an oil change immediately rectify sticking valves?
I admit to not having changed the oil for a very long time. A very very long time, as the oil still looks yellow....Just top it up every year....It hardly burns any....
Another possiblility is the air flow meter, since the backfiring isn't strong, and not into the back of the exhaust, which indicates an insufficient fuel supply. Are airflow meters easy to check out?
OK, I have done an oil change, added Wynn's hydraulic valve lifter treatment and let the engine run for 45 minutes.
Unfortunately, the engine misfires just as it did before...
In summary, ruled out so far as possible cause of misfire:
sticking valves
worn valve seats (compresion is OK)
O2 sensor
lpg installation
plugs, leads, coil
In my view that leaves the ECU (but it gives no error messages, TDC sensor or airflow meter...
How can I test the air flow meter?
Unfortunately, the engine misfires just as it did before...
In summary, ruled out so far as possible cause of misfire:
sticking valves
worn valve seats (compresion is OK)
O2 sensor
lpg installation
plugs, leads, coil
In my view that leaves the ECU (but it gives no error messages, TDC sensor or airflow meter...
How can I test the air flow meter?
My Ford Ka is still misfiring...
I've just about checked/replaced everything obvious: coil, plugs, leads, TDC sensor, injectors. No leaks on intake manifold. Changed oil and added cleaning agent - no sticking valves. Compression OK on all 4 cylinders. No error messages on diagnostics port. 4 garages have looked at it and the general conclusion is: faulty ECU.
But I don't believe that, as I've read in several places that ECUs either work properly, or not at all, or go into some kind of safe idling mode.
Symptoms are:
perfect start on cold & no misfire even at full throttle, but after about a mile it misfires terribly, almost not possible to drive. Press the accelater a little bit and it misfires badly. Then, after a good half hour run, including a blast on the motorway, it gets better to the point that I can keep up with traffic in the fast lane, press the accelerator all the way down and there is no problem...
Thrn I leave it overnight, and it's the same story again.
What can it be? It must be something blindingly obvious, but I don't see it !?
Jim
I've just about checked/replaced everything obvious: coil, plugs, leads, TDC sensor, injectors. No leaks on intake manifold. Changed oil and added cleaning agent - no sticking valves. Compression OK on all 4 cylinders. No error messages on diagnostics port. 4 garages have looked at it and the general conclusion is: faulty ECU.
But I don't believe that, as I've read in several places that ECUs either work properly, or not at all, or go into some kind of safe idling mode.
Symptoms are:
perfect start on cold & no misfire even at full throttle, but after about a mile it misfires terribly, almost not possible to drive. Press the accelater a little bit and it misfires badly. Then, after a good half hour run, including a blast on the motorway, it gets better to the point that I can keep up with traffic in the fast lane, press the accelerator all the way down and there is no problem...
Thrn I leave it overnight, and it's the same story again.
What can it be? It must be something blindingly obvious, but I don't see it !?
Jim
Keith thanks for your reply.
I have checked the ECU before ( by looking at it) and it seems clean and dry. But I have not taken the plug off. I will do that when I get home on Friday.
The ECU is in an awkward place and it looks like quite a job to remove it.
Since my last post I've established beyond doubt it is an ignition issue: on tick-over misfire is mostly in cylinders 2 and 3 (which fire as a pair of course). When I replace the (LPG) injector 2 plug with that of no 4, and the no 3 by no 1, the misfire is still mostly on cylinders 2 and 3... (checked by sequentially removing each of the injector plugs).
(by the way as explained previously, the LPG installation is absolutely ruled out as the cause)
If it is the ECU, I won't bother replacing it, and will scrap the car. It a 2004 Ka, but has 193,000 miles on the clock. It doesn't owe me a thing but I'll be sad to see it go...
I have checked the ECU before ( by looking at it) and it seems clean and dry. But I have not taken the plug off. I will do that when I get home on Friday.
The ECU is in an awkward place and it looks like quite a job to remove it.
Since my last post I've established beyond doubt it is an ignition issue: on tick-over misfire is mostly in cylinders 2 and 3 (which fire as a pair of course). When I replace the (LPG) injector 2 plug with that of no 4, and the no 3 by no 1, the misfire is still mostly on cylinders 2 and 3... (checked by sequentially removing each of the injector plugs).
(by the way as explained previously, the LPG installation is absolutely ruled out as the cause)
If it is the ECU, I won't bother replacing it, and will scrap the car. It a 2004 Ka, but has 193,000 miles on the clock. It doesn't owe me a thing but I'll be sad to see it go...
Thanks Keith. I checked the ECT sensor. It has just two wires which, when diconnected from the sensor, have 5 volts across them. I measured the resistance of the ECT sensor: 55 kohm/cold, 10 kohm/handwarm, 2 kohm/hot. I don't unbderstand the autodata info, but these changing resistance values indicate to me that the sensor is OK.
The garage checked the oxysensors, by replacing with used ones that were known to be OK - again no problems here.
I tried to get the connector off the ECU to check for corrosion, but could not get it off. But I don't believe there could be corrosion, as the ECU, cable and connector, and surrounding steel surfaces seem all very clean and dry. There is no water there...
So, it must be the ECU....Or the valves...
The garage checked the oxysensors, by replacing with used ones that were known to be OK - again no problems here.
I tried to get the connector off the ECU to check for corrosion, but could not get it off. But I don't believe there could be corrosion, as the ECU, cable and connector, and surrounding steel surfaces seem all very clean and dry. There is no water there...
So, it must be the ECU....Or the valves...
I've just done a test drive with injectors 2 and 3 disconnected.
Result: the backfiring stops completely and cylinders 1 and 4 run OK (lumpy but evenly, if you see what I mean). Just to be sure, I managed to get hold of a good coil pack and put that on, but results the same.
Conclusion: The ECU is not firing properly on cylinders 2 and 3. To me that is the end of the story (faulty ECU). Time for the scrapyard. Ka RIP...
Result: the backfiring stops completely and cylinders 1 and 4 run OK (lumpy but evenly, if you see what I mean). Just to be sure, I managed to get hold of a good coil pack and put that on, but results the same.
Conclusion: The ECU is not firing properly on cylinders 2 and 3. To me that is the end of the story (faulty ECU). Time for the scrapyard. Ka RIP...
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