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?
jiimbo said:
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?
Get the bloody oil changed, no wonder it's missfiring.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?
Do the 2004 models have the newer engines or the old Valencia pushrod derivative?
If it is the newer engine, they use hydraulic adjusters on the tappets. Basically the cam pushes against a piston, which pushes against a pressurised cylinder of oil, which itself pushes against the top of the valve. Over time, dirty oil deposits a lacquer like substance on the adjuster components. Eventually the deposits cause friction and result in the valve sping not being able to close the valve in time.
http://www.kvquattro.com/hydraulicTappets/hydrauli...
If it is the newer engine, they use hydraulic adjusters on the tappets. Basically the cam pushes against a piston, which pushes against a pressurised cylinder of oil, which itself pushes against the top of the valve. Over time, dirty oil deposits a lacquer like substance on the adjuster components. Eventually the deposits cause friction and result in the valve sping not being able to close the valve in time.
http://www.kvquattro.com/hydraulicTappets/hydrauli...
jiimbo said:
Thank you Zad, I understand how it works.
Will changing the oil clean the parts, or do I need to replace the hydraulic parts?
By your own admission you haven't changed the oil for a very long time, so it needs doing anyway, so change the oil and filter and see what happens.Will changing the oil clean the parts, or do I need to replace the hydraulic parts?
It amazes me how many people don't think oil changes are important.
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?
At this point I would be putting an oscillosope (yeah I know, not everyone has one, but most local garages and all mot testers will) on the ht leads and on the ht pack drive. If it is getting a nice even pulse train then the fault is mechanical. If it misses pulses then the ecu is getting duff info. Usually if an ecu "breaks" then it will either feil totally or go into limp home more, which I dont think it is.
Im not even sure what sort of AFM it is on those, hot wire maybe?
Im not even sure what sort of AFM it is on those, hot wire maybe?
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