Buying a cheap Android device rather than throwing parts at it is a no-brainer.

OBD saves $$$ if you use it.

 

Many thanks for the comments and advice.

For those who advocate getting the OBD, please note that I have tried a couple with different apps before, and I don't trust the cheap clones abundantly available across the border, while others have to be acquired overseas and it takes time for purchases to arrive. Delivery from UK typically takes 3-7 days; 10 to 14 days from rest of the world. There is a long thread about OBD scanners in this forum and I hope to get the most reliable tools. I believe this has to be a hardware AND software/apps issue. My goal is to find one that would cater for my 1995 and 2005 Jaguars. The 1995 Jag is a pain; very few readers go as far back as 1995.

In fact, I had OBD readers ELM327 and iCarsoft i930 before but both failed to read my two Jaguars (1995 XJR6 and 2005 X350 3.0 V6). Thought it was the free apps so switched to paid apps DashCommand but the ELM327 when plugged into car flagged all dash warning lights and stopped car from starting (can't read any live data if engine is not running).

I have visited two local workshops to let them diagnose the problem. Both have professional-level diagnostic scanners: Autoland and Autologic. Both scanners detected the fuel too lean/rich codes and helped me turned off the ECL during three visits. The workshop that has the Autologic scanner claimed Autologic cannot read live data - pity that this workshop does not know how to use the tool - so I walked away. The one with the Autoland scanner never works with Jaguar; I just borrowed his scanner. It is probably not original as the interface is all in Chinese. The joint wisdom of both workshops is to try replace the MAF sensor (done, but problem unresolved) and then the fuel filter (replaced, the outgoing filter was indeed dirty yet problem remain unresolved).

So all effort now go to the finding the right tools first. Sigh... The last thing I wish to see is I ended up with a tools that tell me no more than the last two workshops, but I hope at least the scanners do provide live data to help the human brain to track down on the prime suspect for the fuel too lean/rich saga.

 

While current attention shifts to the tools, I still wish to make a best guess on the causes of the problem.

Symptoms recap: The ECL has been on for a few weeks now. When the "Restricted Performance" warning is hoisted, the engine would hesitate on brisk acceleration, but otherwise drives like normal. Freeway cruising is fine, and it is often times when the RP message disappears and car drives like never has any problem (ECL still on though). The DTCs seen so far using the ELM 327 are just confined to "fuel too lean/rich" - which came on and went away a few times during each journey, with no codes but almost shaking engine on cold start- no other codes have shown up.

So it is not the MAF sensor, not the fuel filter; it could be one or more or all of the sensors; it could be the fuel pressure regulator, air system leak, exhaust, and others.... My another wild guess is the spark plugs and/or the car battery, as they are three years old and Jaguar equipment is widely known to be very sensitive. My car fires up first time on every occasion but I noticed that one day on cold start (first start of the day) the brightness of the cabin light varied with the engine shaking idle.

 

The ELM 327 should be thought of as a bridge that allows the onboard OBD II port to communicate with the standard RS232 serial devices used by computers and smart devices since they can not read the OBD data without it.

If, as in the cheap Chinese iterations, the chip manufactured and programed with the ELM327 functionality is poorly made or implemented either through sloppy manufacturing or the use of discarded substandard chips buyers get a useless poor performing unit at best or the real possibility of damaging the programing of the car they're working on.

Since these chips are mass produced and what you're really buying is the cable and the visual interface that displays on your screen, which are also somewhat cookie cutter, the difference between the generally available and good quality $30-40 unit and the higher dollar ones is a matter of just how many more bells and whistles are included in the software accompanying the cable itself. At a price much lower than $30 you begin to edge into dicey territory as far as functionality and build quality so buyer beware. After all what have you "saved" if your $15 find doesn't work and you end up paying $30 for a working unit anyway?

For most of us DIY'rs the 'extras' are of little value since all we really need are the universally available codes required by law and you're not going to get the much larger database of Jaguar proprietary codes without buying one of the versions of SDD from any vendor at any price so why pay for things you'd only use if diagnostics was a part of your business plan.

While some have had good luck with apps designed for their 'smart phones' and the use of blue tooth communications others have not faired as well. I believe that's due to the variety of smart device programs in general use, from the proprietary Apple I-Phone software to the various iterations of the Android's Ice Cream floating around, and the ability of the sometimes suspect programmer's to write a stable program that will operate in a variety of environments which is further complicated with the Blue Tooth implementation of wireless. That's why I prefer to use a suitable laptop or Netbook with a hardwire connection to the USB port. Both minimize the variables involved. Maybe not as cool or even a little "old school" but more reliable. Just my two cents.

By the way, according to British Diagnostics the reason for the need of a Mongoose cable is that the internal wiring is somewhat different from a standard OBD II cable and the two cables are not interchangeable . If you want to use a version of SDD you need a Mongoose and if all you need is the base OBDII data you need a standard OBD II cable.

The OBD 'standards' weren't introduced until the 1996 model year and the previous set was then referred to as OBD I although they weren't really a standard and were implemented differently by different manufacturers. Only in California was there a mandated "standard" across the board so it would be possible to own a pre-1996 model that could not have its data read correctly by any of the currently available OBD scanners due to that non-standard implementation.

That may well be a problem for non-U.S. owners of cars never intended for export to the U.S.

 

Stumbled across this YouTUbe video on a similar diagnostic for lean codes with rich codes. Good watch to see what PCM data is necessary to make a diagnosis. Any cheap-ish OBD data stream reader can show you LT, ST, and O2 voltage values just not side-by-side as in the $10k scan tool.

To summarize the video above, the lean codes were caused by an intake vacuum leak, while the rich code was caused by an intermittently dead upstream O2 sensor. So it's possible you have that combination, or simply a bad O2 sensor(s) that are failing intermittently.

 

Many thanks for the video and the tip-off. I have ordered an OBD scanner and will see how live data from it can help me with tracing the real problem. For now, what I noticed is the lean/rich codes normally emerge at low rpm, and disappear during highway cruising and re-appear during slow traffic or coming to or leaving a parking lot, and all codes involve BOTH banks, which is intriguing.

A local Jaguar workshop said it would be a pain to identify vacuum leak, as it has to remove many covers above and around the engine block, in which case it would be opportune to replace the spark plugs. Somehow, I also believe that the spark plugs are long overdue for replacement and might be an attributing factor to the fuel lean/rich codes. It could be the injectors as well, but the use of a can of injector cleaner did not seem to be of much help. So, I think I can wait a bit longer until my OBD scanner arrives, as the engine is working fine - just the engine light and intermittent dash "Restricted Performance" warnings that are irritating.

 

Find a new Jaguar shop. Nothing irks me more than "professional" shops who give misinformation.

1. You don't remove anything to check for vacuum leaks. You use a smoke machine, brake cleaner, water, or half a dozen other methods.

2. Spark plugs are a 30 minute job and require removing nothing except the vanity cover.

3. Unless you have a misfire, plugs are not contributing to your issue.

Agree with waiting to get the correct diagnostic tool to fix the problem correctly. Unless your CEL starts flashing, you won't be hurting anything to continue driving.

 

Agreed. Decided long time ago to walk away from this workshop. It does not even know how to use the Autologic Bluebox to conduct O2 and TPS adaptation procedures for my XJR6. Jaguar owners in Hong Kong can only practice limited DIY as we rarely have the space, tools and knowledge to do so, and I have learned to find my own diagnostic tools and source my own parts, and find a trustworthy mechanic to confer on what I wish done and share with him all pertinent advice I picked up from this Forum.

 

Your symptoms are ones I also experience on my '99 XK8 although only on one bank and I'm plugging along trying one thing at a time. In your case with codes for both banks your problem isn't likely to be limited to one injector or one plug so think along line of what could possibly effect BOTH sides at the same time. Not likely to be a fuel pressure problem as it disappears once you get rolling.

When you get the OBD reader look for any misfire codes In the P300-P308 which report random misfires and point to specific plugs when it can. You'll also look for any codes referencing the various upstream and downstream O2 sensors that might be going bad and giving false readings of the exhaust gases....not likely to be simultaneously failing on both sides....but the Titanic was unsinkable wasn't it?<G>

If you haven't done so yet download the list of DTC's for your year and model and start getting familiar with them even if you depend upon a tech to do the actual work as art least you'll know if he's blowing his own version of "smoke" .

As for your Jag "tech" saying it's a pain to track down air leaks, he's right and also a bit wrong. He could run a smoke test that forces a tracer into the intake system under pressure and looks for where it leaks out.....then you have a better idea of where the leak may be and what parts need to be removed without blindly searching. It's similar to putting at tracer dye into a leaky A/C system.

 

Here is an update. Engine light and amber warnings of "Restricted Performance" continue intermittently. On first start of the day, engine RPM is low and unsteady and the cabin light flickers with the shivering engine revolution. Seems to suffer from suffocation or interrupted fuel supply, but no code or light at this stage, step on the gas to keep engine slightly above 1000 rpm and all is well within a minute. Once warmed up, and when car comes to a flat spot after rolling downhill, the engine then hesitates and misfires - car shows no reaction to the gas pedal and is inclined to stall. The engine light and RP warning then emerge. This would last for about one minute and the RP warning just go away and all return to normal except the engine light remains lit. Highway cruising is fine and the engine light may go away automatically.

Found a diagnostic cable (OBDLink SX) which returned the following codes
P0171 Bank 1 Fuel too lean
P0172 Bank 2 Fuel too rich
P0174 Bank 1 Fuel too lean
P0175 Bank 2 Fuel too rich
P1638 Instrument to ECM , CAN (control area network) short circuit failure
P1642 CAN Circuit Malfunction

There were no other codes. Turned all DTCs off and all is well until the symptoms return, vanish and re-appear. Scanned and re-set again and two Codes P0172 and P0175 re-emerge (Banks 1 & 2 Fuel too Rich), and then go away after some highway cruising. My mechanic checked one of the spark plugs and found it brownish (fuel too rich) and due for replacement. It is a Motorcraft plug probably the same one from Day 1 (mileage is now 99000 km).

Until I have more sophisticated scanner, I would try to identify the possible culprit by reasoning eliminating other possible factors, for example, it is not vacuum leak or else the warning lights would have stayed on constantly. It is also not the fuel filter, the MAF sensor, or the injectors. The remaining suspects are
air filter
engine temperature sensor
fuel pressure regulator.
My inclination is the fuel pressure regulator which explains symptom coming up during cold start, rolling down hill or rolling dead slow.

I also suspect that the in-car OBD connector might be faulty, as the scanner is unable to show more codes, nor does it able to show whether indeed there was engine misfire and if so at which cylinder. Any thoughts?

 

Thoughts based on your post.


At 99K your plugs are probably toast as 100K is pretty much the limit on top quality plugs.

P0171 and P0174 are lean codes for left and right sides respectively but the codes you posted are conflicting. You posted P0171& P0174 as both being lean on bank 1 and P01712 and P0175 as both being rich on bank 2 so I'm not sure what your getting.

The code that jumps out, however, is the P1634. The service manual only makes one entry for that particular code and the entry makes sense out of the jumble that the other codes indicate. Your ECM is failing. Same comment is made for the P1656 code.

You can throw a lot of parts at the plugs, injectors, filters, etc., but it sure looks as if the root cause is you Engine Control Module and Jag doesn't show a fix for that other than replacing with a new or rebuilt one.

 

My Post #1 already pointed out that the fuel too lean/rich codes are conflicting. Question is, given the other symptoms and pattern of disorder I discovered more lately, and IF the ECU is not faulty, which part is more likely the source of the problem. Anyway, I would replace the spark plugs to see if there is any significant improvement. Hopefully the human brain can help complete the picture not fully completed by OBD scanners.

 

Of course codes can sometimes lead to several conclusions but that particular code has only one source and it's a failing ECM which would certainly lead to a variety of conflicting codes of the type you're experiencing as it tried to sort out signals it is having a problem interpreting. I can't recall off hand if the SDD software has a section that addresses reconfiguring/reprograming an ECM on the off chance it's strictly a software problem but another member might be of help.

 

Qvhk.....scratch that previous post. I don't know where I latched onto that code # but I screwed it up big time<G>


Your P1638 code does point to an ECM failure but it's also possibly one of the following.


CAN open circuit fault - IC to ECM


CAN short circuit fault


IC failure


ECM failure

All of which point to an electrical problem and if that's the case and it does involve the ECM then all the other problems almost certainly come from that source.

 

The Motorcraft plugs have not been in since new. It was never oem or iridium. It's not the cause of you problems, but isn't helping either. When you replace the plugs, go with the correct plug. NGK Iridium.

 

Mark,

Note that Qvhk's car has the 3.0L V6 engine based on the Ford Duratec. Per the X350 Workshop Manual the OE plugs were Motorcraft AWSF22FS. Jaguar now supplies NGK TR6AP-13E as replacements, but Motorcrafts were definitely the OE plugs, and the Motorcraft AGSF22FSMs in Qvhk's engine may have been Jaguar's recommendation at the time they were installed. See our conversation on this topic in this thread:

https://www.jaguarforums.com/forum/x...3-0-v6-182012/

Cheers,

Don

 

RDMinor, Codes P1638 and P1642 only appeared once since the "Restricted Performance" saga started. I cleared all codes the day before and drove the car whole day. Everything normal, no lights, no hesitation or anything, until end of day when parked for 30 minutes, restarted the car and slowly rolling out of a parking lot. The engine light and RP message lit up on dash. This was exactly the same situation when the RP warning ever emerged the first time almost two months ago, i.e. when the engine was still warm and only slightly under operation temperature.

Other symptoms are
(a) shaking idle at first start of the day, but no dash warning when this occurs. Ambient temperature is 26 degree C., not cool or cold by any standard.
(b) engine hesitated after rolling downhill and slowing for the traffic light;
(c) most of the time when the RP warning is on, it has no effect on normal driving, only in rare occasions that when I need brisk acceleration would engine hesitated;
(d) the RP warning would cancel by itself after normal driving for 5 minutes; sometimes even the CEL disappeared at the same time.

I imagine that if it were the ECU playing up, it should attack anytime, not following a pattern. I was expecting other codes relating to O2 sensors, Catalyst Converters, engine temperature sensor, MAF, or anything that would affect the fuel-air mixture.

I know the scanner and DTC codes would be of help, but these observations have only brought me thus far. So it could be the ECU, or any of the sensors that feed the ECU with data. I do not want to proceed with repair by guess work, but I believe the symptoms so far could help us diagnose the problem by logical thinking. Unfortunately, I have not seen any other “Restricted Performance” threads that are of help to my case.

 

Qvhk,

You've got multiple threads going and I can't recall all the things you've done, but a few questions come to mind:

1. Have you cleaned the ECM electrical connector? To separate the connector you need a special 5-lobe tamper-proof Torx bit with a hole in the center of the bit to accommodate a pin in the recess of the head of the screw that secures the connector to the ECM. A common issue is water pooling around the connector due to leaves and seeds clogging the drain in that area below the cabin air microfilter housing (engine bay side of the firewall).

2. Have you cleaned the ground points used by the ECM? They are identified in the Electrical Guide. Use a small brass-bristle wire brush and zero-residue electrical contact cleaner (do not use sandpaper which leaves scratches that promote future corrosion). Note that the torque specification for the nuts on the ground studs is a very low 6.5 ft. lbs., or just over hand tight. Many owners have discovered how easy it is to snap off an aluminum stud by over-tightening the nut.

3. Have you cleaned the MAFS and its electrical connector with special MAFS cleaner spray?

4. Have you checked the transmission fluid level? This has been associated with stalling when coming to a stop or slowing to make a turn.

While your attempts at diagnosing these issues by logic are admirable, I'm not sure all of your conclusions thus far can be relied upon. For example, you could have a vacuum leak in an area such as the EVAP system that is only connected to the engine under certain operating conditions. You could have a problem with the MAFS, injectors or fuel filter that is borderline and only triggers a DTC under certain engine operating conditions.

You really need some time with a scanner capable of giving you Live Data from as many sensors as possible, and ideally one that can read the proprietary Jaguar DTCs, especially the network-related U-prefix codes.

Cheers,

Don

 

Replies to Don's message above below:

1. Have you cleaned the ECM electrical connector? To separate the connector you need a special 5-lobe tamper-proof Torx bit with a hole in the center of the bit to accommodate a pin in the recess of the head of the screw that secures the connector to the ECM. A common issue is water pooling around the connector due to leaves and seeds clogging the drain in that area below the cabin air microfilter housing (engine bay side of the firewall).

2. Have you cleaned the ground points used by the ECM? They are identified in the Electrical Guide. Use a small brass-bristle wire brush and zero-residue electrical contact cleaner (do not use sandpaper which leaves scratches that promote future corrosion). Note that the torque specification for the nuts on the ground studs is a very low 6.5 ft. lbs., or just over hand tight. Many owners have discovered how easy it is to snap off an aluminum stud by over-tightening the nut.

Not yet. I don't have the tools but have asked the mechanic who rescued my X300 before to have a look.

3. Have you cleaned the MAFS and its electrical connector with special MAFS cleaner spray?

Yes. MAFS cleaned with MAFS cleaner spray weeks ago; problem persisted so bought a new MAFS, but as explained before, the new MAFS only provided relief for one day; the next day the CEL and "Restricted Performance" dash warning re-appeared.

As per my mechanic's advice, I have also replaced the Fuel Filter. It was very dirty but the new fuel filter (Jaguar original parts) again only provided relief for another day; problem returned the next day. Even before the fuel filter change, I have tried injector cleaner - a product used by workshop professionals (see picture below). It failed to tackle the symptoms.



4. Have you checked the transmission fluid level? This has been associated with stalling when coming to a stop or slowing to make a turn.

Checked; no issue with level, but as car has occasional jolts before coming to a stand still, my mechanic has advised to replace the auto gearbox sump filter kit and seals with the transmission fluid. This will be done once the parts arrive.

While your attempts at diagnosing these issues by logic are admirable, I'm not sure all of your conclusions thus far can be relied upon. For example, you could have a vacuum leak in an area such as the EVAP system that is only connected to the engine under certain operating conditions. You could have a problem with the MAFS, injectors or fuel filter that is borderline and only triggers a DTC under certain engine operating conditions.

It is a pain to track down the real culprit(s). Car has been running perfectly well in the past three and a half years. It has to undergo the first health check starting with the spark plugs (you are aware of my other thread). Bought a set of NGK TR6AP-13E (laser platinum plugs) and my mechanic will replace them. He said he would also check and clean the coils as well which could sometimes present problem without being detected by after-market OBD scanners. To address shaky idling, the mechanic also cleaned the throttle body. However, CEL and RP re-appeared the next day.

You really need some time with a scanner capable of giving you Live Data from as many sensors as possible, and ideally one that can read the proprietary Jaguar DTCs, especially the network-related U-prefix codes.

Agreed. I have ordered a set of proper VCM kit to help me sort my X300 and X350 as I want to make life easier for myself and my mechanic. However, I am not convinced that we cannot live without the VCM kit - it is not the total answer, just telling us more where and what to look for. Eventually it is a judgment call like the master mind game.

 

More findings today.

Air Filter checked, not dirty but nonetheless replaced (to rule out air restriction as a contributing factor for "fuel too rich" n both banks).

One side of the V6 engine's Motorcraft spark plugs (AGSF22FSM) replaced by NGK Laser Platinum Plugs (TR6AP-13E) packed as Jaguar OE Plugs C2S46895. The changed out plugs have pretty much served their life and replacement was long overdue (see picture).


The mechanic will change out the other three plugs and conduct a mre thorough check of any possible air leak when he has more time removing the intake manifolds, engine covers, and various connecting hose next week. His assessment of air leak is very low for now, as engine idling is pretty steady at operation temperature.

He borrowed an OBD scanner (Autoland) from another workshop and detected the previous Codes Fuel too Lean/Rich on both banks, and P1672, i.e. CAN ECM/ASM Network Malfunction. He removed the pollen filter near the firewall and found no debris, leaves or signs of water near the ECM.

After replacing the air filter and three of the spark plugs, he deleted all codes and re-scanned the engine. Only two codes re-appeared: P0171 and P0174, i.e. Bank 1 & 2 Combustion too Lean.

He then fired up the engine and went on to check on Live Data, as we wanted to know how the O2 sensors and Cats were doing. This Autoland scanner is probably a cloned copy with translation into Chinese. From the live data displayed, it appeared both Banks 1 and 2 have readings varying a great deal, from -0.28 to -1.4 mA (don't know how to interpret these figures) but the variance in Bank 2 is larger of the two, always dropping below -1.0. My mechanic believed that the O2 sensors are on the way out, and are marginally effective, hence causing occasional fuel lean/rich codes when engine speed is above idling at low or sub-operation temperature.

These seem to make sense, as spark plugs and O2 sensors are supposed to have served their time nearing 100,000 km. Have ordered O2 sensors (2 upstream 2 downstream) and will see if they would sort out the codes.

Any more thoughts meanwhile welcomed.