Cylinder No.5 not firing

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Now I'm confused and I need help. I checked and changed all the spark plugs hoping that would fix it, it didn't. So, I have spark, not sure of the quality, from the wire. I checked the injectors for open circuit, all good.
Plugged the laptop into the ECM and read the data. Told me what I already new, Mode 1, Message $00, word 27: BADCYL = 5.
Next I will check the wire resistance, maybe I have a bum wire. However, is this "BADCYL" message a good clue? How does it know it's not firing? If I knew how it knows, then I would be closer to the problem.
Steve
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Just learned, the "BADCYL" is the "Current Weak Cylinder" indicator. WTF?
Steve

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all
If
Run a compression check. H
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Steve Mackie wrote:

The ecu recognizes a lack of increase in rpm due to no power in #5. It can think in billionths of a second, or billionths of an rpm change between cylinders.
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Cool, I will be doing a compression test (Hairy's advice) and spark test tonight. Maybe I will be a little closer. If I can't find a problem there, looks like it may be the injector then. The engine has felt like it was missing a few times before, but I just give it a shot of gas and it smooths out. Now it just misses all the time, so I'm leaning to towards a sticky injector.
If it turns out it may be an injector, what's a quick test? I already checked for an open circuit on that injector and it's okay. but it could still be sticking couldn't it? If I hook a 6V test light to it, crank the engine and it flashes, that's only telling me it's getting a signal and there is no open circuit right? So how do I check if it's sticking?
Steve
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"Steve Mackie" wrote:
I will do compression and spark tests tonight. If I can't find a problem there, it may be the injector. I already checked for an open circuit on that injector and it's okay but it could still be sticking couldn't it? If I hook a 6V test light to it, crank the engine and it flashes, that's only telling me it's getting a signal and there is no open circuit right? If it is the injector, what's a quick test?
Steve ________________________________________________________
Is it possible to swap the #5 injector with one from another cylinder?
If so, and if the ECM can identify a particular injector's response, when the engine runs the failure indication will be shown as coming from the other swapped cylinder if the injector is defective,
Good luck.
Wendy & John. _________________________________________________________
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Definatly a good option. I was hoping for something a little simpler, but that should work.
Steve

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Steve Mackie wrote:

Hi Steve...
Not a mechanic, rather an old retired electrical guy, so take what I suggest appropriately :)
My Haynes book gives you one tiny upgrade to the continuity check - says you can *carefully* use a long screwdriver while the engine is running as a stethoscope. Pointy end on the injector, handle end carefully against your ear, and you will hear it clicking away. Compare the suspect one against another.
Take care,
Ken
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Nice tip, however, being a 3.4L DOHC I can't even access the rear injectors without removing the upper intake manifold.
So here's some more stuff I did tonight: I did a compression test like Hairy said, all checks out okay, all cylinders are the same. Check the quality of the spark coming from the plug wire and according to my crappy little guage I am getting a little less than 30,000 volts. I believe I read in the manual that 27,000 volts is the nominal value.
I just installed all new plugs yesterday, pulled them all tonight. They all smell like gas except for number 5, doesn't smell at all. They are all dry except for number 5, which has a little bit of oil on it. I am assuming that this means no fuel is getting to cylinder No. 5. I have order a rebuilt injector from a local parts store for about $50 CDN, just to have on hand incase the injector turns out to be bad.
So, tomorrow I will pull the upper intake manifold off, check to see if the injector is firing ("clicking"). Then I will probably just replace it and cross my fingers.
Anyone have any more thoughts?
Steve

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The 3.4 DOHC engine is notorious for vacuum leaks at the lower intake manifold to cylinder head, as long as you're pulling the upper to do the injector, you might as well do the lower gaskets also.
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Been there done that. About 8 months ago I had a lower intake manifold gasket leak. I replaced ALL gaskets related to the intake manifold. Also replaced all injector O-rings. But that is a good tip.
Steve

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Steve Mackie wrote:

No easy injector test that I know of without removing the injector in the first place. Best you can do is what you have done to narrow it down. In my experience, a bad injector is likely more noticible at idle, as you discovered awhile back. The plug wire: 15k ohms max on the longest wire. 10k would be better. Check 'em while they are hot! - I know... not easy to do. Remove the wire and heat with torch or oven. Measuring 27k-30k volts is ok, but without the amperage the plug will not fire under compression. E=IR.
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On Tue, 11 Jan 2005 09:52:37 -0500, "Steve Mackie"

FWIW, there is something called a NOID light to test the electrical signal to the injector. Someone with more experience in this area might shed more light on this. I don't know if the test light is the correct procedure to diagnose this. It may well be, but in your place I might revisit that issue to be sure. FWIW YMMV DFB
"When a legislature undertakes to proscribe the exercise of a citizen's constitutional rights it acts lawlessly and the citizen can take matters into his own hands and proceed on the basis that such a law is no law at all." - Justice William O. Douglas
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You might want to read some of these http://www.autotap.com/obdii_library.asp

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Well, I haven't fixed it yet. All spark is okay, fuel injector is okay, compression is okay. After find out everything is okay and cylinder number 5 still not firing, I decided maybe the injector was plugged. Thinking since it's the first injector on the inlet side of the fuel rail, maybe a chunk of something somehow got lodged in the injector inlet screen.
Got the car ready to replace the injector, unplugged the fuel pump, started the car. Usually it'll run for 30 seconds to a minute before the fuel pressure is gone, but it only ran for 2 seconds. Didn't think much of it. Pulled the top of the engine apart, pulled the fuel rail off and noticed that injector #5 is NOT the first injector, but the last. The way the feed and return pipes are run it's deceiving at first look. I replaced the injector while I was there anyways.
Put the engine back together, started it, no go, cyl no. 5 still not firing. Now, with the fact that it took only a couple of seconds to bleed the pressure, and no. 5 is at the end of the rail, I am assuming lack of fuel pressure is the problem. Changed fuel filter. Although it was old and somewhat clogged, this did not fix the problem.
Now I'm going to do what I should have done a week ago, check the fuel pressure. One valuable lesson I learned, don't skip steps in the flow chart because you think it's okay.
Steve

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FWIW - many years ago I tried to track down a similar problem on a 1966 Mercury with a 289 V-8. It had a small miss that seemed to defy all attempts to ID it. New plugs, wires, tune-up, fuel filter, etc. Turned out to be a slightly wiped out lobe on the camshaft - just enough to affect fuel inlet. Now, I know your engine's valve train is different, but it might be worth a look. Best of luck!
doug

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Sounds plausible. First I will check the fuel pressure, if it's up to snuff I will check the valve train. I hoping its not the intake cam shaft, that would suck. This couldn't be happing to one of the cylinders on the front bank, that would just make this ordeal a little bit easier.
I have my fingers crossed. In my head I will rule out the cam, there are two intake valves, so to impede fuel entering the cylinder wouldn't both lobes have to be bum? Maybe. Let's just hope it's low fuel pressure so I don't have to take your advice. ;)
Steve

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Took the car to the garage today. They checked the fuel pressure, all is okay. I told them to spend an hour on it and see what they can find. Now we are down to either a mechanical problem (worn cam) or the computer. Can't think of what else it could be.
Steve

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Got the car back from the garage, turns out that the computer is not telling the number 5 injector to fire. The mechanic is suggesting either a bad ground or an internal computer problem. A while back I had the check engine light come on with a QDM A module error. I took the computer out and apart, cleaned it up, cleaned up the connections and put dielectric grease on the connectors. The QDM A error went away and has never returned. I am thinking the same solution may work in this case. I will do some testing to it later this week to find out if it's an internal or external grounding problem.
Steve

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Steve Mackie wrote:

Interesting saga. Let us know how it works.
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