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Need to jump into another recent issue here and looking for some troubleshooting ideas.
Just last week my car threw it's first "Restricted Performance" lockout and when I checked the codes, they came back with a lean code and a secondary O2 sensor heater failure on bank 1.
Ordered a new O2 sensor for that and last evening a 3rd code jumped in for lean on bank 1. Now I am not so certain the issue is O2 sensors at all. Smells like a "single-point" issue further upstream.
Just wondering who may have experienced a global lean with both banks and where it back up to.
Also I have a question on spark advance.
Since I have been monitoring live data on this, I caught out of the corner of my eye spark advance on cylinder 1 in excess of 40 degrees. Since I am uncertain about what the normal window of advance is, would like to learn more about this.
I honestly don't even feel excited about this as the issue was so bloody convoluted from the beginning but at least I have a car that I can get through smog.
Here is a really quick summary. If you are having lean codes, there is a lot of data in the entire thread which may or may not be helpful but that's the way I roll. I document as much as I can for people down the road as finding quick answers to problems can be difficult.
So if you just scrolled right to the bottom here, I can tell you in brief fashion what happened.
1- Lean across both banks and codes thrown. This means I can't smog the car and I have a restricted performance warning coupled with some engine knocking under load. Not good
2- So begins the forum research looking for any ideas as to common problem areas.
3- Had new cam-cover gasket kit so went ahead and installed that thinking it was the issue. Hadn't done a lot of looking into the root cause of the problem at this point - no change
4- Now I went in and started to look at live data to watch trims. At idle, LTFT was great but would go lean as fuel was applied - so simple, i have a unmetered air leak
5- Searched and searched but couldn't find anything obvious so on a hunch went a purchased a new MAF sensor. Not original Denso but Delphi
6- Installed sensor and everything went to ****. Now I got high LTFT at idle but normal trims on throttle? Bizarre so I guess my old MAF was really messed up. I have a vacuum leak, not a unmetered air leak?
7- For hours and hours, I sought out vacuum leaks. I made a smoke machine to check the integrity of the system and did indeed find some smoke leaking out. Most notably at the lines on the throttle body, the VVT seals and the o-ring on the dipstick. All fixed up with zero change to the trims - WTF?
8- Could not find any other leaks and if I were being paid to do this, I would have amassed a fortune by now.
9- Kept going between the 2 MAF sensors wondering why the results were so different. Surely the old Denso was bad and the new part was giving me the proper intel right?
10- This morning after I wrote the post above, I decided to check one more time. I wanted to verify that the the trim number on the LTFT went up on both MAF's when the engine bay got soaked with engine heat. I knew for certain that was the case for the new Delphi MAF but I wasn't completely sure for the old Denso. I got to swapping the old unit back into the car.
11- In putting the old Denso back into the casing, I noticed that I struggled with it to slide it back in. There is a o-ring on it to make the seal and for whatever reason, I couldn't get it to slide in without a struggle. The new Delphi went in and out without issues so as I stood there, I had yet another automotive epiphany - could it really be?
12- Took the new o-ring off of my "non-returnable" new Delphi and placed it on the old Denso unit. Miraculously, the unit slid in nicely with the new o-ring so I buttoned it up and my brain was on-fire now.
13- Disconnected the battery and reset the ECM. Fired the car up and waited
14- Car got to nominal operating temp with trims sitting at 0.5 on bank one and 2.4 on bank two. Ok so maybe a little vacuum leak still somewhere on bank 2 but the issue won't reveal itself until I give the car pedal.
15- Pulled out of the drive and yup - you guessed it! Fuel trims never got over +/- 4%
So the issue all along was the o-ring on the MAF sensor itself. Now maybe it was leaking all along but it took some other leaks to develop on the engine before there was enough to force a code to be thrown. There is some margin on the trims +/- to account for an aging vehicle. What I had was a pretty large unmetered air leak right there at the MAF so how did this go undetected you ask? Its called redirect my friends. The purchase of the new Delphi unit which turned out to be a total piece of ****, sent me in a completely different direction, chasing down vacuum leaks while distracting me away from the real problem which was unmetered air at the intake. The smoke being pumped into the car would never have found the issue because I take the entire intake off and block the throttle body opening to put smoke pressure in the engine.
I don't know what advice to give anyone else other than to say that I will never - and I mean NEVER purchase a aftermarket sensor for this or any other car. The cost of time that went into this tail chasing problem, if calculated by what my time is worth, would have been enormous. I could have purchased dozens and dozens of new Denso MAF sensors with the money. There is a big difference in approach when looking for vacuum vs unmetered air leaks. So as stated on the Delphi package, once opened - the device cannot be returned so I will keep the o-ring from it which ultimately cost me 120.00 and way too much personal time.
Need to jump into another recent issue here and looking for some troubleshooting ideas.
Just last week my car threw it's first "Restricted Performance" lockout and when I checked the codes, they came back with a lean code and a secondary O2 sensor heater failure on bank 1.
Ordered a new O2 sensor for that and last evening a 3rd code jumped in for lean on bank 1. Now I am not so certain the issue is O2 sensors at all. Smells like a "single-point" issue further upstream.
Just wondering who may have experienced a global lean with both banks and where it back up to.
Also I have a question on spark advance.
Since I have been monitoring live data on this, I caught out of the corner of my eye spark advance on cylinder 1 in excess of 40 degrees. Since I am uncertain about what the normal window of advance is, would like to learn more about this.
Lean code: one common source is a leak in the air duct that leads from the air filter to the throttle body. Take that off and inspect it carefully.
[edit] ... oops, forgot; also a bad or dirty MAF sensor is often the culprit when both banks are lean. There is a spray cleaner that's worth a try.
Had SDD hooked up today and was watching my STFT and LTFT's.
I had disconnected the vent line that runs between the drivers side cam cover and the throttle body after working out my own cold air intake setup.
Since it didn't have the plumbing for the line, I had left it dangling. Now this was certainly causing an issue as when I plugged it, the trims all slowly went back to normal. Car was idling only.
Thought I had licked it with a duh moment but after I took it back out to test, I got a restricted performance display again.
At idle, the trims all settle down to near zero.
On throttle, the trims go bonkers adding fuel so it seems to me this may be a case of fuel delivery and not a air leak.
The fuel pump measures between 53.5 and 56.5 as I drive around and I have heard that it should not deviate more than .5 PSI.
I also checked some of the fuel vapor recovery items and noticed that my purge valve always shows "off". Not sure when it should be showing on or whether it's supposed to alternate on/off when the car is running.
Does it make sens that the problem is pointed at fuel and not air leaks?
I also sprayed all over the engine with brake cleaner and never heard the idle change. I also simply pulled the dipstick and it did have an effect.
Seems that everything operates normally at idle. I am going to clean the MAF just so I know it has been done and then see if it changes anything.
Something else to check: A leaking oil breather hose will create just the scenario you're presenting, and is highly suspect if there's no other indication of a leak using your brake cleaner spray. There is a tremendous amount of vacuum in the crankcase while the motor is running, which is normal for this automobile, and a whole lot more under throttle. (Ever crack open the oil filler cap while the car is just idling? Impressive!) The oil breather hoses get very hard and fragile after years of driving too slowly in the heat-soaked engine compartment. (lol.) The lower connector and first 4" of breather hose just to the right (passenger) side of the throttle body get the worst of it. Even a slight leak will generate lean error codes on one or both banks. When the engine is cold, pull the air intake pipe from the right side of the car and find the oil breather hose below it. Check the engine connector (Norma V2) and the hose itself (gently!) for soft or weak spots, or for outright collapses. Be careful, that first 4" are subject to crumbling in your fingers even without a lot of pressure. If there is a leak in the hose, patch temporarily and get some flexible, heavy wall, 3/4" corrugated tubing and some dual wall, high temp, adhesive shrink wrap, and use your old connectors with the new breather hose. Don't get cheap, lightweight stuff, it will only last about 10 miles before the heat outside and the vacuum inside collapse it like an overworked straw stuck on an ice chunk in a Slurpee. If there is no leak, squeeze and remove the connectors (Gently!) and make sure the o-ring is in perfect condition. Our good friend, Gary Vanremortel, (who writes that amazing 2003-2006MY Jag XK8 bible we all love), can save you time and expense in replacing the breather hose with a better-than-OEM one as long as you can send him the old parts with your Norma V2 connectors. He has a picture of his offering in the newest Rev K release, found elsewhere on this forum. Also check the o-rings for the dipstick and the oil filler cap...
Here's the error codes I got from my deteriorating breather hose:
Something else to check: A leaking oil breather hose will create just the scenario you're presenting, and is highly suspect if there's no other indication of a leak using your brake cleaner spray. There is a tremendous amount of vacuum in the crankcase while the motor is running, which is normal for this automobile, and a whole lot more under throttle. (Ever crack open the oil filler cap while the car is just idling? Impressive!) The oil breather hoses get very hard and fragile after years of driving too slowly in the heat-soaked engine compartment. (lol.) The lower connector and first 4" of breather hose just to the right (passenger) side of the throttle body get the worst of it. Even a slight leak will generate lean error codes on one or both banks. When the engine is cold, pull the air intake pipe from the right side of the car and find the oil breather hose below it. Check the engine connector (Norma V2) and the hose itself (gently!) for soft or weak spots, or for outright collapses. Be careful, that first 4" are subject to crumbling in your fingers even without a lot of pressure. If there is a leak in the hose, patch temporarily and get some flexible, heavy wall, 3/4" corrugated tubing and some dual wall, high temp, adhesive shrink wrap, and use your old connectors with the new breather hose. Don't get cheap, lightweight stuff, it will only last about 10 miles before the heat outside and the vacuum inside collapse it like an overworked straw stuck on an ice chunk in a Slurpee. If there is no leak, squeeze and remove the connectors (Gently!) and make sure the o-ring is in perfect condition. Our good friend, Gary Vanremortel, (who writes that amazing 2003-2006MY Jag XK8 bible we all love), can save you time and expense in replacing the breather hose with a better-than-OEM one as long as you can send him the old parts with your Norma V2 connectors. He has a picture of his offering in the newest Rev K release, found elsewhere on this forum. Also check the o-rings for the dipstick and the oil filler cap...
Here's the error codes I got from my deteriorating breather hose:
Thanks P,
I did get around to checking that line when I get back to the Bay Area and it has no cracks whatsoever.
Too bad because I was considering bending up my own metal tubing as we had talked about given that those lines get brittle with heat and then the issue finding connectors.
Heck, I may do it anyway for grins lol
For a spell, I wasn't worried about the CES lamp on the XK but now I need to smog it before I can renew my registration so I am back to working on this again.
I only throw the lean codes now it seems and I have poured through a number of threads on the subject. Sadly, none of the common issues point to my problem - yet.
So here is what I have poked and checked to date.
1) I have a cold air intake with aluminum tubing so no cracks or leaks after MAF
2) To the best of my knowledge, the MAF is performing normally based on the readings I see
3) New plugs and cam cover gaskets.
4) No cracks in any of the air tubes on top of engine
5) Sprayed cleaner around the top of engine and around intake plenum - I did get a slight change when spraying around the VVT seal on the passenger side but nothing dramatic
6) FRP is +/- 55 PSI. A quick stab of the pedal shows a rise to 62PSI. Never dips below 54.5 PSI
7) All O2 sensors are functioning normally. STFT at idle are usually +/- 1-2% at idle
8) LTFT while driving are nearly always at +19.5 %. Sometimes it drops like under decel, etc but usually high.
9) I have noticed some stumbling when the car is first started and this car has always had a 1400RPM warmup for about 15 seconds before dropping to normal idle
So that leads me to some questions.
1) Car is lean on both banks which leads me to believe that whatever is causing the issue is pre-exhaust. Meaning I shouldn't need to worry about air leaks pre cat
2) Can the MAF sesnor appear to be operating correctly but have some issue?
3) Ditto for the fuel pump?
4) I have noticed that at times I can smell fuel up near the driverside fender. I know the purge valve is in there so could that be contributing in some way?
5) Any other areas of interest when reading lean on both banks?
One more important question I need to understand.
At idle, the STFT's are at or near zero but the LTFT's are always +14% or higher.
My assumption on the LTFT's is that they are more or less long term changes to the map while the STFT's are immediate corrections.
My assumption is that if everything were fine at idle (not enough air leakage) that the STFT's would be the opposite of the LTFT's? That they would be -14% until the LTFT's returned to at or near zero.
This doesn't appear to be the case here as the LTFT's stay north of 14% even at idle while the STFT's are at or near zero as I have said. To make this even more strange is that there have been a couple of testing incidents where my statement has shown true on the STFT's. So what am I really looking at with this?
A couple of years ago a car belonging to a friend had reasonable fuel trims at idle but way out while driving. A well known specialist could find nothing wrong, but eventually the MAFS was replaced and it was fixed.
A great way to identify air leaks is to use a smoke generator. There are somewhat affordable units for home mechanics like us on eBay, but it is still a bit pricey to just get it. On aging cars like ours, with all the o-rings, seals, gaskets, tubes, etc, I bet this would pay for itself pretty quickly...
Have a few updates on my lean code hunt down.
I went ahead and purchased a new MAF sensor. It did not correct my problem but must have corrected something because my readings now show high likelihood of a vacuum leak. At idle my LTFT's are +15.6 and +18 on 1 and 2 respectively. When I apply throttle the trims, including STFT's go negative and both settle into +/- 3%. As soon as I lift throttle however the trims all go mad adding fuel. This is pretty consistent
I made a rudimentary smoke machine and did a bit of a test. I found 2 notable leaks. The first being the oil dipstick o-ring and the second being the hard line from the brake booster at the throttle body. Both known leak locations. I replaced the o-ring on the dipstick and did a patchup on that hard line until I can get the repair kit. Everything came up good but neither had any impact on the trim issue. Looks like the leak is bigger than either of those which is not making any sense now.
Went into the SDD software and found a code P0110 for bad IAT sensor however the real time monitoring shows that the IAT is functioning normally. There was a note in the software about it not being predictable sometimes in clearing old codes so I don't know if that might have been the problem coming from the old MAF? For now I know the MAF + IAT are producing results in the monitors.
Here is the odd thing that I want to ask about
The EGR valve motor can be monitored in the software. It has a range of 0-255 according to SDD. With the car running after 30 minutes of watching, that monitor did not move from 0 once. I do not have any codes relating to a EGR issue so I am wondering if that stepper motor might ultimately be my culprit? Has anyone else tested and could report on the monitor and what they have witnessed in testing? It is called the "Exhaust Gas Re-circulation Target Position"
I am going to smoke the car again, I just needed to pick up a couple of things to do a better job with it.
Once I do, I will see if there are any further outlets
I decided to unplug the connector to the EGR and started the car.
The fuel trims did not change when I did that nor did the performance of the car.
I did get a code upon second startup so the module electronically is recognized as being there. I believe it simply is not working anymore even though the electronics are still active. The
software still shows no data changes on it
Exhaust gas is introduced in the intake to reduce the production of NOx, product of lean-running conditions and high combustion temperatures. This is something a catalytic converter cannot deal with, so the ECU has to stay away from the conditions generating it. If the ECU does not think these conditions are in effect, there would be no reason to open that valve. To my knowledge, the EGR system is heavily monitored, so if you have no codes, I would move on.
Have you checked the VVT seals? Oil around probably means air leak, too. Cheap, easy fix.
Also, the accordion pipe between the EGR valve and the exhaust manifold sometimes cracks, and lets air in the exhaust stream, confusing the O2 sensors.
This car has so many opportunities for air leaks, from aging Norma connectors and plastic pipes, several intake gaskets, etc.. This is where your smoke machine will pay off nicely, I believe.
For the brake booster vacuum line brass fitting thing, check part# C2S15816. It is somehow not offered for the XK8, but apparently people have had great success with it (o-ring and plastic collar)...
Exhaust gas is introduced in the intake to reduce the production of NOx, product of lean-running conditions and high combustion temperatures. This is something a catalytic converter cannot deal with, so the ECU has to stay away from the conditions generating it. If the ECU does not think these conditions are in effect, there would be no reason to open that valve. To my knowledge, the EGR system is heavily monitored, so if you have no codes, I would move on.
Have you checked the VVT seals? Oil around probably means air leak, too. Cheap, easy fix.
Also, the accordion pipe between the EGR valve and the exhaust manifold sometimes cracks, and lets air in the exhaust stream, confusing the O2 sensors.
This car has so many opportunities for air leaks, from aging Norma connectors and plastic pipes, several intake gaskets, etc.. This is where your smoke machine will pay off nicely, I believe.
For the brake booster vacuum line brass fitting thing, check part# C2S15816. It is somehow not offered for the XK8, but apparently people have had great success with it (o-ring and plastic collar)...
I certainly won't be giving up on smoking the vehicle as it has already illuminated 2 leaks and I am sure it will uncover more as I go.
My thinking at the moment is this - The swing the ECM makes from on-throttle to off-throttle fuel response is drastic and quick. From the small values to high teen values in a very short period so something drastic is leaking I believe.
Being that drastic, I would believe that I would have found something quite obvious which I did with the brake booster line I think but after repairing the two leaks I found, it made no difference and I cannot find a gross leak anywhere.
My EGR tube was already replaced with a modern accordion version - I have a solid air intake tube and I have replaced and/or inspected all of the major culprits of air or vacuum leaks - I think?
The one I haven't checked on yet is anything to do with the fuel vapor system inside the wheel-well but that is on the list.
I have learned that a misbehaving EGR valve can upset the fuel / air balance and since I have never touched that on my car, I believed it to be a possibility.
When scanning the EGR position in SDD, I noticed no movement whatsoever in the value at any time. It sits at 0 and stays at 0. Even unplugging it didn't change anything about the trims and I would have thought I would see something getting upset.
Every other value I look at in SDD changes as the car runs so why not that one? I get your point on the potential issue making it not want to move but it's something I believe warrants a look at least.
One more thing I remembered and that was prior to the codes coming up, I was experiencing some detonation on acceleration. It was only light but noticeable to me so that is also wrapped in the potential for a bad EGR.
And finally, I need to remember that these codes came overnight. One day the car was error free and the next, I have codes across both banks. So the concept that this is due to something going south quickly is reasonable. I just need to check things off the list and satisfy my curiosity. After all, I need to remember that it was this curiosity that saved me many thousands of dollars when I discovered the problem with my transmission turned out to be wheel bearings of all things.
I'll stick with it and take any and all advice.
The end result will ultimately be a greater understanding for me and maybe less trouble shooting for others
I was experiencing some detonation on acceleration.
I experienced the same thing going uphill, low rpm, high load, when my trims were high (15%). I went around the heads, replacing all o-rings in all Norma connectors, plus VVT seals, etc. When the trims came down to, say, 5%, this "detonation" was gone.
I experienced the same thing going uphill, low rpm, high load, when my trims were high (15%). I went around the heads, replacing all o-rings in all Norma connectors, plus VVT seals, etc. When the trims came down to, say, 5%, this "detonation" was gone.
I am going to replace the VVT seals anyway as part of the entire valve cover upgrade
Doesn't seem to be clear on the PN though. Are all the V8 4.2L engines using PN - AJ82856?
Most vendors say this part doesn't fit engines newer than 2002 in the XK class
The AJ82856 VVT seals do indeed fit the 4.2 engine. I have tried OEM and non-OEM but regardless of where they come from, they never last more than two to three years for me before they begin to seep oil (and air). Sure wish we could find a set that would hold up much better to the heat of the engine bay....
11-12-2018, 09:45 AM
Lean codes across both banks RESOLVED
