Contour Enthusiasts Group Archives

stingray454 wrote:

I have the software, and I loaded your file. I'm new at this, so I don't know what I'm doing yet. I figured out how to replay everything. I see 2 fail codes in the test tab, both called MANUDEF with a CID of $21. I have no idea what any of this means, and the software doesn't explain anything. Since I don't have my car's data yet to compare it too, its tough for me to comment.

  That's odd.  Loading the same file into my system, no item shows up under tests with the TID of $21, nor with the name ?MANUDEF?.  I have two FAIL results.  The one we seem to be most focussed on right now is ?$10 CATRAT2?, ?$10 Catalyst Rear to front Ratio Bank 2 is 0.8 to 1 with maximum limit of 0.6 has FAILED?.  Anyone know what, exactly, this means?

  I spent some time today chatting with a mechanic.  He thinks I should focus on fixing the EGR, and that there's a good chance that that's the real cause of the entire problem.  I'm thinking now that perhaps another possibility is that the cat and the EGR are two separate problems, having nothing to do with one another.  Anyway, the cat doesn't seem to be causing, at least not directly, any DTCs; I've so far only seen P0402, which points at the EGR valve.  My mechanic doesn't think a clogged cat would cause increased EGR flow, as I had theorized.

There was a known issue with defective cat converters on 95's and 96's where the catalyst material would disintegrate and plug up. I had this happen to my '96 at 40k miles. They were covered under the federal emissions warranty and all three cats were replaced for free. Your mileage puts you out of that warranty however.

  On the other hand, perhaps there's some reason to hope that if this problem was going to affect this car, it will already have done so long ago, well before it came into my hands with 109,320 miles.  I guess I'm back to wondering what this ?rear to front ratio? is, and whether having a ratio of 0.8:1 when it should be no more than 0.6:1 is consistent with a clogged condition.

There should be 2 cats on your car - a precat next to the exhaust manifold, and the main cat under the car. Both should be replaced. Figure about $500 in parts if you do it yourself.

  Is that what they cost from a Ford dealer?  Any hope there's a cheaper aftermarket source?  I suppose this is the sort of thing that is best not obtained from a junkyard.

You may want to seek another mechanic, because he's wrong there. A clogged cat would definitely increase EGR flow.

However, I think that the OBD-2 systems can detect a problem with the cat converters, and has a seperate code for it that would cause the CEL to come on. I'm not sure on this though. All I remember is my Ford dealer had no problem diagnosing my car as having plugged cats, and my CEL was on. But then again, my car lost all power above 3,000 RPM, so maybe that was a good clue

Bob
I asked Alex Peper what would be the most useful/helpful book should I first start with when I get my Tricom?
Told me to check out the library for Mitchell's. Good source for troubleshooting.
I can't confirm yet, Mitchell's at my library having mainframe problems.
Be nice to have a copy that the Ford mechanics use, but two problems I'm assuming. 1. Not availble to public/propietary? 2. Might only make sense if you have their laptop/Star System or whatever it's called?
Paul
As with any troubleshooting tool learning how to interrupt always fun.
Oh yeah, higher EGR flow, downstream restriction is only logical reason thing I could think of at this time.

stingray454 wrote:

I have the software, and I loaded your file. I'm new at this, so I don't know what I'm doing yet. I figured out how to replay everything. I see 2 fail codes in the test tab, both called MANUDEF with a CID of $21. I have no idea what any of this means, and the software doesn't explain anything. Since I don't have my car's data yet to compare it too, its tough for me to comment.

  I just figured something else about this that I had previously missed.  Two things, actually.  I figiured this out as I was sifting through data from a friend's car, that has suddenly shown substantially-decreased fuel economy, and a change in how it sounds.  I'm looking at the TESTS tab from this car, and all the tests are called ?MANUF DEF?.  The system, as I have it configured doesn't know the names or meanings of test results for a 2000 Buick.  It probably knows then for my Mystique only because I've downloaded and installed the ?Defined Ford test results file?.  The other thing I had failed to notice before is that there are two columns that contain hex numbers.  When you referred to a CID of $21, saw the TID column, and seeing no $21 in there, didn't know what, further, to think.  I now see that TID $10, CID $21, is the CATRAT2 result on my machine, but if you don't have the ?Defined Ford test results file?, then to you, it's probably just ?MANUF DEF?.

  There are two things that may be relevant, that I don't think I've mentioned yet.

  First, is that I've only ever seen the CEL come on within a minute or two after starting the engine.  If it's not on within that time, it doesn't come on for the rest of the drive.  Since I've been using my new 3-Combo to monitor my car, I've only ever seen the P0402 appear as a PTC or a DTC within this same time frame, and I have so far not seen at all any other PTC or DTC than P0402.


Second, is something I've now noticed, looking at recorded results for several runs, in which I've run the tests on the TESTS tab.

  There are two particular tests related to the EGR, one of which always fails. There is the EGRUPHDIS test, ?Exhaust Gas Recirculation Upstream DPFE Hose Disconnect?, which should have a minimum limit of 504 inches of water, and there is the EGRDNHDIS test, ?Exhaust Gas Recirculation Downstream DPFE Hose Disconnect?, which has a maximum limit of 4 inches of water.  Apparently, this is some measurable parameter which should change when the EGR changes some mode, so that it is either less than 4, or greater than 504.  In every single case, both of these measured parameters are the same number, which results in one of the two tests failing.  In some cases, the number returned by both tests is less than 4, meaning that EGRDNHDIS passes, and EGRUPHDIS fails, while in some other cases, it is a number greater than 504, in which case EGRUPHDIS passes and EGRDNHDIS fails; in one case, it was a number in between, causing both tests to fail.

  I'm not quite sure what the dignificance is of these parameters with respect to what is physically happening under my hood, but I think this seems to very clearly indicate a malfunction in the EGR itself.  Perhaps there is something about this malfunction which is causing the CATRAT2 test to fail also, or perhaps the CATRAT2 failure is something else, not related to the EGR failures.

  Alex Peper, of <http://www.obd-2.com>, has provided the following bit of wisdom in an email message to me:

Excessive EGR can throw off the front and rear 02 sensors due to lack of O2. The ratio is catalyst efficiency, can be determined by ratio of front and rear 02 sensor switch frequency (high to low volts)

  So here is an explanation of how a problem with the EGR system, consistent with the DTC I've been getting, can cause the cat test to appear to fail in the manner that I've been seeing.

  Today, I saw a new test failure, EGRSTUCK.  I also saw, for the first time, a DTC (actually a PTC) set at a time other than within a minute or two after starting the engine.  As always, the code was P0402.

  I think it's very clear, at this point, that there is something wrong with my EGR system itself ? that this isn't some phantom being created by, for example, a clogged cat forcing more gas through an otherwise fine EGR.  I think I am going to stop worrying about the cat, at least until after I get the EGR system fixed.

  So, what wisdom can any of you offer me as far as the EGR system istelf?  I'm rather hazy on just what it does and how it does it and why.  I think I understand that, in certain circumstances, it causes some exhaust gas to be fed back into the intake, and that this somehow causes the engine to run cooler, and to thus produce lower amounts of nitrogen oxides.  I understand that cooler means less nitrogen oxides, but how does feeding exhaust gas, which must be very hot, back into the engine, make it run cooler?  And under what circumstances is this being done?

  What can you tell me about the actual repair work I have ahead of me?  How difficult is it to get to, and remove the EGR vave?  Should I just plan on buying a new one before I start, or should I expect there to be a very good chance of my being able to repair the existing one?  What's a new EGR valve likely to cost?

  Looks to me, from the test failures I've seen, that this valve is sticking at times, that it is often staying open when it should close, and staying closed when it should open.  The Haynes manual describes a test that involves hooking a vacum pump to the valve, but I don't have a vacuum pump, and I suspect that the test results I'm getting by way of my OBD-II system are telling me everything that the vacuum pump test would tell me.

You are correct in the purpose of the EGR valve. The way it reduces combustion temperatures is by mixing in exhaust in the intake stream, the exhaust is mostly inert and contains little oxygen. Thus, it has a tendency to richen the combustion mixture, thereby reducing combustion temperatures, and thus reduce nitrogen oxide emissions. The computer's timing map is programmed to consider the EGR effects on combustion temps. When an EGR valve sticks closed or the ports are blocked, the combustion chamber temps increase, resulting in detonation or pinging. My V-6 had clogged EGR ports resulting in no EGR flow at all, and it would ping even on 93 octane. I took the intake apart and cleared the ports, and it solved the problem.

I'm not familiar with the Zetec, but the EGR valve itself was about $40, and should be roughly the same for your motor. At your mileaege, I would just install a new one anyway - they don't last forever and tend to get gunked up with carbon, and the vaccuum diaphrams tend to crack and leak due to the heat. It's a really simple device and is easy to replace. It basically mounts to the intake manifold with two bolts, and has about a 3/4" exhaust tube connected to it, and a small vacuum line up top. That's it. Assuming its easy to get at on the Zetec, it would probably take you 15 minutes to replace.

Again, I'm not familiar with the Zetec, but you may want to check the EGR ports behind the throttle body. If its anything like the Duratec's arrangement, expect to find ports clogged with carbon. These must be clear or the EGR won't work right.

stingray454 wrote:

Again, I'm not familiar with the Zetec, but you may want to check the EGR ports behind the throttle body. If its anything like the Duratec's arrangement, expect to find ports clogged with carbon. These must be clear or the EGR won't work right.

  These ports would be where the EGR valve feeds exhaust into the intake manifold?

  This suddenly makes me wonder about something else, that's really off-topic.  My mom has a 1986 Chevette, with very low mileage, but which has a very high tendency to knock, ping, and diesel, even on high-octane fuel.  Do you suppose it could have clogged EGR passages or ports?  This is a car which, before my parents bought it, spent many, many years as a ?spare? car that sat around a lot and very rarely got used.

  I just spent most of today in my parents' driveway, working on my car.  The EGR valve is a major pain in the ass to remove, and an even bigger pain to put back in.  It turns out that my EGR valve is fine; it was rather dirty, but still fully functional.  I cleaned it up as well as I could, before I put it in.  The important thing to know, if you're looking forward to removing and reinstalling an EGR valve on a Zetec is this:  Make sure you have, before you begin, a 22mm or 7/8" ?crow's foot? wrench.  Any kind of normal wrench just won't work; there's no room to swing it.

  It appears that my problem is the EGR Vacuum Regulator Solenoid.  According to the official Ford service manual, the test for this valve is that you should not be able to blow air through it when there is no electrical power applied to it, and you should when there is.  Mine seems to be behaving in a manner that I cannot rationally describe, but at times, it is opposite of how the Ford manual says it should behave ? that is, I can blow air through it when there is no power, and I can sometimes not blow air through it when power is applied.  It doesn't make sense, and I am sure this means that this part is bad.  A check at two online parts sources failed to find anything about an available replacement.  I am wondering if I can get a replacement through any aftermarket source, or will I have to get it from Ford; and how much is it likely to cost?