4.0 resurrection from the dead.

[Juice]

Just to be clear. STFTs look ok because LTFTs have matured.
If you were to clear KAM and log, STFTs will show the bank-to-bank difference while LTFTs would be zero correction for a while.

 

[Cancerman]

So my next issue is the front end alignment. I believe the previous owner put front lowering springs on it. The camber is noticeably off. I feel the car "Hunt" a bit, but the steering is tight. Toe in can be done locally, but everyone I talk to doesn't want to mess with the camber adjustment. There is a set of cam bolts that have to be added to the strut to adjust the camber for lowered suspensions. I've ordered the kits and will install them myself. Then head for the alignment shop. I don't want to wreck my new tires.

I installed the cam bolts to give me 1.75 degrees more camber on each wheel. It the rack with the Harris computer on it, the camber was perfect! So if you drop your front end1.5 inches, this si the way to solve your alignment issues. Also, the toe in was off quite a bit, so now it's all in factory spec. Caster was unaffected. It's much more stable, the steering is a bit heavier, but it feels the way it should. $88 with tax.

 

[Cancerman]

Looking for some opinions. I change out ALL the O2 sensors. All the sensors just F up the PCM, threw a bunch of codes, etc. After resetting PCM, doing all the things known, I removed the upstream O2's, put in the OEM sensors. Better but the downstream still threw codes, so out they came and back in went the OEM's. No more codes. I'm getting a refund on the ebay sensors, there is no way they are compatible. So the cars is running ok, but I still have the stumble.

One thing I have found is, the stumble/lean spot is below 2500 rpm, at 1/4 throttle position or less. If I add throttle it goes away. I have found if I set cruise control at these rpm/speed, problem goes away and runs smooth. Go back to throttle, it's there. All the Forscan testing does not show any APS accelerator position sensor codes or anything I can see. I'm considering replacing the sensor pedal assy to eliminate that as a potential issue. TPS say's its ok. I still think it could be a tune issue, but the cruise control testing has me wondering. THE PCM is running the fuel system when on CC, and the pedal is out of the loop. Ideas?

 

[Dino Dino Bambino]

If you're still considering replacing the O2 sensors, I recommend you go for nothing other than NTK. These are the best for our cars.
You might want to check in your datalogs whether the lean stumble occurs at the same rpm in any gear or at the same TPS % i.e. throttle position each time.
Use a DVM to find out if the TPS voltage ramps up smoothly as you open the throttle manually from fully closed to WOT (key on, engine off).

 

[Cancerman]

I'm not throwing any codes with the old OEM sensors back in it. I'm waiting on my refund on these Ebay sensors, I'll have to look and see if I know the brand of them. My testing shows that the lean surging, if that's what it actually is, only happens at partial throttle opening using the pedal, in any gear, in the lower rpm, below 2000 or so. Using cruise control in any gear, in this rpm range, it's smooth as silk and runs fine. I think the TPS is used for RPM control in both CC and pedal operation. I'll work on checking the voltage as you offered. It only seems to happen using the damn gas pedal. Also, when using the pedal the Forscan real time has the upstream mixture jumping between rich and lean, but I think that just says it's adjusting real time. Just my thoughts. Again, the cars seems to run well if I don't drive it on the very low part of the pedal, which I do driving in stop and go traffic, and pulling away from stop lights, or trying to get good gas mileage. It was doing this pulling into traffic one day, and revved it up to clear the stumble, while I was letting the clutch out. The clutch hooked up,, I was making a left turn, it lit the tires and I was sideways going into traffic! I thought "Oops", I was lucky no coppers were around. This is my only real issue with the car since I have it back on the road. I drive it, but I know this little issue is there. The damn gas pedal switch / assembly is over $100, I hate to try a used one, and waste money on another worn out switch. The TPS is another thing, some only want to sell you the body with the switch in it. I think I've seen bare switches online. I'll replace what's bad, I just hate to throw good money after bad at sensors. We'll see if the seller of my Ebay sensor really refunds me. Probably Chinese junk.

 

[Juice]

If you do have some sort of an issue brewing, it will throw codes.
Can your scanner read PENDING codes? Those do not throw the light or show in most scanners. To date, only Dashcommand can read pending codes. Not the X4, Torque, or Forscan. Most only read the current codes.
These cars have three tiers of codes:
Pending - no light till the code matures.
Current - check engine light on.
Permanent codes- these are stored hard codes, think of it like history of faults. No check engine light, cannot be reset. Once the issue is fixed, the pcm will clear these.

I would suggest to keep driving and see if the CEL comes on.
I "think" there is a throttle body relearn proceedure for these, but not 100% sure.

 

[Cancerman]

Driven the last 2 days, no codes so far. No CEL. I'll be doing the voltage checks on the TPS later today just to cross that one off the list.

 

[Cancerman]

TPS values are all very smooth, linear. The APS's first position of the sensor shows a value of 1.5, when you touch the pedal, it goes to zero, then a low negative number before jumping around then as you transition to the next position of the sensor which has a linear positive climb through the next position until the wide open position. I think the pedal sensor has a pad or worn part of the first position part of it. I think I'll order a accelerator position sensor.

 

[Cancerman]

Success, the Accelerator Pedal Sensor was the root of my problems. Idles smoother, no surging, not herk and jerk away from idle, it even feels stronger through the midrange. Very happy now.

 

[Cancerman]

Still running occasionally rich, throwing a Bank 1 upstream o2 stuck rich every so often. I'm going to find a Motorcraft OEM or a NTK sensor for troubleshooting next. Car is still running pretty good. Occasionally throwing a EVAP tank vacuum code. Driving well. Just want the bugs gone.