'97 4.2 failed emissions
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From: kitch
'97 4.2 failed emissions
My 97 4.2 F-150 failed emissions with very high HC and CO at idle and on the 40KM/H tests. NOx was well within the pass range. Also showing a 304. I am changing plugs and wires, but I know they are fairly new.
Because the NOx was low, I am assuming that the Cats are ok.
What else would likely give high HC and CO but not NOx?
Because the NOx was low, I am assuming that the Cats are ok.
What else would likely give high HC and CO but not NOx?
Last edited by BrokenSockets; Feb 26, 2006 at 11:00 AM. Reason: additional info
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No, NOx is not an indicator of how healthy the cats are. NOx is created in times where combustion temperatures are at their highest. Since HC and CO levels are your failure point, you are running too rich - a condition where NOx will be naturally low, since too much fuel (or not enough air) will lower combustion temps.
Check your air filter recently? You stated that plugs were changed recently. Did you put the proper heat range in? Change the oil, and put a bottle of denatured alcohol in the gas tank. The alcohol will act as an oxygenate in the fuel.
Check your air filter recently? You stated that plugs were changed recently. Did you put the proper heat range in? Change the oil, and put a bottle of denatured alcohol in the gas tank. The alcohol will act as an oxygenate in the fuel.
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From: kitch
I indicated the code in my first post, PO304, misfire on cyl. 4.
I just changed the plugs and wires out. When I measured with a meter, the wires I removed had more than 10 times the resistance of the new ones.
I also happened to be putting in a new battery I had just charged so that took care of clearing the codes and resetting the CEL.
I drove to work today and no CEL yet. I think it feels less rough(?) I also used a $5 bottle of that "Guaranteed to Pass" formula on the last tank of gas. I will take another run at the test today and compare the results.
I just changed the plugs and wires out. When I measured with a meter, the wires I removed had more than 10 times the resistance of the new ones.
I also happened to be putting in a new battery I had just charged so that took care of clearing the codes and resetting the CEL.
I drove to work today and no CEL yet. I think it feels less rough(?) I also used a $5 bottle of that "Guaranteed to Pass" formula on the last tank of gas. I will take another run at the test today and compare the results.
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Broken,
I looked at a lot of wires and found none that met OEM. Went to ford for mine.
To test the primary and secondary coil-pak circuts (ignition off of course)
The primary is where the plug goes into the pak, facing it, the terminal on the left is positive, the three on the right are negative. With the ohm meter, hold the positive to the positive and check eack negative. You should be getting 0.3-1.0 ohms and they should be all close to each other. For the secondaries, check them where the plug wires go in. Here you're checking resistance between paired secondaries so it doesn't matter where you put the +/- terminals of the meter. Check the 1/5, 2/6 and 3/4. You should be getting between 6.5-11.5 K-ohms.
Just a thought,
Both paired plugscoils fire at the same time regardless of which of the 2 paired cyclinders is on the compression stroke so, you could try what I did and switch your 3/4 wires at the coil-pak and see if it changes where your mis is. I had a mis in the #2 and switched the 2-6. I don't know why but the mis dissapeared and has been gone now for about 4K miles.
I looked at a lot of wires and found none that met OEM. Went to ford for mine.
To test the primary and secondary coil-pak circuts (ignition off of course)
The primary is where the plug goes into the pak, facing it, the terminal on the left is positive, the three on the right are negative. With the ohm meter, hold the positive to the positive and check eack negative. You should be getting 0.3-1.0 ohms and they should be all close to each other. For the secondaries, check them where the plug wires go in. Here you're checking resistance between paired secondaries so it doesn't matter where you put the +/- terminals of the meter. Check the 1/5, 2/6 and 3/4. You should be getting between 6.5-11.5 K-ohms.
Just a thought,
Both paired plugscoils fire at the same time regardless of which of the 2 paired cyclinders is on the compression stroke so, you could try what I did and switch your 3/4 wires at the coil-pak and see if it changes where your mis is. I had a mis in the #2 and switched the 2-6. I don't know why but the mis dissapeared and has been gone now for about 4K miles.
Last edited by Grsyhands; Feb 27, 2006 at 09:19 AM.
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From: kitch
I am seeing 1.0 to 1.1 on the three primary and all about 12.3 K on the secondaries. On the outside of the specs you were suggesting, but does it seem ok?
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That's about what my reading swere and since I switched the 2 mentioned above, no problems. I've been wondering if the coil pak can have issues that show up only under load conditions and not with the ohm meter. Maybe someone else out there could answer that???
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From: kitch
I went to a shop that specializes in engine electrical to take a look at it. They suggested trying to flush the injectors and did so. No change, but suggested replacing the injectors may fix the problem and quoted over a grand.
If an injector is causing the miss, couldn't just the problem injector be found and replaced?
I forgot to mention that the engine is running very rich. Going through gas at about twice what it should be. I don't think there are any O2 sensor codes though.
If an injector is causing the miss, couldn't just the problem injector be found and replaced?
I forgot to mention that the engine is running very rich. Going through gas at about twice what it should be. I don't think there are any O2 sensor codes though.
Last edited by BrokenSockets; Feb 28, 2006 at 07:56 PM. Reason: added info
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From: kitch
Here are the numbers from the test result:
HC ppm at idle: pass level - 200, my reading - 4856
HC ppm at 40 km/h: pass level - 52, my reading - 415
CO at idle: pass level - 1.0, my reading - 6.51
co at 40 km/h: pass level - .29, my reading - 10.26
NO ppm at 40 km/h: pass level - 578, my reading 40
So NO is very low and CO and HC are insane.
HC ppm at idle: pass level - 200, my reading - 4856
HC ppm at 40 km/h: pass level - 52, my reading - 415
CO at idle: pass level - 1.0, my reading - 6.51
co at 40 km/h: pass level - .29, my reading - 10.26
NO ppm at 40 km/h: pass level - 578, my reading 40
So NO is very low and CO and HC are insane.
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From: kitch
Missing is worse than ever. I don't know if the injector flush exascerbated the problem or if it would have gotten worse on its own.
Missing badly, CEL is usually flashing as I drive.
any other ideas?
Missing badly, CEL is usually flashing as I drive.
any other ideas?
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From: Durant, OK (SOSU)
I know this might not be it, but figure I'll add it anyways.
Our Silverado popped a code on a cylinder seven miss. Took our mechanic two weeks of searching before he ended up tearing the block down and replacing a head gasket that was leading to a miss. I have no idea if it could even relate to your problem, but something to think about.
Our Silverado popped a code on a cylinder seven miss. Took our mechanic two weeks of searching before he ended up tearing the block down and replacing a head gasket that was leading to a miss. I have no idea if it could even relate to your problem, but something to think about.