High LTFT on bank 2, car is bogging , no codes

[sdleo29]

I am running lean on one side of the motor causing car to bog down when into the throttle. I have cleaned the MAF and the O2 sensor seems to be fine on the scan tool graph. No codes are being thrown ... Fuel trim is +14 on bank 2

I am going to run smoke through EVAP intake hose and see if I have any vacuum leaks. The fuel trim does come down when I snap throttle which is sign of vacuum leak, yes?

If I wind up having no vacuum leak, what could it be?

Injectors on that side are dirty? If it was a weak fuel pump or bad MAF, I would see it on both banks, yes? The fuel pressure at rail is fine and I have pressure when in the throttle..

Thoughts ?

 

[Dino Dino Bambino]

What voltage readings are you getting from the bank 2 02 sensor 1?

 

[07gts197]

What brand and age is the sensor on that side?


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[Juice]

Swap upstream O2 sensors, sounds like bank2 sensor is on its way out.

 

[sdleo29]

I will re- check 02 sensor and report back, but I thought I saw good vintage swings 0.1 - 0.9 ... I will report back what I find

 

[sdleo29]

Well I put a brand new Bosch sensor in , same result fuel trim stuck up high @14, car still bogs down when getting into throttle.. sensor reads lean at 0.065, bank 1 is .75...

I just got smoke machine and need to see if I have a vacuum leak ... if there is no vacuum leak , is it injector related ??

 

[Juice]

Assuming you reset KAM after sensor change?

I would not jump to conclusions and say "bad injector". The only sure thing is the issue is on bank 2. I would pull plugs and look for one that is not like the others, that would be the cylinder with issues. Im just wondering why you dont have any codes like cyli der misfire or system lean bank 2,

 

[07gts197]

Also its well known that Bosch o2 sensors fail prematurely with these cars. If its not too late, though it probably is, return it and get either an NTK or Motorcraft unit. Itll save you from replacing it again in 6 months.


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[GlassTop09]

I am running lean on one side of the motor causing car to bog down when into the throttle. I have cleaned the MAF and the O2 sensor seems to be fine on the scan tool graph. No codes are being thrown ... Fuel trim is +14 on bank 2

I am going to run smoke through EVAP intake hose and see if I have any vacuum leaks. The fuel trim does come down when I snap throttle which is sign of vacuum leak, yes?

If I wind up having no vacuum leak, what could it be?

Injectors on that side are dirty? If it was a weak fuel pump or bad MAF, I would see it on both banks, yes? The fuel pressure at rail is fine and I have pressure when in the throttle..

Thoughts ?

I'll assume that you've checked the B2 exhaust system ahead of the O2 sensors for leaks as well? What was the B1 LTFT reading? If B1 LTFT reading is anywhere around normal (+2% to -2%) w\ the B2 LTFT reading at +14% then this should rule out any vacuum leaks into the intake manifold proper as the manifold is an open plenum design (all intake runner tracts share the same plenum area so if vacuum leaking into IM plenum area B1 LTFT should also be fairly high +% as well) & would point the issue to B2 side only which isolates the leaning issue to either of the following that I can identify off the top of my head....a very small vacuum leak on at least 1 of the intake runner to cylinder head gaskets that won't show up in the plenum area in sufficient quantity to affect B1 due to the volume of outside air entry being small, an injector(s) O-ring is leaking where injector mounts into intake manifold, small vacuum leak thru the CMCV shaft seal at rear B2 (#8 cylinder) intake runner if these are still being used, exhaust leak ahead of the B2 O2 sensors, wayward fuel injector(s) or fuel injector wiring (signaling issue) issue not injecting any\enough fuel to reach AFR or cylinder(s) misfire (#5, #6, #7, #8). Not much else that would isolate to B2 side only...………….

For the ECU to flag a misfiring cylinder(s) the misfire count threshold number for MIL activation is 63,000 misfires but since you have a scan tool you can check each cylinder for any record of misfires as there should be a count of any recognized cylinder misfires for each cylinder recorded thus an indication of the cylinder's COP, COP wiring & spark plug to check. If no data is found then you should check all COP's & plugs on at least B2 but if you're going that far then you should check them all & repair\replace as necessary & ALWAYS apply some fresh dielectric grease to the COP boot where plug inserts to help eliminate misfiring when these are disturbed IMHO.

Hope this helps.

Also its well known that Bosch o2 sensors fail prematurely with these cars. If its not too late, though it probably is, return it and get either an NTK or Motorcraft unit. Itll save you from replacing it again in 6 months.


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Well as for buying any Ford Motorcraft O2 sensors for these 3V's from the Ford dealership, they're using Bosch now to supply them under the Ford Motorcraft name, not NTK anymore (been there, done that already) & they'll charge you more for them than if you got the exact same Bosch O2 sensor from AZ or O'Reilly's. FYI...…………..….

 

[Dino Dino Bambino]

I will re- check 02 sensor and report back, but I thought I saw good vintage swings 0.1 - 0.9 ... I will report back what I find

If that's true, your problem lies elsewhere and it isn't the O2 sensor that's at fault.

 

[Juice]

Since you don't get a check engine light AND you have a performace/bogging issue. I ask: do you have catalytic converters on the car? That one side starting to clog up would explain the symptom of power loss without DTCs (yet)

 

[Dino Dino Bambino]

In such a case the bank 2 sensor 2 O2 voltage readings would be abnormal.

 

[sdleo29]

Since you don't get a check engine light AND you have a performace/bogging issue. I ask: do you have catalytic converters on the car? That one side starting to clog up would explain the symptom of power loss without DTCs (yet)

No CATS on car

 

[sdleo29]

Assuming you reset KAM after sensor change?

I would not jump to conclusions and say "bad injector". The only sure thing is the issue is on bank 2. I would pull plugs and look for one that is not like the others, that would be the cylinder with issues. Im just wondering why you dont have any codes like cyli der misfire or system lean bank 2,

I didn’t rest KAM, I thought of the same thing , let me do that and see what happens

 

[GlassTop09]

Assuming you reset KAM after sensor change?

I would not jump to conclusions and say "bad injector". The only sure thing is the issue is on bank 2. I would pull plugs and look for one that is not like the others, that would be the cylinder with issues. Im just wondering why you dont have any codes like cyli der misfire or system lean bank 2,

As for why the lack of a MIL for system lean code this ECU is programmed for the NB STFT\LTFT limit threshold of +25% rich command (indicates a lean condition) thru -25% lean command (indicates a rich condition) (adding both LTFT + STFT readouts) from ideal of 0% so if the B2 LTFT +14% w\ the B2 STFT at switching voltages (-2.3% thru +2.3% indicates bank has reached AFR--0%--for the conditions given) = +16.3% max (14 + 2.3) which is well within the accepted range of +25% error from 0% so no MIL but the large LTFT readout difference between B1 vs B2 does indicate an issue involving fueling (or any other condition that will affect fueling) on B2 vs B1 as the difference should be very close to or the same readout to each other and close to 0% ideal....usual industry acceptable good STFT/LTFT range here is within + or - 10% from 0% on both banks.
This creates a shotgun type effect if the ECU can't determine a misfire on a particular B2 cylinder then the fueling will be richened up on all 4 B2 cylinders which can cause the engine to stumble especially at low speeds depending upon the amount of additional fuel being called (LTFT readout) for to reestablish AFR (STFT switching across 0%).

Pulling the plugs (as well as checking the COP's & their boots as well as COP wiring) as mentioned here is 1 way to try to isolate the issue to individual cylinder(s) then work backwards from there but there are other measures to use as well to diagnose the issue.

To do a KAM reset you can use a hand held tuner (like a SCT X series for example) to do this but I prefer to use the FoMoCo method (pull - batt cable from batt then attach a lead between the + & - batt cables keeping the - batt cable off the - batt post) as this method works 100% of the time & achieves full cleanout of old data but be advised that when you do this using either method you should perform a full drive cycle procedure starting w\ engine hot idle relearn afterwards to prevent idle hunt so that the ECU can relearn all learned parameters-including emissions components test results-outside of the tune table data. You don't have to do this but be advised that it'll take much longer for the ECU to relearn & could create some quirkiness along the way until all is sorted out, especially w\ an automatic trans....just saying.

FYI for anyone that didn't know this already.

 

[sdleo29]

I thought I would let everyone know who replied that it turned out to be a plug on the #8 cylinder.. everything checked on cops and injectors. The all ohmed our the same etc. I learned through many YouTube videos, scannerdanner in particular, that a slight misfire can absolutely cause a lean condition not rich as I had thought... the raw fuel in not combusting so therefore the o2 sees more air etc etc...

Regards and thanks for replying along the way

 

[GlassTop09]

I thought I would let everyone know who replied that it turned out to be a plug on the #8 cylinder.. everything checked on cops and injectors. The all ohmed our the same etc. I learned through many YouTube videos, scannerdanner in particular, that a slight misfire can absolutely cause a lean condition not rich as I had thought... the raw fuel in not combusting so therefore the o2 sees more air etc etc...

Regards and thanks for replying along the way

Good deal!

Just curious, what in particular was the issue w\ the #8 spark plug? Was the porcelain tracked\cracked or plug electrode(s) burned/carbon coated or plug gaps so wide from spark erosion?
Something is happening/going on that is specific to #8 cylinder in your engine......thus my curiosity.

 

[RLF9409]

I love reading through these issues and getting a resolutuon!

2006 Saleen SC #409 MMR 1000S stroked 4.6 3.0 pulley 1 piece driveshaft