boilermaster
Well-known member
Hello all,
Got a call the other day and was requested to go to a local business to troubleshoot a misfiring ford truck.
Now I am a retired person, and have little interest in doing such things, but one of my personal friends is their mechanic and he is pretty good at what he does, needless to say I was up for a challenge, so here is the scoop.
1985 ish. F700 with a 429 efi that misfires on cylinders 2 and 8.
spark plugs for those cylinders will fuel foul and eventually coat with oil from not firing.
compression tests good on all cylinders as well as cylinder leakdown tests good on all cylinders, I have checked
valvetrain is in good shape, no rounded off cam lobes or weak or broken valve springs.
Ignition components have been changed several times with no effect base timing is at 10 degrees with the timing shunt removed and with the timing at 10 degrees the shutter wheel align up with the hall exactly at the leading edge of #1
all fuel injectors are working electronically and have a good spray pattern at fuel pressure, catalysts are not plugged because this model was a non catalyst unit.
the ignition firing order is correct (15426378 ) and have checked the injector pairings 1458 and 2376.
this engine pulses all 4 injectors at the same time for each bank of injectors and therefore one would assume that the intake valves for any of the injector bank would either have to be in overlap or its intake valve would have to be open to create an A/F charge that would be capable of supporting combustion.
Going to check this out tomorrow.
Their mechanic states that he had checked the egr valve for operation and actually blocked it off by substituting a gasket with no opening with no effect.
I just asked him this morning, what intake port (s) is the EGR paired with ? (could be #7 or 8 and also #2 ?
Was thinking that possibly the intake is rotted out under the egr flange where we can't see it between intake and exhaust and therefore contaminating the fuel charge for #2 and #8 ?
Thinking that I am going to charge my friends employer for the amount of sleep I lost last night, lol
This vehicle has no service codes that are hard faults and is capable of storing codes, as we errantly got a few in there while testing.
The ecm is a one of a kind and a replacement cannot be found anywhere, however they did send the one for this truck out to a business to have it rebuilt/reconditioned.
if my buddy finds nothing in the egr system, the next step for me is going to remove the rocker covers, see when #1 injector turns on and then check the valve positions with the remaining injectors in that bank, and oh yes have checked the injector pulse rate of each and every injector.
Feel free to jump in anyone ?
Boilermaster
Got a call the other day and was requested to go to a local business to troubleshoot a misfiring ford truck.
Now I am a retired person, and have little interest in doing such things, but one of my personal friends is their mechanic and he is pretty good at what he does, needless to say I was up for a challenge, so here is the scoop.
1985 ish. F700 with a 429 efi that misfires on cylinders 2 and 8.
spark plugs for those cylinders will fuel foul and eventually coat with oil from not firing.
compression tests good on all cylinders as well as cylinder leakdown tests good on all cylinders, I have checked
valvetrain is in good shape, no rounded off cam lobes or weak or broken valve springs.
Ignition components have been changed several times with no effect base timing is at 10 degrees with the timing shunt removed and with the timing at 10 degrees the shutter wheel align up with the hall exactly at the leading edge of #1
all fuel injectors are working electronically and have a good spray pattern at fuel pressure, catalysts are not plugged because this model was a non catalyst unit.
the ignition firing order is correct (15426378 ) and have checked the injector pairings 1458 and 2376.
this engine pulses all 4 injectors at the same time for each bank of injectors and therefore one would assume that the intake valves for any of the injector bank would either have to be in overlap or its intake valve would have to be open to create an A/F charge that would be capable of supporting combustion.
Going to check this out tomorrow.
Their mechanic states that he had checked the egr valve for operation and actually blocked it off by substituting a gasket with no opening with no effect.
I just asked him this morning, what intake port (s) is the EGR paired with ? (could be #7 or 8 and also #2 ?
Was thinking that possibly the intake is rotted out under the egr flange where we can't see it between intake and exhaust and therefore contaminating the fuel charge for #2 and #8 ?
Thinking that I am going to charge my friends employer for the amount of sleep I lost last night, lol
This vehicle has no service codes that are hard faults and is capable of storing codes, as we errantly got a few in there while testing.
The ecm is a one of a kind and a replacement cannot be found anywhere, however they did send the one for this truck out to a business to have it rebuilt/reconditioned.
if my buddy finds nothing in the egr system, the next step for me is going to remove the rocker covers, see when #1 injector turns on and then check the valve positions with the remaining injectors in that bank, and oh yes have checked the injector pulse rate of each and every injector.
Feel free to jump in anyone ?
Boilermaster