Okay, guys, you got me, and good. Three pages into a thread before I finally wised up and realized one of you has been pulling my chain all this time. Little bits of important info slowly dribbling out... Numeric values that change with the wind (see posts #55 and #58)...

I can take a joke as well as the next guy, but who was it? JagV8? Motorcarman? Steve? Come on, 'fess up and take a bow. I fell for it hard.

 

☀️
🦧
🐅

kinda mindset …

 

I’m afraid to ask about the repair. From Troubleshooting 101: Take care of the known faults before digging deeper elsewhere.

I don’t think an air leak here would cause a rich code, but it still needs to be corrected. Who knows how everything is interconnected? I would not trust any kind of tape repair here. I’d suggest getting some serviceable used parts, such as from a junkyard or eBay.

 

Right on
So awhile ago I messed up trying to clean it with regular electronic cleaner , so when I reinstalled it , one of those two screws holding it was loose due to a misplaced metal thread piece on it , therefore I wrapped up gorilla tape to hold it tightly in place … and a few days ago I’ve improvised and got it all screwed in right and right ( and also got a slightly bigger gasket ) and the MAF reading has improved right away 🛠

 

Went for a long ride today , and sometimes the MAF reading fluctuates from 1.7ish on idle ( meaning the trim is also -20s or +20s when driving , and noticeably burning too much fuel ) to 0.3ish ( when the trim is USUALLY nicely zeroed in )
And here’s what comes up on the scanner 📶





🤔

 

Reads like a massive air leak and/or 2 bad O2 sensors.

 

So I’ve been driving up steep hills on full throttle lately to help clear up the VVTs (ands already been around 700 miles with that quart of ATF)
🤔
And those trims still fluctuate from -20s to +20s

 

I think its weird to see a rich code from a vacuum leak but A vacuum leak after the MAF is reported to to the ECM as a lean condition for the given known air flow reported by the MAF. So the ECM gives the motor more gas causing the Stft and Ltft to increase In a positive direction as the ECM tries to cure the supposed lean condition. Fuel trim go positive for lean conditions

 

Oh and certain vacuum leaks will throw a p0430 “catalytic inefficiency” code under certain conditions. In fact ive never had a bad cat but ive seen many p0430 codes after fixing the majority of vacuum leaks in my STR. So whenever I see p0430 I think vacuum leak.

I need to see a running graph of the voltage (for
downstream o2) and current outputs from the upstream O2 sensors over a few minutes. I bet the first o2 sensors showing low (negative) currents and the second 02 sensors (voltage) are biased high.

 

One last thought- Depending on where the vacuum leak is located, it could cause a rich condition depending on certain engine designs. Some fuel pressure regulators are vacuum modulated, and so would jump to high pressure when vacuum is lost. This could result in fuel trim problems and a check engine light, possibly with Fuel System Rich DTCs, such as P0172 or P0175.

 

Check out eBay item number # 392980353150. It’s the air cleaner housing, flex duct, and a MAF sensor. It’s a fixed price listing, set you back around $50 with shipping.


https://www.ebay.com/itm/392980353150

 

That looks pretty reasonable, all things considered. Karl, this thread reminds me of the lengthy saga (different DTCs though) of "jakesdad" whose woes were eventually cured by attention to the intake "plumbing"...

 

Yeah, that one crossed my mind, too. That was a late model V6, throwing lean codes, but still worth noting. See post #32 here:

https://www.jaguarforums.com/forum/s...2/#post1934812


Back to our current problem, my thoughts are it's time for a futile and stupid gesture. We've analyzed the snot out of it, and hopefully narrowed down the issue to a few possibilities. Who knows the exact source of the problem, but the whole Gorilla Tape repair thing is enough to give me nightmares. I've revisited that eBay listing and keep hoping to see it has been sold. (Hint! Hint! Hint!) I'd say gamble the $50 on fixing a known problem, no matter how good you think the tape repair may be. Clean up that part of the mess and see it it brings any improvement. As a bonus, that particular eBay listing also includes the MAF sensor. Boy oh boy, that listing sure looks like a good deal. (Hint! Hint! Hint!). If nothing else, if the presently installed MAF sensor is bad (a leading candidate) it's highly unlikely that a used replacement would have the exact same fault. What a fantastic and low-cost way to troubleshoot.

Say, here's that same listing again. I was just typing and the link magically appeared. What a wacky coincidence:

https://www.ebay.com/itm/392980353150

How does eBay work? On this type of listing, don't you just click where it says "BUY IT NOW" and then the part appears at your door in a few days?. Wow, that seems incredibly easy...

 

C’mon , brothers … This problem is already resolved , the proper gasket’s in place and it’s screwed in nice and tight ✅ Ps and I would have considered getting that piece from eBay just for an extra MAF sensor’s sake , thou I’m currently real low on fuel …

 

🤔

 

Well, at some point, you're just going to have to try something and see what happens. We don't need any more videos of fuel trims. Unless someone else can chime in to interpret them, I've no idea what to do with them. Maybe post some cat videos instead. They will provide a similar level of information but at least be more amusing.

Yeah, I'm busting your butt. Not sure any of us can come up with some magical 100% guaranteed solution based on all the clues so far. Remember, you've reached the stage of stupid and futile gestures. It's time to just try something and see what happens.

Resist the urge to try several things at once. Don't change a whole bunch of sensors at the same time. Make your best guess and try that one thing. Drive for a few days and watch the symptoms. This is to prevent the dreaded situation where symptoms get worse, but you don't know which of the 6 parts you just changed had caused it.

Where to start? Are you absolutely, positively sure all intake air leaks have been repaired? If so, I still think the P1121 code is your primary concern. That's the computer's way of saying the TPS and MAF values don't agree with each other. Which is more likely to be wrong? The TPS has two independent channels that are constantly compared to each other. You'll get a different fault code if the channels don't match. It's extremely unlikely that both channels would fail in such a way as to still agree with each other yet put out a combined erroneous signal. Not totally impossible, but I think it's more likely that Nancy Pelosi would get a tattoo of Trump's name inside a heart.

So working on probability alone, I'd suggest an MAF sensor first. JagV8 was thinking you might have a pair of bad O2 sensors instead. His guess is as good as mine. Pick your poison. Anybody else brave/foolish enough to chime in? Anyone? Anyone? Whatever you do, STAY AWAY from no-name bargain parts, such as offered on eBay. Same goes for the store brand at discount chains. This stuff is almost always Chinese junk that will cause nothing but grief. Stick with quality name brands such as Denso, Delphi, Bosch, etc. There's a reason they cost more. Don't skimp out here.

 

Question … So I’ve changed that hub lately , and this ‘03’ part has a different kind of sensor ( detachable ) than my (wired ) ‘01’ …
Thus ABS 🚨 is flashing due to this dislocated sensor …
Does this have anything to do with that MAF & TPS synchronicity ?

🤔

 

And here’s what I’ve noticed > When I turn the ignition key and the battery kicks in , if the MAF Sensor reading is above 1 then it’s gonna be too high when the engine is running … So I’ve been starting the engine when that reading is <1
🤔

 

Okay, I'm even more confused than normal. Are you saying with the key to RUN, but the engine not yet started, the MAF is already showing a value above zero?

I played around with my scanner this morning. Not sure what you have, but it looks similar to the Blue Driver that I have. One quirk I noticed is it will not read live data until I start the engine first. If I want to read live data with the engine not running, I have to start the engine first, turn the key off, and then back to run quickly. That's the only way I can get it to read live data with the engine not running. Otherwise, it would sometimes show the last value recorded, but in the same spot as live data. Any chance you've got something like that happening? Because with the engine off, reading live data (as described above), the MAF displayed zero. If you are reading live data with the engine not running, you should not see anything above zero for the MAF.

 

Yeah , when the live data screen is on , shutting the engine and then turning the key , keeps that screen on , and the coolant temp and MAF Sensor gauges reading 📶 (and sometimes the MAF Sensor reading shows from 1 to 3 , and either zeros out or is stuck on something above zero , so I usually wait till it’s below 1 to start the engine for fuel efficiency ) 🤔
Drove it a few hundred miles today and the MAF reading looks aligned with the trims ( thou occasionally it’s easy to notice the VVTs getting clogged and then unclogged ‘)
O2s , P1383s, p1121 , and cats are 🚨
So will it be alright reinstalling the O2s while the cats are dirty ?