For most of the summer, 15,000 miles or so, I have been fighting the above codes. It started out as short “restrictive performance” with the yellow “check engine” light every two or three weeks with the “RP” showing for a very short time, 30 seconds or so. It is now to the point of coming on each time I drive more than a half hour for 5 minutes up to 25 -30 minutes. Since the start of this problem, I have read all I could find on the issue and tried a few different fixes. The first was to check and test all the vacuum lines. They seem OK and I get about 19 in/hg of vacuum. I then changed the air filter, the old one had only been it for a few thousand miles, but it was an aftermarket one so I order one from Jaguar. Changed the plugs, also from Jaguar, cleaned all the electrical plugs with contact cleaner. I still had the issue. I then bought a code scanner that would collect live data and checked the readings of the MAFS and checked them against a table I found in this forum. Idle/park 5.1 g/s, 2500 RPM/park 17.0 g/s, Idle/drive 5.9 g/s and 1500 RPM/Drive 39.3 g/s. I read 5.75, 19.23, 6.33 and 43.17. These were a little high so I order a new MAFS from Jaguar and changed it. My New readings were 4.67 g/s, 15.42 g/s, 5.21 g/s and 34.41 g/s, a little closer to what they should be, maybe low? After a few miles of driving the codes reappeared. I than bought a fuel pressure gage and read the fuel pressure. I read 43 lb. with no difference when I connected the vacuum line to the fuel pressure regulator. I thought I had my problem. I ordered a new regulator, not from Jaguar, but from an aftermarket supplier (Rock Auto).The fuel pressure starts at 43 lbs dropping to about 35 lbs when the vacuum line is connected to the regulator. Thought I had my problem solved. But the trouble codes came back. I’m hoping that someone out there can tell me what I could check next or if a Jaguar service department would be my next step. Thanks

 

Glenn, do the coolant and intake air temperature readings over OBDII look correct?

You might consider running a can of BG-44K in the fuel to help in case you have sticky injectors. If that improves the problem at all, having the injectors reconditioned may make sense.

 

Thanks for your help.
The coolant temp look good. I can watch it rise to 90'C. and stay there. When I did the 1500 RPM in drive test it got up to a bit over 100'C.
The Intake air temp. seems to be all over the place.
When I get a DTC, I can get a read out of the freeze frame of the readings when it went bad. I have readings of 13,36, 26, 30, 29. This would be when the car is moving. However when I take readings for the MAFS and the car was parked, I had readings of 36, 39, 50, 40. 61, etc. I am not sure if this is a problem or the intake gets very hot when the car sit and idles. My car would not idle for long times, just 3 or 4 minutes to take a set of reading, off for 10 minutes while I transferred them to my computer then another 3 or 4 minutes...
One thing I am trying to do now, is to leave the code reader hooked up while driving and I can set it so if I get a DTC it will store 10 frames before and after the code. Maybe this will show something.

 

Also, I will give the BG-44K a try. Thanks

 

Since my last post, I have been driving around with my code scanner hooked up.
It was set to record a set of freeze frames with a trouble code as a trigger, 10 frames before the code and 10 frames after. I have attached the freeze frames of the stored live data. I am hopping that someone can read this and give me a clue of what is going on. One thing that stands out is that the speed reading dropped to zero for a few frames before and after the trouble code. Could cause my problem?
Thanks

 

I'm better at lean codes but here's roughly what the PCM does.

It mostly believes critical sensors unless they're clearly broken: MAF, IAT, ECT, and O2s (especially upstreams). It puts the throttle where it wants (if this is a drive by wire) and trusts TPS (there are 2 when drive by wire).

It mainly decides fuelling from MAF (adjusted for IAT etc) and trims it as the O2s show. (Let's not get into torque/load calc.)

Essentially it goes round a loop redoing the calculations and adjusting the actuators (such as injector open times) all the time.

Yours is hating the outcome - it's seeing too much fuel, which it detects by not seeing O2 until it backs off a long way.

Both banks have similar O2 values so it's hard to imagine they're bad.

You've already changed the MAF so probably isn't that.

You have some weird VSS values unless you came to a stop.

I don't actually know what's wrong - I really am better at lean codes! - but what are the trims like with warmed up engine, parked, at idle & 2500rpm? I'm guessing still -ve. The main time I've seen that with an OK MAF is blocked cats but they're kinda costly to mess with. Sometimes you can check before & after cat temps using an IR gun. Sometimes you can get an O2 out and look in with a borescope (but O2s can be virtually welded in).

Hope a tech helps...

 

Thanks, this was very helpful, I hope.
The fuel trims when I did the 4 MAFS test are as follows
Idle/park
STFT-1 0.0
LTFT-1 -7.03
STFT-2 1.56
LTFT-2 -4.69

2500 rpm/park
STFT-1 4.69
LTFT-1 -3.91
STFT-2 18.75
LTFT-2 -3.91

Idle/drive
STFT-1 7.81
LTFT-1 -4.69
STFT-2 7.03
LTFT-2 -2.34

1500 rpm/drive
STFT-1 9.38
LTFT-1 -0.78
STFT-2 8.59
LTFT-2 -6.25


"Sometimes you can check before & after cat temps using an IR gun"
What would the IR gun read, big differences in readings before and after the cat?
I have been wanting to try the Nameless Cats. This may be my chance.
Thnaks Glenn

 

Sorry to say I don't know what those imply. I think the idea of an IR temp test is that with clogged cats there's poor flow so the upstream is hotter than it ought to be and downstream cooler. The back pressure messes up the fuelling. But I think you need someone who knows more than I do!

 

OK Thanks, Since the bad weather is coming to Chicago and the car will not be used much, I will keep plugin along with this issue. I have till next spring, but before that I will get it in to a Jaguar service center and give them a shot at it. Anyone have any suggestions. I have had a few Jaguars in the past, but they were new and just took them to the dealer for service. Any good independents in Chicagoland?

 

I have 2 documents on my page that might help you better understand fuel trims and may help in you search for the problem.

This is the link to them JagRepair.com - Jaguar Repair Information Resource

 

OK this should keep me busy for a few hours. Thanks. By the way, thanks for your excellent site. It a help for all Jaguar owners.

 

I am ready to give up. Last fall I used some BG-44K and it seem to make a difference so I sent all my injectors in to be cleaned to a site that I found in this forum. After receiving them, I re-installed them and drove the car about 300 miles with no errors. I then put the car away for the winter. Yesterday, with the temperature warming up to almost 20 in Chicago and the roads somewhat dry, I need a Jaguar fix so I took the car out for a shout 30 minute drive. All seem very good, until I turned into the garage and the “restrictive performance” light came on. DAMN!!
2 Questions…Can a low battery issue cause this. I notice that my windows needed resetting when I got in the car. I use a battery tender to keep it charged up, but there may be an issue with the battery. I plan on getting a new one, but I was waiting for spring. I might be the original battery..It’s a Jaguar battery and while I have all the services records, I can’t see where it has been replaced. That would make it 14 years old. Anyone want it, are they worth anything for Show cars?

Second, if a new battery doesn't help, would it be worth taking it to Jaguar dealer or service center. Would they be able to fine the problem? It is getting to the point where cost is secondary. About the only thing I can think of changing is the throttle body and those are expensive to just buy to give it a try.
Any suggestions would be helpful

 

One thing at a time first get the battery tested at your local auto parts store like Autozone or Sears. Chances are that the battery is part of the problem but get it tested first.

 

The window reset issue sure makes it sound like a battery problem, so that would be my first guess and the easiest to check.

If your battery tender doesn't show voltage, take it to any major auto parts store (e.g. AutoZone) and they will check it for free. Can't hurt and always start with the easiest, least expensive solution.

Good Luck.

 

RP is not any sign of P0175/P0172 but can be due to quite a few things - and a failing battery is one.