advice please folks
Discussion
p reg Dakar special edition 1.8 just done cambelt /waterpump
car was a do upper on purchase and was running a little rough
presumed cam change / service would resolve
put back together and the car is running v badly, hunting / occasional misfire, just not happy.
Firstly timing is spot on, have run it, stripped back down and everything lines up perfectly
battery is good ,12 volts + , to 14 volts running
standard air box, pulling the meter wires kills the engine
ht leads 4 1 2 3 as they should be, good spark on all cylinders
all electrical plugs well fastened in
all vacuum pipes attached
cant swop out ECU as key coded i believe
been tearing my hair out for the last couple of days and all suggestions, however wild / mad/ ridiculous will be gratefully received
car is on ramps so underneath easily accessible
two other 1.8's (working) in the yard so can swop out bits ( apart from coil which curiously has different connections to the other two 1.8's ( one of which is another Dakar....you would have thought they had identical engines??)
as an update, ht leads swopped out still runs rough
starting from cold, she does what i would expect and idles around 1500 for a little then settles, it's when she starts to warm through that the lumpiness begins, with the idle dropping until she nearly stalls and then picking up again......its like she is starved of fuel for a moment ( gauge indicates quarter of tank, fuel pump is working, i haven't changed filter yet. pull the injector leads and she stumbles as you would expect
many thanks in advance
car was a do upper on purchase and was running a little rough
presumed cam change / service would resolve
put back together and the car is running v badly, hunting / occasional misfire, just not happy.
Firstly timing is spot on, have run it, stripped back down and everything lines up perfectly
battery is good ,12 volts + , to 14 volts running
standard air box, pulling the meter wires kills the engine
ht leads 4 1 2 3 as they should be, good spark on all cylinders
all electrical plugs well fastened in
all vacuum pipes attached
cant swop out ECU as key coded i believe
been tearing my hair out for the last couple of days and all suggestions, however wild / mad/ ridiculous will be gratefully received
car is on ramps so underneath easily accessible
two other 1.8's (working) in the yard so can swop out bits ( apart from coil which curiously has different connections to the other two 1.8's ( one of which is another Dakar....you would have thought they had identical engines??)
as an update, ht leads swopped out still runs rough
starting from cold, she does what i would expect and idles around 1500 for a little then settles, it's when she starts to warm through that the lumpiness begins, with the idle dropping until she nearly stalls and then picking up again......its like she is starved of fuel for a moment ( gauge indicates quarter of tank, fuel pump is working, i haven't changed filter yet. pull the injector leads and she stumbles as you would expect
many thanks in advance
Sure its running lean not rich once warmed up?
Check the various temperature sensors, dud sensor will let it warm up properly but will run very rich once warm, enough to cause misfire.
Also check lambda sensor, run engine, once warm, pull the plug, see what happens. If lambda sensor working it should over about ten seconds richen right up, you'll hear, smell, and feel it.
If there's no change when unplugged, could be dud.
Check the various temperature sensors, dud sensor will let it warm up properly but will run very rich once warm, enough to cause misfire.
Also check lambda sensor, run engine, once warm, pull the plug, see what happens. If lambda sensor working it should over about ten seconds richen right up, you'll hear, smell, and feel it.
If there's no change when unplugged, could be dud.
if it helps anyone else, the end to the sorry tale.
Lambda swopped out for known good one, HT leads changed, water temp sensor removed, checked for resistance, replaced once cleaned up, etc etc etc
Yesterday one of the other mechanics at the garage whose lift i'm borrowing popped in. Have you checked the AFM, he says. No I haven't , as Dave looked at that early on and made no comment as to the efficiency of it...
well can you swop it out he says, so I go and get another one off the other car, fit it, and low and behold the car purrs like a kitten!!
Check the original and looking into the aperture there appears to be something ( plastic, cotton, material) laying across the two wires. Don't know exactly how these work, but for the benefit of others
engine fine when starting from cold, but within 20 seconds staring to run roughly, failing the rev correctly , check the Air Flow Meter!!! save yourself the heartache ( and knackered hands) of trying to work around the back of the engine block!!!!
Lambda swopped out for known good one, HT leads changed, water temp sensor removed, checked for resistance, replaced once cleaned up, etc etc etc
Yesterday one of the other mechanics at the garage whose lift i'm borrowing popped in. Have you checked the AFM, he says. No I haven't , as Dave looked at that early on and made no comment as to the efficiency of it...
well can you swop it out he says, so I go and get another one off the other car, fit it, and low and behold the car purrs like a kitten!!
Check the original and looking into the aperture there appears to be something ( plastic, cotton, material) laying across the two wires. Don't know exactly how these work, but for the benefit of others
engine fine when starting from cold, but within 20 seconds staring to run roughly, failing the rev correctly , check the Air Flow Meter!!! save yourself the heartache ( and knackered hands) of trying to work around the back of the engine block!!!!
Mattlan said:
Check the original and looking into the aperture there appears to be something ( plastic, cotton, material) laying across the two wires. Don't know exactly how these work, but for the benefit of others...
1.6 has Air flow meter (AFM) - a moving flap, the flap moves a variable resistor to output a varying voltage.1.8 has a hot wire MAF - Mass Air Flow sensor.
Thin wire or filament which has a defined resistance. The volume of air flowing past cools the wire, changing its resistance.
So a foreign body in the MAF will definitely screw it up!
(That's why you need to be careful using oiled air filters on a car with a MAF - the oil can screw it up too. )
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