surging under load
#2
RF Veteran
iTrader: (1)
How many miles on the engine?
When were the O2 sensors changed last?
They should be changed at 100k miles, 150k miles FOR SURE
O2 sensors use a chemical reaction so wear out just like a car battery does, chemical just gets used up.
The P0420 code means the O2 sensor at the engine, and the O2 sensor behind the CAT are not showing a big enough difference in the exhaust oxygen level, so CAT may not be working............BUT..........
This assumes the O2 sensors are in good working order
CATs could indeed need replacing but that wouldn't cause the surging UNLESS they were broken up inside and clogging exhaust at higher speeds.
Bang on the CATs with piece of wood or rubber mallet, if you hear a rattle inside then that one is broken up internally so could be causing the surging
When were the O2 sensors changed last?
They should be changed at 100k miles, 150k miles FOR SURE
O2 sensors use a chemical reaction so wear out just like a car battery does, chemical just gets used up.
The P0420 code means the O2 sensor at the engine, and the O2 sensor behind the CAT are not showing a big enough difference in the exhaust oxygen level, so CAT may not be working............BUT..........
This assumes the O2 sensors are in good working order
CATs could indeed need replacing but that wouldn't cause the surging UNLESS they were broken up inside and clogging exhaust at higher speeds.
Bang on the CATs with piece of wood or rubber mallet, if you hear a rattle inside then that one is broken up internally so could be causing the surging
#3
still there
the cats did rattle
had them replaced along with o2 sensors and MAFS
also tuned up, plugs/wires/fuel and air filter, along with pcv valve
still get miss, under high speed/load (intermediate now)
no codes this time
ps notice when i get on it, it's gets worse, clears up when i drive normal
Hot weather seems to be worse
had them replaced along with o2 sensors and MAFS
also tuned up, plugs/wires/fuel and air filter, along with pcv valve
still get miss, under high speed/load (intermediate now)
no codes this time
ps notice when i get on it, it's gets worse, clears up when i drive normal
Hot weather seems to be worse
#4
RF Veteran
iTrader: (1)
See if miss goes away at WOT(wide open throttle)
First check that you get WOT, pop hood, put something heavy on gas pedal and then check if you can open the throttle up some more at the engine end of the cable, if so then no WOT.
Google: Ranger throttle cable mod
Simple fix to shorten cable at gas pedal to get WOT again.
At WOT the computer ignores O2 sensors, economy is not considered, lol, computer just pumps in as much fuel as air flow requires for max. power.
Warmer air temps is a Leaner fuel mix, could be IAT(air intake temp) sensor is not reporting correct temp, but it is part of MAF sensor, the two outside wires on connector, so not likely if you replaced MAF.
Coil Pack has 3 coils inside, ignition coils are known to be effected by heat since they were first used in the late 1800's, lol, so since day one.
It could be one of the coils in the coil pack has become heat sensitive, really hard to test for this.
Since overall heat in the engine bay does go up in warmer weather it could be causing that coil to misfire.
Long shot but not no shot.
You can test coil packs with ohm meter, and it will show a problem, but not always if its a heat issue
Worth a try
Short Video here: www.youtube.com/watch?v=c1zhgsnyZWw
First check that you get WOT, pop hood, put something heavy on gas pedal and then check if you can open the throttle up some more at the engine end of the cable, if so then no WOT.
Google: Ranger throttle cable mod
Simple fix to shorten cable at gas pedal to get WOT again.
At WOT the computer ignores O2 sensors, economy is not considered, lol, computer just pumps in as much fuel as air flow requires for max. power.
Warmer air temps is a Leaner fuel mix, could be IAT(air intake temp) sensor is not reporting correct temp, but it is part of MAF sensor, the two outside wires on connector, so not likely if you replaced MAF.
Coil Pack has 3 coils inside, ignition coils are known to be effected by heat since they were first used in the late 1800's, lol, so since day one.
It could be one of the coils in the coil pack has become heat sensitive, really hard to test for this.
Since overall heat in the engine bay does go up in warmer weather it could be causing that coil to misfire.
Long shot but not no shot.
You can test coil packs with ohm meter, and it will show a problem, but not always if its a heat issue
Worth a try
Short Video here: www.youtube.com/watch?v=c1zhgsnyZWw
#5
#7
RF Veteran
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#9
RF Veteran
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#10
#11
RF Veteran
iTrader: (1)
You were battling a misfire, i.e. "still get miss, under high speed/load"
so that is gone and you now have a hesitation?
An ignition coil can not test "good", it can only test "not obviously bad", lol.
Thats because an ignition coil can still be faulty when it warms up or at higher RPMs(less recovery time)
Why was the old coil replaced?
so that is gone and you now have a hesitation?
An ignition coil can not test "good", it can only test "not obviously bad", lol.
Thats because an ignition coil can still be faulty when it warms up or at higher RPMs(less recovery time)
Why was the old coil replaced?
#12
#15
RF Veteran
iTrader: (1)
Looks like 4 and 5 have the problem, blown head gasket between cylinders most likely since there is no overheating issues
You could put 4 or 5 at TDC, both valves closed, and apply air pressure to that one cylinder, i.e. Leak down test.
Then listen at the other cylinder for air coming in, vacuum hose down spark plug hole as stethoscope, that would confirm blown head gasket
It is possible that both 4 and 5 got burnt exhaust valves that are leaking, but long shot, in the above test you would hear air escaping from listening at the tail pipe
You could put 4 or 5 at TDC, both valves closed, and apply air pressure to that one cylinder, i.e. Leak down test.
Then listen at the other cylinder for air coming in, vacuum hose down spark plug hole as stethoscope, that would confirm blown head gasket
It is possible that both 4 and 5 got burnt exhaust valves that are leaking, but long shot, in the above test you would hear air escaping from listening at the tail pipe
Last edited by RonD; 05-18-2018 at 10:11 AM.
#16
#17
RF Veteran
iTrader: (1)
Certainly could be valve springs but would expect lower compression than 125 and not in two adjacent cylinders, could happen that way but long odds when there are 6 cylinders.
Also would have expected you to say, "....and there's a ticking noise"
Valve springs hold the valve up but also are the tension in the valve train, they hold rocker arm, push rod and lifter tight against the Cam.
So if spring breaks you lose some tension, so valve doesn't close tightly, loss of compression, but also a "tick" from rocker/push rod because they are no longer as tight
broken springs would be much easier and cheaper to fix, so I hope thats it
Also would have expected you to say, "....and there's a ticking noise"
Valve springs hold the valve up but also are the tension in the valve train, they hold rocker arm, push rod and lifter tight against the Cam.
So if spring breaks you lose some tension, so valve doesn't close tightly, loss of compression, but also a "tick" from rocker/push rod because they are no longer as tight
broken springs would be much easier and cheaper to fix, so I hope thats it
#19
RF Veteran
iTrader: (1)
Block test looks for exhaust gases in the coolant?????
You don't have an overheating issue so surprised they did that test.
If you have a blown head gasket between a cylinder and cooling system, or a cracked head, exhaust gases will be pushed into cooling system, this is basically air so with air being pushed into the head it displaces coolant in the head, so head starts to over heat until that "air" can be pushed out by water pump circulation.
So you get temp gauge going up and down and then just up as coolant is pushed out into the overflow tank and coolant level in engine gets too low.
Behind the crank pulley is the Tone Ring or tone wheel, it looks like a gear with teeth.
It sets the timing for the engine, spark and fuel injectors.
Crank Position(CKP) Sensor is located next to this Tone ring and "reads" each tooth as it passes by.
There is one missing tooth, on purpose, that gap tells the computer when #1 cylinder is at TDC(top dead center).
This tone ring will have one tooth every 10deg, so 360deg in a circle means there will be 36 teeth, - 1 tooth for TDC, so 35 total.
The crank sensor is the BIG KAHUNA of sensors, your engine will not start or run if there was a problem with the CKP sensor or the tone ring, 2nd missing tooth, and CEL would be on with CKP code, and even Flashing CEL while you tried to start engine, with this sort of problem
So not sure about these mechanics???
These are not Ford things, all vehicles have head gaskets and Crank sensors(distributorless), this is just general mechanics.
You don't have an overheating issue so surprised they did that test.
If you have a blown head gasket between a cylinder and cooling system, or a cracked head, exhaust gases will be pushed into cooling system, this is basically air so with air being pushed into the head it displaces coolant in the head, so head starts to over heat until that "air" can be pushed out by water pump circulation.
So you get temp gauge going up and down and then just up as coolant is pushed out into the overflow tank and coolant level in engine gets too low.
Behind the crank pulley is the Tone Ring or tone wheel, it looks like a gear with teeth.
It sets the timing for the engine, spark and fuel injectors.
Crank Position(CKP) Sensor is located next to this Tone ring and "reads" each tooth as it passes by.
There is one missing tooth, on purpose, that gap tells the computer when #1 cylinder is at TDC(top dead center).
This tone ring will have one tooth every 10deg, so 360deg in a circle means there will be 36 teeth, - 1 tooth for TDC, so 35 total.
The crank sensor is the BIG KAHUNA of sensors, your engine will not start or run if there was a problem with the CKP sensor or the tone ring, 2nd missing tooth, and CEL would be on with CKP code, and even Flashing CEL while you tried to start engine, with this sort of problem
So not sure about these mechanics???
These are not Ford things, all vehicles have head gaskets and Crank sensors(distributorless), this is just general mechanics.
#22
RF Veteran
iTrader: (1)
Can't see that causing an issue, the tone wheel doesn't touch any thing.
Crank sensor is a variable reluctance(VR) sensor, it generates its own AC voltage, its a simple 2 wires sensor, 3rd wire is a ground/shield
Each time a tone wheel tooth passes by the Crank sensor it induces a pulse, when its spinning fast enough say 200rpm sensor will generate about .5v AC, but its the frequency that is used to time spark and injectors, and the "gap" in that frequency.
If that tooth was missing then there would be two "gaps" so computer would not know which one was #1 TDC so you would have a No Start.
Because the engine starts that tooth, even though it looks odd, is still being seen by crank sensor, or as said you would have a no start.
My guess is it came from factory that way or some one may have dropped crank pulley when doing engine work.
In any case not the source of the problem, or you would have crank sensor codes up the wazoo, lol, it IS the BIG KAHUNA of sensors
Crank sensor is a variable reluctance(VR) sensor, it generates its own AC voltage, its a simple 2 wires sensor, 3rd wire is a ground/shield
Each time a tone wheel tooth passes by the Crank sensor it induces a pulse, when its spinning fast enough say 200rpm sensor will generate about .5v AC, but its the frequency that is used to time spark and injectors, and the "gap" in that frequency.
If that tooth was missing then there would be two "gaps" so computer would not know which one was #1 TDC so you would have a No Start.
Because the engine starts that tooth, even though it looks odd, is still being seen by crank sensor, or as said you would have a no start.
My guess is it came from factory that way or some one may have dropped crank pulley when doing engine work.
In any case not the source of the problem, or you would have crank sensor codes up the wazoo, lol, it IS the BIG KAHUNA of sensors
#24
RF Veteran
iTrader: (1)
#25
could a exhaust valve cause intermediate miss?
shop test drove it this morning, no problem
did leak down test, #5 exhaust valve leaking
truck has 163K on it, they want to install reman. motor $5100
i've removed heads before, on other vechicles, but is it worth it, with that mileage?
and i'd have to wait for a bay to open up, at home
nate
shop test drove it this morning, no problem
did leak down test, #5 exhaust valve leaking
truck has 163K on it, they want to install reman. motor $5100
i've removed heads before, on other vechicles, but is it worth it, with that mileage?
and i'd have to wait for a bay to open up, at home
nate