Hi i'm newb to the forum and also jaguars, however i have a good knowledge and understanding of the mechanical side but not too sure on electrics. I have recently purchased a 2003 2.1 V6 X-Type, I was driving home last night and suddenly losing power intermittently noticing lumpy noises. I got the EML so plugged my reader in and give me a p1638, I have been trying to figure the problem out reading similar posts but not had much joy. I have noticed a strange red wire running from the 4 pin connection on the alternator to a 10A fuse in the passenger compartment. I have put my tester on the case of the alternator to neg battery terminal and got a reading of 0.02V then tested the battery and got a reading of 14.14V (whilst heater, lights..etc were on). Then disconnected the 'strange red wire' then re-tested again.. i got a reading of 0.00V from alternator and battery reading was dropping rapidly. I would appreciate it if somebody could help me out please, thank you.

 

 

https://www.jaguarforums.com/forum/x...e-p1638-51992/

 

Sinko,

With my 2005 X-Type I’ve had a similar problem to what you’ve described “I was driving home last night and suddenly losing power intermittently.”

I’ve only recently received the P1638 code; I was usually receiving misfire codes, but the symptoms are always the same. I’m cruising down the highway and typically above 3,000 RPM the engine power suddenly dies with a thud. I can drive an hour or two with never a problem. Other times it can repeat three times in 15 minutes. Once the power stops, I can push the clutch in (I have a 5-speed manual) and coast for a minute and power resumes when I release the clutch and hit the gas. Last week when the problem kept returning, when I downshifted to 4th I had no power, but back to 5th gear and I was OK. Perhaps RPM related. I have an electrical gauge and I noticed perhaps a slightly high voltage at occurrence (13.5v), whilst normal is more like 12.4v. That may have been due to higher RPMs.

After battling this intermittent issue on and off for nearly a year I can find no pattern (for months I stopped driving the car). It happens at night, it happens in day. It usually happens after driving awhile (more than an hour) or after resuming driving after driving awhile, but has once happened as I leave my driveway in the morning. It can be warm or it can be cool (I live in California, so it’s never very cold). It's happened under cruise control driving.

Never any issues with dash gauges or flickering lights or the sort. Really no other symptoms, other than loss of engine power. Feels like fuel or electrical.

I recently had an almost identical occurrence when driving my PT Cruiser and I received an ODB code for the crankshaft positon sensor. Replacing it fixed the PT Cruiser easily. I thought aha, that’s the Jag problem. I replaced the crankshaft sensors for both banks of the 2.5L engine and two driving trips later the same damn problem repeated itself. VERY FRUSTRATED!

Here are the various codes I’ve received over the past year for the same problem.

P1314 Misfire Rate Catalyst Damage Fault - Bank 2
Concern with ignition system and wiring harness on bank 2

P1313 Misfire Rate Catalyst Damage Fault - Bank 1
Concern with ignition system and wiring harness on bank 1

P0300, P0302, P0305
Random misfire detected. Misfire at cylinders 1 to 6

P1638.
Concern with CAN network. CAN network modules and circuits.

P1000 System check not complete since last memory clear.
OBD errors not cleared by diagnosis.
Carry out comprehensive component monitor drive cycle.

P0171 (Bank 1), P0174 (bank 2),
Concern with fuel system too lean/rich. Fuel injector(s). Fuel delivery fault.

 

Fix it!!

Don't ever ignore misfire (or other) codes.

 

Easier said than done.

 

Lots of people fix them. No reason why your car can't be fixed too.

 

That's what I keep telling myself. Two professional mechanics, lots of my own time and perhaps a dozen parts, still no resolution.

A new development is that I've realized than when the problem occurs, if I drop the RPMs to below 3000, the engine operates fine.

The problem seems to occur between 3K and 4K RPM, although I can often drive for long periods of time above 3K RPM with no incident. At 3K RPM I'm driving about 70 MPH in 5th gear.