I'm getting P0174 with ltft on bank 2 thu the roof. Bank 1 is normal. Where should I start looking for bank 2? If it were bank 1, it would be easy to start looking for vac leaks egr, ect.
Everything Iv'e read for the past 3 hours covers either P0171 and P0174, or just P0171. What areas are prone to leaking on bank 2 only.
I'll throw the reader on it again sunday to get ALL my readings and post.
I pray that it is not an intake or exhaust manifold leak.
Prior to the fault,car was running perfect. Took an hour run on the highway, started car back up and surprise - check engine light, No restricted performance CEL, just check engine light. And slight surge at idle. My reader should confirm what the surge is caused from. Most likely ecu trying to overcome vac leak and level out maxed fuel trims.
I'll take readings at idle and at higher rpm. At what higher rpm should a vac leak be masked?
Mark

 

2500 or so. Just so vastly more metered air that the leak is relatively small.

 

Here are my numbers from today (Ambient temp 25F)

Cold 25F (no codes, no surging)
Bank 1
stft 7.0 ltft 3.1
Bank 2
stft 21.0 ltft 14.1
Fuel press 380 kpa (55.11 psi)

Hot idle (197f) (code pending P0174, surging)
Bank 1
stft 0.0 ltft 6.3
Bank 2
stft 20.3 ltft 20.3
Fuel press 380 kpa (55.11 psi)

This is where it gets crazy
Hot 2500 rpm
Bank 1
stft -3 ltft -0.8
Bank 2
stft -23 to +10
Fuel press 380 kpa (55.11 psi)

Back to idle
stft max 14.8, min -29.7 (massive variance)consistent on graph.

It seems bank 1 is spot on. Bank 2 is a mess. up and down consistently.
This surging with stft has me worried. Where do I start to look? Should I be looking at additional readings.
Any help? My gut is twisted up!

 

I don't see hot 2500 ltft2

Without it, guessing it's a lot less than the huge one you had at idle. You're looking at a bank2 fault either way.

Surging might be a blocked cat, air leak that varies, part-firing coil (not so likely, but you could swap bank to bank and at least check the plug wells are clean).

 

Hot at 2500 rpm

Bank 1 stft -3 ltft -0.8
Bank 2 stft -23 to +10

 

Common causes of a P0174 are:

An air leak after the mass air flow (MAF) sensor, such as a torn intake boot, or bad intake manifold gaskets

A dirty or faulty mass air flow sensor

Faulty oxygen sensor

Incorrect fuel pressure

Leaking positive crankcase ventilation (PCV) valve

Clogged exhaust gas recirculation (EGR) Port

Leaking brake booster

As it seems to be only bank 2 some of the above I think can be discounted.

Have you recently done anything to the car maintenance wise?

If you had a crack in the exhaust manifold you possibly could hear a "ticking" sound if the leak is small. If it were big it would be very noticeable.

If it is a leak in the intake try spraying down in there by the side of the charge cooler with engine starter and see if the readings change.

Also can you read Jaguar specific codes at all?

 

On my XJR I have TWO PCV type take offs from the valve covers.

One on the RHS which is the actual PCV looks like a mushroom and one on the lhs which is not a PCV just a pressure relief thingy I think.

However leaks in these areas can cause a P0174.

So it would be the Mushroom side where you might have a leak in the join or piping. It does not take much of a leak.

I had trouble in this area when I fitted an oil catch can.

The pipe that connects the mushroom PCV travels around the front of the charge coolers all the way back on the lhs of the engine and curves round and down into the back of the throttle body area.


Sort of brainstorming here.
So having said that I would think a leak would affect both banks??

 

Could a dirty throttle body or crap gas cause only bank 2 issues?
I have a friend at the dealer that is going to read Jag specific codes for me thursday.

 

https://www.jaguarforums.com/forum/x...-codes-173972/

I am sure you read the above thread.

Look at post #15 tho

 

I would think they would affect both banks.

It looks highly likely to be a leak affecting bank 2 only.

Propane is what I would try and I would get the Jag specific codes Thursday.

 

So is the word "to" above meant to be the ltft reading (+10)?

My 2 cents. Best to get Jag specific codes. This is what I'd be looking for in order of my preference.

Vacuum leaks tend to reflect worse at idle and come down as speed increases, which is what yours is doing, just not back to normal.
1) Air intake leak between MAF sensor and cylinder head. Include Jack's reference to the propane test. (though I might swap the O2 sensors before doing a propane test, but either way...)
2) I honestly don't know if the Front O2 sensors are interchangeable, but swapping them out will determine if the sensor is faulty. The sensors are the same. I'm just not sure that the pigtails are. If they are, they are an easy swap out. If your problem changes banks, then you need a new O2 sensor.
3) Fuel Filter
4) PCV/ EGR
5) exhaust leak before CAT (not really likely)
6) Faulty MAF sensor
7) Faulty/ Dirty injector

 

Pig tails are the same on the front O2 sensors. Just different between front and back.

I did not find them difficult to access or take out when I replaced my cats.

 

Concerning checking this issue, it should be done at idle. You will need something to display live data, like an ELM327 device or SDD. Get a can of carb and brake cleaner, using little squirts down the affected bank at the base of the intake, pausing for numerous seconds between shots, and watch for STFT to take a dip. The closer you get to the leak, the faster you'll see it dip.

 

Sorry
Bank 1 stft -3 ltft -0.8
Bank 2 stft -23 to +10, ltft 20.3

Should I use propane, or carb cleaner? I was concerned about carb cleaner eating any paint in the areas.

 

I used carb cleaner to clean gunk from the top of the engine and TB area when I took out my SC with no problem.
You could use engine starting fluid which evaporates faster or just go with propane from one of those hand held units many people use for say loosening rusted bolts and the like which you would be able to aim easily.

 

Thanks John,
I'll fire up the propane weds morning. I'll have to put my son (21) in the seat to watch my carsoft readings, as it won't reach to the engine bay. I'll set it on graph first, so even he will see a change. I'll use both fluid and propane. The propane will get me in the right area, and the fluid should pinpoint a leak.
I'll update after.
Thanks for all the help from everyone.
Mark

 

Good luck Mark.

Will be interesting to see if you have any results and if you can pinpoint the leak.

 

Ran propane everywhere. No change to anything. Pulled the dipstick out to cause vac leak, it did but went back when reinstalling it.
Still the same readings.
Bank 1 perfect
Bank 2 radical readings. Really seen on graph. Top to bottom (min to max) with no short readings (consistently up and down.)
I know what you all are going to say after this next statement...
Could I have a O2 sensor acting up even with no O2 codes popping up?
I know that O2 sensors only read data and adjust fuel pulses. But I would think that a vac leak would constantly be one number, high or low, constant, not up/down/up/down wave form. I know that poor mechanics just throw O2 sensors at any emission fault and hope for the best.
A freind said if it is a sensor, most likely is downstream.
Will check O2 readings this afternoon, and compare bank 1&2, and upstream/downstream. and report back.
Goes to dealer thurs morning. Service manager said probably dirty throttle body. I would think that a dirty TB would affect both banks. Will jaguar specific codes be more detailed?

PS when I ran it up to 2500 rpm the numbers were up and down, but tighter. Not much tighter.

 

Hey Mark. Your friend is wrong on the O2 sensor. If it's causing the problem, it will be the forward sensor. You can swap them L to R or test the one with a multimeter. Swapping takes about ten minutes and is free (except for your time). But theoretically if the sensor was bad you should also see a lean code/ bad O2
P0151 - HO2 Sensor sense circuit low current – bank 2, upstream (2/1)
(Universal oxygen sensor: lean condition at ECM – high current at sensor)
P0152 - HO2 Sensor sense circuit high current – bank 2, upstream (2/1)
(Universal oxygen sensor: rich condition at ECM – low current at sensor)
P0153 - HO2 Sensor sense circuit slow response – bank 2,
upstream (2/1)
Those are the only Bank 2 HO2 codes and those are typically thrown after 2 cycles, same as P0174. The reason I went there is based on your original post, it's unique to Bank 2 as would be fuel injectors, misfires (plugs or coil packs), exhaust leak before the CAT. (and you checked for intake leaks)


Before going to the shop, I agree that a dirty throttle body would likely mess with both banks.

It's easy enough to check and clean the PCV and EGR valves.
Confirm no exhaust leaks before the CAT.

there are no Jag specific P0174 codes other than the one you're getting:

DTC - P0174

SYS - EMS OBD II

FAULT DESCRIPTION - Bank 2 combustion too lean

MONITORING CONDITIONS - Start engine and bring to normal operating temperature >82 ̊C (180 ̊F)
Idle for 10 minutes

CK ENG 2 - 2 TRIPS – indicates that the CHECK ENGINE MIL is activated by a fault occurring during TWO CONSECUTIVE “TRIPS”2

DEFAULT ACTION - ECM Default:
– Bank 2 catalyst warm-up ignition retard inhibited
– Bank 2 closed loop fuel metering inhibited
– Canister purge inhibited
– Maximum engine speed reduced

POSSIBLE CAUSES -
Engine misfire
Air intake leak between MAF Sensor and cylinder head
Fuel filter / system restriction
Fuel injector restriction
IP Sensor fault (low fuel pressure)
Low fuel pump output
HO2 Sensor(s) (2/1, 2/2) harness wiring condition fault
EFT Sensor fault (low fuel temperature) MAF Sensor fault (low intake air flow) Exhaust leak (before catalyst)
ECM receiving incorrect signal from one or more of the following components:
ECT Sensor, MAF Sensor, IAT Sensor, IP Sensor, EFT Sensor, TP Sensor
Clogged EGR
Leaking PCV
Leaking Brake booster

 

If that's 20.3 at 2500rpm you've something other than an air leak there. (See post #2)