Hi Guys,

I know there is another current P0171 thread that was solved - I didn't want to tag to that thread since it was resolved.

I have a 2006 XK8 4.2 with 119k miles. I have never had any major engine issues with the car. The last year I had huge issues with the AC system and the AC system and car was torn down a couple of times by 2 different shops. The AC system was finally resolved in March of this year.

Since March I have put maybe 2k miles on the car and had no issues.

4 weeks ago I am driving and the Check engine light and 'Restricted Performance' Light comes on while driving on the Freeway. After a minute Restricted goes away and I get home no problem.

I get home and check my codes and have the PO171 and PO174. Those are the only codes. I clear them. Over the next few days sometimes when I start the car in the morning for the first minute the car is running the engine is clearly missing and shaking. And then it goes to normal.

I check the codes - Sometimes after the shuddering startup I have mis-fires on 4-7 cylinders. But not always. And the mis-fire start ups don't happen everytime or everyday.

Over the next couple of weeks I get the 171 & 174 randomly. Some long drives (1 hr at 80+) no errors / codes. And sometimes in a drive it might happen twice. I have been driving with the OBD plugged in, and if I clear the codes when they happen - they don't usually occur again during the same drive.

I came to the forum and read a few threads. I found Gus's link (thank you). I went and checked the intake tube - (I replaced it 3-4 years ago). I didn't see anything obvious.

I bought a "newer" OBD - The last mechanic that worked on the AC had a Snap-On tablet that knew everything about my car. But the newer OBD doesn't do much more than the original $30 one.

I went to my mechanic. He plugged in his fancy Snap-On and he only had the 171-174 - There were no mis-fire codes and I hadn't reset the codes in about a week. The mechanic checked the air box, intake tubes, and the connections to the intake tubes and couldn't see anything. He reset the codes and said drive it for a week and bring it back.

This weekend I took off the intake tube - and I closely checked all the connected tubes and could not find any leaks.

Having read the Gus Attachment - There is a long list of items after the intake tube that this could be.

As a smart at home mechanic - How can I deduce which of these:
Engine misfire
Air intake leak between MAFS and throttle
Fuel filter, system blockage
Fuel injector blockage
Fuel pressure regulator failure (low fuel pressure)
Low fuel pump output
HO2S harness wiring condition fault
Exhaust leak (before catalyst)
ECM receiving incorrect signal from one or more of the following components: ECTS, MAFS, IATS, T

Is the culprit? Are there values in the OBD Live data stream that will help me narrow my issue? And because this happens infrequently and only for a moment, will I be able to figure this out before the problem becomes bigger and more constant?


Thanks for the help!!!!

Dave B

 

Check the fuel trims. Long and short term, for each bank. Chances are, your air leaks are making the long term trims hover slightly under 25% (no code zone) until it goes over and a code is thrown. Fuel trims should be in the low single digits.

Other possibility is a bad air flow meter. These can be had cheap on eBay (tons of cars use the same one, Denso 197-6030), so you might want to throw a new one in there anyway. 5 min job to replace.

Best of luck, keep us posted.

 

It could also be the two VVT O-ring seals. They sit there and bake in the engine compartment for a few years, get hard and brittle, and then begin to leak oil and air. My wife's 2006 XK8 began throwing the P0171 and P0174 codes back in February. I tried a new Denso 197-6030 MAF sensor but that was not the culprit. A smoke test eventually revealed leaking VVT O-ring seals. They both were replaced with new ones and the problem was solved. This is the third set of VVT O-ring seals that I know of for this car (my wife's daily driver). If your XK8 is your daily driver, plan on replacing them every three or four years if not sooner....

 

+1 on the VVT solenoid seals. A good indication they need to be replaced is when they appear to be damp with oil.

DTCs are P0171 and P0174, both caused by air leaks. Have a smoke test performed on the system to locate the source of the leaks. Much less expensive than replacing parts.

 

I've been chasing an as yet unresolved but similar issue with my '99 XK8 with a sporadic 171 being thrown. Frustrating as hell but since I drive this car somewhat sparingly and I don't focus enough attention on it still eludes me.

I won't repeat the litany of things I've tried but will offer this point of view. Think about the specific codes themselves and ask the question "what could be causing a symmetrical problem (i.e. both sides at the same time) versus what would cause an asymmetrical but similar problem".

In my case it is always just the right side which would indicate that anything that should effect both sides isn't the likely cause...low fuel pressure, failing fuel pump, air leak BEFORE the throttle body, etc. should effect BOTH sides....as in your case

In your case it's consistently been both sides so while it could happen that BOTH VVT seals have gone bad at exactly the same time how likely is that.


As fmertz consistently points out in similar threads getting a good look at the fuel trims under the appropriate driving conditions and engine temps specified in the svc. manuals will give you a major clue as to where the problem lies and save you a lot of time and wasted money just throwing parts at it.

Also what exactly was done to cure your major A/C problems as mine started shortly after a tensioner/cam chain upgrade from my first gen. tensioners which meant that a lot of stuff got disconnected (I also had to replace one valve which meant a cyl. head removal & all that goes with it). It's possible that your A/C repair led to your current problem so trace back to what was done then and what they may have "disturbed".

After 30 years in the business from sales to ownership I hate to admit that way too many "technicians" are pretty ham handed in their approach to repairs and it's considerably more apparent when they have little experience with the make and model of car they're working on.

 

Hi Guys,

Following the advice hear and along with a couple of Jag Maintenance bulletins I ordered some MAF Cleaner, a New MAF, and a Pair of VVT Seals.

This morning I went out and before doing anything had the following codes/data
PO171, PO174, 0300, 1316 -- The 1316 is an injector code and I have never seen it before
ShrtFT1 - .8 to -1.6 occasionally jump to -3.9
ShrtFT2 - .8 then 3.1 - stable
LongFT1 - 7.1
LongFt2 - 2.3
FRP 55
MAP 5.8
MAF .01

---------------------- I removed the VVT gaskets. They were rock hard. When I removed the electrical clip to the VVT on the Right side of the engine (next to intake box) there was oil inside the connector. I sprayed it out with Contact cleaner several times before replaced the connector. I also removed the MAF and cleaned it with the MAF cleaner.

I started the car and

ShrtFT1 - 2.3 to 3.9
ShrtFT2 - .8 stable
LongFT1 - 7.8
LongFt2 - 3.1

I let the car warm up to operating temp in the drive way at the values were

ShrtFT1 - 0 to .8 -- with occasional bounce to 1.6
ShrtFT2 - .8 random bounce to 3.9
LongFT1 - 7.8
LongFt2 - 3.1

Outside temp was 80 deg F

-------------------------------------

5 Mins of Hard Driving

ShrtFT1 - -3.9
ShrtFT2 - -3.9
LongFT1 - 7.8
LongFt2 - 3.1

---------------------

Let Idle for 2 mins

ShrtFT1 - 3.1
ShrtFT2 - 4.7
LongFT1 - 7.8
LongFt2 - 3.1

------------------------

20 Mins of Hard Driving

ShrtFT1 - 3.1
ShrtFT2 - 3.1 to 3.9
LongFT1 - 7.8
LongFt2 - 7.3

----------------------------------

Pull into driveway - Check codes - Now have a P010 Cam Shaft Position Actuator - This code was listed as 'Pending'

After letting car idle in driveway for a few minutes

ShrtFT1 - 0 to .8
ShrtFT2 - -1.6 most of time - occassional -2.3
LongFT1 - 7.8
LongFt2 - 2.3


*******************************

I'm guessing the oil in the VVT connector is a bad thing.... Order one or 2 of those?

And does that explain the other numbers or is there still something off ?

Thanks Guys.

Dave B

 

Those are reasonable numbers, looking for zero is obsessive.

 

I agree that the STFT and LTFT look to be pretty good since the computers is always going to be adjusting them to account for all the variables in air temp, load, etc.

Did the other codes clear or are they still present?

The P0010 is in the '99 XK8 manual the right hand variable camshaft timing oil control solenoid circuit and not the cam position sensor.

The svc. manual for a '99 directs you to page 1534 in the downloadable PDF version under the heading:


Electronic Engine Controls - 303-14

AH : DTC P0010, P1384; RIGHT-HAND VARIABLE CAMSHAFT TIMING (VCT) OIL CONTROL SOLENOID CIRCUIT OPEN/SHORT CIRCUIT


AH1 : CHECK ECM TO VCT SOLENOID VALVE + CIRCUIT FOR HIGH RESISTANCE

1. Disconnect the battery negative terminal.


2. Disconnect the VCT electrical connector, PI31.


3. Disconnect the ECM electrical connector, EM81.


4. Measure the resistance between PI31, pin 01 (OY) and EM81, pin 01 (OY).




Is the resistance greater than 5 ohms?

-> Yes



REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the DTC. TEST the system for normal operation.




-> No


Goto <<AH2>>

AH2 : CHECK ECM TO VCT SOLENOID VALVE + CIRCUIT FOR SHORT TO HIGH VOLTAGE



1. Reconnect the battery negative terminal.




2. Turn the ignition switch to the ON position.




3. Measure the voltage between PI31, pin 01 (OY) and GROUND.


Is the voltage greater than 3 volts?

-> Yes



REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTC. TEST the system for normal operation.




-> No


Goto <<AH3>>

AH3 : CHECK ECM TO VCT SOLENOID VALVE + CIRCUIT FOR SHORT TO GROUND



1. Turn the ignition switch to the OFF position.


2. Measure the resistance between PI31, pin 01 (OY) and GROUND.




Is the resistance less than 10,000 ohms?

-> Yes



REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTC. TEST the system for normal operation.


-> No


Goto <<AH4>>

AH4 : CHECK ECM TO VCT SOLENOID VALVE - CIRCUIT FOR HIGH RESISTANCE

1. Disconnect the battery negative terminal.


2. Measure the resistance between PI31, pin 02 (RY) and EM81, pin 02 (RY).




Is the resistance greater than 5 ohms?

-> Yes



REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the DTC. TEST the system for normal operation.


-> No


Goto <<AH5>>

AH5 : CHECK ECM TO VCT SOLENOID VALVE - CIRCUIT FOR SHORT TO HIGH VOLTAGE



1. Reconnect the battery negative terminal.


2. Turn the ignition switch to the ON position.


3. Measure the voltage between PI31, pin 02 (RY) and GROUND.



Is the voltage greater than 3 volts?


-> Yes



REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTC. TEST the system for normal operation.


-> No INSTALL a new VCT solenoid. CLEAR the DTC. TEST the system for normal operation.


************************************************** ************************************************


Is there anything you did in replacing the VVT seals or other work you did that could even remotely have affected the VCT solenoid or its circuit since I can't imagine it decided to fail at this particular moment. Check back through what you did to see if it's possible.


It would help if you put your year and model in your signature line for those of us who may not know or who may not have picked up the thread from the very beginning.

 

So, did you actually replace the air flow meter, or just clean the old one?

What part number did you get? I believe you need a Denso 197-6030.

Negative fuel trims indicate you are running too rich...

 

Hi Guys,

I thought my car info was in my signature. I have an 06 Xk8 Victory Edition Copper Black Convertible. 119k miles.

This morning the cold start was a rough idle for 30 seconds. Driving 10min got check engine light. Only one pending code for cam position sensor. Cleared it but it immediately reappeared as a pending code.

Dave B

 

On the jags I've met P1316 is a (severe) misfire-related code. Nothing to do with injectors.

Be sure to look codes up in the appropriate jag data. Do not use non-jag data, especially for codes starting P1.

 

Have you checked your fuel pressure?

Use this for your codes Link http://jagrepair.com/DTCforms/X103_P_DTC_OBDII_R1.pdf

 

In your earlier post you wrote that the only code you had was P0010 which isn't a cam position sensor but rather one of the controlling solenoids. If it was a cam position sensor the code should be a P1340 series I think as I don't think the numbering series is that different between a 4.0 and a 4.2

 

I went yesterday (Weds) the car sat. This morning i checked everything under the hood. The right side vvt,.which was leaking oil, the connector plug had come off. A previois mechanic had snapped the lock clip and used some goop to hold it.

I used some wire ties and locked the connection. I just drove the car 25 miles at 75+. Car drove well, no lights on dash. When i pulled over I have p0171 and p0174 codes pending. Nothing else.

Gus, the Fuel pressure is 66.1 at idle.
shrtft 1 is 2.3
shrtft 2 is 0
long ft1 id 5.5
long ft is 0

Checked the connection on the right side vvt... oil in it again (electrical connection)

Dave B

 

Hi Guys,

The 171 and 174 codes went from pending to stored and I got a check engine light - But no Limited Performane message.


Is the next step to replace the VVT with the oil in the connector? Should I replace both?

Thanks

Dave

 

Replace both VVT seals and clean the connectors.

P0171 and P0174 do also appear at times with exhaust leaks. May be unlikely, but good to also check.

Have you checked the area around the throttle body to manifold gasket and the air pipe bellows between the air flow meter and throttle body for cracks?

 

NBcat -

I replaced both VVT seals last week. That is when I found the oil in the right side electrical connector to the right side VVT. I cleaned that out and then after a couple of drives there was oil in the connector again.

I did check all the bellows and the intake connection points and did not see any issues.

Dave B

 

Seems like oil is seeping out from within the actuator, through to the electrical connector. Probably boils down to a blown o-ring, but I am not sure if those can readily be repaired. A quick look on eBay, and these seems to have been used on a ton of Jaguar models, and are not terribly expensive. Looks like these are held by just one bolt, so the valve cover would have to come off.

Replacing the VVT actuator seems like the next logical step. The ECU can tell if these actuators fail when they do not actually perform a change in the valve timing as per the cam position sensor. You had a cam sensor code at some point, so there is some logic to this path.

For the fuel trims, remember these have to be understood as a 3D elevation map, with the Load and RPM as the other coordinates. In other words, you have only shown the "elevation" at idle. These codes are triggered by much larger trims somewhere else on the map (higher rpm and/or higher load). Some of the nastier leaks come from high load that torque the engine on its mounts and open cracks that are otherwise closed off at idle. FWIW, TorquePro has some data recording function. You might want to keep a session going while you drive through the rpm and load map, and keep your eyes on the road. The recording can then later be looked at for the problem area.

Best of luck, keep us posted.