My pops truck had suddendly gotten 308 error code - misfire cyl 8 long story short the cop and plug was replaced and still having a miss got a new code lean bank 1 I think? Well it was for the side where 8 is so we got the special tool and there was no ground pulse but checking the vcc it was getting good power.

After going to replace the pig tail connector we could not finf the light blue wire anywhere in the connections there where they go since we could find the wire to test he just tested there inside the loom getting good continuity.

So we put all back togeather and then we did have pulses with the tested for number 8 injector plug but soon after a few starts it stayed solid like a bad pcm.

So once the truck warms up there is no light at all with the tester but we also get new codes out of no where.

Codes r P0171 P0308 P0316

So we tested the one sensor that looks sorta like a map, per Haynes manual, getting 4.8 volts and ohm Is .40 also good.

So we are baffled is the pcm on the way out? Help help afraid we will have to take to a shop we can't afford.

 

The codes indicate two separate troubles.
The 316 is the result of the 308 misfire on driver side.
The 171 code is a lean indicator for bank 1, passenger side..
.
The #8 cylinder is on the driver side back cylinder.
Treat these troubles as separate.
Solve the 308 code first.
It is not the PCM. Reason is the code would be a 358 not a 308.
Theses codes are detected a different way for each kind of failure.
The 308 code is detected my measuring the crank rotation time.
The 358 is detected by current waveforms generated and monitoring in the PCM. If the circuit were open or sorted it is detected as such.
.
Back to the 308 code; If any issue prevents the cylinder from producing the same pressures the average of all good cylinder produce, it is a logical misfire in computer terms.
This could be a plug, a coil, a cylinder fault or even a lack of Fuel injected.
.
The 171 code tells you the OX sensor bank 1 detected too much oxygen in the exhaust.
This is a logical signal to move the Long Term Fuel table richer trying to compensate for the excess oxygen. When the table moves more then 25% the code is set.
This can be seen with a Scanner looking at bank 1 LTFT.
The usual trouble is an air leak into the intake tract as the cause of excess oxygen.

You just have more detective work to find and fix the issues causing the codes.
The 316 will clear when you solve the 308 trouble.

Great to see your interest and good luck.

 

Well that's just it the other codes were not present until after we put everything back together. . Original fault was just misfire 8 after replacing cop clearing codes and running it it produced also lean for that bank. Listened to the injector wasn't tapping swapped with one that was.. still was not tapping. Like I said we checked it and checked it and getting no pulse ground.

From here we took everything back apart going to replace the connector but could not find a fault. (again though could not find the blue wire into the harness it's like it's not even there (anyone know what pin it should be into the harness there by the battery)

So after that we decided to put everything back together and that's when the additional new code came up. This time we checked right at starting dead cold and the tester was flashing a little but went solid. We poped a code for too rich seems logical being the injector was just constant open state. After this it simply stopped having ground pulse again. So its seemed this entire time we are chasing something with that injector and can't figure it out.

So that's where we're getting confused.

 

The pin for injector 8 should be #98.
If you see a solid ground on that pin with the connector off, the injector driver is shorted.
Btw, coil drivers all work the same way.
Normally the coil and injector drivers have a medium resistance for testing from the outside with an Ohm meter.
That resistance is in the order of 10,000 ohms.
If the pin measures substantially lower it is a short, or very much higher it is an open as far as the circuit operation.
So you could tell if the driver is faulty by comparing the readings to other good drivers.
Near by on the PCM is pin 99 for #6, pin 100 for #4 and pin 100 for #2.
It's the only way to prove what you have.
Keep at it.
Good luck.

 

We will check that out today; pops going to go out with the noid tester today see if it does the same thing or not and will post; as it seems like it flashes a few times right as its cranking then once its cranked as indicated it stayed on.. as well we could smell the unburnt fuel in the exhaust. COP is tested and shown good; also swapped with another cyl as well

After it warmed up a little it seemed it stopped having ground pulse all together.

well see if its similar or not today or if it just remains off or what and will post back..

well also try the oming out and cont. test on that being we cant find lt blue wire at the harness. its like it goes to the loom and some where from point a to point b changes colors or something.

THer are 2 lt blue's and we cant find either. LOL

 

Also one other question.

Do you have a photo or diagram of that connectors there by the battery? cant seem to find one for these years only the previous years (Autozone's)

Second; the Haynes manual shows the injectors going to the PCM; but doesnt say plug numbers or wiring diagram or anything; my one question on that is there anything other than the connectors there by the battery that goes to the firewall that operates the injectors like a relay or something or does it truly go directly to the PCM.

I guess im asking as if we cant figure out what wire the connector is what about directly off the PCM it self to test?

 

I musta missed it, but I can't even figure out what year and what engine pop has.

 

Click on JON'S handle, then on 'about me'. In the list is 2002 4.6L.
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Jon, the injectors and coils are driven out of the PCM by special drivers as I have described in how to test them.
Relays could not act fast enough or be reliable enough over the long term in this application.
Did you miss it?.
Good luck.

 

Sorry 2002 F150 5.4

He tested with noid again nopulse at all, vcc has power not getting ground pulse. Can't find the other end of wires so at this point not sure what else we can do except a mechanic

 

There likely is a connector in the harness between the injectors and the PCM.
Look for one and check to see if a pin is pushed that is hardly making connection a ground out or a cut of some sort..
If you see the pulses at times, it has to be an intermittent open due to vibration or temperature change or the driver has a fault on the PCM board.
You have the problem identified now carry on with the search for the open.
Taking it to a shop, they will have to do the same thing.
Good luck.

 

Many Thanks Bluegrass. Didn't know about that.
Couldn't find the 4.6 but I prolly didn't look hard enough.
Much easier if in the sig line or first post.

 

Thank You.
No pulse - meaning the noid is not lighted, or its lighted steady on?
And what is the vcc you speak of?


The other end of the light blue control wire for injector #8 is over at pin #98 at the PCM connector, as Bluegrass pointed out. If the noid light is on steady the light blue wire is picking up a ground somewhere, so unplug the PCM connector and the injector #8 connector. With your DMM check this wire for continuity to ground. If it has found a ground on its own, that's why the PCM can't ground and unground it when it wants to.


If the light blue wire hasn't found a ground, while the PCM is disconnected, ohm it out to be sure it has good continuity from the injector/harness side to pin 98 of the PCM. If it doesn't, there is an intermediate 42 pin connector between the injector and pin 98. It contains a couple of light blue wires but you are interested in pin #21. (Sometimes a little green goo (trademark name) on a pin will FUBAR good current flow.

If the noid light is not blinking AND is off, make sure injector #8 is getting power when it happens as the power to injector #8 looks to me like it takes a slightly different path than power to all the other injectors.


Goog Hunting!