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P1520 Clarification

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JaketheSnake

New CEG'er
Joined
Jul 1, 2000
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Location
Farmington, Connecticut
Hi CEG !

I'm due for my emissions testing in order to re-register my '99 SE duratec MTX, and naturally my check engine light came on a few weeks ago and I'm a bit stumped.

Over the course of the fall/winter, about half the times I would fuel up, the CEL would come on about 15 miles after fill-up. If I fiddled with the cap, the CEL would go away. Since its been on constantly for a month now, I brought the car down to Autozone to get a new gas cap and also to scan the CE codes.

Here's the scoop:

0420: bank 1 threshold (hopefully solving the EVAP leak will fix this too)

0455: evap leak (large) - I *hope* its just a faulty gas cap

1520: now here's the puzzler.. the scan tool said this was the code for a "idle speed control auxilary input fault" and the list here on CEG says "Intake Manifold Runner Control circuit fault."

So my questions are: Which 1520 interpretation should I go by? Is there a chance that fixing the EVAP leak and a PCM reset will cure the 0420 and 1520? I've just replaced the cap and unhooked the battery. Will let it sit 5-6 hours and then go for a few drives in the meantime. Thanks in advance!

- Jake
 
well after sitting for 5-6 hours, i hooked the battery back up, and have driven about 15 miles since with a few errand stops in that time. No CEL -- huzzah!!! :D

how many warmup/cooldown cycles before I know I'm in the clear on this one?
 
www.fleet.ford.com for Owners Manual and

(OBDIIDrive cycle) http://www.obdii.com/drivecycleford.html

Change the cap or clean the seal P0455

P0420, fuel injector or vacuum UIM cleaning
From Duratec Maintenance-Read First.
http://www.contour.org/ceg-vb/showthread.php?t=41

(if it doesn't work, mileliminators).
From M&M howto http://www.contour.org/ceg-vb/showthread.php?t=760

P1520. Change IMRC or transistor. Also in Duratec Maintenance-Read First
http://www.contour.org/ceg-vb/showthread.php?t=41
 
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JaketheSnake said:
well after sitting for 5-6 hours, i hooked the battery back up, and have driven about 15 miles since with a few errand stops in that time. No CEL -- huzzah!!! :D

how many warmup/cooldown cycles before I know I'm in the clear on this one?
Click to expand...

Minimum of two cycles to set the CEL. A lot depends on your weather and your driving conditions as to when certain diagnostic tests execute.

There's not a chance in you-know-where that you're in the clear.

If you're lucky, it's the gas cap or the filler tube that's causing the P0455. If you're not lucky, you'll need a shop with a smoke machine to locate the EVAP leak.

Injector or intake manifold work will do nothing for a P0420. The computer is measuring your rear pre-cat as chemically dead. MIL elimininators are your most expedient recourse.

As for the P1520, the IMRC is the most likely problem. Changing the driver transistor inside the IMRC can not address this fault code. Additional possiblilites include the PCM and the interconnecting wires/connectors., etc. If you need the complete diagnostic routine for the P1520 fault code, PM your email address to me and I'll send you a pdf file.

Steve
 
well in either case, I passed my emissions test! the normal OBDII computer test failed due to the recent battery disconnect, so it had the car perform the traditional 'smog' test with the tailpipe sensor and it passed with flying colors :D
 
JaketheSnake said:
so wait, the codes are still stored in there? unhooking the battery for 6 hours just got rid of the check engine light?
Click to expand...

No, the codes are erased when power is removed and KAM power is drained. The other poster was indicating what whould happen if either power wasn't removed or the codes had not been reset via a scan tool.

I'm surprised you were allowed to use the alternate method of testing. here, they just tell you to come back in a few days and see if the OBDII monitors had run. In any event, enjoy your legal license status.

Steve
 
projectSHO89 said:
Minimum of two cycles to set the CEL. A lot depends on your weather and your driving conditions as to when certain diagnostic tests execute.

There's not a chance in you-know-where that you're in the clear.

If you're lucky, it's the gas cap or the filler tube that's causing the P0455. If you're not lucky, you'll need a shop with a smoke machine to locate the EVAP leak.

Injector or intake manifold work will do nothing for a P0420. The computer is measuring your rear pre-cat as chemically dead. MIL elimininators are your most expedient recourse.

As for the P1520, the IMRC is the most likely problem. Changing the driver transistor inside the IMRC can not address this fault code. Additional possiblilites include the PCM and the interconnecting wires/connectors., etc. If you need the complete diagnostic routine for the P1520 fault code, PM your email address to me and I'll send you a pdf file.

Steve
Click to expand...

Please tell me what you underestand about how the P0420 code is set. It sounds like you may have a misunderstanding.
 
Big Jim said:
Please tell me what you underestand about how the P0420 code is set. It sounds like you may have a misunderstanding.
Click to expand...

No, Jim, I understand perfectly how it's "supposed" to work.

It's simply a mathematical relationship between the switching rates of the upstream O2 sensor vs the switching rate of the downstream O2 sensor.

As the catalyst material looses its ability to store oxygen, the downstream sensor signal starts to more closely track the signal of the upstream sensor. When the switching ratio becomes to close, the PCM's programming concludes that the catalyst is no longer functioning at an efficient level.

Prior to the PCM executing this test, it first tests both the upstream and downstream sensors for their ability to properly switch and to measure the oxygen content in the exhaust stream. This helps to verify that the efficiency test is run with functional sensors, otherwise, the results would be quite invalid. Watching the upstream and downstream sensors' signals in realtime on a graphical interface scan tool is a very definitive confirmation of the lack of catalyst performance.

Intake manifold leaks or other faults SHOULD exhibit in other fault conditions. Same with O2 sensors. However, it is my opinion that if overly rich operating conditions prevail for too long of a period of time, the catalyst is damaged or contaminated and its operating efficiency is reduced, eventually leading to the indicated failure of the catalyst.

There have been posted reports of individuals who have used a strong concentration of a cleaner such as B12 and have cleared the catalyst and restored it to a level of functionality. I'd suspect the cleaner either cleared out a contamination or otherwise rejuvenated the catalyst (think of the old CRT rejuvenators for TV sets) back into a functional condition.

Now, we're all aware that Ford did widen the catalyst efficiency testing parameters in a PCM reflash (available only for certain versions) that allowed more vehicles to avoid pre-cat replacement under emissions warranty. Exactly how they did that has not been revealed. I'm also aware that the idealized function of all these components is sometimes far greater that what Ford's engineers were able to implement in this vehicle's control systems.

I welcome your discussion and ideas as to whether my analysis and logic is in need of either adjustment of refinement. It is the result of my individual experience, my technical background, and my research. Any comments, i'd like to hear them.

Steve
 
projectSHO89 said:
...There have been posted reports of individuals who have used a strong concentration of a cleaner such as B12 and have cleared the catalyst and restored it to a level of functionality. I'd suspect the cleaner either cleared out a contamination or otherwise rejuvenated the catalyst (think of the old CRT rejuvenators for TV sets) back into a functional condition.
....
Click to expand...
Why can't this be the situation for the Original Poster? :shrug:

I seem to have to reference this thread and its links more in recent times.
http://www.contour.org/ceg-vb/showthread.php?t=7122&highlight=p0420
 
Tony2005 said:
Why can't this be the situation for the Original Poster? :shrug:

I seem to have to reference this thread and its links more in recent times.
http://www.contour.org/ceg-vb/showthread.php?t=7122&highlight=p0420
Click to expand...

Tony,

I selected word "expedient" carefully. I did not mean to imply there were no other options.

Jim,

See section D of TSB 01-9-7. Also, see http://en.wikipedia.org/wiki/Catalytic_converter otherwise google "catalytic converter oxygen storage"

Regards,

Steve
 
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Steve,

Perhaps you can more closely show me where a cat "stores oxygen". I can't find it in that Wikipedia article.

Without the hassle of reading the entire article again, here is a brief definition from Webster's Dictionary for "catalyst":

catalyst
One entry found for catalyst.
Main Entry: cat·a·lyst
Pronunciation: 'ka-t&-l&st
Function: noun
1 : a substance that enables a chemical reaction to proceed at a usually faster rate or under different conditions (as at a lower temperature) than otherwise possible
2 : an agent that provokes or speeds significant change or action

It looks like the Wikipedia article describes the more detailed application on a car's exhaust system. It show a two way cat and a three way cat. A two way cat is an oxidizing cat and continues the burn or continues the start of oxidation of hydrocarbons. It allows the available oxygen to better combine with carbon monoxide to become a more stable carbon dioxide (one way of two) and the continued burn of hydrogen to become water (the second way of the two).

A three way cat adds the ability to remove oxygen (reducing), in this case from oxides of nitrogen or NOx.

If we are clear on this, we can continue the discussion. By the way, don't BS me with something like the Wikipedia article as I could have written it. I was a smog tech and later taught how to use smog testing equipment.
 
Are you saying you don't know how or "where" a TWC stores oxygen and need to learn this? If so, it can be researched and the details posted for the curious. Hint: Cerium: 2 Ceo2 <--> Ceo3 +0.5 02

I'm an electronics person with specialization in electronics sensing and control systems and circuits. Don't try to BS me about electronics or sensors. Cars are just a necessary hobby and evil.

From my training and as seen specifically by the up- and down-stream O2 sensors, the TWC is a big time-integrating oxygen storeage device. I'm not a chemical or materials scientist,but I am perfectly aware of what a catalyst is.

As for the Wiki article, it was presented as a quick confirmation of the TWC's OSC. Obviously you didn't write it....

Steve
 
Look guys, your missing the point. A catalyst aids in chemical reactions. Any storage taking place there is a very tiny bit of what is happening overall. If you think that's the main way the cat functions, releasing stored oxygen most of the time while driving, you won't understand fully how the codes are set.

Now back to the relationship between the upstream and downstream sensors. You are correct in that an effecient cat will dampen the signal of the downstream sensor. That is how the cat monitor identifies an ineffecient cat and sets those codes. But what happens when you have a lazy upstream sensor, one that isn't bad enough to set a code, particularly when the cat may not be at it's optimal operating condition? Although it is true that you might discover that with a real time scan, you might not unless you catch conditions perfectly. Also, most readers here don't have that capability. Even sadder, most shops only read the codes and start replacing parts without pinpoint testing, so if it comes in with cat codes, they try to sell cats.

I'll add some personal experience about my own car. It has ocassionally set cat codes, usually bank one but sometimes bank two. It started after the extended emissions warranty on the cats had expired (California 7/70). On two of those ocassions I had access to a real time scanner and confirmed that indeed the cat was fine while I was monitoring it. So I would just reset the light and keep driving. When I have taken it in for a smog test, it has had reading very near zero, indicating that at least for the smog test (dyno loaded test) the cats were effecient. When the precats are dead if you are lucky the main cat will still clean things up enough to pass the test, but on the high side of spec.

Another interesting thing happened about 18 months ago. I got a code for the bank one upstream oxygen sensor reading lean. I read the code and reset the light. It came back within 50 miles. So I figured that at aroud 200,000 miles it was finally time to replace the upstream sensors. I replaced both. The cat codes have not returned. The prior pattern was about once to three times a year. Certainly not conclusive, but still interesting.

Depending on how badly coated the cat substrate is, sometimes they can be brought back to life. It helps immensely if the engine is in good tune and that includes good plugs, clean air filter, and intake manifold, combustion chamber, ports, valves not coked up. Sometimes the same cleaner that cleaned up the carbon in the engine can also help clean up the cat. Sometimes it just needs a good hard run to get the cats real hot again. Is it foolproof? No, but it is certainly worth trying before spending the money on cats.

But evidently you know something that doesn't match the experience of many of us here.
 
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