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Hello,
so recently while I was driving, during kick down I heard a muffled crack/bang and smelled bakelite in the interior . After I released the gas pedal the car went in restricted performance mode and after shutting the car off and taking the key out the cooling fan continued working even when the engine was at 90°c.
I used my OBD to read the codes and got a code for the fuel tank ventilation valve. I check the valve and all was good. After puting it back on the car the code went away but I got a new code P0335 for crankshaft sensor. Got the sensor out and it was cracked. Replaced it but it was all the same. Same code same restricted performance mode. Checked the wheel on the crankshaft from which the sensor reads but it was all fine.
The last thing that was checked today was what the crankshaft sensor and the camshaft sensors read but the interesting thing was that when the engine is running the sensors switch on and off non-stop.
The engine has ruff idle in restricted performance but when you clear all codes it starts running smooth. If you touch the gas pedal the car enters restricted performance again immediately.
Now Im in a dilemma is the timing chain skipped a tooth or the ECU got cooked.
Anyone knows how to check the ECU or the timing chain without taking the engine out?
Gotcha. You had mentioned codes so I thought there was more than one.
I take it this is a new problem out of the blue, and the engine had recently been running okay with the old sensor until recently? If so, I'd suggest removing the new one and comparing the physical dimensions with the old one.
Next, I'd check the installed gap. I think you can put a little blob of non-hardening putty (Play-Doh comes to mind) on the end of the sensor and install it. Put a thin layer of light oil on the putty so it doesn't stick to the target. Then remove the sensor (with putty) and measure the thickness. Compare that to specs for the gap.
If all good, I'd want to check continuity on the wiring, measured from the ECM connector.
Gotcha. You had mentioned codes so I thought there was more than one.
I take it this is a new problem out of the blue, and the engine had recently been running okay with the old sensor until recently? If so, I'd suggest removing the new one and comparing the physical dimensions with the old one.
Next, I'd check the installed gap. I think you can put a little blob of non-hardening putty (Play-Doh comes to mind) on the end of the sensor and install it. Put a thin layer of light oil on the putty so it doesn't stick to the target. Then remove the sensor (with putty) and measure the thickness. Compare that to specs for the gap.
If all good, I'd want to check continuity on the wiring, measured from the ECM connector.
Interesting. Didn't know that the same sensor (fitting the same car) can have different length. Sounds dangerous if it hits the wheel that it reads on. But again that does not explain the pop that I heard and the smell of burned electronics. Tomorrow Im gonna take out the Engine computer that's behind the glovebox and inspect it visually. If it indeed popped and something inside burned enough to smell like that I think there will be visual signs of that. If I have time I will get the old sensor and the new one out and compare them one to the other.
Im open to hints of what pins I need to check on the connectors to see if there is continuity in the wires from the sensor to the ECM.
Interesting. Didn't know that the same sensor (fitting the same car) can have different length...
If the sensors are indeed different, it's not by design. More like an oversight by QC at the Fling Dung factory in China.
Most likely you will find them the same. Just something quick to rule out.
FWIW, I encountered a problem with the fit of the water pump on my '02 V6. Apparently there was a change in design partway through the production run. Per their listings, my local parts store sold me the wrong one. Upon further research, I found approximately 80% of all vendors had the wrong style listed as applicable.
So I did get to the ECM but it seems that there is special screw that they used. And I cant get it out to inspect.
The other thing that I saw was the connector is one big one and on videos ppl show two connectors. I have read that on '99-'02 models you cant change the ECM but after that you can. Is it possible that my car being '03 has the old ECM.
Interesting thing happened. While I was writing this my dad tried to unscrew this bolt with a flat head and the cooling fan started to spin fast and slow while the key was in my pocket. When I tried to put the key and turn to ignition the fan went to max speed. I know that it was stupid to not unplug the battery first but I dont have a lot of time and rushed things out.
Check the MY from your VIN (10th character) but sounds almost for sure 2003.
Picture under the text.
So after inspecting the ECM circuit there is no sign of something wrong.
Another thing that I saw was when the car is in restricted performance mode the Timing advance is -7° at idle. If I clear all codes it becomes +7° at idle. I dont know if this leads to possible timing chain problem.
I will upload a pic with the codes. The first 3 codes were there before the problem and the car was running fine. I just never got to resolving them cause of other problems...
The PDF says each of the possible causes for each of the codes and is a huge help.
The thing is that the car ran fine for a year and a half with P1646 & P1647, they are old. And the car also has LPG that the mechanics didn't manage to connect to the ECM and it is on its own tune. The car runs bad and spits out the crank code on both fuels/computers. So I don't think all of a sudden the filing became a problem. And that does not explain the pop, smell just before the car went in restricted performance. Does not explain the cam and crank sensors switching on/off non-stop while the engine is running. So something happened that day, and it's not related to the codes that were present long before that.
I read a thread in another Jag Forum about an S-type 3.0 owner that experienced the same symptoms as mine and in his case it was the ECM but it had an obvious burn mark on it. Mine looks ok. But that's only looking at it. I'm not great at car electronics so I don't know how to test it.
Yes all the PCM's I have dealt with use security type fasteners. It's kind of silly really as anyone can buy the bits and they are cheap!
Your picture shows what's called a Pentalobe or Torx or sometimes called a Torx Plus security screw.
Yes all the PCM's I have dealt with use security type fasteners. It's kind of silly really as anyone can buy the bits and they are cheap!
Your picture shows what's called a Pentalobe or Torx or sometimes called a Torx Plus security screw.
All over and around $10 or so for a set.
.
.
.
Or just use a small flat head screwdriver. Works good 😄
For a CKP circuit malfunction, the chart says CMP Sensor 1 signal is used for synchronization. If the CKP sensor circuit was cutting in and out, for reasons still unknown, you might see CMP 1 intermittently becoming the master signal. Not quite the switching on/off you mentioned, but it may be similar.
Originally Posted by Venko007
I read a thread in another Jag Forum about an S-type 3.0 owner that experienced the same symptoms as mine and in his case it was the ECM but it had an obvious burn mark on it. Mine looks ok...
Can you please post a link to that thread? I'd like to see the damage on the circuit board. A picture of the area on your board would be very helpful for comparison. No promises, but we might be able to tell you to check for X resistance between two points on the board, or something like that.
For a CKP circuit malfunction, the chart says CMP Sensor 1 signal is used for synchronization. If the CKP sensor circuit was cutting in and out, for reasons still unknown, you might see CMP 1 intermittently becoming the master signal. Not quite the switching on/off you mentioned, but it may be similar.
Can you please post a link to that thread? I'd like to see the damage on the circuit board. A picture of the area on your board would be very helpful for comparison. No promises, but we might be able to tell you to check for X resistance between two points on the board, or something like that.
Right off the bat, I was quite surprised to see a through hole circuit board instead of surface mount. The latter seems to be more prevalent these days. Hard to say for sure, but the overheating damage seems to come from one of the soldered connections, not the actual component on the other side of the board. Wish I could see the other side to be sure. If the component itself had overheated, I'd expect to see two leads equally burned, but it only looks like one.
But if the connection is what failed, it's most likely due to a cold solder joint. That's when a soldered joint doesn't quite reach the required temperature during manufacture, or the two pieces moved while cooling. The end result is a solder joint with a dull, grainy appearance that is prone to cracking. A good solder joint will have a smooth, shiny appearance. Most likely that board was soldered robotically. If so, and the joint had failed, it's also likely other boards from that same production run will have the same potential fault in the same area. The only difference is yours did not overheat when it failed, and only shut off the circuit. Since you already have the module removed, I'd carefully inspect the solder joints in that area, using a magnifying glass. If you were to find a cold solder joint, you may be able to repair it by resoldering the joint.
Back to my theory on a production problem, here's an excellent thread on a failed solder joint on the instrument cluster for a '99-02 model. I had the exact symptoms as the original poster. I removed the cluster and went straight to the one suspect area. Sure enough, the solder joint had cracked. I reflowed the solder and it has been fine ever since:
S-Type 3.0 ECU or Timing Chain problem
