P0341, and P0340

[Cougar]

Unlike earlier models, there is only one engine temp sensor on the 2000. It's a 3-wire, and incorporates both the ''thermometer'' (gauge) and ECU functions in the single unit. (The white/green wire is for the gauge, but there are two others.) A problem with either function naturally requires changing of the CTS.

 

 

EDIT: I attached a picture of the TPS connector end to minimize any possible confusion.

 

 

Thanks very much for the notice on this OB99W. This is good to know. I should have known you would have pointed this out earlier if it was an issue. Looking at my info more closely it shows pin 3 (wht/grn) is for the gauge, pin 2 (blk) is ground, and pin 1 (blk/yel) goes to the ECU.

Edited June 30, 2009 by Cougar

[OB99W]

Thanks very much for the notice on this OB99W. This is good know. I should have known you would have pointed this out earlier if it was an issue. Looking at my info more closely it shows pin 3 (wht/grn) is for the gauge, pin 2 (blk) is ground, and pin 1 (blk/yel) goes to the ECU.

You're welcome, Cougar. The wire coloring info you provided agrees with what I have.

 

I'm beginning to wonder if certain assumptions have been made that could be leading us astray in diagnosing the problem. I reread rvac99's first post in this thread, concerning the appearance of the plugs and the smell of the exhaust, but no details were given. It's possible to misread similar symptoms. For example, plugs that are sooty and exhaust that smells of unburned fuel would usually point to a rich mixture. However, if the plugs are wet and the exhaust smells of raw fuel, one might also assume that the mixture was too rich, but it would more likely indicate that reliable combustion wasn't occuring -- along with the cam sensor code, that could indicate a timing-related problem.

 

A quick check of compression could help determine if timing issues are likely. If compression is low and if all the belt covers haven't been pulled and the crank/cam timing checked, it would probably be one more thing to consider looking at (especially if investigating #3/#4 ignition hasn't lead anywhere).

[rvac99]

I broke the end cap of one of my injectors on Saturday. Ordered a new one from the dealer on Monday and won't have it until tomorrow (Wed).

 

Going back to the temp gauge issue. I'm assuming that it is working properly since it did not jump up. After I thought about it for a while it should have been right where it was. I over tightened the original one. It is as "OEM" as it is going to get (Delphi) as this issue has become expensive.

 

My friend at the part store let me "borrow" a new coil pack and new wires. Same condition with cylinders 3&4.

 

I tested the fuel injector wires from the ECM pins. Proper resistance across each injector, continuity of each wire and no shorts.

 

When I get the new injector and get it running I'll test the fuel pressure.

I ran a compression test with the engine cold. My gauge it old and beat up so these may be higher than actual, 210, 205, 215, and 220.

I have not had any misfire codes or temp sensor codes. P0340 has been very consistent. P0341 came up with P0340. I also had a 1505 and 0340 but the 1505 went away.

The Crank position sensor was replaced in February and the Cam position sensor after the first appearance of code 0340.

If it does not rain tomorrow I’ll have more info for you then.

Thank you!

[OB99W]

Going back to the temp gauge issue. I'm assuming that it is working properly since it did not jump up. After I thought about it for a while it should have been right where it was. I over tightened the original one. It is as ''OEM'' as it is going to get (Delphi) as this issue has become expensive.

The OEM unit for a 00-03 Legacy is reasonably priced at about $20 list. I don't know for sure, but I suspect the Delphi replacement goes for at least as much.

 

 

My friend at the part store let me ''borrow'' a new coil pack and new wires. Same condition with cylinders 3&4.

It was nice of your friend to allow you to try those parts, and to determine that they're not the cause of a problem. (Perhaps buying non-OEM has some advantages.) It's still important to verify that there's strong spark at the plug end of the wires on 3&4. You can check that by pulling each wire at the plug, and seeing how far the spark will jump from that end to a nearby ground (the block). Of course, make sure you don't get shocked, and don't allow the spark to jump to any other wires.

 

 

I ran a compression test with the engine cold. My gauge it old and beat up so these may be higher than actual, 210, 205, 215, and 220.

As you said, your gauge might be a little optimistic (typical for your engine would be somewhat lower), but at least the readings are well balanced. There could be some carbon buildup. However, it's also possible that the valve (cam) timing is a bit advanced, due to the timing belt being off a bit. If you haven't recently verified that all the timing marks align, it might be worthwhile checking.

 

 

I have not had any misfire codes or temp sensor codes. P0340 has been very consistent. P0341 came up with P0340. I also had a 1505 and 0340 but the 1505 went away.

The OBD-II trouble codes are only as reliable in pointing to problems as the ECU's programming. If something is wrong that the programmer didn't anticipate (or isn't easy to detect), the trouble code(s) generated may not accurately reflect the nature of the problem. The reason I keep coming back to the timing issue is because the ECU ''assumes'' crank versus cam timing is correct, and directs systems to function based on that. Both fuel delivery and ignition timing/dwell are very much dependent on the pulses the ECU gets from the crank and cam sensors, which if mistimed will throw everything off. The P0340, possibly higher than normal compression, and the apparent fuel (and possible ignition) issues might be linked via the timing belt alignment. (And yes, I know it's no fun to pull things apart to check.)

[rvac99]

Checked the timing very early in this process. Also reset timing when I installed the new tensioner. There was also that fluke time where everything ran fine, no codes, power, normal exhaust.

No work today. It is raining and I don't have a garage.

[Cougar]

It is seldom I suspect the ECU of causing any kind of trouble in these kind of problems but after the testing you have done and the intermittent times the trouble appears I am now thinking it may be time to look at it. OB99W brought this up earlier also.

[OB99W]

Since a new/rebuilt ECU can be expensive, and because (as Cougar said) ECUs don't typically have this sort of failure, I've been trying to suggest alternative possibilities that fit the symptoms. Although apparently under the circumstances it isn't practical, if certain test gear was available, some further checking might reveal something that hasn't been obvious, allowing us to be more targeted. For example, even though it's been replaced, I'd certainly feel more comfortable if we could verify that the cam sensor was outputting proper pulses.

 

Perhaps a used ECU can be found at a reasonable price.

[Cougar]

I agree OB99W. Looking at pulses of the CAM sensor with a scope would be a very good thing.

[OB99W]

This thing is apparently bugging me . Looking at both the cam and crank sensor pulses might be revealing. The reason I'm mentioning the crank is because it's the reference signal, and the cam trouble code(s) can be generated when there's a timing discrepancy between the crank and cam pulses. Since there's been a lull in this thread, I thought I'd post some further conjecture on what might be the cause of the problem.

 

The crank sprocket has 6 reluctors in two groups of three -- each of the ones in a group has a corresponding one 180 degrees around from it. Each group of three corresponds to two cylinders, one group to #1 & #2 and the other to #3 & #4. If there was a sufficiently weak pulse from one of the groups of three, it could affect just #3 & #4. It might then cause the ECU to see a timing problem between the crank and cam pulses, triggering the P0340.

 

A weak pulse can be due to a damaged reluctor tooth. It could also be that the crank sensor's output is slightly low in general, and normal variation in output from tooth to tooth might bring one below the triggering threshold.

 

Just a thought, might not be worth 2 cents.

[rvac99]

Thanks OB99W and Cougar. I'm back to work today after some bad weather and the 4th holiday. I'm going to get the fuel injector back in and test fuel pressure. I don't think there is an issue with it but I need to know. I'm going to try a new Crank sensor before I replace the ECU. My friend also mentioned the crank and cam sensor dependency.

What tool would be needed to check the wave form of these sensors? I’d like to search to see if I could pick up a used one or ask some of these mobile mechanics that advertise on Craig’s.

[rvac99]

Put everything back together today. New fuel injector in #4. Found some frayed wires on the Crank pos. sensor and repaired both. Now cylinders #1 and #4 are not firing. I checked the wires; yellow has voltage with key on and no shorts in either wire from the wire connectors at the back of the engine. 13.5 ohms across each injector from the ECM pins. No resistance when checking each injector wire from ECM pin to injector plug.

Switched #2 with #4 injector and same cylinders were not firing.

So before the engine was running on just #1 and #2 cylinders. Today just #2 and #3.

I went back and checked the Cam sensor wires again and today I can’t get an infinite resistance value when the ECM pins are disconnected. Both cam sensor wires are registering a resistance even when every connector is unplugged (resistance fluctuates). That is telling me there is a short somewhere from the ECM pin connector to the b22 connector on the back of the engine. Wires from the sensor to the b22 connector had infinite resistance when disconnected. They have not shorted with the braided wire that sheathes them as the resistance from 2 and 9 with 10 showed infinite resistance.

Lost my daylight so I’m stopping for the day. I’ll check back in the morning for any other insight. Anyone want to make a bet on which cylinders are going to work tomorrow?

[Cougar]

It appears you have a problem in the wiring alright. I assume you are checking for any ties to ground on the wires also.

[OB99W]

I went back and checked the Cam sensor wires again and today I can’t get an infinite resistance value when the ECM pins are disconnected. Both cam sensor wires are registering a resistance even when every connector is unplugged (resistance fluctuates). That is telling me there is a short somewhere from the ECM pin connector to the b22 connector on the back of the engine. Wires from the sensor to the b22 connector had infinite resistance when disconnected. They have not shorted with the braided wire that sheathes them as the resistance from 2 and 9 with 10 showed infinite resistance.

It seems that you're on a path to finding the problem. However, you have me a bit confused, both as to where you're seeing conduction, and the connector you're referring to. As I mentioned in post #9 of this thread, ''E2/B21(gray) are a 20-pin connector pair where pins #18 & #20 are used for the cam sensor''. E2(Engine) mates with B21(Body). B21#18 corresponds to B135#2 (at ECU), and B21#20 to B135#9.

 

- Where you refer to B22, did you mean B21?

- I'm assuming you're disconnecting B21 from E2 (as well as disconnecting the ECU).

- Are you saying that there is conduction (non-infinite resistance) between B135#18 and B135 #20, or that the conduction exists from those pins to ground?

 

It might be important to note that there are two separately connected shields (''sheaths'') for the cam sensor wiring. As you know, the wires for the cam sensor have a shield covering them in the body harness from the ECU to B21, and the shield's connection to ground is made via the ECU (so that when B135 is disconnected, the shield is no longer grounded). In addition, the cam sensor wires in the engine harness from the sensor to E2 (mates to B21) are also shielded, but that shield is directly connected to an engine ground (so pulling the connectors we've been discussing still leaves that shield grounded).

 

Since I'm unsure exactly how to interpret your findings, the following might not apply. Sometimes salt from road deicing finds its way into connectors that are exposed, causing unintentional conduction between pins. That conduction can vary with humidity, etc. The engine connectors (E2/B21 in particular) could be experiencing the problem. I've dealt with such a problem by decoupling the connectors, spraying them thoroughly first with water and then with alcohol to displace the water, and allowing the alcohol to dry before reconnecting.

[rvac99]

- Where you refer to B22, did you mean B21?

- I'm assuming you're disconnecting B21 from E2 (as well as disconnecting the ECU).

- Are you saying that there is conduction (non-infinite resistance) between B135#18 and B135 #20, or that the conduction exists from those pins to ground?

 

Yes I meant B21 the grey connector. I just guessed last night.

Yes, disconnected B135, B21/E2, and E15.

Yes, conduction B135 #2 with ground, B135 and B21 disconnected. No conduction from E15 to E2. No conduction of B135 #10 with B135 #2 and #9 or ground.

[OB99W]

Yes I meant B21 the grey connector. I just guessed last night.

Yes, disconnected B135, B21/E2, and E15.

Yes, conduction B135 #2 with ground, B135 and B21 disconnected. No conduction from E15 to E2. No conduction of B135 #10 with B135 #2 and #9 or ground.

Good, you're closing in on something. With those connectors pulled it obviously isolates the cam sensor wiring in both the engine and body harnesses. Based on what you said, the red wire which connects B135 #2 to B21 #18 is partially shorted to ground somewhere within the body harness. Since that wire is shielded for much of its length, and yet B135 #10 (the shield connection) isn't showing conduction to the other wires, in theory that shouldn't leave much of the length vulnerable.

 

I'd proceed by making a reliable connection from your ohmmeter to the wire with the short and ground. Then try flexing the body harness from B21 to the firewall, and also from the ECU end -- I've found that sometimes it requires pushing, pulling or twisting the wiring to see a change in meter reading that could lead to finding the short. You could also try disconnecting B22 from E3, since several ground wires run through there, and see if the short is affected.

 

By the way, I understand that the measurement is varying, but what range of resistance readings to ground are you seeing?

[rvac99]

Since I have a Cam code I tested the two wires from connector B21 to the ECM connector B135. On B21, #18 and #20 are the cam wires and #18, red, did not have infinite resistance as expected. I tested #18 with all the others and found continuity with many other wires including the ground. It is a high enough resistance that my multimeter does not beep on the continuity setting. The continuity is different between some of the wires and varies from milliohms to K ohms.

Continuity between B21/18 and:

Ground, 5, 9,10,12,13,and 17.

Continuity between B135/2 and:

Ground, 1,5,6,7,11,12,18,19,and 28

During one test with B21 I was getting a fluctuation. The resistance was alternating from infinite to continuity. I wiggled wires and then observed a steady continuity reading. I suspect a short in the wire harness between B21 and the firewall.

Two questions: (1) Do you agree with my test and diagnosis? (2)The braided sheath around B135 #2 is not showing continuity. Is it possible that the short is within but not with the sheath ?

Just read your latest thread OB99W. I’ll disconnect B22 and test further. Rain delay right now.

[OB99W]

[...]The continuity is different between some of the wires and varies from milliohms to K ohms.

Continuity between B21/18 and:

Ground, 5, 9,10,12,13,and 17.

Continuity between B135/2 and:

Ground, 1,5,6,7,11,12,18,19,and 28

While trying to find a short in the body harness, it should be disconnected at both the ECU (B135) end and the engine (B21) end. If those readings were obtained with the harness disconnected in that manner, then something very strange is going on. On the other hand, if the readings were obtained with the harness attached, that will cloud the issue.

 

 

During one test with B21 I was getting a fluctuation. The resistance was alternating from infinite to continuity. I wiggled wires and then observed a steady continuity reading. I suspect a short in the wire harness between B21 and the firewall.

Two questions: (1) Do you agree with my test and diagnosis? (2)The braided sheath around B135 #2 is not showing continuity. Is it possible that the short is within but not with the sheath ?

The shield (''braided sheath'') covers much, but not all of the length of the cam sensor wiring, and has the crank sensor wires within it as well. However, there should not be a ground reference once the body harness is disconnected at the ECU and engine even if those wires shorted to each other within the shield.

 

 

Just read your latest thread OB99W. I’ll disconnect B22 and test further. Rain delay right now.

Okay, but if you haven't been checking for shorts with the body harness disconnected as above, please do so. It does, however, seem that you might eventually have to peel back the body harness covering and do a physical inspection.

[rvac99]

The ECM is totally disconnected. B134, 135, and 136 are disconnected. Both B21 and B22 are disconnected as is every connector I could find that tied into the harness heading into the firewall.

I’ve got resistance values (continuity) even though both ends of the wires are disconnected (listed previously. I can’t seem to find the short. I’ve removed all the covers and every wire looks good.

Here is some data for you. I tested all of B21 with the ground and recorded my observations. Then I used the lowest resistance and checked all the others with that one. Here is what I found.

B21 connectors w/ ground: All values are in Ohms.

5- 4.81 K

9- 163 K

10- 4.86 K

12- 0.2 M

13- 0.7 M

17- 1.6 M

18- 1.8 M

Testing #12 w/ the above:

5- 0.4 M

9- 2.79 K

10- 0.5 M

13- 0.8 M

17- 1.6 M

18- 1.7 M

I don’t have a diagram that shows me B21 in any detail. I can’t find an area where all these wires come into close to each other. Some of these wires run off to fuses and others test connectors which I have not found.

[OB99W]

Here is some data for you. I tested all of B21 with the ground and recorded my observations. Then I used the lowest resistance and checked all the others with that one. Here is what I found.

B21 connectors w/ ground: All values are in Ohms.

5- 4.81 K

9- 163 K

10- 4.86 K

12- 0.2 M

13- 0.7 M

17- 1.6 M

18- 1.8 M

Testing #12 w/ the above:

5- 0.4 M

9- 2.79 K

10- 0.5 M

13- 0.8 M

17- 1.6 M

18- 1.7 M

I don’t have a diagram that shows me B21 in any detail. I can’t find an area where all these wires come into close to each other. Some of these wires run off to fuses and others test connectors which I have not found.

I suspect that you're confusing milliohms (thousandths of ohms) with Megohms (millions of ohms). Even lab grade equipment doesn't readily measure resistance in the milliohm range, and for the purpose of automotive circuit testing it's rare that a measurement below 0.1 ohm (100 milliohms) would be necessary. When dealing with low-voltage/low-impedance circuits, leakage resistance readings over 100 Kohms (0.1 Megohms) usually isn't problematic. Some electrical connectors intentionally have a small amount of conductive material added to the plastic in order to help dissipate static charges, and in others contamination will sometimes cause slight conduction.

 

The low readings on B21 #5 and #10 are explained by the fact that they directly connect to the oil pressure lamp and temp gauge respectively. If we're concerned with the cam sensor wiring, concentrating on B21 #18 and #20 is probably going to be more productive. If you want to check for possible shorts within the shield, B21 #17 and #19 (for the crank sensor) are within that shield along with the cam sensor wiring. Therefore, check the resistance from B21 #17, #18, #19 & #20 to each other (and #19 to ground).

[rvac99]

Just dismantled B21. Mysterious fluid that is electrolytic. Probably antifreeze. Going to clean and then go through the tests you have mentioned.

[OB99W]

Just dismantled B21. Mysterious fluid that is electrolytic. Probably antifreeze. Going to clean and then go through the tests you have mentioned.

It could be what I mentioned in the last paragraph of post #38. (Gee, this thread is getting ''a bit'' long. ) It will often appear to be greenish in color due to reacting with the metal pins of the connector.

[rvac99]

Yes fluid reminded me of your post and I stuck my tester in it and got a reading. I doused the connector a few times with alcohol.

Ok I tested all possible combinations of the four wires and only 17 and 18 have continuity. 8 to 9 M ohms. 10 minutes later the resistance was up to 14 M ohms. 10 minutes later 18 M. Now there is infinite resistance.

I’m guessing that the resistance changed because the alcohol had to fully evaporate. I’m going to go back and check again.

[OB99W]

Ok I tested all possible combinations of the four wires and only 17 and 18 have continuity. 8 to 9 M ohms. 10 minutes later the resistance was up to 14 M ohms. 10 minutes later 18 M. Now there is infinite resistance.

I’m guessing that the resistance changed because the alcohol had to fully evaporate. I’m going to go back and check again.

That's sounding promising. Conduction due to an electrolytic solution will change with the voltage applied, so a modern ohmmeter (which typically applies a rather low voltage) might not reveal the full impact of the contamination. I sometimes use a hair dryer to accelerate the alcohol evaporation. (Heat guns are faster, but if used too ''ambitiously'' can result in melted insulation. )

[rvac99]

Both 17 and 18 no longer have conductivity with the ground or each other. This is huge and so is the thunderstorm that is going to make me wait to find out.

[OB99W]

The weather here has been variable as well, and gambling with lightning's megavolts can have serious health consequences. If you can be patient, tenacious and hopeful, so can I.