It is hard to say what is going on but if he has no vacuum leak and the P0171 & P0174 are directly related to air and fuel it is worth exploring. Yes it could be a MAFS, Intake tube, Air Filter, Low fuel pressure (Fuel filter) and an exhaust leak or poor fuel presentation. Oh the battery being replaced.

With the codes coming off and on I am guessing that fuel and air are not right. For that reason I am suggesting that the problem is fuel presentation and a way to eliminate that area of concern it to treat it with BG44K. Looking at the codes they suggest lack of fuel can and will cause this problem.
Link http://www.jagrepair.com/images/Auto...tos/P20003.PDF

Link http://www.jagrepair.com/images/Auto...r%20Rev2-1.pdf

 

I suppose that BG stuff is not very expensive but even so how can both sides have evenly clogged injectors? (They'd need to be even to explain both sides results being alike.) Ain't gonna happen - especially as S-Types don't seem at all prone to injector problems.

 

The BG44K is around $20.00 but it is worth it. Both banks are feeding from the same fuel tank. This would not be the first time injectors needed cleaning.
Without having my hands on the car and taking what is given as to what is taking place it is my gut feeling that the presentation of fuel is the issue.

Is there any real science to what we do on the forum?

 

I agree JagV8, but in all fairness I'll try the BG44K as per Gus's recommendations,( gotta find it first!), and in the meantime I will inspect the air intake system: air filter canister, and associated piping, and look for anything obvious. I'll clean the MAF sensor for the hell of it, although I know its pretty clean already.

I cleared the codes last night and will take live data again this afternoon when I get home from work ( 35 mile commute one way). I'll post them.

Oh, the battery I will have load tested after it spennds a night on the battery tender. Its a Jag battery that I am embarrased to admit that I got rooked at the dealer's two years ago: $220 USD! As expected I'm a little apprehensive to buy another battery ( wouldn't be a Jag one thats for sure!)

 

Amazon has it by the single, and the 4-pack.

 

Any good repair shop will have it however, most parts stores do not.

Gus
www.jagrepair.com

 

I have been chasing 0171 and 0174 for years. I have taken advantage of all forum help. Replaced mafs, replaced coils and plugs, replaced fuel filter, gas cap, smoke tested for leaks at a trusted indy shop.......Stood on my head and threw coins in a wishing well. I can not stop these recurring codes. I just get used to driving with restricted performance and find that as long as I don't stomp on it, it's driveable. I am convinced it is a weak fuel issue and plan on next step being a professional injector flush. Other than that, I'm thinking weakening fuel pump but I'm hoping not that. PS....My understanding is that if stft and ltft values exceed +20 combined at any given moment, it will throw the lean codes.

 

It's a bit more complex (if needs be, read the doc LOL) as to when it will flag codes but always bear in mind calling them "lean" does not always imply an air leak (though checking is easy).

 

Ok, took live data yesterday when I got home from work:
@ IDLE:
B1 STFT 3.9%
B2 STFT 3.9

B1 LTFT -1.6
B2 LTFT -3.1

@ 2500 RPM

B1 STFT 7.8
B2 STFT 7.8

B1 LTFT -0.8
B2 LTFT -1.6

I'm going to disassemble airbox, tubing to TB, clean MAF, and replace battery.

I also sprayed TB cleaner on all vacuum and intake tubing, joints,etc and found nothing.

 

Similar both sides, so looking for common (to both banks) item.

No sign of an air leak in those.

So, it's either an air leak that only occurs under certain conditions or not an air leak but something like bad fuelling.

That kind of air leak would be something like a valve opening (EVAP?) or I suppose maybe a hose that flexes, opening a gap.

Bad fuelling isn't going to be injectors (you really can't get those readings with blocked ones and anyway they just do NOT block evenly on both sides) but maybe MAF.

I don't see it being an exhaust leak, as the readings incl freeze frame are so alike both sides.

 

I would not argue with that but still would not rule out a fuel issue. Unlike others please post what you find.

 

Maybe a bad fuel pump, or fuel filter, but looks like it would have to be intermittent (to explain why it's not in the parked, revving data).

 

I would like to go through the process of elimination so we can narrow down and get to the problem.

 

Update:

1 Replaced existing battery today with new one (12.7 volts off the shelf)

2 Replaced air filter

3 Cleaned MAF & TB ( both not dirty, but cleaned anyway)
4 Inspected airbox and piping to TB for any splits, cracks, etc... none.

5 Reinstalled airbox, piping, etc and drove home 35 miles, all highway.

6 Took more fuel trim live data, parked at idle and 2500 rpm:

@ idle:
B1ST: 1.6
B2ST 0.8
B1LT -7.0
B2LT -7.8

@ 2500 rpm:

B1ST -0.8
B2ST -1.6
B1LT 3.1
B2LT 1.6

note: also replaced fuel filter at 86,800 miles, have 107,400 now, always 93 octane petrol, top tier name brand BP, Sunoco, Exxon.

 

See if the codes recur, I suppose.

The -ve LTs at idle might mean something fuel-related (usually MAF but doesn't have to be) but it's not way out.

 

Yes, I'll also order the BG44K online and put that in as per Gus' recommendations, but I think I've done all I can do for now. Car runs and feels great, I'll see if any codes come up , but for the meantime that's it. Thanks for everyone's help!

 

Well, the MIL came on again on Friday. Parked the car, didn't get a chance to check, and then yesterday I noticed it disappeared by itself!

Can someone explain how the MIL resets itself???

I thought that was impossible

Second time this has happened

 

Not sure unless it is temporary code and did not set a hard code.

 

The MIL will go off if a fault clears (either you fix something or it's a transient fault) after 3 warm ups (each without the fault).

It's by law. (Search the web should you enjoy reading those sorts of things!)

There is a (serious) school of thought that one should never clear the codes using an OBD tool and a push to change future cars to ignore such attempts on the basis that it would make people actually fix their cars.

When I fixed an O2 sensor I didn't clear the codes to see if this stuff really works - and it did.

 

Thanks for explaining, JagV8.

BTW, MIL on again!

I did find the oil smell in the cabin again, and the engine is leaking oil on the bank 1 exhaust manifold heat shield. IMT's were done last year, (w/green o rings), also cam cover gasket, twice for this issue. Half moon metal insert near firewall on cylinder head was leaking last time, and looks like yet again!!!

On bank 2, I found a small oil leak off the cam cover nearest the power steering pump mount.

Possibly my cause of lean codes I suppose.

These covers were done, bank 2 once, bank 1 three times, and followed JTIS diligently, and Jaguar OEM gaskets! What gives?!?