Injector codes

[gator]

Hey folks. My car shut down the other day, with no warning and left me on the highway.
The PCM was throwing 12 codes altogether, the most notable of which were for all 8 injectors being out, or having an issue of some sort. I have good spark from all 4 coils.
The fuel pressure and flow have checked out fine. I'm pretty sure the injectors aren't firing, but have no idea why. All my fuses are fine and there are no obvious issues with the harness. Does anybody have a suggestion what I should check next? I'm at a loss here.
Gator

[sall]

What are the codes?

[Randy T.]

A couple outright guesses, pcm or ignition switch.

Bobsblue posted how to test it at the bottom of an ignition switch writeup.

If you want to try an extra pcm, come and get it, or I can ship you one to borrow if you pay shipping. I also have plenty of injectors and injector harnesses if you want to go that route.

If there is anything I can do, let me know, I have no cell at the moment, if you don't have my home phone send me a pm.


aurorah.proboards.com/index.cgi?board=Audio&action=display&thread=23583

[XJSman89]

Sorry to hear that, gator! Gotta get that 4.6 back on the road!

Between the two of you I bet you and randy can figure it out!

[ntrenn]

I'm learning that when you hit that kind of code lottery, you have lost power feeding something.

[gator]

I thought it was the PCM at first, but everything else is working just fine. I've got spark, and fuel (at the rail) and the engine cranks just fine, so I'm guessing the PCM works at least partially, if that's even possible. I'm almost positive its in the harness somewhere. Never even thought about the ignition switch. Would a bad switch let the engine get spark and fuel pressure? Does anybody know what voltage should be at the injector wires? The red wire doesn't give me anything and the other wire spikes to about 2 volts when I'm cranking it. Anybody want to measure that for me or point me to the right thread?
Gator

[Randy T.]

Ignition switches can do some weird stuff, as far as your problem, I am not sure but it could not hurt to check.

I was able to measure my injector voltage with the car running, I had over 12 volts at the injector plug.

[sall]

Check Pins N and P for +12V ignition in run. If not getting voltage there then go further down the line toward fuse block. Cross that bridge if comes to it.



If have voltage there check here next...+12V in run/start at PIN A at each injector connector.



Specific codes would be helpful though other than grasping straws.

[gator]

Thanks for the diagrams sall. I don't remember the codes, but they were for all 8 injectors malfunctioning. I think its P0201-P0208.
Randy, thanks for the info. I'll try to check all of this out before I go buy my new F4i tomorrow.
Gator

[bobsblue95]

First, check all fuses. Use a meter or test light, don't rely on visual.
If fuses are good, it's either PCM or, more likely, wiring. Start by inspecting that connector, next I'd start checking grounds.
The PCM *can* have failures on individual outputs, shown on a scanner as "QDM fault."
All eight injector outputs failing at once is about as likely as all eight injectors failing at once... 'bout a gazillion to one.
I don't believe the ignition switch could be the problem here.

Harbor Freight sells an injector test set for about $20. Basically light bulbs that will show you if the computer is firing the injector. Useful once in a blue moon, but it takes the guess work out. Having 12v on the injector rail is half the battle. The other wire to each injector is grounded by the PCM, using pulse-width-modulation to control the amount of fuel sprayed.
HTH, keep us posted!
Bob

[sall]

Noid light! Have seen them but never could justify the purchase.

But yes the PIN B is sent low by PCM.

[gator]

Well, she is running. Very rough, but running. There is a lot of 'backfiring' and it sounds horrible, but it does run. When I went to check the connector this morning, I noticed it was unplugged. I don't remember unplugging it, but I do remember inspecting the underhood area, especially this connector and harness diligently. Now to figure out why it runs like crap. Thanks again for all the help.
Gator

[bobsblue95]

Well that's really bizarre! It must have been loose all along and finally popped off somehow.
Check the spark plugs to see if you can tell which cylinders aren't firing.

[gator]

Never mind. It fires up and runs real weak for a couple of seconds then dies, or it won't fire at all. It really sound as if it is out of time when it does run. I can't imagine the timing chains slipping out, but I guess its possible. When I had the cam cover off, I took a good long look at the chains and didn't see anything unusual. They were tight, and the ones I could see in the back looked fine as well. I'll put a code reader on it in the next couple of days and see if that tells me anything.
Gator

[boldsmobile]

Water in the tank from rusted fuel pump ring?

[bobsblue95]

Ditto... I'd suspect bad gas before timing chain. I don't think I've ever heard of a northstar timing chain slipping, but who knows.

[Randy T.]

Apr 4, 2013 10:57:55 GMT -6 gator said:

Well, she is running. Very rough, but running. There is a lot of 'backfiring' and it sounds horrible, but it does run. When I went to check the connector this morning, I noticed it was unplugged. I don't remember unplugging it, but I do remember inspecting the underhood area, especially this connector and harness diligently. Now to figure out why it runs like crap. Thanks again for all the help.
Gator

Is it possible someone could have messed with your car?

[gator]

I'm inclined to believe its not the fuel filter or pump. The pump was just replaced with a new unit from Rock Auto in Aug or Sep. I have around 50 psi at the rail, but the injectors aren't firing. There is no gas smell at the tail end when I crank it for a bit like there usually is if there is no ignition. Plus it died all of a sudden, while going about 70mph, after driving for about 20min.
Randy, its always possible, but I can't think of when or where. I can most certainly think of several reasons why, but not when or where.
I really think I just have to track down a good reason why the injectors won't fire. Could it be a sensor gone bad or shorted out?
I appreciate everybody's input.
Gator

[bobsblue95]

First, how do you know the injectors are not firing?
If it's a bad sensor or wiring or pcm, it should throw a code. I can't think of any sensor that would cause the injectors not to fire though. Either they are not getting a power pulse (bad wiring or PCM) or your injectors are clogged. You said it runs but very rough, so I still suspect bad gas or clogged injectors.

Try pulling the vacuum line of the regulator. This maxes out the fuel pressure, might push more fuel thru a clog. Just try it and see if it runs any better.

[sempar]

I don't have a classic electrical diagram, but I believe the PCM injector circuits are similar to the 2nd gen cars. It's worth noting that the injectors get a constant 12v from two 10A fuses, each provides 12v for four injectors. The PCM provides a ground path for the injectors through the injector "drivers". On the 2nd gen Aurora there is four separate ground paths for the PCM routed through two connectors. If the Classic is similar, I'd be looking at a possible bad ground for the injector drivers. Since the drivers handle a fair amount current to ground, they may have their own ground.

It's always possible that there may be a bad sensor or connection. For example, a bad or missing signal from a MAF or MAP sensor may not provide a signal for the PCM to fire the injectors, but still allow ignition and fuel pump activation. Would have to dig a bit more to see if that's the case.

Hope this helps some...

John

[bobsblue95]

I would think that if it was a PCM grounding issue you'd have more problems than weak injectors.

[gator]

Bob, its not running at all. I assume the injectors aren't firing because there is no fuel smell at the tail pipe after cranking for a bit. I've ruled out bad gas because there was no warning. The car was running fine and the next second it was not running. There was no chugging or running rough for a bit, it just died. After checking all the fuses and checking the harness for power, it fired up and ran for a few seconds but sounded horrible, worse than usual. After that, it would not fire up again. I've had dirty fuel and clogged injectors before. It doesn't just happen in a split second like that. It has to be a component or wire somewhere not doing its job.
Thanks again.
Gator

[sall]

Have you actually verified spark and tested fuel pressure? Lifted the rail and see if the injectors are squirting(or try a noid light as Bob suggested?).

[gator]

I have not lifted the rail and seen the injectors not fire, but in my past experience, when you crank an engine for 20+ seconds and it doesn't fire, there will be a faint smell of gas in the air. I have verified spark at all four front cylinders, 2,4,6 and 8. I have also verified 50 psi at the rail. I guess I will raise the rail and crank it a bit to see if there is any spray. Also I will revisit the code reader as well. I assumed the other 4 codes (O2 sensor, MAF sensor etc) were just hanging on because the injectors weren't working, but I may have that backwards.
Gator

[boldsmobile]

Take the fuel from the rail port and put it in a glass jar. It's a fast check to make sure you aren't trying to ignite water.

[Randy T.]

I bought this Aurora a couple months ago. I found the front head exhaust cam sprocket had a loose bolt, which sheared the stay pin in the cam off, the cam was turning randomly. I tried to start it a lot, and it ran a little bit here and there, sounded horrible, so I probably have some bent valves. I am in the process of pulling the head in my spare time.

I caught it on fire the first day I worked on it, pulled the return fuel line, got distracted, went to start it, it ran about 10 seconds and then backfired, it was quite a big fire, but I got it put out and it didn't hurt much of the car.

[Randy T.]

I am surprised! No sign of bent valves, and no sign of any valves touching the pistons. I did have good compression, but I had to make sure that nothing happened. I am thinking about doing both head gaskets again while I have it apart, I see a little oil mixed in with the coolant, but I will probably have to lower the engine to get the rear head off.

[Randy T.]

The vin "9" exhaust looks a lot better than the dual wall crap we have going on in the Auroras. I am going to check on what it would take to switch my Aurora over to this style, dropping the trans would probably be involved, unless the crossover is still the same, and it probably is since there is not much space to work with.